GSSA-Publications-2005

Abstract: CONTENTS Foreword Acknowledgements Contributors Glossary of technical terms and abbreviations used in the text Chapter 1 - INTRODUCTION Purpose of the book Structure of the book Complementary information resources References Chapter 2 - THE CHANGING FACE OF PASTORAL SYSTEMS IN GRASS DOMINATED ECOSYSTEMS OF EASTERN AFRICA R.S. Reid, S. Serneels, M. Nyabenge and J. Hanson Scope Mapping rangelands, livestock and pastoral peoples Plant communities in grasslands and rangelands Political and social systems in pastoral lands of eastern Africa Integration of grasslands into smallholder farming systems Case studies of the evolution of extensive range systems over the last 40 years General Evolution of land use changes in the semi-arid rangelands surrounding the Serengeti-Mara Ecosystem, straddling the Kenyan- Tanzanian border Protected areas and local land use: source of conflict in Tanzania Control of the tsetse fly and evolution of a subhumid-grassland in southwestern Ethiopia: Ghibe Valley Current research in pastoral systems of eastern Africa Management of grasslands Desertification: driven by climate or overgrazing by livestock? How have pastoral ecosystems changed in response to livestock and human-use changes? Overgrazing Competition between livestock and wildlife Changes in rangeland burning regimes Rangeland fragmentation and loss of wildlife habitat Impacts of expansion of cultivation and settlement Carbon sequestration Bush encroachment Rehabilitation of grasslands Priorities for research and development programmes in pastoral lands Some history Rapidly changing systems with changing needs Focus generally on human welfare and maintaining environmental goods and services More emphasis on providing pastoral people with high quality information Restoring pastoral access to key resources, increasing mobility and flexibility, and ensuring security Addressing gaps in our knowledge about how pastoral systems work in eastern Africa Addressing gaps in our knowledge about how these systems can be improved References Chapter 3 - GRASSLANDS OF SOUTH AFRICA Anthony R. Palmer and Andrew M. Ainslie Introduction Physical features Climate Rainfall Seasonality of rainfall Temperatures Soils People Livestock Wildlife Land tenure Freehold and commercial sector Communal and subsistence sector Authorities responsible for management Market systems Landforms and agro-ecological zones Biomes Grassland Savannah Nama-karoo Thicket Succulent karoo Fynbos Forest Pastoral and agricultural systems Veldt grazing Legume and fodder introduction Dryland fodder Irrigated fodder Exceptional circumstances fodder Constraints to pasture and fodder production and improvement Evolution of grasslands over the last 40 years Research Management of grasslands Development of techniques for the rehabilitation of grasslands Sustainable management of the environment and maintenance of biodiversity Seed production Recommendations and lessons learned concerning sustainable grassland management Maintenance of production and productivity Priorities for the development of programmes and research References Chapter 4 - GRASSLANDS OF PATAGONIA Andrés F. Cibils and Pablo R. Borrelli Introduction Political system Land tenure Aboriginal distribution Welsh colonization First settlers Last settlers Management authorities Market systems Wool market systems Meat marketing Dominant natural vegetation Patagonian shrub steppes Semi-deserts and shrub steppes Shrub-grass and grass-shrub steppes Grass steppes Monte shrubland s and Monte ecotone Pastoral and agricultural systems Sheep farming systems Grazing management Sheep management Fine-wool production systems Lamb and fine-crossbred-wool production systems Ongoing research, management, restoration and biodiversity maintenance activities Research activities Management activities Restoration activities Biodiversity maintenance Seed production Recommendations and lessons learned Adaptive management - the Santa Cruz example The value of simple or flexible stocking strategies Conflict between short- and long-term production References Chapter 5 - THE SOUTH AMERICAN CAMPOS ECOSYSTEM Olegario Royo Pallarés (Argentina), Elbio J. Berretta (Uruguay) and Gerzy E. Maraschin (Brazil) Introduction General description of the region Climate Livestock production Wildlife Floristic composition Climax vegetation Grassland types and production systems in Argentina Growth and forage production Production systems Productivity of the best farms Grassland types and production systems in Uruguay Vegetation limitations for animal production Production systems Grassland production systems in Southern Brazil Dry matter accumulation in natural grasslands Optimizing animal production from natural grassland ecosystems Natural grassland dynamics Fertilizing Campos grassland Fertilization in Argentina Fertilization of Campos Grasslands in Uruguay Fertilization of natural grasslands in southeast Brazil Structural changes on fertilized natural grasslands in SE Brazil Improvement techniques Over-seeding Legume introduction Sward preparation for seeding Legumes for improvement Stock management Research and development priorities Ecological grassland management for maintaining productivity References Chapter 6 - GRASSLANDS OF CENTRAL NORTH AMERICA Rex D. Pieper Introduction Location and general description of the region Climate Topography and soils Fauna Vegetation patterns Primary production Pastoral and agricultural systems Crop production Grazing management Balancing seasonal variations of forage supply Grazing systems Intensification? Rangeland burning Development of grasslands Current status of grassland research and management Future of the Great Plains References Chapter 7 - GRAZING MANAGEMENT IN MONGOLIA J.M. Suttie Introduction Changes in administrative systems in the twentieth century Grazing lands, pasture and fodder Hay from natural pasture in arkhangai Grazing livestock production Livestock in herding systems Evolution of stock numbers Intensive livestock production The present grazing situation The recent droughts and zuds Sustainability References Chapter 8 - THE TIBETAN STEPPE Daniel J. Miller Introduction General description Climate Grassland biodiversity Dominant natural vegetation Vegetational attributes Botanical composition Grassland productivity Nutrient content of herbage Grassland degradation The Tibetan Pastoral Production System Historical and cultural aspects Livestock management Herds on the move Land tenure Transformation of the traditional pastoral production system Snowstorms and pastoral system dynamics Dilemma on the Tibetan Steppe Mobility Conclusion References Chapter 9 - AUSTRALIAN GRASSLANDS John G. McIvor Introduction Location Physical features Climate Rainfall Temperature and evaporation Growing seasons Soils Livestock Wildlife Social aspects and institutions People Political system Land tenure and ownership Authorities responsible for land management Market systems Pastoral and agricultural systems Natural vegetation Tropical tall -grass Brigalow Xerophytic mid-grass Temperate tall -grass Temperate short -grass Sub-alpine sodgrass Saltbush-xerophytic mid -grass Acacia shrub-short -grass Xerophytic tussockgrass Xerophytic hummockgrass Sown pastures Temperate pastures Tropical pastures Available species and cultivars Seed production Current grassland issues Research Management of grasslands Resource issues and rehabilitation Biodiversity in grasslands Environmental management Sustainable pasture management: learning from the past, managing for the future Importance of legumes Role of native pastures Environmental weeds Future References Chapter 10 - THE RUSSIAN STEPPE Joseph G. Boonman and Sergey S. Mikhalev Introduction The steppe in perspective Semantics Climate, vegetation and soils Ecological classification Ecological (site) potential Ramenskii’s grassland classification Botanical condition (ecological monitoring) Steppe dynamics in relation to botanical composition Weather From fallow to steppe The Steppe and its types Forest steppe Steppe Virgin steppe Semi-desert Meadow types Liman Floodplain meadows Fallow Mid-term to old fallow Young fallow Avenues of steppe improvement Management interventions Grazing Grazing (stocking) management Haymaking Fire Ploughing Physical improvements Examples of the effect of management on botanical composition Fertilizer Mid-term depression Sown forage The dilemma Crop-pasture rotations Physical effects of grasses on the soil Mixed farming based on crop-grass rotations Conclusions References Chapter 11 - OTHER GRASSLANDS Introduction Africa North Africa West Africa Madagascar South America The Llanos The Gran Chaco Pampas Flooding Pampas grasslands Cropland Pampas cultivated pastures Monte shrubland Asia Central Asia China South Asia Himalaya-Hindu Kush India Pakistan The near east Syrian Arab Republic Jordan Europe Turkey Bibliography Chapter 12 - GRASSLAND PERSPECTIVES Introduction Grassland systems The state of the grasslands Grassland development, improvement and rehabilitation Grassland resources Pasture development methods Herd management Stocking rates and stock distribution The lean season Stratification Sown pasture and fodder Sown fodder Social and economic factors Tenure Markets and trade Herder organization and community participation Demotic factors Diversification Grassland in the environment Some conclusions References

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Abstract: The impact of rangeland degradation on soil characteristics (compaction, temperature, soil-water content, infiltrability, root and litter turnover, and the organic matter content), was determined for a semi-arid rangeland. Sampling was from rangeland artificially maintained in three different rangeland conditions, viz. good, moderate and poor. Due to the lower basal cover of rangeland in poor condition, soil compaction increased (p[less-than-or-equals, slant]0.01) and temperature, water-content, infiltrability and organic matter content decreased (p[less-than-or-equals, slant]0.01) with rangeland degradation. The mean soil compaction of rangeland in good, moderate and poor conditions was 6.37, 11.51 and 18.34 kg cm-2, respectively. The highest temperatures on top of the soil of 55, 49 and 46 °C for rangeland in poor, moderate and good conditions respectively, occurred during December. Where rainfall is the biggest determining factor for production in rangeland in poor condition, under higher soil-water conditions, nitrogen is for rangeland in good condition. After only 5 years following degradation, organic C was significantly lower (22.15%) over the first 50 mm soil layer and total N significantly lower (12.91%) over the first 100 mm in rangeland in poor condition than that of good condition rangeland. Rangeland degradation lengthened the replacement of total root system with about a year and decomposition time of litter with 8 months. The importance of maintaining rangeland in good condition and soil quality to help ensure sustainable utilization of the grassland ecosystem was stressed.

Abstract: Summary Agriculture has claimed a large share of terrestrial environments in the tropics and subtropics through cultivation of native grasslands or forests. The impact of this anthropogenic change on speciation, dynamics, and ecological significance of sulphur (S) compounds is still poorly understood. We combined degradative wet-chemical reduction and S K-edge X-ray absorption near edge structure (XANES) spectroscopy techniques to evaluate the impact of long-term agricultural management of native grassland soils in South African Highveld on the amount, form and dynamics of S species. Sulphur XANES in the humic substances extracted by 0.1 m NaOH/0.4 m NaF solution showed the presence of strongly reduced (polysulphides, disulphides, thiols, monosulphides and thiophenes), intermediate (sulphoxides and sulphonates) and strongly oxidized (ester sulphates) organic-S. It showed that strongly oxidized-S is the predominant form (39–54%) of the total organic-S in the humic substances, and organic-S in the intermediate oxidation state represented 30–37% (78–93% of which was attributed to sulphonates). The strongly reduced organic-S comprised only 17–24% of the total organic-S. We did not find a close correlation between the results of a degradative wet-chemical procedure and XANES spectroscopy conducted in both the bulk soils (ester SO4-S from XANES versus HI-fractionation, r = 0.27; P < 0.05) and the humic substance extracts (ester SO4-S from XANES versus HI-fractionation, r= 0.39; P < 0.05). The ratio of reduced-S to strongly oxidized-S (R-S/O-S) in the humic substances decreased from 0.61 to 0.21, while the ratio of intermediate-S to strongly oxidized-S (I-S/O-S) declined from 0.93 to 0.61 after 90 years of arable cropping of the native grassland soils. Hence, there was a shift in oxidation state towards strongly oxidized-S (+6) and, thereby, a change in the relative proportion of the organic-S moieties associated with each oxidation state following cultivation of the native grassland soils. Therefore, we conclude that changes in land-use practice brought about not only quantitative change but also altered the composition of organic-S functional groups in these native subtropical grassland soils.

Abstract: The seasonal trend in root mass, root distribution with depth and root/shoot ratios along a degradation gradient were quantified over a 2 year period (2000/01 and 2001/02 growing seasons) for a semi-arid rangeland. Water-use efficiency (WUE) for each rangeland condition is defined as the quantity of above-ground phytomass produced per unit of water evaptranspired. Sampling was from rangeland artificially maintained in 3 different rangeland conditions viz. good, moderate and poor. Roots were extracted to a depth of 900 with 50 mm intervals, using a corer and then separated front the soil by wet sieving. Sampling of both above- and belowground phytomass production including litter. were at approximately bimonthly intervals to account for major seasonal changes. Most of the grassroots were found in the first 150 mm soil layer, but root distribution tended to be more superficial with rangeland degradation. Root mass in semi-arid rangelands are strongly seasonal with the most active Growth taking place during March and April. when the aboveeround is dormant. Both the above- and belowground phytomass productions decreased by rangeland degradation (p less than or equal to 0.01). The growing seasonal (October-March) average root mass to a depth or 900 mm was 3185, 2336 and 1162 kg ha(-1) respectively, for rangeland in good. moderate and poor condition, compared to the average above-ground phytomass production over the same period of 2341, 1648 and 695 kg ha(-1). It seems that root mass is greater than above-ground biomass for this semi-arid rangeland, with root production also more sensitive to rangeland degradation than above-ground production. The root/shoot ratios for rangeland in good, moderate and poor conditions ranged between 1.57-3.20, 1.65-3.46 and 2.06-7.14, respectively. Water-use efficiency declined (p less than or equal to 0.01) with rangeland degradation. Rangeland in good condition averaged a WUE of 2.97 kg above-ground phytomass produced ha(-1) mm(-1) evapotranspiration. The average litter productions were 99.55, 61.51 and 24.00 kg ha(-1), respectively, for rangeland in good, moderate and poor condition. As a proportion of annual phytomass production, litterfall of 5.35% for rangeland in good condition was obtained. This study is one of few root studies available where different rangeland conditions were evaluated and can serve as guidelines for sustainable utilization of the rangeland ecosystem in semi-arid climate. (C) 2004 Elsevier Ltd. All rights reserved.

Abstract: Changes in litter production following back and head fires, some soil characteristics and root and litter turnover were quantified over two growing seasons for a semi-arid grassland. Sampling of litter production took place at approximately bi-monthly intervals to account for major seasonal changes over the 2000/01 and 2001/02 seasons. Soil compaction was determined by a simple rod penetrometer, soil temperature by mercury thermometers and soil-water content by a neutron hydroprobe. Litterfall of 5.88% and 1.13% (as a proportion of annual aboveground phytomass production) for unburnt and burnt grassland, respectively, was obtained. Two seasons following the fire, litter was still 47% lower due to fire. The litter production was not significantly different between the head and back fires. The fire, while causing a lower plant cover over the two years following burning, also significantly increased soil compaction and soil temperature. The biggest difference in soil temperature between burnt and unburnt grassland to a depth of 50mm was 7degreesC. After only two months the soil-water content over the first 900mm depth decreased by 23% due to burning. Fire lengthened the period for replacement of the total root system by about a year and decomposition of litter by three months. Small changes caused by fire to the fragile ecosystems of semi-arid climates may have longlasting consequences. The overall effects of fire on belowground systems and the resulting processes that feed back to aboveground systems are complex.

Abstract: The seasonal trend in root mass, root distribution with depth and root/shoot ratios along a degradation gradient were quantified over a 2 year period (2000/01 and 2001/02 growing seasons) for a semi-arid rangeland. Water-use efficiency (WUE) for each rangeland condition is defined as the quantity of above-ground phytomass produced per unit of water evap-transpired. Sampling was from rangeland artificially maintained in 3 different rangeland conditions viz. good, moderate and poor. Roots were extracted to a depth of 900 with 50 mm intervals, using a corer and then separated from the soil by wet sieving. Sampling of both above- and belowground phytomass production including litter, were at approximately bi-monthly intervals to account for major seasonal changes. Most of the grassroots were found in the first 150 mm soil layer, but root distribution tended to be more superficial with rangeland degradation. Root mass in semi-arid rangelands are strongly seasonal with the most active growth taking place during March and April, when the aboveground is dormant. Both the above- and belowground phytomass productions decreased by rangeland degradation (p[less-than-or-equals, slant]0.01). The growing seasonal (October-March) average root mass to a depth of 900 mm was 3185, 2336 and 1162 kg ha-1, respectively, for rangeland in good, moderate and poor condition, compared to the average above-ground phytomass production over the same period of 2341, 1648 and 695 kg ha-1. It seems that root mass is greater than above-ground biomass for this semi-arid rangeland, with root production also more sensitive to rangeland degradation than above-ground production. The root/shoot ratios for rangeland in good, moderate and poor conditions ranged between 1.57-3.20, 1.65-3.46 and 2.06-7.14, respectively. Water-use efficiency declined (p[less-than-or-equals, slant]0.01) with rangeland degradation. Rangeland in good condition averaged a WUE of 2.97 kg above-ground phytomass produced ha-1 mm-1 evapo-transpiration. The average litter productions were 99.55, 61.51 and 24.00 kg ha-1, respectively, for rangeland in good, moderate and poor condition. As a proportion of annual phytomass production, litterfall of 5.35% for rangeland in good condition was obtained. This study is one of few root studies available where different rangeland conditions were evaluated and can serve as guidelines for sustainable utilization of the rangeland ecosystem in semi-arid climate.

Abstract: During the dormant winter period the semi-arid grassland areas of South Africa are characterised by planned and unplanned fires, either by lightning or negligence by man. The influence of burning (head and back fire) on the germinability of grass species in the soil seed bank was quantified in the greenhouse over the 2000/01 to 2001/02 growing seasons for a semi-arid grassland. The behaviour of the head and back fires was also monitored. Soil seed bank samples were collected immediately after burning and then every third month over a two-year period from 0.25m(2) blocks 50mm deep. The same was done on unburnt grassland. At ground level, the back fire exceeded 100 degrees C, while the head fire had temperatures of less than 100 degrees C. The fire caused a flush of seedlings from the seed bank over the first season after the fire. The head fire stimulated seedling density significantly (P <= 0.01) more than the back fire. The mean (head and back fire) seed bank density the first season following the fire, for burnt and unburnt grassland, was respectively 84.6 and 52.1 grass seedlings m(-2) for September, 50.5 and 21.9 grass seedlings m(-2) for December and 347 and 58 grass seedlings m(-2) for March. The pioneer species Aristida congesta and Tragus koelerioides only occurred in the soil seed bank of the burnt grassland, while the climax species Cymbopogon plurinodes, Digitaria eriantha and Panicum stapfianum only germinated in the unburnt grassland seed bank. The Eragrostis species showed the highest germination due to fire. The burning of semi-arid grassland did have a quantified impact on the soil seed bank over the short-term.

Abstract: The impact of fire (head and back fires) on the seasonal change in above- and belowground production in grass species, was quantified over two growing seasons (2000/01 and 2001/02) for semi-arid grassland. The behaviour of the head and back fires was also identified. Roots were extracted to a depth of 900mm with 50mm intervals, using a core and then separated from the soil by wet sieving and flotation. Sampling of both above- and below-ground phytomass, took place at approximately bi-monthly intervals to account for major seasonal changes. The intensity of the back fire was higher than the head fire at ground level. Most of the grass roots were found in the first 150mm soil layer. While fire increased grass root distribution over the first 100mm depth, it was decreased deeper in the soil. Root mass in semi-arid grassland is strongly seasonal, with the most active growth during the months of March and April when aboveground parts are dormant. Both above- and belowground phytomass production decreased significantly over the first year following burning. The above- and belowground phytomass (900mm depth) was respectively 806kg ha(-1) and 2 002kg ha(-1) less due to burning, over the first year after burning. The seasonal root/shoot ratios for the unburnt and burnt grassland ranged between 1.62 to 2.80 and 1.20 to 3.12 respectively. It seems that root mass exceeds aboveground biomass for this semi-arid grassland. Over the short-term, fire decreased productivity and could subsequently influence the sustainable fodder production of a semi-arid grassland ecosystem

Abstract: Stable carbon isotope analyses have shown that South African australopiths did not have exclusively frugivorous diets, but also consumed significant quantities of C4 foods such as grasses, sedges, or animals that ate these foods. Yet, these studies have had significant limitations. For example, hominin sample sizes were relatively small, leading some to question the veracity of the claim for australopith C4 consumption. In addition, it has been difficult to determine which C4 resources were actually utilized, which is at least partially due to a lack of stable isotope data on some purported australopith foods. Here we begin to address these lacunae by presenting carbon isotope data for 14 new hominin specimens, as well as for two potential C4 foods (termites and sedges). The new data confirm that non-C3 foods were heavily utilized by australopiths, making up about 40% and 35% of Australopithecus and Paranthropus diets respectively. Most termites in the savanna-woodland biome of the Kruger National Park, South Africa, have intermediate carbon isotope compositions indicating mixed C3/C4 diets. Only 28% of the sedges in Kruger were C4, and few if any had well-developed rhizomes and tubers that make some sedges attractive foods. We conclude that although termites and sedges might have contributed to the C4 signal in South African australopiths, other C4 foods were also important. Lastly, we suggest that the consumption of C4 foods is a fundamental hominin trait that, along with bipedalism, allowed australopiths to pioneer increasingly open and seasonal environments.

Abstract: Disturbances from road management activities are often considered to be a major threat to plants in roadside environments, however effects may not be deleterious to all plants. The post-disturbance response of three Acacia species with different life-history attributes was compared in four road reserves impacted by soil disturbance from grading activities. Recovery of acacias to grading was variable, however basal resprouting, root suckering and seedling emergence led to a 6.2% population increase for all road reserves combined. In two road reserves, there was significant resprouting of the facultative seeder A. decora, and 2 years after disturbance, resprouts reached mean heights of 71 and 74 cm. One year after disturbance, 71% of A. decora resprouts flowered and 49% also set viable seed, and there was a significant positive relationship between flowers produced and viable seed set. Similarly, 65% of resprouts of the facultative seeder A. montana flowered but only 10% set viable seed. In contrast, there was patchy seedling emergence of the obligate seeder A. pycnantha and to a lesser extent A. montana, and seedlings did not reach reproductive maturity 1 year after disturbance. Drought most likely reduced seedling numbers, as seedlings were only recorded in shaded road reserves, where additional water was applied from roadworks activities. Grading of roadside environments appears to favour plants with strong resprouting ability, and persistence of Acacia populations will depend on the timing of soil disturbances from grading activities in relation to species life-history attributes.

Abstract: Abstract 10.1002/ldr.644.abs Restoration of degraded soils is a development strategy to reduce desertification, soil erosion and environmental degradation, and alleviate chronic food shortages with great potential in sub-Saharan Africa (SSA). Further, it has the potential to provide terrestrial sinks of carbon (C) and reduce the rate of enrichment of atmospheric CO2. Soil organic carbon (SOC) contents decrease by 0 to 63 per cent following deforestation. There exists a high potential for increasing SOC through establishment of natural or improved fallow systems (agroforestry) with attainable rates of C sequestration in the range of 0·1 to 5·3 Mg C ha−1 yr−1. Biomass burning significantly reduces SOC in the upper few centimeters of soil, but has little impact below 10 to 20 cm depth. The timing of burning is also important, and periods with large amounts of biomass available generally have the largest losses of SOC. In cultivated areas, the addition of manure in combination with crop residues and no-till show similar rates of attainable C sequestration (0 to 0·36 Mg C ha−1 yr−1). Attainable rates of SOC sequestration on permanent cropland in SSA under improved cultivation systems (e.g. no-till) range from 0·2 to 1·5 Tg C yr−1, while attainable rates under fallow systems are 0·4 to 18·5 Tg C yr−1. Fallow systems generally have the highest potential for SOC sequestration in SSA with rates up to 28·5 Tg C yr−1. Copyright © 2005 John Wiley & Sons, Ltd.

Abstract: Arid grasslands are often presumed to exist in one of two alternate stable states: grassland or desertified shrubland. While the conversion to shrubland can occur rather rapidly following intense overgrazing, the recovery of perennial grasses is often presumed to be difficult or impossible even with livestock removal. We examined vegetation and rodent communities at a desertified shrubland site from which livestock had been removed for more than four decades. Total shrub cover was similar but differed in composition across the grazing fence. Larrea tridentata had significantly higher cover outside while Parthenium incanum had significantly higher cover inside the fence. Basal perennial grass cover was significantly higher inside the fence. Rodent diversity was significantly higher inside the fence due to higher abundance and diversity of pocket mice. These data suggest that recovery of perennial grasses at severely desertified sites is possible but may require several decades and that rodent diversity responds positively to such recovery.

Abstract: Global environmental change problems due to their unstructured characteristics, being marked by great uncertainties and a big number of stakeholders, prove to be too difficult to solve in a traditional way alone. They call for a more proactive approach. One of them advocates systems change driven by technological innovations accompanied by institutional and sociocultural transformations. Transition management is a new policy strategy based on this philosophy. It has recently emerged in the Netherlands and has been adopted by the Dutch government as a relevant framework for shaping its policy towards sustainability. The transition management writings emphasise the importance of [`]learning' in the process of induced change towards sustainability. Although this can indeed be quite a significant means for inducing change, the literature on transition management is not explicit enough about the methodological organisation of the learning process. Since transition management has become an important approach in the Netherlands, we consider it relevant to deploy some learning insights and experience gained in the Dutch Climate OptiOns for the Long-term (COOL) project to analyse and improve the process of transition management. In particular, we look into the first two steps of transition management, i.e., organising a transition arena and making visions.

Abstract: Abstract Predicting the probability of successful establishment of plant species by matching climatic variables has considerable potential for incorporation in early warning systems for the management of biological invasions. We select South Africa as a model source area of invasions worldwide because it is an important exporter of plant species to other parts of the world because of the huge international demand for indigenous flora from this biodiversity hotspot. We first mapped the five ecoregions that occur both in South Africa and other parts of the world, but the very coarse definition of the ecoregions led to unreliable results in terms of predicting invasible areas. We then determined the bioclimatic features of South Africa's major terrestrial biomes and projected the potential distribution of analogous areas throughout the world. This approach is much more powerful, but depends strongly on how particular biomes are defined in donor countries. Finally, we developed bioclimatic niche models for 96 plant taxa (species and subspecies) endemic to South Africa and invasive elsewhere, and projected these globally after successfully evaluating model projections specifically for three well-known invasive species (Carpobrotus edulis, Senecio glastifolius, Vellereophyton dealbatum) in different target areas. Cumulative probabilities of climatic suitability show that high-risk regions are spatially limited globally but that these closely match hotspots of plant biodiversity. These probabilities are significantly correlated with the number of recorded invasive species from South Africa in natural areas, emphasizing the pivotal role of climate in defining invasion potential. Accounting for potential transfer vectors (trade and tourism) significantly adds to the explanatory power of climate suitability as an index of invasibility. The close match that we found between the climatic component of the ecological habitat suitability and the current pattern of occurrence of South Africa alien species in other parts of the world is encouraging. If species' distribution data in the donor country are available, climatic niche modelling offers a powerful tool for efficient and unbiased first-step screening. Given that eradication of an established invasive species is extremely difficult and expensive, areas identified as potential new sites should be monitored and quarantine measures should be adopted.

