"" GSSA-Publications-2009

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Abstract: This handbook, updated edition of the 2002 edition, seeks to address planning, monitoring, and evaluation in the context of the United Nations Development Programme (UNDP) and its evaluation policy. These documents provide the prescriptive content on what needs to be done, by whom, and by when. This handbook complements this content by providing UNDP programme units with guidance on 039;how to 039; and practical tools to strengthen results-oriented planning, monitoring, and evaluation in UNDP. The guiding framework of UNDP for planning, monitoring, and evaluation is provided in the ‘Programme and Operations Policy and Procedure’ (POPP), the evaluation policy , and the United Nations Evaluation Group (UNEG) 039;Standards for Evaluation in the UN System 039;. The contents include the following: 1. Planning, monitoring, and evaluation for development results 2. Planning for results: Practical applications 3. Planning for monitoring and evaluation 4. Monitoring for results 5. Evaluating for results 6. Initiating and managing an evaluation 7. Assuring the quality of evaluation design and methodology 8. Enhancing the use of knowledge from monitoring and evaluation

Abstract: The mediterranean ecosystems of the world harbor exceptional biodiversity, and factors such as livestock grazing which may negatively affect biodiversity are of global concern. The mediterranean ecosystems of southern Africa have only sporadically been exposed to high densities of indigenous herbivores and may not be as typically resilient to livestock grazing pressure as the savannah and grassland ecosystems of semiarid Africa. We investigate this issue by assessing the impacts of two contrasting livestock grazing intensities associated with communal and commercial ranching systems on the dwarf succulent shrublands of the Succulent Karoo in Namaqualand, South Africa. We interpret the results in terms of vegetation dynamics and the implications for the current debate on nonequilibrium rangelands. The results demonstrate that the relative extent of plant community divergence between the communal and commercial rangeland has been maintained over the past 10 years, overall and within different plant growth forms. Recruitment of certain palatable shrub species occurred on the heavily grazed communal rangeland, indicating that a further decline in their populations is not inevitable. Recruitment of the unpalatable shrub Galenia africana on the communal rangeland was disproportionately greater than that of the palatable species, reenforcing the dominance of this species. Due to the longevity of woody shrubs, short-term vegetation shifts are small, limiting the potential for the recovery of overgrazed shrublands during periods of low grazing pressure. The shift on the communal rangeland toward annuals and geophytes has increased the variability of forage production and contrasts with the dominance of dwarf shrubs on the commercial rangeland. Shrub-dominated ecosystems create the potential for forage storage and inter-annual transfer of excess production, buffering livestock numbers in the face of a fluctuating environment. Despite the semiarid nature of the area and contrary to the predictions of the nonequilibrium theory, livestock and vegetation in Namaqualand interact strongly, and a close relationship between livestock numbers and primary production persists over the long-term on the communal rangeland.

Abstract: Summary The West African monsoon interacts strongly with the land surface, yet knowledge of these interactions is severely limited by the lack of observations of surface energy fluxes. Within the framework of the AMMA project, three eddy covariance flux stations were installed to sample the three main surface types near Hombori (Mali) in the central Sahel at 15.3°N, and a fourth station was installed near Bamba in the northern Sahel at 17.1°N to sample semi-desert conditions. Observed land types near Hombori comprised a grassland growing on sandy soil (near the village of Agoufou), a flooded forest in a clay-soil depression (Kelma), and a bare rocky soil (Eguerit). The energy balance closure at the grassland site was satisfactory, but less so at the flooded forest site. Surface water heat storage during the flood and advection probably were responsible for most of the imbalance. The daily sensible heat flux (H) was fairly constant throughout the year at Bamba and Eguerit, with only a slight increase during the monsoon season corresponding to increased net radiation. By contrast, the seasonal cycle of the grassland site was marked, with H decreasing during the monsoon season from 70 W m-2 in May to 20 W m-2 in August. The flooded woodland exhibited the strongest contrast between the dry and wet seasons, with daily sensible heat flux close to zero during the flood. During the peak monsoon season, the two vegetated sites had the highest net radiation and the lowest sensible heat flux, as a consequence of the strong evapotranspiration rates caused by both high soil moisture availability and high leaf area index. Lateral fluxes of water were found to be strong drivers of inter-site sensible and latent heat fluxes variability, with water leaving bare rocky soils as surface runoff and ending in the clay depressions (e.g., Kelma), whereas the sandy soils were locally endorheic, with most of the rainfall being rapidly returned to the atmosphere. An attempt was made to scale the sensible heat flux up to the scale of the AMMA northern super-site (60 km � 60 km), following a simple scaling scheme, which accounted for the contrasting surface types and water regimes. The super-site average sensible heat flux proved to be close to the grassland sensible heat flux, in part because grassland occupies 55% of the area. A strong spatial variability was caused by the difference in water regime and vegetation type, at a scale large enough to potentially influence the atmospheric properties such as the boundary layer.