Abstract: Issues of equity and justice are high on international agendas dealing with the impacts of global climate change. But what are the implications of climate change for equity and justice amongst vulnerable groups at local and sub-national levels? We ask this question for three reasons: (a) there is a considerable literature suggesting that the poorest and most vulnerable groups will disproportionately experience the negative effects of 21st century climate change; (b) such changes are likely to impact significantly on developing world countries, where natural-resource dependency is high; and (c) international conventions increasingly recognise the need to centrally engage resource stakeholders in agendas in order to achieve their desired aims, as part of more holistic approaches to sustainable development. These issues however have implications for distributive and procedural justice, particularly when considered within the efforts of the UNFCCC. The issues are examined through an evaluation of key criteria relating to climate change scenarios and vulnerability in the developing world, and second through two southern African case studies that explore the ways in which livelihoods are differentially impacted by (i) inequitable natural-resource use policies, (ii) community-based natural-resource management programmes. Finally, we consider the placement of climate change amongst the package of factors affecting equity in natural-resource use, and whether this placement creates a case for considering climate change as [`]special' amongst livelihood disturbing factors in the developing world.

Abstract: The in vitro biological activity of nine frequently used medicinal plants in South Africa was assessed and re-assessed after various lengths of storage. The plants investigated were Alepidea amatymbica, Leonotis leonurus, Drimia robusta, Vernonia colorata, Merwilla natalensis, Eucomis autumnalis, Bowiea volubilis, Helichrysum cymosum and Siphonochilus aethiopicus. Water, ethanol and hexane extracts of fresh, 90-day-old and 1-year-old material were assayed for antibacterial activity against four strains of bacteria and for COX-1 inhibition activity. TLC-fingerprints of the fresh and stored extracts were produce to document chemical changes. Alepidea amatymbica, Eucomis autumnalis, Helichrysum cymosum, Leonotis leonurus, Siphonochilus aethiopicus and Vernonia colorata were investigated further as to the effect of 1 year's storage. Elevated temperature and humidity (55 °C and 100% relative humidity) were used to accelerate the ageing process of Alepidea amatymbica, Leonotis leonurus and Vernonia colorata plant material for further investigation. The TLC-fingerprints indicated that there was chemical breakdown during storage in certain species. The degree of changes in biological activity and chemistry due to storage were species-specific. In general, antibacterial activity was retained in most species while COX-1 inhibition activity was lost rapidly.

Abstract: Devil's claw is the common name for two species in the genus Harpagophytum. Their root extracts contain the iridoid glycoside, harpagoside, which has been found to be effective in the treatment of degenerative rheumatoid arthritis, osteoarthritis, tendonitis, kidney inflammation, and heart disease. Most of the world's supply comes from Namibia, with lesser amounts from South Africa and Botswana. In 2002, the peak year of export, 1018 tonnes of dried tubers were exported from southern Africa, representing the harvest of millions of plants. In 2001, sales in Germany were estimated at 30 M euros, accounting for 74% of the prescriptions for rheumatism. Harvest has improved income levels in marginalized communities but it has also raised questions of sustainability. In 2000, recommendations were made to the Convention on the International Trade in Endangered Species (CITES) to add devil's claw to Appendix II. In 2004, the proposal was formally withdrawn due to the efforts of the range states to address sustainability issues. Replacing wild collection with cultivation has generated a debate on the positive and negative effects on harvester income and rural farmers. Successful cultivation efforts have involved micropropagation techniques and growing the plant without water or fertilizers. The governments of the main range states are working with local communities to develop policies and regulations to protect the species and to determine a sustainable harvest.

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Abstract: The remote sensing of fire severity is a noted goal in studies of forest and grassland wildfires. Experiments were conducted to discover and evaluate potential relationships between the characteristics of African savannah fires and post-fire surface spectral reflectance in the visible to shortwave infrared spectral region. Nine instrumented experimental fires were conducted in semi-arid woodland savannah of Chobe National Park (Botswana), where fire temperature (Tmax) and duration (dt) were recorded using thermocouples positioned at different heights and locations. These variables, along with measures of fireline intensity (FLI), integrated temperature with time (Tsum) and biomass (and carbon/nitrogen) volatilised were compared to post-fire surface spectral reflectance. Statistically significant relationships were observed between (i) the fireline intensity and total nitrogen volatilised (r2 = 0.54, n = 36, p < 0.001), (ii) integrated temperature (Tsum-[mu]) and total biomass combusted (r2 = 0.72, n = 32, p < 0.001), and (iii) fire duration as measured at the top-of-grass sward thermocouple (dtT) and total biomass combusted (r2 = 0.74, n = 34, p < 0.001) and total nitrogen volatilised (r2 = 0.73, n = 34, p < 0.001). The post-fire surface spectral reflectance was found to be related to dt and Tsum via a quadratic relationship that varied with wavelength. The use of visible and shortwave infrared band ratios produced statistically significant linear relationships with fire duration as measured by the top thermocouple (dtT) (r2 = 0.76, n = 34, p < 0.001) and the mean of Tsum (r2 = 0.82, n = 34, p < 0.001). The results identify fire duration as a versatile measure that relates directly to the fire severity, and also illustrate the potential of spectrally-based fire severity measures. However, the results also point to difficulties when applying such spectrally-based techniques to Earth Observation satellite imagery, due to the small-scale variability noted on the ground. Results also indicate the potential for surface spectral reflectance to increase following higher severity fires, due to the laying down of high albedo white mineral ash. Most current techniques for mapping burned area rely on the general assumption that surface albedo decreases following a fire, and so if the image spatial resolution was high enough such methods may fail. Determination of the effect of spatial resolution on a sensor's ability to detect white ash was investigated using a validated optical mixture modelling approach. The most appropriate mixing model to use (linear or non-linear) was assessed using laboratory experiments. A linear mixing model was shown most appropriate, with results suggesting that sensors having spatial resolutions significantly higher than those of Landsat ETM+ will be required if patches of white ash are to be used to provide EO-derived information on the spatial variation of fire severity.

Abstract: For estimating herbage intake during grazing, the traditional sward cutting technique was compared in grazing experiments in 2002 and 2003 with the recently developed n-alkanes technique and with the net energy method. The first method estimates herbage intake by the difference between the herbage mass before and after grazing and the regrowth between the 2 points in time. The second technique estimates herbage intake by the ratio of a dosed even-chain synthetic n-alkane (C32) and a naturally occurring odd-chain n-alkane (C31 or C33) in the herbage and feces. The third technique calculated the intake from the animal's energy requirements for milk production and maintenance. The sward cutting technique estimated herbage intake with the highest coefficient of variation and had different results in the 2 experimental years. The n-alkanes method yielded less variable results, whereas the net energy method gave the least variable results. In 2002, the estimates of the alkane ratio C32:C33 were best related with estimations of the net energy method. In 2003, the estimates of the alkane ratio C32:C31 were best related. The estimate based on the alkane ratio C32:C33 had a lower coefficient of variation than the one based on the alkane ratio C32:C31. Therefore, the C32:C33 alkane method was considered to be a better direct estimator for herbage intake by grazing lactating dairy cows.

Abstract: Savanna water management is predicated on the hypothesis that surface water availability can be manipulated at scales that influence herbivore distributions. Using a case study in the Kruger National Park, South Africa, we assess the contribution of perennial and ephemeral water sources to surface water availability in the dry season. We posit that surface water availability in savanna ecosystems exists along a continuum of being determined primarily by perennial or ephemeral water sources and propose that locating an ecosystem along this continuum provides a means to evaluate the utility of water management. We also develop general hypotheses about the relative response of herbivore species to ephemeral water sources.

Abstract: This 556-page book examines current grassland problems and issues, and provides an insight into grassland productivity in diverse areas of the world. There is a focus on recent technical advances and the prospects for further innovation. The book contains 21 individually-authored chapters divided among 7 sections. The text is in English and each of the chapters is individually referenced. The first section focuses on forage germplasm and this section contains chapters 1-4, which individually discuss prospects for temperature forage legumes, the future role of forage legumes in the Mediterranean climatic areas, advances and perspectives for new grasses and legumes in the tropical zones of Latin America, and perspectives on forage tree legumes. The theme of section II is forage conservation and the 2 chapters in this section discuss silage from a global perspective, and prospects for haying systems around the world. Grass-based systems and organic production are the focus of section III, which contains chapters 7-9. Specific topics discussed in these 3 chapters include: meat and milk production from grass-based systems; pastoral industries and the efficient use of pastoral resources in New Zealand; and principles, practices and the potential of organic grassland. Section IV focuses on climate change, biodiversity and biotechnology and this section contains chapters 10-12, which individually cover: rising atmospheric carbon dioxide and global climate change and the management implications for grazing lands; current changes and scenarios in grasslands biodiversity; and biotechnological approaches to temperate forage improvement. Geographical information systems (GIS) are the focus of section V and this section contains chapters on GIS-based adaptation mapping of forage species and the application of remote sensing technology to grassland resource management in China. The sixth section of the book focuses on farmer and pastoralist participation and the 2 chapters in this section discuss: recent developments, impacts and opportunities for new forages for smallholder livestock systems in Southeast Asia, and the present and future of rangeland development in West Asia and North Africa. The theme of final section, section VII, is regional development and this final section contains chapters 17-21, which individually discuss, respectively, forage and ruminant livestock integration in tree crop plantations of Southeast Asia; intensive forage production in smallholder dairy farming in eastern Africa; rural depopulation and grassland management in Patagonia; changing philosophies and future prospects in Australian temperate grasslands; and finally, the future for savannah and tropical grasslands from a Latin American perspective. The book highlights a list of the contributors and their respective institutions. This book was published by Science Publishers, Inc. in association with the Food and Agricultural Organization of the United Nations, Rome, Italy. This book will be of interest to researchers, lecturers and students in grassland science and its associated disciplines, land use advisers and policy makers.

Abstract: This study addressed the effect of landscape attributes on the spatial distribution of soil physical properties in an alpine rangeland in a semi-arid area of Iran. Soil physical properties are recognized for their important role in supporting plant growth. To identify the effects of landscape attributes on soil physical properties the present study collected and analysed information from air photos, satellite images, field survey, and the laboratory using statistical analyses. Land stratification allowed the study area to be subdivided into Land Unit Tracts (LUT), according to specified criteria including landform attributes (slope, aspect, and altitude) and vegetation type. A factorial model on the basis of a completely randomised design was used to analyse the data collected from 234 LUT. The interrelationships between soil physical properties and landscape attributes were investigated and interpreted based on statistical analysis and expert knowledge. Slope significantly (P<0.05) affected most properties of the 0-10 cm topsoil including grade of pedality and slake test. Also, many soil properties that reflect parent material and likely to be related to soil moisture status including coarse fragment ratio, soil profile effective thickness, first layer effective thickness, water retention capacity, and depth to water table were significantly related to slope gradient. These soil properties noticeably affect range productivity.

Abstract: In the late 1930s, the presence of a highly organized labor force, the Civilian Conservation Corps (CCC), in the Jornada Basin of southern New Mexico provided the capability for rangeland scientists to conduct experiments to determine the effectiveness of various techniques for remediating or reversing the encroachment of shrubs into grasslands. Unfortunately, soon after the treatments were performed, the CCC disbanded and most records of the treatments were lost. Despite sketchy documentation, some rangeland treatments left legacies on the landscape, and effects on water retention, erosion, and vegetation dynamics remained long after the CCC work ended. The discovery of historical documents from long-closed files and aerial photography in widely scattered archives allowed some of the experiments to be located and reexamined. Two research areas established in the mid-1930s were of particular interest, namely a tarbush (Flourensia cernua DC.) site where shrubs were grubbed and quadrats established and a creosote (Larrea tridentata [Sesse & Moc. ex DC.] Coville) site where the creosote and tarbush shrubs were grubbed. Here we outline how these sites were rediscovered, how historical measurements were repeated for the first time since the late l930s, and conclusions drawn regarding specific rangeland remediation strategies and vegetation dynamics. Our results show that shrub populations recovered from a radical removal treatment in less than 65 years. Remediation of these sites so that grass will recover to pre-shrub-dominated amounts will require measures additional to just removal of shrubs in order to restore hydrologic function. The fact that we were able to relocate, revisit, and resample these treatment areas provided unique opportunities to understand the long-term vegetation dynamics of these arid ecosystems. It is evident that woody plant populations have a high degree of resilience, that density dependence or interference appears to limit plant size in arid shrub communities, and that shrub populations had not reached any stable equilibrium state at the time of treatment in the 1930s. These insights would have been impossible to gain from short-term studies and without long-term studies initiated in the 1930s combined with recent discoveries of original documentation and historical aerial photography.

Abstract: Cultural landscapes in Europe provide a wide range of food products and fulfil social and environmental functions. In order to maintain agricultural practices that contribute to maintaining the biological and cultural value of semi-natural landscapes, agri-environmental schemes are being implemented in many western European countries. In the mountains of southern Europe a major issue is the encroachment of shrubs and trees through natural forest succession following agro-pastoral extensification. In this paper we analyse trends in land use strategies of sheep breeders in response to milk pricing and in relation to various within-farm mechanisms. We show that changes in production rules within the Roquefort cheese protected geographical indication have caused farmers to develop an alternative land use strategy. In this alternative model, farmers now consider rangelands as a valuable resource. By increasing the use of rangelands for sheep grazing and alimentation, this new strategy provides a more effective control of shrub and tree encroachment. We suggest that this involuntary consequence of production and market decisions has been at least as important as agri-environmental schemes in leading ewes' milk producers to make changes in their land use strategy.

Abstract: An experiment commenced in 1998 to test the effects of superphosphate fertiliser application and grazing on production and botanical composition of a native grassland in south-eastern Australia. Superphosphate application resulted in an increase in sheep production but a decline in native perennial grasses and an increase in exotic annual grasses. The study reported here aimed to determine if arthropod assemblages showed changes in community composition on the same experimental plots. The experiment was conducted in grassland dominated by the native perennial wallaby grass, Austrodanthonia duttoniana, and consisted of six replicated treatments that were designed to improve grassland and domestic livestock productivity. Treatments consisted of a control (no fertiliser), three levels of annually applied superphosphate (62.5, 125, and 250 kg ha-1), and two treatments aimed to raise soil pH (superphosphate plus lime, and sewage ash). Soil properties were measured annually and sheep stocking rates were increased over the duration of the experiment according to increases in available forage. Soil and ground-active arthropod populations were sampled from all plots in spring 2001. Fertiliser application and grazing increased the relative abundance of introduced Acari and Collembola, and changed the community composition of Formicidae and Coleoptera. Lime and sewage treatments had variable effects on taxa. Improving the productivity of native grassland with superphosphate led to a decline in plant and arthropod biodiversity through reduced abundance and/or local extinction of native species and increased dominance of introduced species. These findings support the need to protect and restore a representative network of native grassland ecosystems within the agricultural zone of south-eastern Australia.

Abstract: Comparative field studies were conducted on Acacia tortilis (Forsk.) Hyne and Acacia xanthophloea Benth. trees growing in a semi-arid environment in Kibwezi, Kenya, to assess root access to soil water at varying soil depths and how this may affect the expression of morphological and physiological traits developed during drought. Measurements of soil water content, leaf growth, shoot elongation, sap flow in the xylem of stems and branches, leaf water potential, leaf transpiration and stomatal conductance were carried out. Further, water use efficiency (WUE) over long-term periods was examined via carbon isotope discrimination ([delta]13C) on leaves. Whole tree and leaf specific hydraulic conductance were determined from sap flux or leaf transpiration and the water potential gradient between soil (as predawn potential) and canopy, respectively. Leaf growth and shoot elongation depended on soil water availability (SWC) and plant tissue water status. A. xanthophloea showed greater (40 kg d-1) water use compared to A. tortilis trees of comparable sizes (20 kg d-1) during favorable conditions of SWC. Decline in SWC reduced water use and the onset and rate of decline in sap flux was determined by the rooting depth. A. xanthophloea showed earlier response (onset at SWC=0.24 m3 m-3) to water stress than A. tortilis (onset at SWC=0.14 m3 m-3). Midday depression in stomatal conductance and subsequent decline in transpiration during favorable SWC as observed in A. xanthophloea was attributed to increased hydraulic resistance and stomatal closure. Rooting patterns and root characteristics could account for the observed morphological and physiological differences between A. tortilis and A. xanthophloea as well as between small and large A. tortilis trees. However, seasonal responses were modified by species-inherent characteristics, which are expressed during drought. Access to deeper soil water resources and the abilities of trees to extract and efficiently transport water may explain differences in drought resistance among species and tree distribution in the arid savanna.

Abstract: Wooded rangelands are a vast grazing land resource globally, including shrublands, savannas and forested ranges. They generally provide forage year-round for small ruminants and they are vitally important for livestock production, especially goats. While the productivity of wooded rangelands is low to moderate, their importance to small ruminant production is considerable. In this paper, we begin by discussing some anti-quality characteristics (mechanical and chemical defences) of woody vegetation that reduce their forage value, deter foraging, and reduce performance and productivity of small ruminants. We then present examples of grazing studies that illustrate how small ruminants select their diets on wooded rangelands. We conclude by discussing why small ruminants select the diets they do within the evolutionary processes of plant-herbivore interactions. Finally, we discuss how this knowledge can be integrated into approaches for sustainable management of wooded rangelands for small ruminant production. Plant defences are abundant in wooded rangelands but they are not a complete barrier to small ruminants as they often use woody plants as part of their diets. Indeed plants with such defences may represent a significant forage resource enabling small ruminants to survive on wooded rangelands with a prolonged dry period when more preferred defenceless species are absent. Future research in plant-herbivore interactions should include investigating how plant biochemical diversity influences herbivore preference for various plant communities, and integrating this information to develop recommendations for managing wooded rangelands.

Abstract: Two long-term mechanistic models of grazing systems in the semi-arid succulent Karoo have been used to study factors that influence vegetation changes, livestock productivity and sustainability of the ecosystem. In this region of low and highly variable rainfall, goats and sheep feed on vegetation comprising perennial shrubs and annuals. A previously published model of the Namaqualand system (the "standard" model) explicitly simulates three guilds of perennial shrubs, a guild of annuals, forage consumption, growth of goats and goat reproductive and survival rates. The model also simulates variable rainfall and predicts that, if no steps are taken to control the goat population, stock numbers will vary widely between years and the population of the different plant guilds will fluctuate. Plots of model output indicate that the system is driven by rainfall. Temporal changes in the relative abundance of each guild vary with different sequences of rainfall having similar long-term mean and variability. A single run of the model may display equilibrial, disequilibrial and threshold behaviour. Thus, the system exhibits complex dynamics. If animal numbers are held constant at the long-term average of variable stock or at the recommended stocking rate then the cover of palatable shrubs decreases and that of toxic plants increases substantially. A "simplified" model based on an aggregated forage variable and equilibrium dynamics is inadequate to describe the behaviour of this system.

Abstract: Degradation of semiarid and arid rangelands is a major concern and is usually described in terms of soil movement and changing plant communities. The purpose of this paper was to determine the patterns and rates of soil erosion and redistribution from measurement of the distribution of fallout 137Cesium on the Lucky Hills Watershed, a semiarid rangeland watershed in southeastern Arizona. Soil redistribution ranged from a loss of - 9.8 t ha- 1 yr- 1 to the deposition of + 7.0 t ha- 1 yr- 1. Net soil loss occurred at 54 of the 74 sample sites or approximately 73% of the watershed. Soil erosion rates were significantly correlated to the percent of rock fragments in the surface 25-cm soil layer with erosion decreasing as rock fragments increased. Soil redistribution was not significantly related to vegetation cover at the sample sites. This study supports earlier research on Walnut Gulch Watershed that showed the importance of rock fragments in estimating soil loss.

Abstract: Pollen analysis of material from a variety of sediment types including those from ponds, streams, a rock-shelter and hyrax dung accumulations in the Blydefontein Basin (31°09'S, 25°05'E, Fig. 1b) provide a record of vegetation change in the eastern Karoo over the last 10,000 years. The pollen composition fluctuated as a result of different taphonomic processes inherent in the various sampled deposits. Results further demonstrate that long-term vegetation changes alternated between Karoo shrub and grassland plant communities. Karoo shrubs suggesting relatively dry conditions were generally prominent in the early Holocene until ca. 5400 yr BP when more grassy vegetation began to flourish presumably in response to increased summer-rain conditions. Pollen representation of the early Holocene is not detailed enough to trace millennial scale variations during this period but more detailed middle to late Holocene data show millennial or shorter scale shifts between grassland and drier karroid veld.

Abstract: Anthropogenic fires in Africa are an ancient form of environmental disturbance, which probably have shaped the savanna vegetation more than any other human induced disturbance. Despite anthropogenic fires having played a significant role in savanna management by herders, previous ecological research did not incorporate the traditional knowledge of anthropogenic fire history. This paper integrates ecological data and anthropogenic fire history, as reconstructed by herders, to assess landscape and regional level vegetation change in northeastern Namibia. We investigated effects of fire frequency (i.e. <5, 5-10 and >10 years) to understand changes in vegetation cover, life form species richness and savanna conditions (defined as a ratio of shrub cover to herbaceous cover). Additionally, we analysed trends in the vegetation variables between different fire histories at the landscape and regional scales. Shrub cover was negatively correlated to herbaceous cover and herbaceous species richness. The findings showed that bush cover homogenisation at landscape and regional scales may suggest that the problem of bush encroachment was widespread. Frequent fires reduced shrub cover temporarily and promoted herbaceous cover. The effects on tree cover were less dramatic. The response to fire history was scale-independent for shrub, herbaceous and tree cover, but scale-dependent for the richness of grass and tree life forms. Fire history, and not grazing pressure, improved savanna conditions. The findings emphasise the need to assess effects of anthropogenic fires on vegetation change before introducing new fire management policies in savanna ecosystems of northeastern Namibia.

Abstract: Habitat degradation through over-grazing and wood collection is especially prevalent in developing countries such as South Africa. As human populations expand and the demand for land increases, the traditional idiom of setting aside protected areas for conservation is insufficient and assessment and protection of diversity outside these areas is needed. We assessed the impact of land use on lizard assemblages in communal rangelands in South Africa by comparing abundance, species richness and species diversity between degraded communal lands with a protected area. We first quantified vegetation differences between the study areas and found marked differences. Communal lands had significantly fewer large trees and less ground cover. Contrary to prediction, we found no evidence that any species of lizard was negatively affected by habitat disturbance. Some species were more common in communal lands, and species richness and diversity were also higher using certain sampling techniques. Terrestrial diversity was likely enhanced due to the preference of many terrestrial lizards for open, sparsely grassed areas. We discuss other reasons for increased diversity such as the intermediate disturbance hypothesis and/or reduced numbers of predators and competitors. We also conducted surveys of households and traditional healers to investigate the relationship between human uses of reptiles and abundance. The predominant users of reptiles were traditional healers. The most commonly used species were not encountered in our field surveys, and respondents indicated that they appeared to be declining. Our results emphasise the importance of integrating local knowledge into biodiversity assessment and conservation planning. Although we did not identify a negative impact of disturbance on lizard communities, community structure was different and this likely influenced ecosystem integrity and function in some way.

Abstract: Research was conducted to investigate rapid chemical responses of Acacia karroo to severe defoliation in a semi-arid, subtropical savanna. A flock of 250 goats reduced available foliage by 87% in a 10.5-ha area of Acacia woodland over 3 weeks during May (early dormant season). During the first 10 days, concentrations of nitrogen (N), neutral detergent fibre (NDF) and condensed tannin (CT) did not change. The concentration of potentially hepatotoxic alkaloids (PHAs) decreased. There were no immediately detectable effects of defoliation intensity or recovery time on any of the measured chemical variables. There were no relationships between N and NDF, CT or PHA. Given that the treatments were applied at the start of the dormant season, the metabolism of mature or senescing leaves may have precluded rapid increases in defence. Because a previous study under similar browsing conditions showed increased defence in A. karroo at the same time of year, it was concluded that intra-annual variations in rainfall, and the resulting variations in plant growth activity, lead to intra-annual variations in plant responses to defoliation in semi-arid subtropical savannas. Such variations need to be accounted for in future experiments aimed at investigating induced responses to browsing in savannas.

Abstract: Savanna grass cover is dynamic and its annual extent resonates with wet season rainfall, as shown by satellite observations of normalized difference vegetation index (NDVI) time series for the Kalahari Transect (KT) in southern Africa. We explore the hydrological significance of the dynamic grass cover by applying a soil moisture model to the water-limited portion of the KT, which spans a north-south gradient in mean wet season rainfall, , from approximately 700 to 300 mm. Satellite-derived tree fractional cover, xt, is shown to be highly correlated with ground meteorological measurements of in this region. By implementing a simple expression for grass growth and decay in the model that factored in only xt and near-surface soil moisture, we were able to effectively reproduce the satellite-derived fractional grass cover, xg, along the transect over a 16-year period (1983-1998). We compared the results from dynamic grass model with those yielded by a static grass cover model in which xg was set to its 16-year average for each simulation. The dynamic quality of the grass was found to be important for reducing tree stress during dry years and for reducing the amount of water that is lost from the overall root zone during the wet years, relative to the static grass case. We find that the dynamic grass cover acts as a buffer against variability in wet season precipitation, and in doing so helps to maximize ecosystem water use. The model results indicate that mixed tree/grass savanna ecosystems are ideally suited to reach a dynamic equilibrium with respect to the use of a fluctuating limiting resource (water) by having functional components that respond to variability in rainfall over long timescales (trees) and short timescales (grasses).

Abstract: In spite of a manager's best attempts, a managed rangeland may hit an irreversible state in which it provides neither consumptive nor nonconsumptive services to humans. Therefore, given a particular time-based management regime, it is useful to know how long it takes for a rangeland to hit the irreversible state. The purpose of this paper is to conduct a theoretical analysis of this and related questions. In particular, we first provide a stochastic characterization of a time-based range management regime. Second, we ascertain the expected amount of time it takes for our managed rangeland to hit the irreversible state. Third, we discuss the properties of the above mathematical expectation. Finally, we pose and discuss a simple optimization problem for our range manager.

Abstract: The remote sensing of Earth surface changes is an active research field aimed at the development of methods and data products needed by scientists, resource managers, and policymakers. Fire is a major cause of surface change and occurs in most vegetation zones across the world. The identification and delineation of fire-affected areas, also known as burned areas or fire scars, may be considered a change detection problem. Remote sensing algorithms developed to map fire-affected areas are difficult to implement reliably over large areas because of variations in both the surface state and those imposed by the sensing system. The availability of robustly calibrated, atmospherically corrected, cloud-screened, geolocated data provided by the latest generation of moderate resolution remote sensing systems allows for major advances in satellite mapping of fire-affected area. This paper describes an algorithm developed to map fire-affected areas at a global scale using Moderate Resolution Imaging Spectroradiometer (MODIS) surface reflectance time series data. The algorithm is developed from the recently published Bi-Directional Reflectance Model-Based Expectation change detection approach and maps at 500 m the location and approximate day of burning. Improvements made to the algorithm for systematic global implementation are presented and the algorithm performance is demonstrated for southern African, Australian, South American, and Boreal fire regimes. The algorithm does not use training data but rather applies a wavelength independent threshold and spectral constraints defined by the noise characteristics of the reflectance data and knowledge of the spectral behavior of burned vegetation and spectrally confusing changes that are not associated with burning. Temporal constraints are applied capitalizing on the spectral persistence of fire-affected areas. Differences between mapped fire-affected areas and cumulative MODIS active fire detections are illustrated and discussed for each fire regime. The results reveal a coherent spatio-temporal mapping of fire-affected area and indicate that the algorithm shows potential for global application.

Abstract: It is known that, depending on the degree of degradation, the vegetation recovery of severely degraded areas by means of natural succession processes is very slow, if not impossible, and that active intervention in the form of restoration technologies has to be applied. Combinations of different restoration technologies, including ripping, over-sowing, brushpacking and the addition of organic material, were evaluated in a study site (characterized by denuded saline patches) in the semi-arid areas of South Africa. Quantitative vegetation sampling procedures, which included the monitoring of vegetation cover, frequency and density measurements were carried out over a period of 2 years (2000-2002) to determine the establishment and dynamics of the over-sown species used in the restoration treatments. The germination capacity and viability of the over-sown species were also tested in the laboratory, using methods prescribed by the International Seed Testing Association (ISTA). The over-sown species were positively correlated in the over-sowing treatments, while only annual pioneer species which were still represented in the soil seed bank in the degraded patches, correlated with the control and cultivation-only treatments. Of the over-sown species Digitaria eriantha and Chloris gayana had the highest frequencies. The restoration treatment that included a combination of ripping, over-sowing, brushpacking and organic material showed the highest establishment rate of all over-sown species. The results of the seed purity analysis indicated that seed obtained from a registered seed merchant showed higher purity percentages than seed collected locally by the land user. Species with high frequency and density values under natural conditions in the field trials also had a high purity and germination percentage in the laboratory experiments.

Abstract: Parasitism can limit the effectiveness of weed biological control agents. In this study, we surveyed larval and pupal parasitoids of the leaf-tying moth, Evippe sp. #1 (Gelechiidae), a biological control agent released widely in rangeland Australia against mesquite (Mimosaceae: Prosopis spp.). This moth was expected to be vulnerable to parasitism, as it has a semi-concealed feeding habit, is a member of a well-represented family, and is a herbivore on a well-represented family of trees and shrubs. We conducted surveys in four regions across Australia to determine whether parasitoids were responsible for differential performance of the moth in rangeland Australia, and what the consequences might be for the release of further semi-concealed Lepidoptera. The parasitoid fauna was found to be diverse, but the composition was similar across the four regions surveyed. It included primary and hyperparasitoids of both larvae and pupae. Parasitism rates were generally low, rarely above a few percentage points in any one survey, and therefore, unlikely to threaten moth populations. There was also no relationship between parasitism rates and leaf-tie abundance. These results suggest that any new semi-concealed lepidopteran biological control agents in rangeland Australia might also be parasitised by a diverse fauna. However, a better understanding of what determines parasitism rates is required to predict whether it would be sufficient to threaten biological control.

Abstract: This paper provides some insight into special attributes of the goat as an efficient producer of meat under harsh environments. The overview is not intended to be exhaustive; it gives the readers a comprehensive synthesis on the subject allowing them to consult the list of references. Moreover, it would not be possible to classify the most limiting factor among the numerous and diverse constraints that negatively affect goat production: high ambient temperatures and/or humidity, and erratic and/or low rainfall that have concomitant effects on quality and quantity of feeds, a wide variety of diseases and low levels of animal husbandry. The paper highlights some particular conditions illustrated by data coming from different parts of the world, which can be classified as having harsh environments. Finally, the objectives of this work are not to propose ready-made solutions, but to recommend a holistic approach to the problems and their analyses allude to opportunities for improvement in the future.

Abstract: The potential for wind erosion in South Central Colorado is greatest in the spring, especially after harvesting of crops such as potato (Solanum tuberosum L.) that leave small amounts of crop residue in the surface after harvest. Therefore it is important to implement best management practices that reduce potential wind erosion and that we understand how cropping systems are impacting soil erosion, carbon dynamics, and properties of rangeland sandy soils. We evaluate the effects of cropping systems on soil physical and chemical properties of rangeland sandy soils. The cropping system included a small grain-potato rotation. An uncultivated rangeland site and three fields that two decades ago were converted from rangeland into cultivated center-pivot-irrigation-sprinkler fields were also sampled. Plant and soil samples were collected in the rangeland area and the three adjacent cultivated sites. The soils at these sites were classified as a Gunbarrel loamy sand (Mixed, frigid Typic Psammaquent). We found that for the rangeland site, soil where brush species were growing exhibited C sequestration and increases in soil organic matter (SOM) while the bare soil areas of the rangeland are losing significant amounts of fine particles, nutrients and soil organic carbon (SOM-C) mainly due to wind erosion. When we compared the cultivated sites to the uncultivated rangeland, we found that the SOM-C and soil organic matter nitrogen (SOM-N) increased with increases in crop residue returned into the soils. Our results showed that even with potato crops, which are high intensity cultivated cropping systems, we can maintain the SOM-C with a rotation of two small grain crops (all residue incorporated) and one potato crop, or potentially increase the average SOM-C with a rotation of four small grain crops (all residue incorporated) and one potato crop. Erosion losses of fine silt and clay particles were reduced with the inclusion of small grains. Small grains have the potential to contribute to the conservation of SOM and/or sequester SOM-C and SOM-N for these rangeland systems that have very low C content and that are also losing C from their bare soils areas (40%). Cultivation of these rangelands using rotations with at least two small grain crops can reduce erosion and maintain SOM-C and increasing the number of small grain crops grown successfully in rotation above two will potentially contribute to C and N sequestration as SOM and to the sequestration of macro- and micro-nutrients.

Abstract: Remotely sensed measurements from NOAA-AVHRR expressed as normalized difference vegetation index (NDVI) have generated a 23-year time series appropriate for long-term studies of Sahel region. The close coupling between Sahelian rainfall and the growth of vegetation has made it possible to utilize NDVI data as proxy for the land surface response to precipitation variability. Examination of this time series reveals two periods; (a) 1982-1993 marked by below average NDVI and persistence of drought with a signature large-scale drought during the 1982-1985 period; and (b) 1994-2003, marked by a trend towards [‘]wetter 039; conditions with region-wide above normal NDVI conditions with maxima in 1994 and 1999. These patterns agree with recent region-wide trends in Sahel rainfall. However taken in the context of long-term Sahelian climate history, these conditions are still far below the wetter conditions that prevailed in the region from 1930 to 1965. These trend patterns can therefore only be considered to be a gradual recovery from extreme drought conditions that peaked during the 1983-1985 period. Systematic studies of changes on the landscape using high spatial resolution satellite data sets such as those from LANDSAT, SPOT and MODIS will provide a detailed spatial quantification and description of the recovery patterns at local scale.

Abstract: Concerns about biodiversity preservation through grazing have revived interest in feeding choices made by herbivores. In this article, we study the dynamics of behavioural intake response in heterogeneous vegetation, where the size and quality of edible plants is highly diverse and varies from day to day as a result of grazing. We conducted two experiments with ewes grazing in paddocks located in shrubby rangelands. A direct in situ observation method was used, with continuous observation of ingestive bites taken by a continuously monitored individual. A bite coding-grid enabled us to distinguish the extreme diversity between bites masses and structure, including the ones resulting from plant depletion. Flock activities were also scan-sampled. Observations were made throughout complete paddocking sequences, which lasted for about two weeks. Grazing seriously depleted the paddocks since 75-95% of the herbaceous species was consumed. No trend was detected either in daily activity patterns or in intake time-budgets. These two variables were well synchronised between the continuously monitored individuals and their respective flocks. No inter-day trend was observed for dry matter daily intakes, which was twice higher than predictions from existing models on sheep intake. Our data enabled us to explore the relationship between the diversity of instantaneous feeding choices and the quantitative daily intake. On the instantaneous scale (20 160;s), we confirmed the functional relationship between bite mass and bite frequency. Little variation was observed in daily averages of ingestive behaviour components. But these averages hide the extremely large range of instantaneous values (from 0.04 to 1.2 160;g DM for bite mass). When vegetation size and structure declined as a result of grazing, the ewes progressively took larger bite masses with equivalent nutritive quality, thus adopting a pattern of consumption that is not consistent with the general assumption that such bites are chosen during the first day, as a result of the behavioural quantity-quality trade-off. This article provides knowledge about which type of diversity in plant parts size, structure and composition offers a small ruminant satisfying behavioural leeway in composing its meals and reaching physical satiety. We tend to discard pastoral management practices focused on biomass evaluation, and encourage further studies that will help qualify the nature and structure of vegetation that offers adjustment possibilities at both the individual and flock levels.

Abstract: A strategy for rehabilitating degraded or unproductive native grassland is the establishment of improved pastures to sequester organic carbon (OC) in the soil. Microbial biomass C, N and P are the most biologically active fraction of soil OC, and are thus, useful indices for assessing the health of soil ecosystems. The impact of improved grass pastures and a legume pasture on microbial biomass C, N and P in a savanna soil at Shika (Lat. 11 176;11 039; N and Long. 7 176;38 039; E), in northern Nigeria, was studied. The objective was to determine the pasture plant that best improved the microbial properties of the soil. Five managed pasture fields, consisting of Andropogon gayanus Kunth., Brachiaria decumbens Stapf., Chloris gayana Kunth., Digitaria smutsii Stent. and Stylosanthes guianensis (Aubl.) Sw., were sampled for the study. The concentration of OC in the field under B. decumbens was nearly twice (23.9 160;g 160;kg-1) the concentration in other fields (13.1-14.6 160;g 160;kg-1). The field under D. smutsii had significantly higher microbial biomass C (MBC) than other fields as determined by fumigation-extraction method, and MBC accounted for between 1.5 and 3.9% of OC in the soil. Microbial biomass N (MBN), ranged from 41 to 119 160;mg 160;kg-1 and microbial biomass P (MBP) from 22 to 113 160;mg 160;kg-1. The fields under S. guianensis and D. smutsii had significantly greater MBN and MBP than the other fields. The MBN accounted for between 3 and 10% of total N, while MBP accounted for between 19 and 75% of organic P (Po). D. smutsii and S. guianenesis had the most significant impact on microbial C, N and P, whereas B. decumbens sequestered more OC in the soil. Thus, D. smutsii and B. decumbens are two promising grass pastures that can be established to rehabilitate degraded or unproductive savanna lands.

Abstract: The Blantyre City Area is part of the African savanna in southern Malawi. Sedimentological, geomorphological, chemical and mineralogical studies were conducted to create a lithofacies terrain model. The project involves mapping, cross-sectioning, grain size, heavy mineral analysis, XRD and the study of sedimentary textures under the petrographic microscope. These classical techniques were combined with GIS-based field and office works. The combined efforts led to 2-D maps and 3-D block diagrams that illustrate the geomorphological and sedimentological evolution of the landscape in southern Malawi during the late Mesozoic and Cenozoic. The results obtained through integrated geomorphological-sedimentological studies form the basis for land management (planning of residential areas, waste disposal sites, assessment of bearing capacity of rocks), geohazard prediction (delineation of high risk zones in terms of mass flow and inundation) and the evaluation of high-place (ceramic raw materials) and high-unit value (placers of precious metals and gemstones) mineral commodities in the study area. The study addresses regional and general aspects alike. In regional terms, the study aimed at unraveling the evolution of landforms at the southern end of the East African Rift System during the most recent parts of the geological past. Four stages of peneplanation were established in the working area. Planation was active from the Cretaceous to the Quaternary (stage I: early to mid-Cretaceous, stage II: early Tertiary, stage III: early to mid-Tertiary, stage IV: mid- to late Tertiary). During the most recent parts of the Quaternary, strong fluvial incision was triggered by the base-level lowering of the Shire River. Geomorphological alteration of the landscape goes along with a phyllosilicate-sesquioxide transformation from minerals indicative of more acidic meteoric fluids (e.g., gibbsite, kaolinite) to those typical of more alkaline conditions (e.g. smectite, vermiculite, hydrobiotite). In addition, the investigation is to provide some characteristic features suitable for the recognition and interpretation of terrestrial environments resembling the present-day savanna in the ancient sedimentary record: (1) Conspicuous bimodality in the grain-size distribution. (2) High degree of gravel roundness. (3) Boulder fields (basal conglomerates) with fitting breccias and no rotation of structural elements. (4) Poor to very poor sorting of siliciclastics. (5) Stratification is rare; if present only in sandy beds with antidune and tabular cross-bedding at low angle prevailing over cross-bedding at high angle. (6) Grading rare; in arenaceous deposits poorly developed FU sequences, in rudites poorly developed CU sequences, locally with surface armoring. (7) Directional sedimentary structures in coarse-grained deposits are unimodal. Fabric types: a(t)b(i) and a(p)b(i); shear planes indicative of slide may be present. (8) Ribbon-shaped architectural elements prevail over channel-like types. Bounding surfaces/unconformities are uneven to wavy and more widespread than scour-and-pool structures. (9) Fine-grained carbonaceous interbeds are restricted to shallow depressions. (10) Etch marks such as tafonis, flutes, honeycomb textures are common. (11) Placer deposits of metallic and non-metallic mineral commodities are abundant. (12) Alucretes and ferricretes of bog iron (ferrihydrite > goethite) and lateritic (goethite > ferrihydrite) types are common, calcitic freshwater limestones and gypcretes are scarce. (13) Kandite-group minerals "in" (relic), smectite-group minerals "in", vermiculite "in" (recent), mica-group minerals "out".

Abstract: The effect of three ant species (Lasius flavus, Formica spp., Tetramorium caespitum) on soil seed bank formation was studied in temperate mountain grassland. Seed removal experiments, analysis of soil seed content and seed survival experiments were carried out to evaluate the influence of ground ants on the seed fate. In the seed removal experiment seeds of 16 species, including 5 species with elaiosome-bearing seeds (myrmecochores), were exposed and their removal followed for 39 h. On average, ants removed 63.8% of myrmecochorous seeds and 10.9% of seeds without adaptation to ant dispersal. Analysis of soil seed content revealed that myrmecochores, in spite of expectations that they would accumulate in nests of seed dispersing ants, were most abundant in the soil of control plots. Evidence on seed relocation to the ant nests was obtained from a comparison of mounds of seed dispersing and seed non-dispersing ant species, as more seeds were found in the mounds of Formica spp. and Tetramorium caespitum (seed dispersers) in comparison with the mounds of Lasius favus (non-disperser). The soil seed bank of the compared microhabitats (control plots and mounds of 3 ant species) differed in their species composition, seed abundance and vertical distribution. The most distinct qualitative differences were between seed flora of control plots and mounds of Tetramorium caespitum. Control plots had approximately 30,000 propagules per m2, which was double the number of seeds found in the ant mounds. In control plots, abundance and diversity of seeds steeply declined with depth; this trend was not observed in the mounds probably due to bioturbation. In the seed survival experiment, more seeds (2 out of 3 species) survived in control plots, which may also contribute to the higher seed abundance in this microhabitat. This study showed that seed relocation by ants does not contribute significantly to seed bank build-up at this study site. Ants may, however, increase the regeneration success of myrmecochores, mainly by dispersal for distance and placement in a larger spectrum of microsites, in contrast to species not adapted for myrmecochory.

Abstract:

Abstract: This study addressed the effect of landscape attributes and plant community type on the spatial distribution of soil chemical properties in an alpine rangeland in a semiarid area of Iran. To identify the effects of landscape attributes on soil chemical properties, the present study collected and analyzed information from air photos, satellite images, field survey, and the laboratory using statistical analyses. Land stratification allowed the study area to be subdivided into Land Unit Tracts (LUT), according to specified criteria including landform attributes (slope, aspect, and altitude), and vegetation type. A factorial model on the basis of a completely randomized design was used to analyze the data collected from 234 LUT. The interrelationships between soil chemical properties and landscape attributes were investigated and interpreted based on statistical analysis and expert knowledge. Most chemical properties of the 0- to 10-cm topsoil including EC, OC%, total N%, P, and K significantly related to slope gradient. Soil chemical properties including the grouping described as nutrient elements (CEC, N, P, K, and OC), and pH significantly related to aspect of slope. In addition lower soil temperature and less moisture evaporation on a north-facing slope (shady aspect) resulted in less organic matter decomposition and consequently more organic carbon and total nitrogen accumulation in the soil. Consequently, the soil nutrient pool and general fertility on north-facing slopes was greater than on south-facing slopes. The interdependency of landscape attributes, plant community, and soil chemical properties led to a variety of species, vegetation types, and plant communities existing in the study area. In this research, vegetation type was highly significantly related to all the determined soil chemical properties except for cation exchange capacity.

Abstract: Nitrogen fertilization of rangelands in order to increase dry matter yield results in a decrease in legume ratios in botanical composition, which reduces forage quality. The objectives of the present study therefore were to investigate whether this negative effect of N fertilization on forage quality can be compensated by additional P application and also to determine the optimum fertilizer doses in rangelands to obtain economical benefits. Therefore, 0, 60, 120, 180 160;kg N 160;ha-1 and 0, 26, 52 160;kg P 160;ha-1 fertilizer rates were applied each year over a period of 3 years to 12 plots within each of 4 blocks. Botanical composition of the plots was determined and classified as grass, legumes and others for each treatment group based on dry weights. Dry matter yield, crude protein concentration and crude protein yield in treatment groups for each year were determined. Consequently, averaged over the 3 years of experimental period, nitrogen fertilizer increased the dry matter yield. The dry matter yield was 1467 160;kg 160;ha-1 in control plot, while it increased up to 3293 160;kg 160;ha-1 in plot applied with 180 160;kg N 160;ha-1 without P. Nitrogen fertilization slightly decreased the crude protein concentration in the forage dry matter from 120 160;g 160;kg-1 in the non-fertilized control to 103-116 160;g 160;kg-1 in the plots fertilized only with nitrogen. This effect can be explained by the observation that the nitrogen fertilization resulted in a decline of the legume proportion from 47% in the non-fertilized control to 5% with the highest N rate. The protein concentration in legume plants was always considerably higher than that in the grass and other species. Applying additional phosphorus compensated this negative effect of the nitrogen fertilization on the forage quality in terms of protein concentration. The economic optimum was found with the highest fertilizer doses providing 52 160;kg P 160;ha-1 160;+ 160;180 160;kg N 160;ha-1 producing 4810 160;kg 160;ha-1 forage dry matter with a crude protein concentration of 124 160;g 160;kg-1 and legume proportion of 12%.

Abstract: Two long-term mechanistic models of grazing systems in the semi-arid succulent Karoo have been used to study factors that influence vegetation changes, livestock productivity and sustainability of the ecosystem. In this region of low and highly variable rainfall, goats and sheep feed on vegetation comprising perennial shrubs and annuals. A previously published model of the Namaqualand system (the 34;standard 34; model) explicitly simulates three guilds of perennial shrubs, a guild of annuals, forage consumption, growth of goats and goat reproductive and survival rates. The model also simulates variable rainfall and predicts that, if no steps are taken to control the goat population, stock numbers will vary widely between years and the population of the different plant guilds will fluctuate. Plots of model output indicate that the system is driven by rainfall. Temporal changes in the relative abundance of each guild vary with different sequences of rainfall having similar long-term mean and variability. A single run of the model may display equilibrial, disequilibrial and threshold behaviour. Thus, the system exhibits complex dynamics. If animal numbers are held constant at the long-term average of variable stock or at the recommended stocking rate then the cover of palatable shrubs decreases and that of toxic plants increases substantially. A 34;simplified 34; model based on an aggregated forage variable and equilibrium dynamics is inadequate to describe the behaviour of this system.

Abstract: Prosopis caldenia Burk. is one of the woody species that is increasing in abundance due to poor grazing management in the semi-arid phytogeographic region of central Argentina, commonly known as the Caldenal. The objective of this study was to evaluate the effect of herbaceous cover, cattle dung, soil disturbance, and water supply on emergence and survival of P. 160;caldenia seedlings on sites with different grazing histories: (i) a site exposed to long-term continuous grazing by cattle (grazed site), and (ii) a long-term exclosure to domestic livestock (ungrazed site). Removal of grass cover, addition of cattle dung, and water supply enhanced seedling emergence and survival, especially in the grazed site. Results suggest that factors (direct and indirect) associated with prolonged grazing history markedly affect P. 160;caldenia establishment. This in turn alters the grass-woody plant balance, which might reduce the potential capacity of livestock production in the Caldenal.

Abstract: NASA’s flagship Earth Observing System (EOS) Terra satellite was launched in 1999 and began sensing in March 2000 coincident with the first major field campaign of the Southern Africa Regional Science Initiative (SAFARI 2000). Terra’s five sensors were used to support SAFARI 2000 studies on the southern African environment, and SAFARI 2000’s ground, aircraft and independent satellite data sets were used in turn to validate and improve the remote sensing products derived from Terra. In this article, we review southern Africa’s natural and cultural features that we believe formed an optimal environment in which to test the EOS program (including new sensors, products, validation, scientific research, education and outreach). Through the course of the text, we reference and summarize the articles in the SAFARI 2000 Special Issue to highlight the natural links between remote sensing science and the subcontinent’s characteristics. We also note contemporary forces of change in the southern Africa landscape whose impacts will challenge the remote monitoring capabilities of future sensors and scientists. The article concludes with a brief description of SAFARI 2000 data resources and access provisions.

Abstract: Stable carbon ([delta]13C) and nitrogen ([delta]15N) isotope ratios are commonly used to reconstruct palaeodiets and palaeoenvironments. The method is based on our knowledge of isotopic patterns in plants, which are subject to taxonomic and environmental variability. While previous researchers have addressed isotopic variability amongst plants, no studies have looked extensively at a broad suite of taxa over multiple temporal scales from within the savanna biome so as to provide baseline data for palaeodietary and palaeoenvironmental studies. Here we document variations in the isotopic compositions of plants collected over two years from the Kruger National Park, South Africa, with respect to species and anatomical differences, and the influences of geological substrate and spatio-temporal shifts in climate. Results show that environmentally-induced carbon isotopic variations in plants within this region are generally smaller than 2[per mille sign], which is lower than what has been previously reported for plants compared across multiple habitat-types. These data suggest that [delta]13C differences of 2[per mille sign] or more (or 1[per mille sign] if the diet is predominantly C4) between animals from a given area reliably indicate real dietary differences. Plant [delta]15N values vary greatly between different microhabitats (by up to 4[per mille sign]), responding to a range of environmental influences that may, in turn, significantly influence variation in animal [delta]15N values.

Abstract: Hyperseasonal savannas are characterized by the alternation of two contrasting stresses during each annual cycle, one induced by drought and fire and the other by waterlogging. In South America, the largest savanna region is the Brazilian cerrado, in which there are few hyperseasonal areas. Our aim was to study temporal changes in some community descriptors, such as species density, plant density, basal area, cylindrical volume, diversity, and evenness, in a hyperseasonal cerrado at four different seasons in the year. We placed randomly ten 1 m2 quadrats in an 1-ha area, in which we sampled all vascular plants. We used one-way analyses of variance to test for differences among the seasons. We found in all seasons high cover values of the cespitose grass Andropogon leucostachyus Kunth, which is the dominant species in the hyperseasonal cerrado. Waterlogging caused a decrease in species density, diversity, and plant density, but not in evenness, basal area, and cylindrical volume. The low values of species and plant densities in the waterlogging period may indicate the non-adaptation of most cerrado species to waterlogged conditions. The many savanna plant responses to environmental perturbations may explain the persistence of savanna communities within a broad range of environmental variation. Waterlogging may act as an environmental filter, restricting the number of cerrado species able to stand that condition.

Abstract: The sustainability of introduced technology in rural contexts is based on the socioenvironmental networking of local stakeholders, a point generally ignored in Ghana. A case study is given of an irrigation project from the coastal savanna of Ghana, a region appraised by contested assessments of drought and social conflict. Using a methodology based on a strand of actor network theory (ANT), including social surveys, meteorological and field data, it is concluded that such analyses of spatial linkages, serve as an effective methodology for assessing technological developments and socio-cultural contexts of various scales, and has applied relevance for environmental and development planning.

Abstract: The sustainability of introduced technology in rural contexts is based on the socioenvironmental networking of local stakeholders, a point generally ignored in Ghana. A case study is given of an irrigation project from the coastal savanna of Ghana, a region appraised by contested assessments of drought and social conflict. Using a methodology based on a strand of actor network theory (ANT), including social surveys, meteorological and field data, it is concluded that such analyses of spatial linkages, serve as an effective methodology for assessing technological developments and socio-cultural contexts of various scales, and has applied relevance for environmental and development planning.