Abstract: Central governments have neither the capacity nor the local knowledge to implement a just, large-scale national land registration system. Support to local institutions to undertake intermediate forms of land registration has been shown to be far more effective in many places--although these need careful checks on abuses by powerful local (and external) interests, measures to limit disputes (too many of which can overwhelm any institution) and measures to ensure that the needs of those with the least power - typically women, migrants, tenants and pastoralists - are given due weight. These locally grounded systems can also provide the foundation for more formal registration systems, as needs and government capacities develop. Even if there are the funds and the institutional capacity to provide formal land title registration to everyone in ways that are fair and that recognize local diversity and complexity, and could manage disputes, this may often not be needed. For the vast majority of people, cheaper, simpler, locally grounded systems of rights registration can better meet their needs for secure tenure.

Abstract: In African savannahs, large trees improve grass quality, particularly in dry and nutrient poor areas. Enhanced below-canopy grass nutrients, such as nitrogen and phosphorus contents should therefore attract and benefit grazers. To predict whether ungulates really need these forage quality islands we focused on four grazer species, i.e., zebra, buffalo, wildebeest, and warthog, differing in body size and digestive system. We confronted literature estimations of their feeding requirements with forage availability and quality, observed in three South African savannah systems, through linear modelling. The model predicted the proportion of below-canopy grass that grazers should include in their diet to meet their nutritional requirements. During the wet season, the model predicted that all animals could satisfy their daily nutrient requirements when feeding on a combination of below- and outside-canopy grasses. However, wildebeest, having relatively high nutrient demands, could meet their nutrient requirements only by feeding almost exclusively below canopies. During the dry season, all animals could gain almost twice as much digestible protein when feeding on below - compared to outside-canopy forage. Nonetheless, only warthogs could satisfy their nutrient requirements - when feeding almost exclusively on below-canopy grasses. The other ungulate species could not meet their phosphorus demands by feeding at either site without exceeding their maximum fibre intake, indicating the unfavourable conditions during the dry season. We conclude that grazing ungulates, particularly warthog, zebra, and buffalo, actually depend on the available below-canopy grass resources. Our model therefore helps to quantify the importance of higher quality forage patches beneath savannah trees. The composition of grazer communities depending on below-canopy grasses can be anticipated if grazer food requirements and the abundance of large trees in savannahs are known. The model suggests that the conservation of large single-standing trees in savannahs is crucial for maintenance of locally grazing herbivores.

Abstract: The establishment of enclosures has become an important measure to combat land degradation in many of the world's semi-arid rangelands. In view of the increased pressure exerted by this land reclamation strategy on the neighbouring agricultural lands, knowledge of the time required for restoring vegetation cover and soil health, and of the potential positive impact of an adapted management strategy, is highly required. This paper assesses the vegetation and soil rehabilitation in a 23-year chronosequence of two different enclosure management types. In the severely degraded, semi-arid Njemps Flats plain of the Lake Baringo Basin in Kenya communal enclosures characterised by high quality inputs and strict control, and private enclosures managed by individual farmers, were installed since the 1980s. Six communal enclosures (3-17 years since establishment) and six private enclosures (13-23 years since establishment) were selected. Vegetation cover was estimated along three 50 m transects set within each enclosure and in the adjacent open grazing area using the point-to-line transect method. Five 0.5 m2 quadrats systematically placed alongside each transect were sampled for herbaceous standing biomass and topsoil physical, chemical and biological analyses. Grass cover and herbaceous biomass production proved to be the most responsive biotic parameters under both management types, whereas the recovery of the forbs was unsuccessful. Under communal management, the biomass production fully recovered up to its optimal level as recorded in the neighbouring nature reserves. Within private enclosures however, the adopted management strategies seriously restricted biomass production to a significantly lower level. Soil quality generally recovered more slowly with time. Significant improvements compared to the open rangeland were recorded in topsoil bulk density, organic C and total N stocks, and microbial biomass C and N stocks of the communal enclosures. Unlike the communal enclosures, only topsoil bulk density and the microbial biomass C stock showed a significant difference in the private enclosures. With respect to C and total N stocks, and the microbial biomass N a non-significant improving trend was recorded. The level of chemical and biological soil quality obtained under both management types is still low and draws the attention to the importance of careful monitoring of grazing and grass cutting activities under both enclosure management strategies. The chronosequences further highlight the potential of some well-managed private enclosures, whereas intrinsic soil properties such as high alkalinity, as well as changes in management, limit the rehabilitation of some other private as well as communal enclosures.