Abstract: The ability of simple plant traits used as surrogate of species to reflect environmental variability of grasses and herbs in a West African savanna subject to fallow land rotation is assessed by referring to plants' functional attributes. The aim is to determine the nature and the importance of the loss of information associated with the trait-vs.-species simplification. The traits selected are easily observable and widely documented. They are related to plant responses to resource availability, environmental constraints/disturbances and to plant palatability and capacity to disperse. The co-inertia analyses of both species-environment and traits-environment are compared. Although selected traits account for only a part of the variability recorded by species, they are relevant and most of them have an ecological significance. Syndromes of attributes that reflect the functional plant-environment relationships of the grass layer along a twofold gradient of soil fertility and woody cover could then be established. Periodic clearing and soil fertility decline produced by the fallow system determine vegetation types dominated by herbaceous species ranging from competitive and ruderal-competitive on fertile and wooded sites to stress-tolerant ruderal on unfertile and non-wooded sites. Thus, selected traits do not reveal all functional aspects of the relationships of savanna plants to their environment, such as soil hydromorphy and depth of the clayey horizon. That is possibly due to the scarcity of traits that characterize the root system involved in the analysis.

Abstract: Development of biological control agents for weeds has been motivated by the need to reduce the abundance and distribution of a pest plant where chemical and mechanical control were not cost effective. Primary objectives have been direct reduction in abundance of the target and, secondarily, the increase of desirable species. Recently, wildland weeds have become a focus of biological control projects. Here, desired outcomes include both reduction of the target and indirect effects of increased diversity and abundance of native species and restoration of ecosystem services. However, goals and benefits of biocontrol programs are not always well-articulated and direct and indirect impacts are not easily predicted. We evaluated the extent to which several successful biological control projects for weeds of rangelands and waterways measured indirect impacts on invaded ecosystems. We also examined biocontrol of a wildland pest tree for which the principal objective is restoration of ecosystem services. We found few quantitative assessments of the impacts of pest plant reduction on community composition or ecosystem processes. All examples documented variation in the impacts of agent(s) across the invasive range of the target plant as well as variation in impacts on the invaded ecosystem. However, without appropriate quantitative information, we cannot evaluate site characteristics that may influence vegetation responses. Most successful weed management programs integrated the use of biocontrol agents with other weed management strategies, especially modifications of disturbance and competing vegetation. Discussion and evaluation of responses of nontarget species would improve our understanding of the context-specificity of outcomes.

Abstract: The paper is a response to the surprise with which some policy makers responded to news that greening had been detected in the Sahel. It first views Sahelian environmental change and related policies through the lenses of scientific models of pastoral and agricultural systems. For pastoralism, the lenses are models of equilibrial ecology, those of state-and-transition and those of more recent development. For agricultural systems, they are models of commercialization, modernization and degradation, and those that stress the endogenous development of peasant agriculture. The conclusions are that little, if any, of the recent greening, if and where it has occurred, could be attributed to policy; and that as yet neither models nor interpretations of the satellite imagery yet give firm guidelines for policy. Nonetheless, the review suggests a lesson for the development of policy: it needs to be more dynamic, and in three contexts: (1) the contingencies of pastoral and agricultural economies; (2) continual and sometimes drastic changes in the environment; and (3) changes in political, social, economic and scientific ideas. But policy must retain consistency, and be attuned to the global as well as to local context.

Abstract: Arid vegetation is subjected to more or less frequent fire, drought, and sporadic flooding events and grazing. Whilst fire, drought and grazing have been the subject of considerable research, little is known of the impact of flooding in arid environments. In this study we examined opportunistically the effects of a flooding event, and its interaction with fire and grazing on moulding arid vegetation in New South Wales, Australia. We assessed vegetation approximately 2 and 5 years after recession of the water in fenced and unfenced plots subjected to different combinations of flooding and fire. Number of species per area dropped from 11.8 to 5.7 per 625 m2. Vegetation in plots left open to grazing by vertebrates differed from fenced plots, but the amount of variation explained was small compared with flooding and the change over time. The taxa mostly associated with flooding were Eragrostis spp., Pseudognaphalium luteoalbum and the exotic Nicotiana glauca. Major flooding events not only trigger native species' germination and recruitment but may also create an avenue for exotic species to invade.

Abstract: Invasions of Pinus species are a major environmental concern in South Africa and New Zealand where pines are beginning to dominate native grasslands and shrublands. Pines are widely cultivated in Australia with almost a million hectares growing in large plantations. Plantations are commonly bordered by native Eucalypt vegetation resulting in a high potential for invasion and providing an opportunity to study pine invasion processes within forest environments. In order to determine if Pinus radiata equally invades different dry Eucalypt woodland vegetation types, two areas in the upper Blue Mountains in New South Wales, Australia were surveyed. Similar levels of invasion were observed in both Eucalypt forest types. An average pine abundance of 55 individuals for the Eucalyptus oreades and Eucalyptus sieberi vegetation type and 49 individuals for the Eucalyptus mannifera and Eucalyptus dives vegetation type was recorded in 20 m by 20 m plots located 50 m from the plantation boundary. To characterise the spatial distribution of the pines, transects were placed perpendicular to the plantation edge. As expected pine numbers diminished with distance from the plantation, however, large reproductive pine trees were found up to 4 km from the seed source signifying long distance dispersal. Investigation of wildling pine response to fire suggests that it may not always be an appropriate management tool. Fire stimulated seed release from cones and resulted in high recruitment of seedlings around reproductive pines which were large enough to survive the burn. Infrequent fires at intervals greater than time to maturity will lead to increased pine densities and further spread into the native vegetation.

Abstract: Pollen analysis of a 12.8-m-long core (R96-I) from the southern basin of Lake Rukwa (Tanzania, 8°S, 33°E, 793 m a.s.l.) provides new information on the vegetation history of central eastern Africa and on lake level fluctuations in response to climate changes during the last 23,000 cal yr BP. Between 23,000 and 20,000 cal yr BP (the Last Glacial Maximum), the occurrence of open and poorly diversified local woodland and bushland around the lake, and the significant presence of modern regional afromontane forest components close to Lake Rukwa, indicate cooler and probably drier climatic conditions than today. The deglacial period, between 16,500 and 12,300 cal yr BP, characterised by a retreat of montane elements at higher altitudes on the plateau, under warmer conditions, synchronous with a progressive expansion of local more wooded formations, appears to be climatically transitional, but the permanence of swampy environments near the core site indicates that the lake remained low. From 12,100 cal yr BP, the maximum development and diversity of local woodland and bushland implies an increase in rainfall that persisted until 5500 cal yr BP. More humid conditions are confirmed by the lowest representation of aquatics registered in our pollen sequence, indicating that, during this period, Lake Rukwa was high. After 5500 cal yr BP, a deterioration of the regional and local arboreal cover, the large extension of grasses and of swampy environments near the core site, indicate the progressive establishment of drier conditions in the basin. The aridification trend intensified ca. 3500 cal yr BP toward modern conditions. These palaeobotanical reconstructions in the Lake Rukwa basin for the last 23,000 cal yr BP supplement those previously proposed in central eastern Africa between 4° and 13°S from more incomplete or less well age-constrained pollen sequences.

Abstract: This paper reviews the predictions and management implications of two current paradigms in the ecology and management of arid and semi-arid rangelands. The equilibrium model stresses the importance of biotic feedbacks such as density-dependent regulation of livestock populations and the feedback of livestock density on vegetation composition, cover and productivity. Range management under this model centres on carrying capacity, stocking rates and range condition assessment. In contrast, non-equilibrium rangeland systems are thought to be driven primarily by stochastic abiotic factors, notably variable rainfall, which result in highly variable and unpredictable primary production. Livestock populations are thought to have negligible feedback on the vegetation as their numbers rarely reach equilibrium with their fluctuating resource base. Recent studies suggest that most arid and semi-arid rangeland systems encompass elements of both equilibrium and non-equilibrium at different scales, and that management needs to take into account temporal variability and spatial heterogeneity.

Abstract: Relatively little is known about soil organic carbon (SOC) dynamics in montane ecosystems of the semi-arid western U.S. or the stability of current SOC pools under future climate change scenarios. We measured the distribution and quality of SOC in a mosaic of rangeland-forest vegetation types that occurs under similar climatic conditions on non-calcareous soils at Utah State University's T.W. Daniel Experimental Forest in northern Utah: the forest types were aspen [Populus tremuloides] and conifer (mixture of fir [Abies lasiocarpa] and spruce [Picea engelmannii]); the rangeland types were sagebrush steppe [Artemisia tridentata], grass-forb meadow, and a meadow-conifer ecotone. Total SOC was calculated from OC concentrations, estimates of bulk density by texture and rock-free soil volume in five pedons. The SOC quality was expressed in terms of leaching potential and decomposability. Amount and aromaticity of water-soluble organic carbon (DOC) was determined by water extraction and specific ultra violet absorbance at 254 nm (SUVA) of leached DOC. Decomposability of SOC and DOC was derived from laboratory incubation of soil samples and water extracts, respectively. Although there was little difference in total SOC between soils sampled under different vegetation types, vertical distribution, and quality of SOC appeared to be influenced by vegetation. Forest soils had a distinct O horizon and higher SOC concentration in near-surface mineral horizons that declined sharply with depth. Rangeland soils lacked O horizons and SOC concentration declined more gradually. Quality of SOC under rangelands was more uniform with depth and SOC was less soluble and less decomposable (i.e., more stable) than under forests. However, DOC in grass-forb meadow soils was less aromatic and more bioavailable, likely promoting C retention through cycling. The SOC in forest soils was notably more leachable and decomposable, especially near the soil surface, with stability increasing with soil depth. Across the entire dataset, there was a weak inverse relationship between the decomposability and the aromaticity of DOC. Our data indicate that despite similar SOC pools, vegetation type may affect SOC retention capacity under future climate projections by influencing potential SOC losses via leaching and decomposition.

Abstract: Existing projections of the optimal share of carbon sequestration in an overall portfolio of greenhouse-gas mitigation strategies almost all assume the carbon price to be constant over time. This paper shows analytically that if the price instead increases over time--consistent with projections from integrated assessment models--it becomes optimal to delay certain sequestration projects, whereas the optimal timing of energy-based abatement projects remains unchanged. As a result, the optimal share of sequestration falls, and significantly so. Calibrating our analytical model, we find that a modest, 3% rate of price increase results in about a 60% reduction in the optimal sequestration share relative to constant-price projections. Numerical simulations based on predicted carbon-price paths from Nordhaus' RICE01 model indicate quantitatively similar reductions under an economically efficient scenario, and much larger reductions (80-100% for up to 80 years) under a scenario that aims to limit the atmospheric CO2 concentration to double its pre-industrial level.

Abstract: Local communities use an indigenous classification of environmental land units for natural resource management in central north Namibia. These indigenous land units (ILUs) were compared with a conventional vegetation analysis to improve understanding by scientists. The indigenous classification is based on many criteria. Detrended correspondence analysis was carried out on 388 vegetation samples, collected in a participatory way. The ordination diagrams of species and samples were a good reflection of ecological variation in the area. The data were used to draw sample standard deviation ellipses around the average ILU score. Classes with highly ranked vegetation criteria had little overlap with each other, while classes with no vegetation criteria often had large overlaps with other land classes. Advantages and disadvantages of working with indigenous environmental knowledge are discussed.

Abstract: The construction and validation of a user-friendly index to measure attitude of landowners towards conservation of Overberg Coastal Renosterveld (OCR), a critically endangered, distinctive grassy-shrubland in South Africa is reported. An iterative item reliability analysis was executed on questionnaire data from a random sample of 36 private landowners in the Overberg region of the Western Cape, using Spearman Rank Order correlations and Cronbach's Alpha. Results yielded an index with two dimensions and a Cronbach Alpha co-efficient of 0.67. Dimensions of conservation attitude towards renosterveld included: (i) landowners' perception of the benefit of Coastal Renosterveld; and (ii) willingness to conserve it. The mean conservation attitude score was 0.6 (±0.03), while minimum and maximum scores were 0.22 and 1.0, respectively, indicating that landowner attitudes were generally sympathetic towards OCR conservation. The following variables had significant associations with conservation attitude: (i) area of renosterveld; (ii) landowner environmental group membership status; (iii) presence of ecotourism activities on the property; and (iv) how long the property had been in the owner's family. Index scores can assist conservation practitioners to prioritise resources, on the assumption that high-scoring individuals are more likely to participate in conservation initiatives.

Abstract: This paper explores the physical and imaginative construction of the Zimbabwean [`]lowveld' landscape. A powerful legacy of the colonial encounter with Zimbabwe was the notion that the lowveld is a wilderness. This logic underpinned attempts to preserve or rehabilitate parts of the lowveld landscape as pristine and glorious pieces of national heritage and, more recently, attempts to exploit sustainably [`]wilderness quality' and wildlife. The landscape has been physically modified accordingly - often to the detriment of many of its inhabitants. This has played out in oxymoronic attempts to manufacture wilderness in a national park, conservancies and game ranches. But this vision has recently come under its most severe attack to date as these new wildernesses have been re-peopled, and the politics of land and the needs of black smallholders, pushed to the top of the national agenda. The land occupations since 2000 by both state-sponsored war veterans and peasant farmers have revealed starkly contrasting ways of seeing and understanding this landscape which have radically different implications for conservation and development policy.

Abstract: An investigation into the spread of two alien wattle species (Acacia mearnsii and Acacia dealbata) in rural parts of the Drakensberg region of South Africa and the importance of the trees to the livelihoods of the local communities was carried out. With the aid of aerial photography two plots near the village were selected. Wattle aerial cover increased from 7% and 20% in the two plots, respectively, in 1953, over 21% and 33% in 1975, to 48% and 58% in 2000. In 1995, a government-sponsored national programme, "Working for Water" was established, with the expressed purpose of employing people described as being from the poorest and disadvantaged rural communities to clear areas of invasive alien species from river catchments and water courses. Whilst the programme provides an income to thousands of families in rural areas, it may also be jeopardising the livelihoods of the same communities. The wattle is an important resource for village households; virtually all households used it as their primary heat source and for building materials. Other uses included medicine extraction and 20% of the interviewed households gained income from selling firewood. From the rural communities' perception, the greatest concern regarding the alien species is its high water consumption (although this did not affect them directly), and the fact that it provides cover to thieves and criminals. Consequently, most villagers wanted either a reduction of the wattle stands (58% and 86% in the 2001 and 2003 study, respectively), or that they remained as at present (42% and 10%, respectively). Leaves from woody legumes have demonstrated large potential as green manures and fodder providers in many agroecosystems. The abundance of the wattle in the study area suggested an exploration of alternative beneficial uses in the low input farming systems practiced. The wattle's potential as green manure was evaluated in a decomposition trial. In all treatments, the wattle litter immobilised nitrogen from soil, in spite of a high N content of the litter. Plant available P increased in soil after 4-5 months of incubation. We argue that the current practice of externally funded wattle control is not sustainable in the long term. We discuss alternative approaches with a higher level of community participation and ownership, and conclude that the current underutilization of land may, ironically, be one of the largest constraints for a viable solution to the spread of wattle.

Abstract: Basin sediment yield is the product of all sediment producing processes and sediment transport within a basin. Consequently, the prediction of basin sediment yield should take into consideration all different erosion and sediment transport processes. However, traditional physics-based, conceptual, and empirical or regression models have not been able to describe all these processes due to insufficient systems knowledge and unfeasible data requirements. Therefore, the applicability of these models at the basin scale is troublesome. This paper first illustrates the relation between basin area, dominant erosion processes, and sediment yield by a combination of measured sediment yield at different spatial scales in Mediterranean environments. This clearly reveals that soil erosion rates measured at one scale are not representative for sediment yield at another scale level. Second, the most important semi-quantitative models developed for erosion and sediment yield assessments at the basin scale are reviewed. Most of these models use environmental factors to characterise a drainage basin in terms of sensitivity to erosion and sediment transport. Six of the nine models discussed (PSIAC, FSM, VSD, Gavrilovic, CSSM, WSM) include sheet-, rill-, gully, bank erosion, landslides, and connectivity, at least partly, in the assessment of basin sediment yield. The low data requirements and the fact that practically all significant erosion processes are considered makes them especially suited for estimating off-site effects of soil erosion. The other three models (EHU, CORINE, FKSM) focus mainly on sheet and rill erosion and provide quantitative descriptions of the sensitivity to erosion at basin or even regional scales. These models thus focus mainly on on-site problems of soil erosion. Most of the semi-quantitative models might benefit from a more quantitative description of factors used to characterise the basin. Though an equilibrium should be found between the extra effort and increase in model performance, the increased availability of spatially distributed topographic data as well as high-resolution satellite imagery will probably make this feasible in the near future.

Abstract: Prosopis caldenia Burk. is one of the woody species increasing in abundance due to poor grazing management in the semi-arid regions of central Argentina. The objective of this study was to evaluate the effect of herb cover, cattle dung, soil compaction, and water supply on P. caldenia seedling growth on sites with different grazing history: a site exposed to a long-term (25 or more years) continuous grazing by cattle (grazed experimental site), and a site long-term (around 20 years) exclosure to domestic livestock (ungrazed experimental site). In both experimental sites, regardless of the study period, the highest height and main root length of P. caldenia seedlings were recorded in plots with the herb cover removed, soil disturbed, cattle dung presence, and water supply. Above- and below-ground biomass of P. caldenia seedlings showed a similar response. Direct and indirect effects of livestock grazing favoured P. caldenia seedlings growth, which might increase their establishment probabilities in sites under a chronic heavy grazing. Consequently, this might alter the grass-woody plant balance in the Caldenal causing a drastic reduction of the domestic livestock production in the region.

Abstract: In Morocco the crisis narrative of desertification has been invoked for decades to facilitate and justify policy and legal changes that have systematically disadvantaged pastoralists and damaged the environment. The existing data from southern Morocco, however, do not support the claims of widespread desertification due to overgrazing or other pastoral activities. Furthermore, many anti-desertification and range improvement projects in southern Morocco have not succeeded. In an effort to rethink desertification and range ecology in Morocco, this paper presents an overview of the indigenous knowledge of range ecology among the Aarib, a group of camel pastoralists in southern Morocco, and compares it to the "expert" knowledge of Moroccan range managers. It suggests that this expert knowledge is based on questionable evidence and that it has been privileged over local knowledge primarily for political, economic and administrative reasons. The discrepancies between expert and indigenous knowledges of range ecology presented here underscore the need to reconsider range ecology in Morocco, taking indigenous ecological knowledge into account. Doing so may point the way to more successful development and conservation projects which are more environmentally appropriate and socially just. Not doing so will likely exacerbate environmental degradation in the region.

Abstract: The Bashang area, located in the semiarid agropastoral zone, represents a typical degraded ecosystem under intensified human activities. This region has undergone profound land use changes during the past century. Natural grasslands had been progressively cultivated, and subsequently, part of cultivated lands had been abandoned by farmers due to severe desertification. In this study, we collected soil samples (0-20 cm depth) from four farmlands on both flat and gentle slope lands where cultivation had occurred for 0, 8, 30, and 50 years to assess the effects of grassland cultivation on soil degradation. In addition, soil samples were taken and plant species were investigated from eight sites in age sequence of 0- to 50- year-old abandoned field to assess natural restoration process following field abandonment. The results showed that cultivation of grassland result in a significant soil degradation which is manifested by the coarsening in soil texture and the losses in organic C and nutrients. After 50 years of cultivation, soil organic C, total N, and total P concentrations had declined 73-79%, 60-70%, and 67-68% in the 0-20 cm plough layer, respectively. Over half of these losses occurred during the first 8 years of cultivation, and subsequent was slow. After fields were abandoned, vegetation got self-restoration, and plant species composition moved toward that of the natural grassland community with time. Soil organic C, total N, and total P levels gradually improved with increasing years of land abandonment, with a faster restoration rate in the early vegetation recovery stage and a slower rate in the late succession stage. The results suggested that soil degradation may occurred drastically by inappropriate land use and management with a short time, while soil restoration for a degraded ecosystem may take long period of time, especially in this fragile ecosystem. From the perspective of soil resource management and desertification control, conservational tillage and management for farmlands and proper grazing management for recovered grassland should be taken into account in this area.

Abstract: Competition and compatibility between livestock and wildlife in Africa has been a point of considerable speculation, with implications for conservation. However, controlled replicated experiments are lacking. Here we report on the results of a long-term exclosure experiment in Laikipia, Kenya, in which different guilds of large mammalian herbivores have been independently manipulated since 1995. In plots from which cattle were excluded, the density of zebra dung in 2000 was on average 46% greater than in control plots. This was due to differential zebra use, and not to differential rates of dung removal (by dung beetles or other factors). Vegetation data indicate that cattle fully compensate for the absence of wildlife; all plots accessible to cattle had similarly low grass cover. However, wildlife do not fully compensate for the absence of cattle; plots with only wildlife had more grass cover than plots accessible to cattle. Zebra dung density was strongly correlated with total grass cover, suggesting that zebras are effectively tracking resource abundance. There is also evidence of pair-wise competition between cattle and elephants, and between elephants and zebras. The strong competition between cattle and zebras appears to be mitigated by the presence of elephants. A significant cattle x elephant interaction on the abundance of zebra dung indicates that elephants reduce the negative effects of cattle on zebras. In the presence of cattle, elephants facilitate the abundance of zebra, apparently by suppressing resource extraction (bite rates) by cattle. The precise mechanism for this indirect facilitation is not clear, but it may be related to the demonstrated reduction in forb cover associated with elephant presence.

Abstract: We conducted a grazing experiment from 1992 to 1996 in Inner Mongolia to explore desertification processes of sandy rangeland. The results show that continuous heavy grazing results in a considerable decrease in vegetation cover, height, standing biomass and root biomass, and a significant increase in animal hoof impacts. As a result, small bare spots appeared on the ground and later merged into larger bare areas in the rangeland. Total bare area reached up to 52% and the average depth of wind erosion was 25 cm in the fifth year of the study. We conclude that sandy rangeland with wind-erodible soil is susceptible to desertification. Heavy grazing of such rangeland should be avoided.

Abstract: Publicly funded management programs can enhance important ecological services including watershed functions, wildlife habitat, and carbon sequestration. A mail survey was conducted in 2003 in the Western Edwards Aquifer area of Texas to assess landowner perceptions regarding the supply of ecological services from rangelands and their willingness to participate in various land management programs aimed at enhancing such services, which are receiving increasing public consideration. In general, landowners favorably viewed programs that would reduce woody plant (brush) cover in an effort to increase water yields or to improve wildlife habitat, but they disapproved of programs that would encourage the proliferation of woody plants in an attempt to increase atmospheric carbon sequestration. In addition, whether land management programs were voluntary or mandatory had a much greater influence on the level of landowner willingness to participate in programs than the availability of publicly funded cost-sharing. Three-fourths of respondents indicated they would be willing to enroll in cost-sharing brush management programs, and most viewed short-term (5-10 year) performance contracts as the most acceptable legal instrument for participating. To deal with ecosystem trade-offs resulting from woody plant management, we recommend that publicly funded programs aimed at enhancing ecosystem services through effective woody plant management should be flexible. In addition, we recommend the promotion of ecosystem level planning for such programs and cooperative management strategies for landowners participating in such program in order to maximize the effectiveness of associated public investments.

Abstract: Summary Seed dispersal via ingestion and defecation by large herbivores provides a possible aid for ecological restoration of plant communities, by connecting source communities of target species with habitat restoration sites. It is also a possible threat due to invasion of weeds, grasses or exotic species. Insight into the factors determining internal seed dispersal could therefore improve the management of grazed ecosystems. We recorded viable seed density in cattle, sheep and pony dung samples and monitored dung pat colonisation in the field. In addition, we counted the distribution of dung pats in plots spread over all habitat units in our study site. The three herbivore species appeared to disperse large quantities of many species (61 in total) from a variety of plant families, monocots as well as dicots. The density of viable seeds in herbivore dung and the colonisation of dung pats were positively correlated with Ellenberg nitrogen indicator values and seed supply, but not with seed mass or shape. The results imply that many seeds are dispersed from high productive to low productive parts of the grazed area. In free-ranging systems, we therefore recommend enclosure and separate management of plant communities on nutrient-poor soils with high conservation interest. For habitat restoration sites we recommend integrated grazing only with target plant communities on nutrient-poor soils and not with plant communities on nutrient-richer soils.

Abstract: Question: What is the long-term compositional response of brass and forb species to various combinations of burning and mowina? Can these responses be predicted from simple plant traits? Location: Ukulinga research and training farm (24 degrees 24'E, 30 degrees 24'S), Pietermaritzburg, KwaZulu-Natal, South Africa. Methods: Grass species relative abundance in 1996 in various buming and mowing treatments of a long-term (> 50 a) experiment was calculated from data obtained using a point sampling method, whereas forb species abundance in 1999 was determined using the importance score method. The experiment consisted of different frequencies (annual, biennial and triennial) of burning and mowing in winter or spring in combination with different frequencies of summer mowing (none, early, late or both). Results: Grasses responded to the type of disturbance (burn or mow) and frequency of burning, whereas forbs responded primarily to the presence or absence of any form of disturbance and secondarily to the timing of burning (spring versus winter). Summer mowing and annual or biennial dormant-period burning maintained communities dominated by short grasses, whereas tall grasses dominated under annual dormant-period mowing, triennial burning or protection from disturbance. Grass tittering strategy (below- or above-ground) influenced response to burning frequency. Many erect herbaceous dicot species with aerial meristems were reduced in abundance by summer mowing whereas most small creeping herbaceous dicot species appeared to be dependent upon summer mowing. Conclusions: This long-term experiment demonstrated that: (1) grasses and forbs responded differently to burning and mowing; (2) simple plant traits, such as height, position of tiller initiation, and position of meristems have potential for predicting the response of species to the timing and frequency of burning and mowing.

Abstract: Abstract Aim Using a long-term data set we investigated the response of semi-desert grasslands to altered disturbance regimes in conjunction with climate patterns. Specifically, we were interested in the response of a non-native grass (Eragrostis lehmanniana), mesquite (Prosopis velutina), and native species to the reintroduction of fire and removal of livestock. Location The study site is located on the 45,360-ha Buenos Aires National Wildlife Refuge (31°32′ N, 110°30′ W) in southern Arizona, USA. In 1985, livestock were removed and prescribed fires were reintroduced to this semi-desert grassland dominated by non-native grasses and encroaching mesquite trees. Methods Plant species cover was monitored along 38, 30-m transects five times over a period of 15 years. Data were analysed using principal components analysis on the variance–covariance and correlation matrix, multivariate analysis of variance for changes over time in relation to environmental data, and analysis of variance for altered disturbance regimes. Results Reintroduction of fire and removal of livestock have not led to an increase in native species diversity or a decrease in non-native grasses or mesquite. The cover of non-native grass was influenced by soil type in 1993. Main conclusions Variability of plant community richness, diversity, and cover over time appear to be most closely linked to fluctuations in precipitation rather than human-altered disturbance regimes. The effects of altered grazing and fire regimes are likely confounded by complex interactions with climatic factors in systems significantly altered from their original physiognomy.

Abstract: This study assessed the concentrations of crude protein (CP) and minerals in tef (Eragrostis tef) and grass pea (Lathyrus sativus) residues, noug seedcake (Guizotia abyssinica) and grass pea grain produced on Vertisols of the Ethiopian highland. Soil and feed N and minerals were determined from samples obtained from tef and grass pea crop fields as well as oil extracting plants. The concentration of Ca (16 g/kg), Na (274 mg/kg) (P < 0.001) and Fe (152 mg/kg) (P < 0.05) in grass pea haulm exceeded that of tef straw, while the reverse was noted for P and Mn (P < 0.001). Noug seedcake contained high concentrations of CP (328 g/kg DM) and P (12 g/kg DM), but had low concentrations of other minerals. Grass pea grain had high concentrations of CP (280 g/kg) and Fe (78 mg/kg). The K/(Ca + Mg) ratios of the evaluated feeds were favourable but their Ca:P ratios, with the exception of grass pea grain (1.06), were wide. A strong positive correlation was found between soil Na and the Na content of tef and grass pea residues. Soil P was also positively correlated with tef straw P. For N and the remaining minerals, the correlations between soil and crop residues were not significant (P > 0.05). It was concluded that the observed CP and mineral concentration differences between the examined feed sources can be exploited to ensure optimum supply of CP and most minerals, but Na and Cu deficiencies would likely limit production of animals relying on these feeds.

Abstract: Abstract. Question: What is the long-term influence of nutrient availability, productivity and soil pH on grassland community organization? Location: Ukulinga research farm, KwaZulu-Natal, South Africa. Methods: The influence of fertilization on soil pH, nitrogen (N) and phosphorus (P) on variation in plant traits, community composition and species richness were examined in a 50-year grassland fertilization experiment. Results: Averaged over 30 years, above-ground net primary production (ANPP) was 337, 428 and 518 g.m-2 in sites not fertilized, fertilized with N, and fertilized with N plus P respectively. ANPP depended directly on N-fertilization but not on P-fertilization or liming, and responded positively to the interaction of N (first limiting nutrient) and P (second limiting nutrient). Short narrow-leaved grass species — Themeda triandra, Tristachya leucothrix and Setaria nigrirostris — dominated sites of lowest ANPP where N was limiting (unfertilized, P-fertilized or limed sites). A tall narrow-leaved species, Eragrostis curvula, dominated sites of intermediate ANPP where P was limiting (N-fertilized sites). By contrast, a tall broad-leaved species, Panicum maximum, dominated the most productive sites where neither N nor P were limiting (N- and P-fertilized sites). Certain species responded to liming and type of N-fertilizer apparently because of their effects on soil pH. N-fertilization reduced the density of herbaceous dicots (forbs) from 14 (unfertilized) to two (high N, no P, no lime) and five species per m2 (high N, no P, limed). This effect was attributed to increased ANPP and a decrease in soil pH from 4.6 (KCl) in unfertilized sites to 3.49 (high N, no lime) and 4.65 (high N and lime). Soil acidification had no effect on grass species richness but influenced the abundance of certain species. Conclusions: Grassland community organization is determined not only by the influence of N availability, but also by the hierarchical interaction of N and P availability, in part through their compounded effect on ANPP, and by individualistic species responses to soil pH.

Abstract: A model of a plant community that is biologically reasonable and easily adaptable to economic models is presented. The model includes optimization, competition, stochastic limiting resources, and identification of redundant and invasive species. Species exhibit a rich array of traits that make them suited for some set of environmental factors and not for other sets. And because environmental factors are constantly changing, species that are very successful under one set of factors become redundant under another set, implying that an ecosystem needs redundant species as insurance. Invasive species are the flip side of redundant species as they are successful, at least under some environmental conditions. Identification depends on four physiological parameters defining each plant: two respiration parameters, a parameter that gives the plant's ideal level of the stochastic limiting resource, and the specific leaf area. The parameters are terms in an expression that gives the net energy intake of an individual plant, and the plant behaves as if it optimizes this by choosing its individual biomass. Success of species is judged based on the biomass of the species in steady state. An application extends the range management literature by incorporating the model into a rangeland manager's decision problem extends the range management literature. The model allows for multiple plant species, addresses the influence of limiting resources (other than density dependence), and tracks the response of the entire system to human and natural system perturbations. The methods allow simple predictions of community composition in the face of jointly determined economic/ecological behavior. The power of the method is demonstrated through stylized examples of alternative invasion control techniques.

Abstract: The [`]Sierra de Guara' Natural Park (81,491 ha, Huesca, Spain) is a protected Mediterranean mountain area dominated by shrub and forest pastures. Traditional agriculture, mainly extensive grazing systems, has decreased in the last decades; concurrently, invasion of shrub vegetation, landscape changes and higher risk of forest fires have been observed. A study, which started in 2000, was carried out with two broad objectives: at the farm level, to analyse the farming systems and evaluate management strategies; at the regional level, to give useful information to conservation authorities for better decision-making. An integrated approach with different spatial scales and methods of analysis was used. First, a survey covering all farms that utilized the Park was carried out and livestock farming systems were characterized in terms of grazing management, technical and socio-economic factors. Second, six representative areas were selected to evaluate, depending on livestock utilization, grass and shrub vegetation dynamics (biomass, green/dead ratio). Third, vegetation and livestock data were analysed using a Geographic Information System to identify constraining factors and areas of intervention. Key imbalances were identified that can threaten the sustainability of the Park: low continuity of farming families; intensification of the management system; degradation of grazing resources; and concentration of grazing areas. A number of management recommendations are raised.

Abstract: This paper explores local knowledge and practices in soil management and investment that have frequently gone unrecognised in assessments of soil fertility transformations and trends. Case material drawn largely from the Guinea savannas of West Africa is used to challenge the assumptions and methods that agronomists have been using to assess soil fertility transformations and trends. It outlines the need for an approach to the study of soil fertility that engages more comparatively with local knowledge, and appreciates the social and moral orders which shape the ways both African farmers and western agronomists use and understand soils.

Abstract: Abstract Carbon sequestration programs, including afforestation and reforestation, are gaining attention globally and will alter many ecosystem processes, including water yield. Some previous analyses have addressed deforestation and water yield, while the effects of afforestation on water yield have been considered for some regions. However, to our knowledge no systematic global analysis of the effects of afforestation on water yield has been undertaken. To assess and predict these effects globally, we analyzed 26 catchment data sets with 504 observations, including annual runoff and low flow. We examined changes in the context of several variables, including original vegetation type, plantation species, plantation age, and mean annual precipitation (MAP). All of these variables should be useful for understanding and modeling the effects of afforestation on water yield. We found that annual runoff was reduced on average by 44% (±3%) and 31% (±2%) when grasslands and shrublands were afforested, respectively. Eucalypts had a larger impact than other tree species in afforested grasslands (P=0.002), reducing runoff (90) by 75% (±10%), compared with a 40% (±3%) average decrease with pines. Runoff losses increased significantly with plantation age for at least 20 years after planting, whether expressed as absolute changes (mm) or as a proportion of predicted runoff (%) (P<0.001). For grasslands, absolute reductions in annual runoff were greatest at wetter sites, but proportional reductions were significantly larger in drier sites (P<0.01 and P<0.001, respectively). Afforestation effects on low flow were similar to those on total annual flow, but proportional reductions were even larger for low flow (P<0.001). These results clearly demonstrate that reductions in runoff can be expected following afforestation of grasslands and shrublands and may be most severe in drier regions. Our results suggest that, in a region where natural runoff is less than 10% of MAP, afforestation should result in a complete loss of runoff; where natural runoff is 30% of precipitation, it will likely be cut by half or more when trees are planted. The possibility that afforestation could cause or intensify water shortages in many locations is a tradeoff that should be explicitly addressed in carbon sequestration programs.

Abstract: In this paper, we describe a model designed to simulate seasonal dynamics of warm and cool season grasses and forbs, as well as the dynamics of woody plant succession through five seral stages, in each of nine different plant communities on the Rob and Bessie Welder Wildlife Refuge. The Welder Wildlife Refuge (WWR) is located in the Gulf Coastal Prairies and Marshes ecoregion of Texas. The model utilizes and integrates data from a wide array of research projects that have occurred in south Texas and WWR. It is designed to investigate the effects of alternative livestock grazing programs and brush control practices, with particular emphasis on prescribed burning, the preferred treatment for brush on the WWR. We evaluated the model by simulating changes in the plant communities under historical (1974-2000) temperature, rainfall, livestock grazing rotation, and brush control regimes, and comparing simulation results to field data on herbaceous biomass and brush canopy cover collected on the WWR over the same period. We then used the model to simulate the effects of 13 alternative management schemes, under each of four weather regimes, over the next 25 years. We found that over the simulation period, years 1974-2000, the model does well in simulating the magnitude and seasonality of herbaceous biomass production and changes in percent brush canopy cover on the WWR. It also does well in simulating the effects of variations in cattle stocking rates, grazing rotation programs, and brush control regimes on plant communities, thus providing insight into the combined effects of temperature, precipitation, cattle stocking rates, grazing rotation programs, and brush control on the overall productivity and state of woody plant succession on the WWR. Simulation of alternative management schemes suggests that brush canopy removal differs little between summer and winter prescribed burn treatments when precipitation remains near the long-term average, but during periods of low precipitation canopy removal is greater under winter prescribed burning. The model provides a useful tool to assist refuge personnel with developing long-term brush management and livestock grazing strategies.

Abstract: Leafy spurge (Euphorbia esula L.) is an invasive plant species in the north central and western U.S. and southern Canada. Idaho has established populations in the north and southeastern regions which are spreading into new sites. This study demonstrates the ability of high resolution hyperspectral imagery to provide high quality data and consistent methods to locate small and low percent canopy cover occurrences of leafy spurge. Locating leafy spurge in its early stages of invasion is critical for land managers in order to prioritize treatment, conservation, and restoration activities. Hyperspectral data were collected in 2002 and 2003 for the study area in southeastern Idaho. The imagery was classified with the Mixture Tuned Matched Filtering (MTMF) algorithm. Although classifications from single date images provided discrimination of leafy spurge at approximately 10% cover in one 3.5 m pixel, for repeatability and consistency purposes, the threshold for leafy spurge discrimination is approximately 40% cover. We hypothesize that georegistration errors, small differences in leafy spurge reflectance, training endmember selection, and image processing and field validation biases between years influence multi-date detection limits. Although hyperspectral imagery is costly, in some situations, the advantages of having reliable and repeatable mapping abilities for discrimination of economically damaging invasive species such as leafy spurge outweigh the image and processing costs.

Abstract: A hybrid approach comprising literature review, field investigation and interpretation of multi-date panchromatic aerial photographs at the 1:25,000 and 1:50,000 scales over four time slices between 1963 and 1997 was used to investigate the environmental impacts of increasing population density in Zimbabwe's Serima communal lands of Gutu district in Masvingo province. Results indicate deteriorating environmental trends in the form of deforestation, increased soil erosion, decline in grazing resources and extension of arable land into marginal areas. With high population density initiating unsustainable land use practices, relieving population pressure through land redistribution promises to offer long-term alternatives.

Abstract: Summary There is increasing interest in community-based approaches to the management of natural resources in Africa. Pastoral areas present particular challenges and opportunities to community-based management programs. We consider an example where there are multiple definitions of the community that uses a resource, and these definitions are both nested and overlapping. Working at multiple levels of social organization and in multiple sites was critical for overall program success. We find addressing conflict can be a measure to address resource scarcity. We conclude noting signs that reduced insecurity has established the preconditions under which sustainable resource management can be accomplished.

Abstract: The effects of elevated atmospheric CO2 concentrations on plant polyphenolic, tannin, nitrogen, phosphorus and total nonstructural carbohydrate concentrations were investigated in leaves of subtropical grass and fynbos shrub species. The hypothesis tested was that carbon-based secondary compounds would increase when carbon gain is in excess of growth requirements. This premise was tested in two ecosystems involving plants with different photosynthetic mechanisms and growth strategies. The first ecosystem comprised grasses from a C4-dominated, subtropical grassland, where three plots were subjected to three different free air CO2 enrichment treatments, i.e., elevated (600 to 800 [mu]mol mol-1), intermediate (400 [mu]mol mol-1) and ambient atmospheric CO2. One of the seven grass species, Alloteropsis semialata, had a C3 photosynthetic pathway while the other grasses were all C4. The second ecosystem was simulated in a microcosm experiment where three fynbos species were grown in open-top chambers at ambient and 700 [mu]mol mol-1 atmospheric CO2 in low nutrient acid sands typical of south western coastal and mountain fynbos ecosystems. Results showed that polyphenolics and tannins did not increase in the grass species under elevated CO2 and only in Leucadendron laureolum among the fynbos species. Similarly, foliar nitrogen content of grasses was largely unaffected by elevated CO2, and among the fynbos species, only L. laureolum and Leucadendron xanthoconus showed changes in foliar nitrogen content under elevated CO2, but these were of different magnitude. The overall decrease in nitrogen and phosphorus and consequent increase in C:N and C:P ratio in both ecosystems, along with the increase in polyphenolics and tannins in L. laureolum in the fynbos ecosystem, may negatively affect forage quality and decomposition rates. It is concluded that fast growing grasses do not experience sink limitation and invest extra carbon into growth rather than polyphenolics and tannins and show small species-specific chemical changes at elevated atmospheric CO2 concentrations. Responses of fynbos species are varied and were species-specific.

Abstract: The broad objective of this paper is to illustrate how archival, historical and remotely sensed data can be used to complement each other for long-term environmental monitoring. One of the major constraints confronting scientific investigation in the area of long-term environmental monitoring is lack of data at the required temporal and spatial scales. While remotely sensed data have provided dependable change detection databases since 1972, long-term changes such as those associated with typical climate scenarios often require longer time series data. The lack of data in readily accessible and usable formats for periods predating commercial satellite products has for a long time restricted the scope of environmental studies to temporally brief, synoptic overviews covering short time scales, thereby compromising our understanding of complex environmental processes. One way to improve this understanding is by cross-linking different forms of data at different temporal scales. However, most remote sensing based change research has tended to marginalize the utility of archival and historical sources in environmental monitoring. While the accuracy of data from non-instrumental records is often source-specific and varies from place to place, carefully conducted searches can yield useful information that can be effectively used to extend the temporal coverage of projects dependant on time series data. This paper is based on an ongoing project on environmental monitoring in the world's largest Ramsar site, the Okavango Delta, located on the northeastern fringes of Southern Africa's Kalahari-Namib desert in northern Botswana. With a database covering over 150 years between 1849 and 2001, the primary objectives of this paper are to: (1) outline how modern remotely sensed data (i.e., CORONA and Landsat) can be complemented by historical in situ observations (i.e., travellers' records and archival maps) to extend temporal coverage into the historical past, (2) illustrate that different forms of declassified Cold War intelligence data (i.e., CORONA) can be constructively exploited to further scientific understanding and (3) provide a conceptual framework for collating and disseminating data at regional and international levels through electronic media.

Abstract: The communal areas of the semi-arid (200 mm) winter-rainfall Namaqualand region of South Africa are heavily utilised by a large number of subsistence farmers who keep sheep and goats. For several decades, farmers have maintained, on average, more than twice the number of animals on the rangeland than the number recommended by the Department of Agriculture for neighbouring commercial enterprises. As a result of the continuous high stocking densities, significant changes in the vegetation have taken place. Farmers are now heavily reliant on an annual flush of vegetation following winter rains to keep their livestock alive. Using a combination of empirical data and consensus agreement, a computer model is developed to describe the long-term climate, livestock and vegetation interactions on the communal rangelands and to investigate the impacts of a range of management strategies. The model suggests that the system (including livestock) is sustainable although not stable, and that its sustainability could be due to climatic variability. The model supports the view that when livestock numbers vary in a manner consistent with recorded observations herbivory has little long-term impact on productivity of the system. This supports recent views of rangelands in semi-arid and arid environments where non-equilibrium conditions are thought to dominate ecosystem processes.

Abstract: Land use has a large impact on ecosystem functioning, though evidences of these impacts at the regional scale are scarce. The objective of this paper was to analyze the impacts of agricultural land use on ecosystem functioning (radiation interception and carbon uptake) in temperate areas of North and South America. From land cover maps generated using high-resolution satellite images we selected sites dominated by row crops (RC), small grain crops (SG), pastures (PA), and rangelands (RA) in the Central Plains of USA and the Pampas of Argentina. These two regions share climatic characteristics and the agricultural conditions (crop types) are also very similar. Both areas were originally dominated by temperate grasslands. In these sites we extracted the temporal series of the normalized difference vegetation index (NDVI) from the NOAA satellites for the period 1989-1998 and calculated the mean seasonal NDVI curve for each site. Additionally, we calculated the mean annual NDVI, the maximum NDVI, the date of the year when the max NDVI was recorded and the interannual variability of these three attributes. We compared the mean values of each NDVI-derived attribute between land cover types and between continents. The NDVI seasonal patterns for each land cover type were roughly similar between the Central Plains and the Pampas during the growing season. The largest differences were observed during the winter and spring, when the NDVI of all land cover types in the Central Plains remained at lower values than in the Pampas. This was probably caused by the high annual thermal amplitude in the Central Plains that results in a much more restricted growing season. As a result of these differences in the shape of the NDVI curve, the mean annual NDVI in the Central Plains was lower than in the Pampas for all land cover types but the maximum NDVI did not differ importantly. In both regions, row crops delayed the date of the NDVI peak, small grain crops advanced it and pastures did not change it importantly, compared with rangelands. The interannual variability of the NDVI attributes was higher for small grains than for row crops in both regions. However, small grains crops were consistently more variable between years in the Central Plains than in the Pampas. The opposite occurred with pastures and rangelands, which were more variable in the Pampas than in the Central Plains. This paper confirms and generalizes previous findings that showed important imprints of land use on ecosystem functioning in temperate ecosystems. Our results support the idea that the changes in land cover that have occurred in the Central Plains and the Pampas leaded to similar changes in the way that ecosystems absorb solar radiation and in the patterns of carbon uptake.

Abstract: Grazing lands and their management in livestock systems are a matter of special importance in the search for sustainability. Socio-economic and ecological objectives should be considered jointly in considering livestock production. In addition to the general issues of biodiversity and habitat preservation, the challenges for their management vary according to the regional conditions. In Southern European environments, where the past changes in livestock farming have led to a general decrease in their use, the questions under study are how to find ways to meet the threats to landscape amenity, biodiversity, the sustainability of local animal feeding resources and the rural population. Grazing lands and their management is also an important target of EU agri-environmental policy. The multifunctional use of this land, which is currently sought, reinforces the need for animal scientists to consider the use and management of grazing lands in reference not only to the techno-economical efficiency of animal feeding systems but also in reference to the long-term (e.g. biodiversity change) and at larger spatial scales (for example the landscape and watershed). An overview of the current challenges attached to grazing lands and their management in livestock farming systems in South European environments, an understanding of the ways to jointly meet production objectives and the realisation of sociological and ecological functions is presented.

Abstract: The study was conducted in a semi-arid savanna of South Africa, dominated by an almost pure stand of Acacia mellifera subsp. detinens (Black Thorn). Due to its invasive habits and suppression of the herbaceous layer, this woody species is viewed by land owners as a serious threat. Clearing of all A. mellifera trees in order to restore the production potential of the herbaceous layer is thus a well-established practice. In view of possible beneficial effects of A. mellifera, a study was undertaken with the objective of quantifying differences in soil nutrient status under A. mellifera canopies (canopied subhabitat) in comparison to the open areas (uncanopied subhabitat). The results of the study confirmed the existence of differences in the soil nutrient status between the various subhabitats, which occurred in a specific spatial gradient from the stem base of the plants towards the open, uncanopied areas. These differences were statistically significant (p<0.05) for total N, % organic matter and Ca, with the highest values recorded in the area surrounding the stem base. Though statistically non-significant (p>0.05) the P and K contents, and to a lesser extent Mg, were also higher under the tree canopies, while pH was lower. No differences (p>0.05) were established for Na. Some notable differences to similar studies in other areas were established, of which the reduction of soil pH is an example. The practical significance of these results in terms of land management practices is discussed, which will invariably necessitate a change in attitude of land owners in their approach to the management of A. mellifera.

Abstract: For at least 200 years, Gomoti River people and their neighbours lived interactively with the Okavango flood pulse system, travelling widely in dugout canoes, practicing flood recession agriculture, fishing, hunting, and collecting wild foods. Today they are wetlanders without wetlands. A major outflow channel of the eastern Okavango Delta in the 1930s, the Gomoti River rarely flows these days. This paper explores the Gomoti's demise, through the lenses first of science and second of Gomoti basin residents. Models developed over the past 20 years attribute the Gomoti's drying to a complex set of bio-hydrologic processes and feedback loops that begin with sedimentation and conclude with channel switching, peat fires, and purging of toxic salts. Such models essentially omit the long history of human habitation and ecological interaction with the delta. Local people, on the other hand, tell of deliberate and systematic management of channels and floodplains, and they argue this management kept the river healthy and flowing. The picture is confounded by colonial era interventions and by Botswana government policies partitioning the Gomoti and restricting access to its headwaters. We conclude with a model combining meso-scale scientific explanation with micro-scale indigenous constructions as a context for new thinking about Okavango Delta resource management.

Abstract: Resources for nature conservation initiatives are generally limited; therefore a spatially explicit targeting approach aimed at identifying the most viable sites has the potential to maximise conservation effectiveness. This research developed a multi-species targeting approach for eight threatened bird species associated with rare neutral grasslands within an agri-environment scheme in the UK. Suitable habitat areas for each bird species were identified through the development of two predictive models. The first [`]environmental' model was based on habitat association data developed using multilevel modelling techniques; the second was a geostatistical model developed using indicator kriging techniques. The two models were combined using Bayesian decision rules to produce a refined map of habitat suitability. Probability threshold values symptomatic of sites of highest habitat suitability were chosen in relation to national habitat creation targets, for example the most suitable 500 hectares (ha) for each species were identified. Once determined these areas were overlaid within a Geographical Information System (GIS) to identify sites shared by all target species. As a relatively small area was identified shared by all eight species (1.56 ha) further species assemblages, such as wading bird species, were also investigated. The approach effectively identified land parcels that potentially met the UK biodiversity action plan targets and species requirements of these assemblages where applicable. If applied to other agri-environment schemes this targeting approach could make conservation effort more effective and reliable at both the regional and national scale.

Abstract: In the past 30 years world production of ruminant meat and milk has increased by about 40%, while the global area of grassland has increased by only 4%. This is because most of the increase in ruminant meat and milk production has been achieved by increasing the production in mixed and landless production systems and much less so in pastoral systems. Pastoral systems depend almost exclusively on grazing, while mixed and landless systems rely on a mix of concentrates (food crops) and roughage, consisting of grass, fodder crops, crop residues, and other sources of feedstuffs. A model was developed to describe these two aggregated production systems for different world regions, each having typical production characteristics, such as milk production per animal for dairy cattle, and off-take rates and carcass weights for non-dairy cattle, sheep and goats. The energy needed by the animals for the production of meat and milk is calculated on the basis of requirements for maintenance, grazing and labour, pregnancy, and lactation. We implemented the FAO Agriculture Towards 2030 projection for crop and livestock production and assumed that the past trend in the area of grassland will continue in the coming three decades. This assumption implies a rapid intensification of grassland management with a 33% increase in global grass consumption, which will only be possible with increasing fertilizer inputs, use of grass-clover mixtures and improved grassland management.

Abstract: The aim of the study is to calibrate the phytolith index of tree cover density, D/P (the ratio of ligneous dicotyledons phytoliths (D) over Poaceae phytoliths (P)) with Leaf Area Index (LAI) measurements. LAI is the vertically integrated surface of leaves per unit of ground area (m2 leaves/m2 ground). Modern soil samples from southeastern Cameroon, collected along a continuous forest-savanna transect, have been analyzed for phytoliths. Phytolith assemblages and D/P index clearly record the physiognomy of the forest and savanna communities and of the transition between both of them. A highly significant relationship was obtained between D/P and LAI. The relationship between phytolith data and the vegetation transect is also discussed and compared with existing palynological results obtained along the same transect.

Abstract: Abstract Aim  This study calibrates the relationship between phytolith indices, modern vegetation structure, and a climate parameter (AET/PET, i.e. the ratio of annual actual evapotranspiration to annual potential evapotranspiration), in order to present new proxies for long-term Quaternary climate and vegetation changes, and model/data comparisons. Location  Sixty-two modern soil surface samples from West Africa (Mauritania and Senegal), collected along a latitudinal transect across four bioclimatic zones, were analysed. Methods  Two phytolith indices are defined as normalized data: (1) humidity-aridity index [Iph (%) = saddle vs. cross + dumbbell + saddle], and (2) water stress index [fan-shaped index (Fs) (%) = fan-shaped vs. sum of characteristic phytoliths]. Vegetation structures are delimited according to Iph and Fs boundaries. Bootstrapped regression methods are used for evaluating the strength of the relationship between the two phytolith indices and AET/PET. Additional modern phytolith assemblages, from Mexico, Cameroon and Tanzania are extracted in order to test the calibration established from the West African samples. Accuracy of the AET/PET phytolith proxy is compared with equivalent pollen proxy from the same area. Results  Characterization of the grass cover is accurately made through Iph. A boundary of 20 ± 1.4% discriminates tall grass savannas from short grass savannas. Water stress and transpiration experienced by the grass cover can be estimated through Fs. AET/PET is accurately estimated from phytoliths by a transfer function: AET/PET = −0.605 Fs − 0.387 Iph + 0.272 (Iph – 20)2 (r = 0.80 ± 0.04) in the application domain (AET/PET ranging from 0.1 ± 0.04 to 0.45 ± 0.04). Phytolith and pollen estimate with similar precision (rpollen = 0.84 ± 0.04) the AET/PET in the studied area. Conclusions  This study demonstrates that we can rely on the phytolith indices Iph and Fs to distinguish the different grasslands in tropical areas. Moreover, a new phytolith proxy of AET/PET, linked to water availability, is presented. We suggest from these results that combining phytolith and pollen proxies of AET/PET would help to constrain this climate parameter better, especially when phytolith assemblages are dominated by Panicoideae and Chloridoideae C4-grass phytoliths, are devoid of Pooideae C3-grass phytoliths, and occur with a few tropical ligneous woody dicotyledon phytoliths. As AET/PET is a bioclimatic indicator commonly used in vegetation models, such a combination would help to make model/data comparisons more efficient.

Abstract: We investigate the effect of subsistence harvesting on the ecological status of the pole-size tree component of the understorey at the Ongoye Forest Reserve (OFR; 2611 ha), KwaZulu-Natal province, South Africa. Using generalised linear modelling (GLM) we examine the ecological and social correlates of species preference and harvest intensity. Data were collected from 22 strip transects (5 m × 300 m; 0.15 ha). Only 11.6% of the available pole-size trees (2 cm < DBH < 15 cm) were harvested, mostly for building materials. No instance of canopy tree logging was recorded. Sixty-eight species were identified; however, only seven species (82% of harvested stems) were preferred: Englerophytum natalense (33%), Garcinia gerrardii (19%), Drypetes gerrardii (9%), Tabernaemontana ventricosa (9%), Rinorea angustifolia (4%), Oxyanthus speciosus (4%), and Chrysophyllum viridifolium (4%). Size-class distributions for these seven species were inverse J-shaped, typical of fine-grained species that regenerate over small spatial scales, suggesting that current harvesting intensities may be sustainable. Pole-size stem density was significantly similar among residual stands in harvested areas (2014 ± 31 stems ha-1) suggestive of a stem-density harvest threshold below which further effort was unprofitable. The number of harvested stems increased with increasing stem availability across species and stem size-classes. Small size-classes (2-5 cm DBH) were harvested most intensely, followed by the intermediate (5-10 cm) and the large (10-15 cm) size-classes, for all species except C. viridifolium. For the latter, the harvesting intensity was greatest for the 10-15 cm size-class. Lastly, harvest intensity was greatest in those areas closest to households near the reserve boundary but was not affected by household density. Although subsistence harvesting at the OFR appears to be sustainable at current levels, we note that similar harvest intensities of pole-sized stems in studies from smaller forests (<60 ha) led to local extinction of tree species. In addition, because the dominant understorey species at OFR are almost exclusively harvested, the mid- to long-term effects of this harvesting preference on forest dynamics must be assessed to develop sound ecological forest management policies.

Abstract: Summary * • This paper is the first global study of the extent to which fire determines global vegetation patterns by preventing ecosystems from achieving the potential height, biomass and dominant functional types expected under the ambient climate (climate potential). * • To determine climate potential, we simulated vegetation without fire using a dynamic global-vegetation model. Model results were tested against fire exclusion studies from different parts of the world. Simulated dominant growth forms and tree cover were compared with satellite-derived land- and tree-cover maps. * • Simulations were generally consistent with results of fire exclusion studies in southern Africa and elsewhere. Comparison of global ‘fire off’ simulations with landcover and treecover maps show that vast areas of humid C4 grasslands and savannas, especially in South America and Africa, have the climate potential to form forests. These are the most frequently burnt ecosystems in the world. Without fire, closed forests would double from 27% to 56% of vegetated grid cells, mostly at the expense of C4 plants but also of C3 shrubs and grasses in cooler climates. * • C4 grasses began spreading 6–8 Ma, long before human influence on fire regimes. Our results suggest that fire was a major factor in their spread into forested regions, splitting biotas into fire tolerant and intolerant taxa.

Abstract: A study was conducted to evaluate the effects of supplementing with different tree leaves on nutrient digestion, rumen fermentation and blood parameters of sheep. Thirty adult Malpura rams (39.0 ± 0.56 kg) were divided into five groups of six each. They were grazed as a single flock on a semi-arid rangeland and after the end of routine grazing period (08:00-17:00 h), first group (G1), which was not provided with any supplementation, served as control group. Second group (G2) was supplemented with 200 g of a conventional concentrate mixture per head per day, whereas third, fourth and fifth groups (G3, G4 and G5) were supplemented with approximately 200 g dry matter (DM) per day freshly cut foliage from Ailanthes excelsa, Azardirachta indica and Bauhinia racemosa, respectively. Protein content (g kg-1 DM) in A. excelsa, A. indica and B. racemosa foliage was 197, 128 and 132, respectively. A. indica and B. racemosa foliages also contained 123.2 and 211.2 g kg-1 DM condensed tannin (CT) with protein precipitating capacity (PPC) of 16.5 and 46.5 g kg-1 DM. None of the tree leaves contained hydrolysable tannin (HT). Dry matter intake (DMI, g day-1) was 591, 766, 865, 974 and 939 in G1, G2, G3, G4 and G5, respectively. Digestible crude protein (DCP) and metabolisable energy (ME) intakes in supplemented groups G2-G5 were higher (P < 0.05) compared to control (G1). Supplementation improved digestibility of all nutrients in all groups. Rumen fermentation study indicated lower (P < 0.05) ammonia and total N in the rumen liquor collected from G5 sheep compared to the other supplemented groups. Although haemoglobin (Hb, g dl-1) levels showed small changes among groups, blood urea nitrogen (BUN, mg dl-1) was lowest in G5 compared to the other groups. Initial BW were similar among the groups. After 60 days of experimental feeding, all animals maintained their BW, except sheep in the control group (G1), which lost BW. Results indicate that for adult sheep grazing on a semi-arid range, supplementation with a concentrate mixture could be replaced by tree leaves like A. excelsa, A. indica and B. racemosa, during the lean season to maintain their BW. In addition, supplementing with tree leaves containing condensed tannin has advantages in terms of N utilization.

Abstract: Consideration of a range of evidence from geomorphology, palynology, biogeography and vegetation/climate modelling suggests that a north-south [`]savanna corridor' did exist through the continent of Sundaland (modern insular Indonesia and Malaysia) through the Last Glacial Period (LGP) at times of lowered sea-level, as originally proposed by Heaney [1991. Climatic Change 19, 53-61]. A minimal interpretation of the size of this corridor requires a narrow but continuous zone of open [`]savanna' vegetation 50-150 km wide, running along the sand-covered divide between the modern South China and Java Seas. This area formed a land bridge between the Malaysian Peninsula and the major islands of Sumatra, Java and Borneo. The savanna corridor connected similar open vegetation types north and south of the equator, and served as a barrier to the dispersal of rainforest-dependent species between Sumatra and Borneo. A maximal interpretation of the available evidence is compatible with the existence of a broad savanna corridor, with forest restricted to refugia primarily in Sumatra, Borneo and the continental shelf beneath the modern South China Sea. This savanna corridor may have provided a convenient route for the rapid early dispersal of modern humans through the region and on into Australasia.

Abstract: It is difficult to find references to fire in general textbooks on ecology, conservation biology or biogeography, in spite of the fact that large parts of the world burn on a regular basis, and that there is a considerable literature on the ecology of fire and its use for managing ecosystems. Fire has been burning ecosystems for hundreds of millions of years, helping to shape global biome distribution and to maintain the structure and function of fire-prone communities. Fire is also a significant evolutionary force, and is one of the first tools that humans used to re-shape their world. Here, we review the recent literature, drawing parallels between fire and herbivores as alternative consumers of vegetation. We point to the common questions, and some surprisingly different answers, that emerge from viewing fire as a globally significant consumer that is analogous to herbivory.

Abstract: The Phanerozoic has witnessed major changes, with Africa being an integral part of supercontinental landmass agglomeration forming Gondwana, its amalgamation with smaller landmasses to form Pangaea, and later disintegrating to form the existing continents. At the same time climates, atmosphere, oceanic circulation and tectonic plates shifted. During this upheaval, life was evolving and organisms were adapting and with higher diversity came more ecological interactions, creating more habitats and thus influencing more biological radiation. Plants became more complex, developing from unicellular to multicellular organisms. Moving from water onto land, plants had to cope with desiccation, and features evolved enabling them to do this. Patterns of Phanerozoic plant evolution are strongly driven by major changes in the physical environment, most notably continental drift, climate change and bolide impacts, precipitating massive volcanism and other effects leading to mass global extinctions. The products of this evolution were early land plants during Silurian and Devonian times. Subjected to extinction events and environmental changes, these early plants gave rise to the pteridophytes reaching their diversity peak during the Carboniferous and Permian. After the demise of the pteridophytes, the gymnosperms dominated during the Triassic and Jurassic, followed by the emergence of the angiosperms in the Cretaceous. This melange of factors has produced the present plant diversity on earth, which we will examine in context of the African flora. Plant diversification in Gondwana and Laurasia will be covered focussing on Africa, while factors affecting the vegetation and species composition of the present flora will be discussed.

Abstract: Although much research has been carried out on the crop productivity response to soil erosion, little is known about the role of soil erosion as a driver of land-use change. Given, however, the some-times large erosion-induced reductions in crop yields, it appears likely that erosion has a strong impact on land-use. Abandonment of arable land due to declining productivity is a land-use change that may result from soil erosion. To test this hypothesis, the western part of Lesvos, Greece, was chosen as a case study area. Lesvos has experienced accelerated erosion on marginal soils over the last century during which important land-use changes have taken place. Of the 3211 ha that were under cereals in 1886, 53% (1711 ha) was converted to rangeland (only used for extensive grazing) by the mid-20th century. At the same time, however, cereals partly returned to neighbouring areas that were previously rangeland, implying that certain processes at the local scale resulted in land becoming unsuitable in one place and (relatively) more suitable in other places. In order to identify the relationship between these land-use changes and the occurrence of soil erosion, erosion was modelled backwards for the period 1886-1996 and soil depths reconstructed for the time when the land-use was assumed to have changed (the mid-1950s). A logistic regression was performed with soil depth, erosion and slope as explanatory variables and land-use change as the response variable. Abandonment/reallocation of cereals was found to be fairly well predicted by slope and soil depth. Path analysis showed erosion to be an important driver for the abandonment and reallocation of cereals, although next to slope and soil depth it has little additional predictive value. Based on the logistic model, it is anticipated that cereal cultivation in western Lesvos will probably be abandoned in the near future.

Abstract: For rangelands managed with spatial and temporal controls, [a] the long run expected net cost of management operations, [b] the long run rate of moving grazing from one paddock to another, and [c] the long run rate of moving grazing between paddocks because of adverse environmental factors are salient criteria for a range manager. In this paper, we provide the first theoretical analysis of the relationship between these three economic and ecological criteria. We first characterize these criteria mathematically. Then, we provide necessary and sufficient conditions under which criterion [a] (economic criterion) is equivalent to, in turn, criterion [b] (first ecological criterion) and criterion [c] (second ecological criterion).

Abstract: The paper comprises an overview of important or unusual goat diseases occurring in southern Africa, with the emphasis on current effective disease control measures and recent developments in this field. The diseases are dealt with under four headings: (1) Infections; (2) Parasites; (3) Plants and nutrition; (4) Genetic and other conditions. In each section, the following are given more prominence: (1) Heartwater, certain clostridial diseases, pasteurellosis, abscessation and orf; (2) Haemonchosis, coccidiosis and certain ectoparasites; (3) Redgut and phytobezoars; (4) Abortions, postnatal mortality, exposure, predation and swelling disease. The major diseases of helminthosis and heartwater are dealt with at greater length. Helminth control currently concentrates on individual treatment of badly affected goats, rather than mass treatment. This lowers the selection rate for worms resistant to anthelmintics. A break with the old policy of "treat-all-and-move" is advocated for the same reason. The use of the FAMACHA© system (clinical anaemia evaluation) for haemonchosis control in goats is explained and the potential of body condition scoring for identifying animals heavily infected with other pathogenic helminths is highlighted. Replacement of highly resistant worm populations by a dilution method is outlined and several practical measures for managing worms in goats are given. The control of heartwater is determined by epidemiological and risk factors, comprising those affecting the vector (climate, season, vegetation, wild reservoir hosts, tick control), the organism (strain virulence, infection rate of vectors), and the host (species, age, breed, genetic resistance and immune status). In circumstances of very low infection risk, surveillance and treatment is recommended. In higher risk situations, strict tick control or zero grazing may be the best option. In endemic areas, immunity is the preferred and most reliable approach. This is achieved by exposure to infected ticks, vaccination and animal selection. Details of these options and their practical implementation are given.

Abstract: Information on decomposition and nutrient release from leaf litter of trees in agroforestry parkland systems in Sub-Saharan Africa is scarce despite the significant role of these trees on soil fertility improvement and maintenance. Decomposition and nutrient release patterns from pruned leaves of the two most common species of parklands of the semi-arid zone of West Africa: Vitellaria paradoxa C.F. Gaertn (known locally as karité) and Parkia biglobosa (Jacq.) Benth. (known locally as néré), were investigated by a litter-tube study in Burkina Faso. Litter quality, methods of leaf exposure to the soil and combination with fertilizers were the factors studied. Leaves of néré had a higher nutrient content (C, N, P, Ca) and contained more ash and lignin than leaves of karité. Karité leaves had a greater content of K, cellulose and polyphenols. The pruned leaves of karité and néré showed two distinct decomposition patterns. Néré leaves decomposed more rapidly, with less than 32% of the initial weight remaining after the rainy season (4 months) while karité leaves decomposed more slowly with 43% of the leaf litter remaining after the rainy season. Addition of urea and compost did not significantly affect the rate of decomposition. Significant interaction was observed between species and method of leaf exposure for the first sampling date. Leaf litter of néré buried in soil gave the highest weight loss (34% of the initial mass in 1 month) compared with exposed leaf litter of néré and karité, and buried leaf litter of karité. Except for N, nutrient release patterns were similar for both species but the nutrient release rates were higher for néré leaves compared with karité leaves. N was immobilised in karité leaves most likely due to low N and high phenolic content. The rate of nutrient release from karité leaves followed the general trend K>P>N.

Abstract: Estimates were made of the percentage of area burned and the fire frequency in different ecosystems of non-anthropic savannas located in the north and northeast portions of the State of Roraima, Brazil. Three years of observations (June 1997-May 2000) indicated that the mean percentage of area burned annually, weighted for all ecosystems, was 38 ± 12% (S.D.). The mean frequency of fire (number of years for an area to burn again) was 2.5 years. Both parameters are dependent on the type (structure) of vegetation, the altitude of the savanna and the climatic state (dry, wet or normal) of the year of the observation. Using values for 2-month periods over the 3-year time series (n = 18), a simple regression model was developed to forecast percentage area burned for grassy-woody savanna ("clean field" and "dirty field" types), using as the independent variable the mean precipitation in each 2-month period. The proposed model explains 66% of the reported cases. These results are the first developed for savannas in the Amazon region and are directly applicable to calculations of greenhouse-gas emissions from burning in this ecosystem type.

Abstract: Above-ground biomass (live + dead), was estimated pre- and post-burn in eight types of savanna ecosystem in Roraima, in the extreme northern part of the Brazilian Amazon. The objective was to investigate the stock of pre-burn above-ground carbon and its fate after experimental fires that were set during the dry season (December-March). The total biomass in each ecosystem was divided into two groups ("fine-fuels" and "trees and shrubs"), and the combustion factor and the concentration of carbon were determined for of each of the biomass components within these groups. The ecosystems with the lowest biomasses were the grasslands (1627-4045 kg ha-1), followed by parkland (6127-8038 kg ha-1) and open woodland savanna (10,246-11,731 kg ha-1). The percentage of "live biomass" was higher in the open woodland vegetation types (77.1-85.6%), and lower in the grassland and parkland types (11.4-51.4%). The total emitted carbon ("presumed release") in each ecosystem varied from 551 to 1474 kg C ha-1. These results differ from those observed in the savannas of central Brazil (2909 kg C ha-1 emitted), which were used as the standard in the Brazilian national inventory of greenhouse-gas emissions for the burning of non-anthropic savannas. This suggests that the calculations of Brazilian emissions for savannas should be disaggregated by region instead of using standard national values. Savanna ecosystems in Amazonia, although defined phytoecologically in the same way as those of central Brazil (despite being separated by great geographical distances), possess fire dynamics of their own, implying differences in the emissions of greenhouse gases.

Abstract: Distinguishing between sheep and goats in C4 grass environments using new dental morphology criteria and enamel bioapatite stable carbon isotope ratios ([delta]13C) was tested on 35 modern individuals from the Central Rift Valley of Kenya. Two morphological criteria on the second and third lower molars, one of which had been previously partially described by Halstead et al. [Journal of Archaeological Science 29 (2002) 545], were found to be highly reliable in this population. Identification of species using carbon isotope ratios is made possible in some circumstances by differences in the feeding behavior of sheep, which are mainly grazers, and goats, which are mainly browsers. In environments where C4 grasses predominate, sheep include a higher proportion of C4 plants in their diet, and thus have higher [delta]13C values than goats. In the present study, the annual range and seasonal variation of carbon isotope ratio of diet of sheep and goats was measured from intra-tooth sequential analysis. Although the ranges of goat and sheep [delta]13C values overlap, those higher than -3.4[per mille sign] all belong to sheep; values lower than -5.2[per mille sign] all belong to goats. There is no overlap of the mean [delta]13C values by tooth, which range from -11.8[per mille sign] to -4.2[per mille sign] for goats, and from -3.1[per mille sign] to -1.3[per mille sign] for sheep. These results suggest that carbon isotope analysis of bone collagen and/or apatite will also distinguish sheep from goats in tropical C4 grasslands. Application of the [delta]13C criteria to archaeological material must be restricted to C4-dominated environments, and where potential access to C3 plants (mobility, foddering) can be assessed. The utility of these morphological and isotopic criteria for differentiating sheep and goat breeds in other regions remains to be evaluated.

Abstract: Agricultural intensification is responsible for the dramatic decline of farmland bird populations in the European Union (EU). The joining of eight Central and Eastern European (CEE) countries to the EU will re-structure agriculture there. One of the main threats is the intensification of farmland management. Can agri-environmental programs balance the expected decline in bird assemblages of the CEE countries if farming will be intensified? We studied this question by comparing bird assemblages of 42 extensively and intensively grazed paired fields in three regions of Hungary (alkali steppes and meadows in Central Hungary and alkali steppes in Eastern Hungary). Bird assemblages varied significantly across regions and grazing intensity. Intensively grazed sites showed a higher species number and diversity, but lower densities than the extensive sites. This is probably the consequence of higher landscape diversity of intensive sites, which included farm buildings, shelters, wells and other structures. Several bird species, mainly with European conservation concern, showed contrasting responses to grazing intensity in the three regions, including key grassland species (black-tailed godwit Limosa limosa, redshank Tringa totanus, skylark Alauda arvensis and corn bunting Emberiza calandra). Therefore, threat and sensitivity to grassland characteristics are correlating. Although many of the declining species of Western Europe are still abundant in Hungarian grasslands, our results project the threat of the expected intensification. This study showed that it is not possible to provide a general grassland management scheme that will favour all bird species in all regions of Hungary. In the process of integrating to the EU and re-structuring agriculture, the establishment of scientifically sound schemes is urgent.

Abstract: The sub-montane cultivation belt, with its so-called Chagga home gardens on Mount Kilimanjaro, was investigated for its Saltatoria fauna. Since these cultivated fields still have the structure of a forest, differing mainly in the undergrowth, more than half of the 52 recorded species are forest species, whilst the remainder originate from open habitats. Moreover, the Chagga home gardens harbour >70% of all forest species and >50% of the endemic species of Mount Kilimanjaro. Most endemics in the plantations originate from sub-montane habitats, and contribute 72% of the total number of sub-montane endemics found in the region. More than half of all endemics from the montane zone are also found in the Chagga home gardens. Therefore, the Chagga home gardens act as an important refuge for both generalist forest species and endemic fauna. In recent years, new coffee varieties have been introduced to the gardens that are less shade demanding, and tree removal may impinge on the indigenous Saltatoria fauna.

Abstract: A great many debates have grown up around the notion of desertification as a process of degradation that affects the arid, semi-arid and sub-humid zones of the globe. A fundamental and continuing debate has been over whether desertification actually exists and, if so, how it might be defined, measured and assessed. Rather than simply review the evolution of these debates we examine the contexts in which they take place and how those contexts have contributed to the evolution of our understanding of the intertwined processes that contribute to desertification. The fact that these contexts have changed over time, combined with the fact that some of them are often ignored have both helped to sustain debate. We consider four contexts that frame much of the debate and consider what impact each has had: (1) changes in our understanding of climate variability; (2) changes in our understanding of vegetation responses to perturbation; (3) changes in our understanding of social processes, including household responses to economic perturbation; and (4) changes in our understanding of desertification as a political process or artifact.

Abstract: This paper uses the concept of sustainable development to examine the utilisation of wildlife resources at Moremi Game Reserve (MGR) and Khwai community area (NG 18/19) in the Okavango Delta, Botswana. Using both secondary and primary data sources, results show that the establishment of MGR in 1963 led to the displacement of Khwai residents from their land; affected Basarwa's hunting and gathering economy; marked the beginning of resource conflicts between Khwai residents and wildlife managers; and, led to the development of negative attitudes of Khwai residents towards wildlife conservation. Since the late 1980s, a predominately foreign owned tourism industry developed in and around MGR, however, Khwai residents derive insignificant benefits from it and hence resource conflicts increased. In an attempt to address problems of resource conflicts and promote sustainable wildlife utilisation, the Botswana Government adopted the Community-Based Natural Resource Management (CBNRM) programme, which started operating at Khwai village in 2000. The CBNRM programme promotes local participation in natural resource management and rural development through tourism. It is beginning to have benefits to Khwai residents such as income generation, employment opportunities and local participation in wildlife management. These benefits from CBNRM are thus having an impact in the development of positive attitudes of Khwai residents towards wildlife conservation and tourism development. This paper argues that if extended to MGR, CBNRM has the potential of minimising wildlife conflicts between Khwai residents and the wildlife-tourism sectors. This approach may in the process promote the sustainable wildlife use in and around MGR.

Abstract: Abstract  Patch formation is common in grazed grasslands but the mechanisms involved in the formation and maintenance of patches are not clear. To increase our knowledge on this subject we examined possible reasons for patch formation and the influence of management on changes between patch states in three experiments in native pasture communities in the Crows Nest district, south-east Queensland. In these communities, small-scale patches (tall grassland (dominated by large and medium tussock grasses), short swards (dominated by short tussock grasses and sedges), and lawns (dominated by stoloniferous and/or rhizomatous grasses)) are readily apparent. We hypothesized that the formation of short sward and lawn patches in areas of tall grassland was due to combinations of grazing and soil fertility effects. This was tested in Experiment 1 by applying a factorial combination of defoliation, nutrient application and transplants of short tussock and stoloniferous species to a uniform area of tall grassland. Total species density declined during the experiment, was lower with high nutrient applications, but was not affected by defoliation. There were significant changes in abundance of species that provided support for our hypotheses. With light defoliation and low nutrients, the tall grassland remained dominated by large tussock grasses and contained considerable amounts of forbs. With heavy defoliation, the pastures were dominated by medium tussock grasses and there were significant decreases in forbs and increases in sedges (mainly with low nutrients) and stoloniferous grasses (mainly with high nutrients). Total germinable seed densities and those of most species groups were significantly lower in the heavy defoliation than the light defoliation plots. Total soil seed numbers were not affected by nutrient application but there were fewer seeds of the erect forbs and more sedge seeds in plots with high nutrients. The use of resting from grazing and fire to manage transitions between patches was tested. In Experiment 2, changes in species density and abundance were measured for 5 years in the three patch types with and without grazing. Experiment 3 examined the effects of fire, grazing and resting on short sward patches over 4 years. In Experiment 2, total species density was lower in lawn than short sward or tall grassland patches, and there were more species of erect forbs than other plant groups in all patch types. The lawn patches were originally dominated by Cynodon spp. This dominance continued with grazing but in ungrazed patches the abundance of Cynodon spp. declined and that of forbs increased. In the short sward patches, dominance of short tussock grasses continued with grazing but in ungrazed plots their abundance declined while that of large tussock grasses increased. The tall grassland patches remained dominated by large and medium tussock species. In Experiment 3, fire had no effect on species abundance. On the grazed plots the short tussock grasses remained dominant but where the plots were rested from grazing the small tussock grasses declined and the large tussock grasses increased in abundance. The slow and relatively small changes in these experiments over 4 or 5 years showed how stable the composition of these pastures is, and that rapid changes between patch types are unlikely.

Abstract: The diets of prairie dog (Cynomys mexicanus) and cattle (Charolais cows) in desert grassland of northern Mexico were examined in 1-year study using microhistological analysis of feces. Cattle utilized more (P<0.01) grasses than prairie dogs (86% vs. 68% across seasons). One key forage species in cattle diets was Bouteloua curtipendula, which was eaten in greater (P<0.05) amounts by cattle than prairie dogs in summer and winter. Bouteloua gracilis, consistently appeared in cattle feces in all seasons. With the exception of spring, this grass was two-fold higher (P<0.01) in cattle than prairie dog diets. Prairie dogs consumed 31% forbs compared to 16% for cattle (data across seasons; P<0.05). Due to the low woody plant availability in the pasture, shrub was a negligible dietary constituent of both herbivores. In general, prairie dogs had a greater preference than cattle for forbs. Overall dietary overlap between prairie dog and cattle was 68%, which indicates that large forage competition occurs between prairie dog and cattle in all season. However, the long-term profitability of the ranch where these prairie dogs live, and the steady expansion of prairie dog colonies in this area indicates that controlled livestock grazing can be biologically sustainable, compatible with prairie dogs and economically cost effective.

Abstract: The palaeontological site of Hoedjiespunt 1 (HDP1) represents a fossilized hyaena lair. A rich mammalian fauna, including four hominid teeth, has been recovered from the site. Micromammals were recovered from the same sediments as the larger fauna. Taphonomic analysis suggests that the micromammal assemblages from HDP1 were accumulated by a barn owl. The barn owl produces micromammal assemblages that provide a broad sample of micromammals, within a certain size range, living in the hunting area of the owl. There are size-related and other biases inherent in the prey selection of this predator, and owls may roost in one area and hunt in another however, the barn owl has frequently been found to provide a better indication of micromammals living within an area than trapping. The micromammals from HDP1 were used to reconstruct the microhabitats in the vicinity of the site. Two taxonomic habitat indexes were used to assess the environment and dominant habitat types at Hoedjiespunt 1. The variability and adaptability of many of the southern African micromammals complicates interpretation of the results, however, it appears that the micromammals from the HDP1 fossil assemblages utilized habitats of open, scrub vegetation, and rocky and sandy areas. It is suggested that the environment was not markedly different from today, but it may have been relatively more arid. A comparison between HDP1 and other fossil sites in the area dating from the terminal Pleistocene to the Holocene indicates that HDP1 is lacking certain species that are common to all the other west coast fossil sites. There is some discrepancy in the environment indicated by the large mammals as compared that indicated by to the micromammals at the site. It is suggested that this discrepancy may reflect the fact that an owl is likely to have hunted in the vicinity of the hyaena den, probably in the more open areas around the roost site, whereas the macrofauna, accumulated by the further-ranging brown hyaena (Hyaena brunnea), represents environments from further afield.

Abstract: Agriculture in the southwestern USA is limited by water supply due to high evaporation and limited seasonal precipitation. Where water is available, irrigation allows for production of a variety of agricultural and horticultural crops. This review assesses the impacts of agriculture on greenhouse gas emission and sequestration of atmospheric C in soils of the hot, dry region of the southwestern USA. In Texas, conservation tillage increased soil organic C by 0.28 Mg C ha-1 year-1 compared with more intensive tillage. Conversion of tilled row crops to the conservation reserve program or permanent pastures increased soil organic C by 0.32 ± 0.50 Mg C ha-1 year-1. Soil organic C sequestration was dependent on rotation, previous cropping, and type of conservation tillage employed. Relatively few studies have interfaced management and C cycling to investigate the impacts of grazing management on soil organic C, and therefore, no estimate of C balance was available. Irrigated crop and pasture land in Idaho had soil organic C content 10-40 Mg C ha-1 greater than in dryland, native grassland. Soil salinity must be controlled in cropland as soil organic C content was lower with increasing salinity. Despite 75% of the region's soils being classified as calcic, the potential for sequestration of C as soil carbonate has been only scantly investigated. The region may be a significant sink for atmospheric methane, although in general, trace gas flux from semiarid soils lacks adequate characterization. Agricultural impacts on C cycling will have to be better understood in order for effective C sequestration strategies to emerge.

Abstract: Sustainable agriculture requires the formation of new humus from the crops. We utilized 13C and 15N signatures of soil organic matter to assess how rapidly wheat/maize cropping contributed to the humus formation in coarse-textured savanna soils of the South African Highveld. Composite samples were taken from the top 20 cm of soils (Plinthustalfs) cropped for lengths of time varying from 0 to 98 years, after conversion from native grassland savanna (C4). We performed natural 13C and 15N abundance measurements on bulk and particle-size fractions. The bulk soil [delta]13C values steadily decreased from -14.6 in (C4 dominated) grassland to -16.5[per mille sign] after 90 years of arable cropping. This [delta]13C shift was attributable to increasing replacement of savanna-derived C by wheat crop (C3) C which dominated over maize (C4) inputs. After calculating the annual C input from the crop yields and the output from literature data, by using a stepwise C replacement model, we were able to correct the soil [delta]13C data for the irregular maize inputs for a period of about one century. Within 90 years of cropping 41-89% of the remaining soil organic matter was crop-derived in the three studied agroecosystems. The surface soil C stocks after 90 years of the wheat/maize crop rotation could accurately be described with the Rothamsted Carbon Model, but modelled C inputs to the soil were very low. The coarse sand fraction reflected temporal fluctuations in 13C of the last C3 or C4 cropping and the silt fraction evidenced selective erosion loss of old savanna-derived C. Bulk soil 15N did not change with increasing cropping length. Decreasing [delta]15N values caused by fertilizer N inputs with prolonged arable cropping were only detected for the coarse sand fraction. This indicated that the present N fertilization was not retained in stable soil C pool. Clearly, conventional cropping practices on the South African highlands neither contribute to the preservation of old savanna C and N, nor the effective humus reformation by the crops.

Abstract: An invasive weed can occupy a variety of environments and ecological niches and generally no single control method can be used across all areas the weed is found. Biological control agents integrated with other methods can increase and/or improve site-specific weed control, but such combinatorial approaches have not been widely utilized. The successful leafy spurge (Euphorbia esula L.) control program provides examples for future integrated weed programs that utilize biological control agents with traditional methods. Weed control methods can be used separately, such as when the leafy spurge gall midge (Spurgia esulae Gagné) reduced seed production in wooded areas while herbicides prevented further spread outside the tree line. Traditional methods also can be used directly with biological control agents. Incorporation of Aphthona spp. with herbicides has resulted in more rapid and complete leafy spurge control than either method used alone. Also, the insect population often increased rapidly following herbicide treatment, especially in areas where Aphthona spp. were established for several years but had been ineffective. Incorporation of Aphthona spp. with sheep or goat grazing has resulted in a larger decline in leafy spurge production than insects alone and in weed density than grazing alone. Controlled burns can aid establishment of biological control agents in marginally suitable environments, but timing of the fire must be coordinated to the insect's life-cycle to ensure survival. Integration of biological control agents with revegetation programs required the agent to be the last method introduced because the cultivation and herbicide treatments necessary to establish desirable grasses and forbs were destructive to the insect. In a practical application, herbicides were combined with Aphthona spp. to help the insect establish and control leafy spurge in the habitat of the western prairie fringed orchid (Platanthera praeclara Sheviak and Bowles), an endangered species. Several experimental designs can be used to evaluate biological control agents with cultural, mechanical, and chemical control methods or with additional biological agents.

Abstract: We examined the relationship between the distribution of Martial Eagles Polemaetus bellicosus (and other large eagle species) breeding on electricity transmission pylons in the central and southwestern Karoo, South Africa, and the general environmental health of commercially managed farmland in that region. Eighty-three eagle territories were located along 1400 km of surveyed pylon line. The influence of habitat quality on eagle distributions was assessed in terms of (i) patterns of dispersion and spacing between territories, (ii) macro-scale differences between the habitat composition of eagle territories and an equivalent array of random plots, and (iii) micro-scale differences in habitat quality assessed at points within and outside of eagle territories. Territories were generally irregularly distributed along the pylon line (p<0.025). At the landscape scale, Martial Eagles significantly favoured habitats with lower and/or less predictable winter rainfall and lower primary productivity, while Tawny Eagles Aquila rapax preferred habitats with higher and/or more predictable summer rainfall and higher primary productivity. All eagles avoided areas of highest primary productivity and were absent from cultivated areas. On a local scale, habitat qualities within eagle territories were generally not significantly different to those recorded outside territories. However, eagle densities in areas stocked with indigenous game were significantly higher than in areas supporting only domestic stock (nearest neighbour distances, 7 km vs. 12 km, p=0.025). This study shows that (i) large eagle distributions in the Karoo are significantly influenced by both macro- and micro-scale variation in habitat quality, and by the nature of land management, and (ii) that the Martial Eagle is potentially suitable as an indicator of ecosystem quality and functionality in the Karoo.

Abstract: In evolutionary time frames, grazing by domesticated livestock on the short grass plains of East Africa is a new occurrence resulting in increased animal densities year around and modification to annual timing of grazing. We addressed the following questions: (1) do plant species diversity and vegetation structural differences exist between an area that is grazed only during the wet season and an adjacent area that is grazed year around; and, (2) does plant species diversity and structure correlate temporally with density of grazers? A spatially explicit ecosystem model was used to determine grazer densities. The two areas were similar with respect to grazer density during the wet season but not in the dry season. Dry season grazer densities were solely due to the presence of domesticated livestock. No significant differences in plant species diversity (H'), evenness, or richness were found between the two areas. However, the relative abundance of forbs, shrubs, percent cover of shrubs and bare ground was positively correlated with grazer densities during the dry season.

Abstract: Southernmost Africa (here meaning South Africa, Lesotho and Swaziland) provides an excellent opportunity for investigating the relations between farming, herding and hunting-gathering communities over the past 2,000 years, as well as the development of societies committed to food production and their increasing engagement with the wider world through systems of exchange spanning the Atlantic and Indian Oceans. This paper surveys and evaluates the archaeological research relevant to these communities and issues carried out in the region since the early 1990s. Among other themes discussed are the processes responsible for the emergence and transformation of pastoralist societies (principally in the Cape), the ways in which rock art is increasingly being incorporated with other forms of archaeological data to build a more socially informed view of the past, the analytical strength and potential of ethnographically informed understandings of past farming societies and the important contribution that recent research on the development of complex societies in the Shashe-Limpopo Basin can make to comparative studies of state formation.

Abstract: The dominant narrative of soil degradation in sub-Saharan Africa, as expressed in global surveys and policy documents, is compared with long-term data on the productive performance of smallholder farming systems under climatic and demographic stress. Cases at national, district and village/farm scale are considered (Nigeria; Diourbel Region, Senegal; Maradi Department, Niger; the Kano Close-Settled Zone, Nigeria). The dominant narrative is found to fail as a predictor of agricultural performance over the longer term. Instead there is evidence of farmers' achievements in terms of sustained production, and investments in soil fertility maintenance. However at micro-scale, the constraints affecting farmers' investments are apparent. The dominant narrative is deficient as a guide to policy, which needs to go beyond the fertiliser debate to take a broader view of soil fertility in relation to rural livelihoods and a need to facilitate private investment in natural resources.

Abstract: A simple theory of [`]desertification' is found inadequate for understanding the complexity, diverse patterns and flexibility of farmers' responses to change in environmental conditions and population growth in the Sahel. These include long-term transitions in farming practices, in management of natural resources and in income diversification. This paper reviews evidence relating to deforestation, woodland and rangeland degradation to show that in certain areas, a transition to intensified land use, although initially involving a loss of woodland, has led to the planting or protection of useful trees on farms and maintained biomass levels. Livestock numbers have been maintained, despite declining rainfall and loss or apparent degradation of rangeland, by development of more integrated livestock, arable and marketing systems. The possibility of these trends having impact on Sahelian [`]greening' is discussed.

Abstract: Abstract A yearly global fire history is a prerequisite for quantifying the contribution of previous fires to the past and present global carbon budget. Vegetation fires can have both direct (combustion) and long-term indirect effects on the carbon cycle. Every fire influences the ecosystem carbon budget for many years, as a consequence of internal reorganization, decomposition of dead biomass, and regrowth. We used a two-step process to estimate these effects. First we synthesized the available data available for the 1980s or 1990s to produce a global fire map. For regions with no data, we developed estimates based on vegetation type and history. Second, we then worked backwards to reconstruct the fire history. This reconstruction was based on published data when available. Where it was not, we extrapolated from land use practices, qualitative reports and local studies, such as tree ring analysis. The resulting product is intended as a first approximation for questions about consequences of historical changes in fire for the global carbon budget. We estimate that an average of 608 Mha yr−1 burned (not including agricultural fires) at the end of the 20th century. 86% of this occurred in tropical savannas. Fires in forests with higher carbon stocks consumed 70.7 Mha yr−1 at the beginning of the century, mostly in the boreal and temperate forests of the Northern Hemisphere. This decreased to 15.2 Mha yr−1 in the 1960s as a consequence of fire suppression policies and the development of efficient fire fighting equipment. Since then, fires in temperate and boreal forests have decreased to 11.2 Mha yr−1. At the same time, burned areas increased exponentially in tropical forests, reaching 54 Mha yr−1 in the 1990s, reflecting the use of fire in deforestation for expansion of agriculture. There is some evidence for an increase in area burned in temperate and boreal forests in the closing years of the 20th century.

Abstract: This paper analyses the progress in recent research in goat nutrition since the last International Conference on Goats (Tours, 2000). This review reveals clear progress in the quality of papers, now similar to those on cattle or sheep, particularly on nutritional aspects in tropical areas. Topics dealt with in goat nutrition are feeding behaviour, particularly on pastures or rangelands, feed digestibility, tree leaf or by-product utilization, effects of nutritional factors on growth, milk and hair production, while nutritional adaptation to harsh environments, underfeeding, factors influencing energy consumption, quality of goat products (milk, cheese, meat) and reproduction performance along with the connection between nutrition and pathology require more attention. Goat nutrition in a tropical environment follows the same physiological mechanisms as under temperate conditions, but genotypes can present specificities enabling a better adaptation to feeding conditions. Complete and precise information on the nutritive value of tropical forage, rangeland vegetation in accordance with the season, and new feed or by-products is still missing. Researchers in goat nutrition frequently use different methods, making it difficult to compare results from several research teams. Agreement on the methodology in goat nutrition is easier when the research teams are organized in networks at the national or international level. To be successful with technological transfer in goat nutrition, the message for the end users must be clear and well adapted. At the present time, we are short of review papers that provide an analysis of all results already published to establish quantitative relationships between variables, which can clarify the messages for the field. Methods of meta-analysis can be used to analyse the quantitative results from experimental data banks and to establish response laws and define limits of application. Finally, if we implement a research project on goat nutrition dedicated to application in the field, not only the research works but also the actions of technological transfer must be financed.

Abstract: This study evaluated a non-destructive scientific method that is non-invasive to the animal, for quantifying foraging selectivity by cattle within heterogeneous pasture swards in order to test the utility of a new grazing system designed to aid conservation of native rough fescue (Festuca campestris Rydb.) rangeland in western Canada. Skim grazing is a recently developed strategy that involves a light, once-over-spring defoliation, followed by a late to dormant season grazing period. This practice is thought to conserve rough fescue as cattle are assumed to prefer invasive grass species during spring when fescue is sensitive to defoliation. We examined the preferences of cattle for each of four major grass species, two native and two introduced, within rough fescue rangeland, grazing during spring, fall, or spring and fall of 2000 and 2001. We developed height-biomass models for each grass species in each grazing period, determined biomass removal by species, and despite under-estimating actual herbage removal, successfully evaluated cattle preferences. Though the interpretation of established preferences are limited to the conditions of this study, rough fescue together with the introduced species, Kentucky bluegrass (Poa pratensis L.), were preferred during spring, contrary to our hypothesis. Kentucky bluegrass was also preferred within both fall and fall regrowth pastures. Smooth brome (Bromus inermis Leyss.) and Parry oat grass (Danthonia parryii Scribn.) were generally avoided. The failure of cattle to avoid rough fescue during spring indicates skim grazing may negatively impact the conservation of rough fescue grassland. In contrast, fall grazing appears conducive to sustaining fescue grasslands while capitalizing on forage production from invasive species like Kentucky bluegrass.

Abstract: Summary This study investigates the importance of spatial landscape characteristics and habitat management on the condition of calcareous grassland in the North Down Natural Area, Kent UK. We used a digitised map of the study area containing shapefiles of all the habitats including 82 patches of calcareous grassland together with management information for each patch and data on the presence and abundance of a range of calcareous grassland indicator plant species. We defined habitat condition by presence of indicator species and used classification trees to generate models with rules for predicting habitat condition from the landscape spatial characteristics and management information. We also applied the same method to investigate the factors affecting presence or diversity of three ecological groups of positive indicator species and dominance of a negative indicator species. All the models except one showed good classification accuracy and high kappa statistic. Favourable habitat condition was predicted by presence of different types of grazing management, presence of woodland around patches of calcareous grassland and shape complexity. These results indicate that calcareous grassland in favourable condition is management-dependent but also located in less intensively managed landscapes. Unfavourable habitat condition was predicted by threat factors such as lack of management and high incidence of arable or improved grassland around patches of calcareous grassland, indicating nutrient enrichment and habitat degradation. Some of these factors also predicted high diversity of the different ecological species groups. The value of this method for predicting habitat condition and species diversity from baseline ecological data for conservation monitoring at the landscape level is emphasised.

Abstract: The influence of Colophospermum mopane (Kirk ex Benth.) Kirk ex J. Leonard on surface soil properties and understorey vegetation was investigated in a semi-arid southern African savanna in Bulawayo, Zimbabwe. Soil samples were collected (depth 0-10 cm) under and outside small, medium and large canopied mopane trees in open woodland on shallow sandy loam soils. The concentration of soil nutrients beneath trees increased with tree size. Soils beneath trees had higher fertility than between tree interspaces. Trees seem to be the major suppliers of nutrients to the understorey vegetation in the crown zone in the form of litter. Soil nutrient concentrations outside canopies of small, medium and large trees were significantly similar, implying that tree size had no significant influence on soil nutrient concentrations in the tree interspaces. Soils were sandier and slightly acidic under canopies of medium and large trees compared to small trees, which had slightly alkaline soils. Soils in the tree interspaces had significantly higher silt and clay content than beneath trees suggesting loss of soil nutrients from surface soils through erosion in the former. Standing herbaceous biomass was significantly lower in the tree interspaces than in the below-crown microhabitats. Species richness and diversity increased significantly with canopy distance from the tree bole. The results suggest that C. mopane has a positive influence on soil fertility in its environment and the fertility improvement beneath trees is not at the expense of soil fertility in the tree interspaces.

Abstract: South Africa is a country with both rich floral biodiversity and cultural diversity. Traditional herbal medicines form an important part of the healthcare of most South Africans, and relies heavily on the use of indigenous plants. This article briefly describes the role South Africa has played in recent years, in contributing to the worldwide increase in research in the field of ethnopharmacology.

Abstract: Concern over human impact on the global environment has generated increased interest in quantifying agricultural contributions to greenhouse gas fluxes. As part of a research effort called GRACEnet (Greenhouse Gas Reduction through Agricultural Carbon Enhancement Network), this paper summarizes available information concerning management effects on soil organic carbon (SOC) and carbon dioxide (CO2), nitrous oxide (N2O), and methane (CH4) fluxes in cropland and rangeland in northwestern USA and western Canada, a region characterized by its inherently productive soils and highly variable climate. Continuous cropping under no-tillage in the region increased SOC by 0.27 ± 0.19 Mg C ha-1 yr-1, which is similar to the Intergovernmental Panel on Climate Change (IPCC) estimate for net annual change in C stocks from improved cropland management. Soil organic C sequestration potential for rangelands was highly variable due to the diversity of plant communities, soils, and landscapes, underscoring the need for additional long-term C cycling research on rangeland. Despite high variability, grazing increased SOC by 0.16 ± 0.12 Mg C ha-1 yr-1 and converting cropland or reclaimed mineland to grass increased SOC by 0.94 ± 0.86 Mg C ha-1 yr-1. Although there was generally poor geographical coverage throughout the region with respect to estimates of N2O and CH4 flux, emission of N2O was greatest in irrigated cropland, followed by non-irrigated cropland, and rangeland. Rangeland and non-irrigated cropland appeared to be a sink for atmospheric CH4, but the size of this sink was difficult to determine given the few studies conducted. Researchers in the region are challenged to fill the large voids of knowledge regarding CO2, N2O, and CH4 flux from cropland and rangeland in the northwestern USA and western Canada, as well as integrate such data to determine the net effect of agricultural management on radiative forcing of the atmosphere.

Abstract: In many agricultural systems in the semi-arid tropics, crops use only a small fraction of the total rainfall. Agroforestry can greatly reduce some losses, especially on hill slopes, where soil evaporation, runoff and soil losses are important. This paper reports on soil evaporation from a rotation of intercropped maize and cowpea between contour hedgerows of pruned Senna siamea trees as well as trimmed Panicum maximum grass strips on a 14% hill slope at a semi-arid site in Machakos, Kenya. There were five treatments in order to separate effects of Senna mulch, hedges, and grass strips. Micro-lysimeters were placed between crop rows for three seasons. It followed from their results that, for the three seasons concerned, tree prunings as mulch reduced soil evaporation as percentage of rainfall in the measuring period by absolute values of 9%, 4% and 6% compared to the control sole maize and cowpea with bare soil. The influence of the hedge added to this only insignificantly, even at 1 m distance. The non-mulched plots had soil evaporation reduced by only between on average 1% and 4% in absolute values compared to the control over all the seasons, with a maximum of 5% close to the hedge in the first season. Mulch apparently is the main evaporation reducing factor. Soil evaporation reached the highest percentage of rainfall in the long rains of 1994, becoming 65% in sole maize. It was 50% for sole cowpea in the 1994/1995 short rains and for sole maize in the next long rains. The highest value, although an upper limit could largely be understood from highest early season evaporative demands, rainfall distributions and low crop cover. The other values were in line with earlier reports for dry areas. Some advantages and disadvantages of these agroforestry systems are reviewed.

Abstract: In the arid grazing lands of central Australia, a previous study found that the size and composition of seed banks were changed by heavy grazing. In this concurrent study we found that grazing decreased the number of [`]safe sites' for seeds by reducing soil stability and damaging broad-scale resource traps. The loss of [`]safe sites' was likely to have had a greater initial impact on seed bank size than the direct effect of grazing on seed-bearing plants. In this environment, changes to the soil preceded changes to the vegetation, so that soil-based rather than vegetation-based indicators may provide a better early warning of rangeland deterioration.

Abstract: Agronomic analyses of soil dynamics in Africa have been found to be too simplifying and lacking any perspective on the critical role of farmers. Yet soil degradation is widespread and serious, and in many cases cannot be remedied by low levels of external inputs. To explain the fate of African soils, we use the co-evolutionary approach that critics of simple agronomic analyses propose, focusing especially on the interaction between short-term local and long-term global processes. From the late 19th century, industrialisation has broken the endogenous relation between population and prices that until then had facilitated gradual agricultural intensification. At the same time, Africa's evolution in the world system reproduced social structures that hindered more rapid transformations because they precluded a mass eviction of farm workers. The same structures fostered politics that encouraged taxing farmers rather than supporting farmers to allow gradual intensification in spite of low international prices. In this situation, population growth caused vicious spirals of poverty and soil degradation rather than sustainable intensification. This dynamic cannot be changed by participatory approaches alone: public investment in infrastructure and a reversal in price policies are also needed.

Abstract: Abstract C4 photosynthesis had a mid-Tertiary origin that was tied to declining atmospheric CO2, but C4-dominated grasslands did not appear until late Tertiary. According to the ‘CO2-threshold’ model, these C4 grasslands owe their origin to a further late Miocene decline in CO2 that gave C4 grasses a photosynthetic advantage. This model is most appropriate for explaining replacement of C3 grasslands by C4 grasslands, however, fossil evidence shows C4 grasslands replaced woodlands. An additional weakness in the threshold model is that recent estimates do not support a late Miocene drop in pCO2. We hypothesize that late Miocene climate changes created a fire climate capable of replacing woodlands with C4 grasslands. Critical elements were seasonality that sustained high biomass production part of year, followed by a dry season that greatly reduced fuel moisture, coupled with a monsoon climate that generated abundant lightning-igniting fires. As woodlands became more open from burning, the high light conditions favoured C4 grasses over C3 grasses, and in a feedback process, the elevated productivity of C4 grasses increased highly combustible fuel loads that further increased fire activity. This hypothesis is supported by paleosol data that indicate the late Miocene expansion of C4 grasslands was the result of grassland expansion into more mesic environments and by charcoal sediment profiles that parallel the late Miocene expansion of C4 grasslands. Many contemporary C4 grasslands are fire dependent and are invaded by woodlands upon cessation of burning. Thus, we maintain that the factors driving the late Miocene expansion of C4 were the same as those responsible for maintenance of C4 grasslands today.

Abstract: Satellite remote sensing can be used to assess grazing intensities and provide information on grassland management. A methodology was developed for quantifying the effects of grazing intensities (GI) using the normalized difference vegetation index (NDVI) obtained by the moderate resolution imaging spectroradiometer (MODIS) on-board the earth observing system (EOS) terra satellite. A combination of GPS (global positioning system) and GIS (geographic information system) was used. The study area in the Xilingol steppe lies in a semi-arid region and is dominated by typical steppe and the marshy meadow vegetation on the Xilin riverside area in Inner Mongolia. It covers a total area of approximately 20 km2, and is grazed by sheep and goats. The relationship between MODIS/NDVI and observed plant biomass (g DM m-2) showed a significantly positive correlation (R2 = 0.447, P < 0.01). To quantify grazing pressure, a GI map of three herds of sheep was created using a grid cell method with the tracking data recorded by the GPS. The relationship between GI and estimated plant biomass revealed a poor negative correlation (R2 = 0.217, P < 0.01). It indicated that plant biomass reduced with increasing GI. When the plant biomass data was separated into two different vegetation types, marshy meadow and typical steppe, a stronger negative correlation was obtained (R2 = 0.887, P < 0.001). This suggested that the water environment was affected by both the sensitivity of the spectral reflectance of the MODIS sensor and by plant productivity in different vegetation areas. From these results, GPS/GIS was revealed as being a useful tool for quantifying grazing distribution in Inner Mongolia grasslands. It was further suggested that the combined use of satellite images with GPS/GIS could be considered for estimating the effects of GI on plant biomass. It might provide useful information about the sustainable use of grasslands for range managers.

Abstract: General models of degradation suggest soil and nutrients are lost and conversion of rainfall into primary productivity is diminished when rangeland is degraded. These models are supported by studies on non-resilient landscapes, where loss of primary productivity also translated into loss of secondary productivity, but have not been tested on resilient landscapes. Elsewhere we showed that loss of chenopod shrubs from a landscape characterized as resilient was associated with declines in plant productivity and efficiency of conversion of rainfall into plant mass. To explore whether these differences in primary productivity translated into differences in secondary productivity, we grazed sheep at five rates of stocking for 10 years on 2000 ha of this landscape. The experiment was necessarily replicated in time not space (i.e. pseudo-replicated), which limits confident extrapolation of results to other landscapes. Productivity of sheep at all except highest rates of stocking varied little between sites where shrubs were abundant or scarce. From an animal production point of view, greater rates of stocking were unsustainable through dry years on the degraded site, but animal performance was generally unaffected on the non-degraded site, where shrubs were abundant. While these results provide evidence of economic penalties associated with degrading a resilient landscape, important ecological penalties were only partially explored.

Abstract: The contribution of soil organic matter (SOM) to continental margins is largely ignored in studies on the carbon budget of marine sediments. Detailed geochemical investigations of late Quaternary sediments (245-0 ka) from the Niger and Congo deep-sea fans, however, reveal that Corg/Ntot ratios and isotopic signatures of bulk organic matter ([delta]13Corg) in both fans are essentially determined by the supply of various types of SOM from the river catchments thus providing a fundamentally different interpretation of established proxies in marine sciences. On the Niger fan, increased Corg/Ntot and [delta]13Corg (up to -17[per mille sign]) were driven by generally nitrogen-poor but 13C-enriched terrigenous plant debris and SOM from C4/C3 vegetation/Entisol domains (grass- and tree-savannah on young, sandy soils) supplied during arid climate conditions. Opposite, humid climates supported drainage of C3/C4 vegetation/Alfisol/Ultisol domains (forest and tree-savannah on older/developed, clay-bearing soils) that resulted in lower Corg/Ntot and [delta]13Corg (< -20[per mille sign]) in the Niger fan record. Sediments from the Congo fan contain a thermally stable organic fraction that is absent on the Niger fan. This distinct organic fraction relates to strongly degraded SOM of old and highly developed, kaolinite-rich ferallitic soils (Oxisols) that cover large areas of the Congo River basin. Reduced supply of this nitrogen-rich and 12C-depleted SOM during arid climates is compensated by an elevated input of marine OM from the high-productive Congo up-welling area. This climate-driven interplay of marine productivity and fluvial SOM supply explains the significantly smaller variability and generally lower values of Corg/Ntot and [delta]13Corg for the Congo fan records. This study emphasizes that ignoring the presence of SOM results in a severe underestimation of the terrigenous organic fraction leading to erroneous paleoenvironmental interpretations at least for continental margin records. Furthermore, burial of SOM in marine sediments needs more systematic investigation combining marine and continental sciences to assess its global relevance for long-term sequestration of atmospheric CO2.

Abstract: Above- and belowground biomass of contrasting grass growth forms (Hilaria belangeri--shortgrass vs. Bouteloua curtipendula--mid-height grass) was quantified with respect to partial root barriers (at 35 cm soil depth) with artificial fissures. We hypothesized (a) growth would be greatest in the absence of a barrier; and (b) the shallow-rooted H. belangeri would be relatively less affected by barriers with fissures than B. curtipendula. Alternatively (c) B. curtipendula with its deeper root system would exploit fissures and access the resources below barriers better than H. belangeri. The parameters used to evaluate these hypotheses for plants grown in subirrigated 150 cm pots included above- and belowground biomass after 4 months and monthly gravimetric soil moisture at 20 cm intervals to 150 cm. Root barrier treatments had no affect on either species' above-ground growth. As expected, the mid-height grass produced more root biomass and was more deeply rooted. However, partial root barriers had no effect on total root biomass for either species. Although, some [`]perching' of root biomass above the barrier occurred in both species, it had no discernable influence on the pattern of soil moisture depletion with depth. Thus, under the conditions of this experiment, the lack of a significant species×barrier interaction suggests the two growth forms were not differentially affected by partial root barriers.

Abstract: Abstract A modeling framework has been developed to examine the spatial and temporal aspects of biomass burning emissions from southern African savanna fires. The complexity of the fire emissions processes is described using a spatially and temporally explicit model that integrates recently published satellite-driven fuel load amounts, the GBA-2000 satellite burned area time series and empirically derived parameterizations of combustion completeness and emission factors (EFs). To represent fire behavior characteristics, land cover is classified into grasslands and woodlands using the MODIS percent tree cover product. The combustion completeness is modeled as a function of grass fuel moisture and the EFs as a function of grass fuel moisture in grasslands and fuel mixture in woodlands. Fuel moisture is derived from satellite vegetation index time series. The analysis at the regional scale shows that early burning in grasslands may lead to higher amounts of products of incomplete combustion, despite the lower amounts of fuel consumed, compared with late dry season burning. In contrast, early burning in woodlands results in lower emissions, in both products of complete and incomplete combustion, because less fuel is consumed than in the late dry season when the fuels are drier. Overall, burning in woodlands dominates the regional emission budgets. Emissions estimates for various atmospheric species, many of which are modeled for the first time, are reported. The modeled estimates for 2000 are (in Tg) 296 CO2, 11.7 CO, 0.350 CH4, 0.348 NMHC and 1.1 particulates (<2.5 μm). Especially high is the previously undetermined contribution of oxygenated volatile organic compounds (0.915 Tg). A sensitivity analysis of fixed vs. seasonally variable EFs and combustion completeness demonstrates the importance of accounting for the seasonal variations of these two variables in emissions modeling.

Abstract: Three experiments were conducted on three soil types in south-central Cameroon to evaluate the effects of leguminous fallows on soil quality as compared with nonleguminous fallows. Soil quality was assessed by analysing the status of particulate organic matter (POM) fractions (4000-53 [mu]m): (i) at the end of fallow and after cropping of 3-year-old Chromolaena odorata, fallow with C. odorata removed by hand, and Pueraria phaseoloides fallow; (ii) in soil from 1-year-old C. odorata and P. phaseoloides fallow, before and after 6 weeks of growing maize in a pot experiment, which had two treatments: T1= +P -N and T2= +N -P; and (iii) at the end of a 2-year-old Calliandra calothyrsus and a 2- and 4-year-old C. odorata fallow. Both, the herbaceous (P. phaseoloides) and tree (C. calothyrsus) leguminous fallows improved soil quality of a nonacidic Typic Kandiudult and a Rhodic kandiudult. The N content of either the coarse (4000-2000 [mu]m) or the medium (2000-250 [mu]m) POM fraction was increased as compared to the nonleguminous C. odorata fallow. This trend was also found after cropping all fallows. C. odorata fallow is better adapted to improve soil quality in the acidic Typic Kandiudox, than both leguminous fallows. N addition to soil from C. odorata fallow increased maize growth in the pot experiment as well as the weight of coarse POM (cPOM). P addition to soil from P. phaseoloides fallow had the same effect in the Rhodic Kandiudult, while a more pronounced response to P addition was found in soil from C. odorata fallow in the Typic Kandiudult. A negative effect on cPOM weight after P and N addition was mainly found in soil from P. phaseoloides fallow in the Typic Kandiudox.

Abstract: Production-oriented research in the second half of the 20th century made impressive contributions to technical developments which helped to meet the food requirements of an expanding world population. These developments involved increasing specialisation in land use and in food production techniques, with progressive separation between food crop production and animal production. It is now recognised that these developments have contributed to serious long-term effects on the stability of the world's land and water resources, and on environmental hazards. Grasslands are particularly important in this spectrum of issues, in view of their dominant contribution to land use in many parts of the world, and because they occupy the nexus between the production functions and the environmental impacts of land use strategy, with implications for resource stability, biodiversity and global change. Also, they are an essential component of integrated land use systems which incorporate flexible combinations of cropping, pasture and forestry. This paper argues the need for a re-appraisal of prioritisation and funding in research on issues of land use strategy in general, and on issues of integrated land use and grassland management in particular. There is a need to provide a stronger base for genuine inter-disciplinary research, with the emphasis on integrated land use programmes and effective coordination of production and conservation oriented objectives, and greater emphasis on a coordinated programme of large-scale, long-term, integrated land use research projects on a national or, preferably, a regional basis. Improved linkages between national and international research programmes, and closer coordination of interests between the professional bodies representing particular land use interests, are likely to be required for the effective execution and delivery of such programmes. Achievement of these objectives will require a re-evaluation of conventional research and tertiary education priorities, to encourage both a broader vision and a more informed and flexible attitude to land use issues.

Abstract: Eight climatic events during the Holocene are evidenced in the East Cape Drakensberg by fluvial, archaeological and palynological deposits. Flood plain deposition under relatively moist conditions occurred in the Early Holocene, before ca. 7000 BP. Semi-arid conditions with limited fluvial activity dominated the Mid Holocene until ca. 3200 BP. Alternating flood plain erosion and deposition occurred in the Late Holocene. Four climatic events, for which there is palynological and limited archaeological evidence, have been identified in the Late Glacial.

Abstract: Pollen data from core KW31 recovered off the mouth of the Niger River (3°31'1N-05°34[modifier letter double prime]1E; 1181 m water depth) provide an exceptional record of vegetation changes in the West African lowlands between 40,000 and 3500 cal yr B.P. The highly diverse microflora testify for the permanency of rain and secondary forests in the Niger river catchment, at least as gallery formations along rivers, during the last glacial period when dry conditions occurred in relation to enhanced trade-wind circulation. The direct consequence of the post-glacial warming and the correlative increase in monsoon fluxes over West Africa was the increase in forest diversity and the expansion of rain and secondary forests on the nearby continent. Comparison between KW31 pollen record and continental pollen data from 5°S to 25°N allows the evaluation of migration rates of tropical forest populations throughout North West Africa at the beginning of the Holocene and the vegetation response to the shift toward aridity recorded widely at the end of the African Humid Period around 4000 cal yr B.P.

Abstract: Transformation of South African succulent thicket in response to grazing is widespread and characterized by the extensive replacement of dense closed-canopy thicket with a [`]pseudo-savanna' of remnant trees with an ephemeral field layer. In this study, we examined the patterns of transformation in a semi-arid succulent thicket ecosystem using replicated fence line contrasts. We quantified the changes in plant species and functional diversity, physiognomy and biomass. We tested whether the remnant tree guild of the transformed thicket is in a stable state, using aerial photographs and ground-truthing to track the survivorship of canopy trees over 60 years in transformed landscapes. We investigated the impacts of transformation on recruitment into the canopy tree guild by measuring seedling establishment across the fence line contrasts. Transformation results in a significant loss of plant and functional diversity. There is a significant reduction in the biomass and structural complexity of the vegetation, both vertically and horizontally. The canopy tree guild in transformed thicket is not stable owing to ongoing adult mortality and little successful recruitment. These results are interpreted in a framework of ecosystem functioning and long-term stability. We suggest that the pseudo-savanna typical of transformed succulent thicket is not a stable alternative state to intact thicket, but rather an intermediate stage in a trajectory towards a highly desertified state where only the ephemeral grasses and forbs persist.

Abstract: For the past ten years, sheep farmers from the French Mediterranean area have been able to use agri-environmental farming schemes to prevent the development of forest on rangelands and to preserve biodiversity in these open areas. These new environmental concerns are the background for an investigation into the management of long-term interactions between farm practices and systems on grazed land. This includes an analysis of how farmers change their management practices. Considering these practices in their socio-technical dimension, we carried out a survey among sheep farmers within the Luberon Natural Regional Park to analyse the process of transformation in practice, as sheep farm sizes are also roughly increasing. We will show how changes in practice are linked with the ability of farmers to integrate these into new farming systems. But it is also related to the social status of these practices in relation to local professional groups, who define the social framework concerning farming activities and who attribute value to different practices. Integrating these links between the technical and social dimensions of practices is a challenge for producing indicators able to evaluate the abilities of farming systems to change in order to participate in the medium term environmental management.

Abstract: Agricultural production in the semi-arid agro-ecosystems of the Sahel centres on cereal staple crops and pastoralism with increasing crop-livestock integration. Animals mobilize soil fertility through manure production, graze crop by-products, and transfer nutrients from distant pastures to cropped areas. Yet in these systems various interacting factors, i.e. climate variability, poor soil fertility, poverty, and institutional constraints limit the capacity of agriculture to keep pace with the growing needs of an increasing human population. The major trends associated with population growth are (1) increasing area cropped at the expense of rangelands; (2) reduced availability of and access to good quality grazing resources, and (3) seasonal migration of labourers and transhumance of herds. These trends lead to co-evolution of farming systems towards increased privatisation of resource use. This study examines the implications of the development processes where farming systems co-evolve with their surroundings. It explores the impact of integrated management of livestock and crops in rural communities on both the livelihoods of differently endowed farms, and on the agro-ecosystem. Different scenarios explored the co-evolution of three sites situated in Western Niger with their environment. The sites differ in relative area cropped. The scenarios simulate the different future outcomes for varying socio-economic and biophysical criteria with either current or more intensive management. Explorative bio-economic models are used to compare a range of farm, livelihood and ecological indicators, and to reveal social and ecological trade-offs. If current agro-ecosystems and their environments co-evolve towards increased privatisation of grazing resources, then soil fertility is likely to deteriorate on the lands managed by the agro-pastoral groups. Soil fertility may improve on lands managed by the livestock-scarce farmers settled in villages, at the cost of declining farm incomes. The agro-pastoral groups are likely to resort to more distant pastures for feed. The village-based, livestock-endowed farms will resort to feeding on on-farm crop residues. Intensification, though associated with relative decreases in real incomes, will enhance food security in these new systems, except for the poorer settled farmers.

Abstract: Fire is a prominent disturbance factor and a major force of environmental change especially in the African savannas. The development of an accurate system to map and monitor fires on the African continent is a priority of numerous international research centers and programs. This effort has produced a flurry of research projects in recent years to detect and map areas affected by fires at the continental scale using coarse-resolution satellite imagery. The end product of these projects consists of weekly or monthly maps of burned area, several of which are available to the user community on the internet. It is argued here that the algorithms used to generate these products are designed to capture relatively large and contiguously burned areas and that the heterogeneous patterns of burn scars created by mosaic burning regimes pose a problem for current detection methodologies. Fine-scale burned area maps are generated using a series of Landsat ETM+imagery covering the 2002-2003 fire season for the study area in the savanna of southern Mali. These maps document a seasonal-mosaic pattern of burning in which burning begins early in the dry season and continues for several months ultimately affecting over 50% of the landscape. The majority of these fires burn relatively small areas producing a highly fragmented landscape pattern. A comparison of the fine scale maps with those from two widely available coarse-resolution products finds that the latter fail to detect approximately 90% of the burned area. A general argument is developed which suggests that the documented bias in the coarse resolution products is a function of low-resolution bias which derives from the fine-scale spatiotemporal pattern of burning not uncommon to savanna and other frequently burned environments. The study demonstrates how low-resolution bias can result in a significant underestimation of burned areas and/or a shift in the seasonal burned area profile in areas where mosaic burning occurs. The findings have implications for the development of broad-scale burned area detection algorithms as well as their applications to natural resource management and global environmental change research.

Abstract: A study was carried out to determine the effect of feeding different tree leaves as supplements on nutrient digestion, rumen fermentation and blood parameters of sheep grazing on a semi-arid rangeland. Thirty adult Malpura rams of uniform body weight (39.0 ± 0.75) were divided into five groups of six each. They were grazed as a single flock from 08.00 to 17.00 h on a semi-arid rangeland. After the end of the grazing period, the first group (G1), which was not provided with any supplementation, served as the control. The second group (G2) was supplemented with 200 g of a concentrate mixture per head per day, whereas the third, fourth and fifth groups (G3-G5) were provided with approximately 200 g DM d-1 of freshly cut foliage from Prosopis cineraria, Acacia nilotica and Albezia lebbek. The foliage from P. cineraria contained 133.4 g kg-1 DM condensed tannin (CT) with protein precipitating capacity (PPC) of 66 g kg-1 DM, whereas A. nilotica contained 18.9 g kg-1 DM hydrolysable tannin (HT) with PPC of 11.5 g kg-1 DM. However, A. lebbek did not contain any tannin. The protein contents were 119, 139 and 194 g kg-1 DM, respectively. The DMI (g d-1) was 688, 916, 1024, 1003, 999 in G1, G2, G3, G4 and G5, respectively. Digestible crude protein (DCP) and metabolizable energy (ME) intakes in supplemented groups G2-G5 were higher (P < 0.05) than in the control (G1). Supplementation improved the DM digestibility in all groups, whereas CP digestibility was lower (P < 0.05) in G3 compared to G2, G4 and G5. Rumen fermentation study conducted 6 h after supplementation revealed that total N, ammonia N, and total VFA levels were lower (P < 0.05) in G3 compared to the other supplemented groups. Although the haemoglobin (Hb) levels were similar among groups, blood urea N (BUN) was lowest in G3 compared to the other groups. The initial body weights were similar among groups (mean 39 kg). After 60 days of experimental feeding, all groups maintained their body weight, except the control group (G1), which lost body weight. It was observed, that supplementation with tree leaves containing CT like P. cineraria helps in better rumen fermentation pattern by preventing excessive loss of nitrogen. It was concluded that maximum nutritional benefits of tree leaves could be harvested, if used as supplement rather than as a sole feed.

Abstract: Summary The West Coast Regional Carbon Sequestration Partnership (WESTCARB) is one of seven partnerships established by the US Department of Energy (DOE) to evaluate carbon dioxide capture, transport, and sequestration (CCS) technologies best suited for different regions of the country. The West Coast Region comprises Arizona, California, Nevada, Oregon, Washington, and Alaska. The Partnership is evaluating both terrestrial and geologic sequestration options. Data is being collected to characterize the terrestrial and geologic sinks, and the large CO2 point sources in the region. The terrestrial and geologic data are compiled in Geographic Information System (GIS) layers, which is made available to the public through an interactive internet site. The GIS database also is used for analysis of sequestration options. Supply curves for major classes of regional land use and forest activities are being prepared. In California, these analyses suggest that afforestation of rangeland is one of the best terrestrial options. The geologic formation data layer is combined with other layers containing data on active faults, urban areas, transportation routes, point source locations, restricted lands, etc, in economic and other screening analyses of potential sequestration targets. Activities addressing technology deployment issues involve: compilation and assessment of regulations and permits, development of a geologic risk assessment framework, development of monitoring and verification protocols, and life cycle analysis of the effect of CCS technologies on other emissions. Public outreach is considered to be an essential component of the Partnership effort. Activities include development of a web site, educational materials, materials for informing State and National policy, and stakeholders meetings.

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Abstract: The replacement of indigenous grasslands by commercial forestry plantations on the mountainous eastern escarpment of South Africa, has inevitably led to alteration of nutrient cycling. The overall objective of this study was to determine the nutrient status (soil, litter and foliar nutrient concentrations) of Pinus patula and Eucalyptus grandis plantations and adjacent grasslands. The 2, 13 and 30 year old P. patula plantations and adjacent Driekop grassland were located relatively high up on the escarpment (altitudes ranging between 950–1610 m) and were underlain by dolomite while the 2, 8 and 13 year old E. grandis plantations and adjacent Brooklands grassland were located lower down (altitudes ranging between 900–1100 m) and were underlain by granite. It was assumed that the nutrient status of the soil under the plantations and the adjacent grasslands were similar prior to afforestation. Samples were collected once in winter (August 2002) and once in summer (January 2003). Soil samples were collected to a depth of 20 cm and litter material, to a maximum depth of 20cm. Lower canopy foliar samples were collected within the lowermost metre of the canopies and upper canopy foliar samples were collected within the uppermost metre of the canopies. The data were analysed in the laboratory for various elements and soil physical parameters. The soil pH was lower under the P. patula (pH 4.8-5.2) and E. grandis plantations (pH 4.6-5.3) when compared with the soil under the adjacent grasslands (pH 5.3-5.6). The soil under the P. patula plantations had lower exchangeable base cation concentrations (204-300 mg kg-1) compared with the adjacent Driekop grassland (452-645 mg kg-1), while there were no clear trends when comparing the exchangeable basic cation concentrations in the E. grandis plantations and the adjacent Brooklands grassland. The soil aluminium saturation was similar between the plantations, ranging between 39.7 and 63.3% in the P. patula plantations and 27.4 and 75.6% in the E. grandis plantations. The grasslands had lower soil aluminium saturations, ranging between 17.7 and 35.7% in the Driekop grassland and 17.5 and 39.1% in the Brooklands grassland. Exudates from mycorrhizal associations chelate iv acidic cations, rendering plantations more tolerant of acidic soils. Soil total nitrogen, phosphorus and carbon in the plantations were similar to the adjacent grasslands. Higher nitrogen mineralisation rates in the P. patula plantations corresponded with higher litter and foliar total N concentrations relative to the adjacent Driekop grassland, while there were no clear trends when comparing rates of N mineralisation in the E. grandis plantations and the Brooklands grassland. The concentrations of foliar amino acids and protein were significantly higher (p<0.01) in the plantation foliage, when compared the grassland foliage. The amino acid arginine, occurred in higher proportions relative to other amino acids in plantation foliage, when compared with the relative proportions found in the grasslands. Relative to nitrogen, foliar ratios indicated that phosphorus and potassium were the most limiting nutrients for the plantations, which possibly resulted in N storage in the form of protein and amino acids. The soil and foliage were the more sensitive indicators of the nutrients status than litter. Differences in nutrients concentrations between the lower and upper canopies in both plantations were minor and no major trends were found. Therefore the sub division of lower and upper canopies is not recommended for further foliar nutrient analyses. Age related trends were unclear as a result of higher soil clay contents found in the 13 year old P. patula plantation and the 8 year old E. grandis plantation as well as the various silvicultural practices implemented. In terms of the relative impacts of P. patula and E. grandis plantations, the results of this study imply that the upper 20cm of soil was more impacted under the P. patula plantations than under the E. grandis plantations, in terms of reduced base cation and increased acid cation concentrations. The P. patula plantations are shallow rooters and thus the base cation status of the upper soil horizons may affect the sustainability of the P. patula plantations.

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Abstract: The overall aim of the study was to investigate re-vegetation of disturbed sites, using nursery grown plugs (from seedling trays) of Themeda triandra, Heteropogon contortus and Hyparrhenia dregeana in order to reach practical management guidelines for re-vegetation using indigenous grass plugs. A number of field trials were set up at Kamberg Nature Reserve (29°24'S, 29°40'E) on a site that was clear felled of A. mearnsii in October 1997. The trials were established in January 1998 and January 1999. A total of approximately 52 ,000 nursery raised plugs of T. triandra, H. contortus and H. dregeana were planted into an area of approximately 7,000 m2 . In the planting density trial , plugs of H. dregeana only and a combination of T. triandra/H. contortus were planted at 15 cm and 30 cm spacings. The T. triandra/H. contortus combination at 30 spacing showed the greatest survival and lateral plant growth (tiller number and basal area) and this combination is thus recommended. In the over-sowing trials, the H. dregeana and T. triandra/H. contortus combination at both 15 cm and 30 cm spacing were over-sown with E. curvula. The survival and lateral growth of the T. triandra/ H. contortus combination at 30 cm was again greater than the other treatments. Over-sowing with E. curvula suppressed the survival and lateral growth of the planted plugs across all treatments compared to not over-sowing. The over-sown conditions showed a significant decrease in the diversity of the plots, both in the number of species present and the Shannon diversity index. An area that had been cleared of A. mearnsii and sown to E. curvula 25 years previously was shown to have a lower number of species than the neighbouring veld. Nursery raised plugs of T. triandra were planted into the mature E. curvula in an attempt to improve the biodiversity of these areas. To re-introduce T. triandra into these E. curvula swards the plugs must be planted into the centre of a gap rather than around the base of an E. curvula plant. For improved survival of the plugs the E. curvula tufts must be clipped, while for best lateral growth the E. curvula tufts must be sprayed with a glyphosate herbicide three months prior to planting and clipping. However, the added expense of spraying and clipping is not warranted as the clipped treatments also showed good growth. Transplant shock is common when planting nursery raised plugs out into the field, as there is a relatively small root volume in the plug compared to the above ground leaf biomass. Alleviation of moisture stress at planting using a starch based polymer with high water holding capacity (Terrasorb®) and a white, needle punched geo-fabric (Agrilen®) to provide a seven day period of artificial shade after planting did not show significant improvements over the control with regards to survival or plant growth. Thus these methods of moisture amelioration are not recommended in revegetation through planting of plugs at this study site. A trial was established to investigate the biomass production of six different treatments to determine their potential to support a fire. The total biomass for the plots which were over-sown by E. tef and planted to only H. dregeana were on average sufficient for a fire, but there was a discontinuous fuel load across these plots, especially in the replications that had very low survival rates and thus these plots could not be burnt. The control and herbicide sprayed plots also showed sufficient fuel load for a fire, but this fuel load was made up of A. mearnsii saplings and bramble with very little grass cover and thus a fire would not have burnt through these plots either. The T. triandra/H. contortus combination did not produce sufficient fuel load, due to poor survival. Thus only the plots over-sown with E. curvula were able to burn in this trial and as a burning trial per se the trial was abandoned. Seed bearing hay (thatch) was collected in early summer (December 1997) and late summer (April 1998). Both times of year of harvesting proved to be successful in terms of grass cover, although the early harvested thatch had a greater number of species per plot. The Shannon diversity indexes of the two treatments were not significantly different. The multi-response permutation procedure technique confirmed that there was a compositional difference between the treatments. By the end of the trial Harpochloa falx and T. triandra and H. dregeana were indicators for the early and the late harvested thatch respectively. Comparing the thatching trial and the planting density trial indicated that the T. triandra/H. contortus combination at 30 cm spacing would be recommended to maximize biodiversity. The summer months have been shown to be the best time to plant the plugs, although the actual success will be dependant on the conditions within a particular year. The plugs should not be kept in the nursery for longer than three months and larger plugs (96 seedlings per tray) should be used. Nursery raised plugs of T. triandra and H. contortus were planted in an equal mix in an area that was cleared of A. mearnsii in 1996. By June 1998 661 H. contortus seedlings and 14 T. triandra seedlings had germinated naturally. The November 1998 population consisted of 418 H. contortus seedlings and 18 T. triandra seedlings. By May 2000 the June 1998 population showed a survival of 78.4% and the November 1998 population showed a survival of 91 .1 %. In the various trials, the ability of the nursery raised plugs used for re-vegetation to suppress the regrowth of A. mearnsii was investigated by determining the number of A. mearnsii seedlings per metre squared. The plant spacing and species of plugs used did not have a significant effect on the number of A. mearnsii seedlings per metre squared. Over-sowing with E. curvula did, however, significantly suppress the wattle re-growth. In the thatching trial the early harvested plots showed lower numbers of A. mearnsii per metre squared than the late harvest plots, as they were covered with a thick layer of thatch soon after the A. mearnsii was cleared which suppressed the A. mearnsii re-growth. Although E. curvula is able to produce a high biomass and suppress the A. meansii seedlings, it has a detrimental effect on the biodiversity of the area. Therefore, in conservation areas, where biodiversity is of great importance the planted plugs (at 30 cm spacing) or seed bearing hay must be used in preference to sowing E. curvula , although it must be remembered that greater follow up control is likely to be needed with planted plugs or seed bearing hay. The area must be planted or thatched as soon as possible after clear felling to provide competition for the A. mearnsii seedlings.

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