Abstract: As woody plants encroach into grasslands, grass biomass, density and cover decline as wood plant biomass, density and cover increase. There is also a shift in location of the biomass from mostly belowground in the grasslands to aboveground in the woodlands. In addition, species richness and diversity change as herbaceous species are replaced by woody species. This is not a new phenomenon, but has been going on continually as the climate of the Planet has changed. However, in the past 160 years the changes have been unparalleled. The process is encroachment not invasion because woody species that have been increasing in density are native species and have been present in these communities for thousands of years. These indigenous or native woody species have increased in density, cover and biomass because of changes in one or more abiotic or biotic factors or conditions. Woody species that have increased in density and cover are not the cause of the encroachment, but the result of changes of other factors. Globally, the orbit of the Earth is becoming more circular and less elliptical, causing moderation of the climate. Additional global climate changing factors including elevated levels of CO2 and parallel increases in temperature are background factors and probably not the principal causes directing the current wave of encroachment. There is probably not a single reason for encroachment, but a combination of factors that are difficult to disentangle. The prime cause of the current and recent encroachment appears to be high and constant levels of grass herbivory by domestic animals. This herbivory reduces fine fuel with a concomitant reduction in fire frequency or in some cases a complete elimination of fire from these communities. Conditions would now favor the woody plants over the grasses. Reduced grass competition, woody plant seed dispersal and changes in animal populations seem to modify the rate of encroachment rather than being the cause. High concentrations of atmospheric CO2 are not required to explain current woody plant encroachment. Changes in these grassland communities will continue into the future but the specifics are difficult to predict. Density, cover and species composition will fluctuate and will probably continue to change. Increased levels of anthropogenic soil nitrogen suggest replacement of many legumes by other woody species. Modification and perhaps reversal of the changes in these former grassland communities will be an arduous, continuing and perhaps impossible management task.

Abstract: Many existing parks are currently experiencing difficulties in achieving their conservation aims, yet they remain an important option for maintaining and enhancing the conservation of biological diversity and ecosystem processes. Critics have claimed that many national parks cannot continue to protect the biological resources within their borders, and the sustainability of these areas over the long-term is in question. Ways need to be found to strengthen those that are failing, and to understand and replicate those that are succeeding. This paper presents the empirical results from a systematic evaluation of how effectively six case study national parks and national park reserves in Canada and South Africa have been protecting ecological integrity. Several parks were effective at addressing the priorities for which they had monitoring data, however the effectiveness rating of each park decreased when all indicators, including those identified as priorities but lacking monitoring data, were analysed. This indicates that the parks had generally identified more priority indicators than they were actually able to address (for many reasons, including lack of budget or trained staff, managerial challenges). Overall, a systematic approach to evaluating ecological integrity in national parks is recommended as the managers of protected areas cannot be expected to conserve the biological diversity and ecosystem processes within their borders if they are unaware of the ecological status of the park's biodiversity. The paper concludes with several practical recommendations for monitoring ecological integrity in national parks.

Abstract: Despite the importance of livestock to poor people and the magnitude of the changes that are likely to befall livestock systems, the intersection of climate change and livestock in developing countries is a relatively neglected research area. Little is known about the interactions of climate and increasing climate variability with other drivers of change in livestock systems and in broader development trends. In many places in the tropics and subtropics, livestock systems are changing rapidly, and the spatial heterogeneity of household response to change may be very large. While opportunities may exist for some households to take advantage of more conducive rangeland and cropping conditions, for example, the changes projected will pose serious problems for many other households. We briefly review the literature on climate change impacts on livestock and livestock systems in developing countries, and identify some key knowledge and data gaps. We also list some of the broad researchable issues associated with how smallholders and pastoralists might respond to climate change. The agendas of research and development organisations may need adjustment if the needs of vulnerable livestock keepers in the coming decades are to be met effectively.

Abstract: Farms stood at an ecological frontier in the 1930s. With new and better agricultural machinery, more farms than ever before made the leap to thousand acre enterprises. But did they abandon mixed husbandry in the process? This article explores the origins of the modern relationship between scale and diversity using a new sample of Kansas farms. In 25 townships across the state, between 1875 and 1940, the evidence demonstrates that relatively few plains farms were agents of early monoculture. Rather than a process driven by single-crop farming, settlement was shaped by farms that grew more diverse with each generation.

Abstract: The recognition that a system can appear resilient to changes in the environment, only to reach a critical threshold of rapid and unexpected change, is spurring work to apply threshold models in conservation and restoration. Here we address the relevance of threshold models to habitat management. Work to date indicates these concepts are highly applicable: human impacts can widen the range of habitats where threshold dynamics occur and shift communities into new states that are difficult to reverse. However, in many applied settings, threshold concepts are being adopted without evaluation of evidence and uncertainty. We suggest a framework for incorporating threshold models that reflects an emphasis on applicability to decision making and management on relatively short timescales and in human-impacted systems.

Abstract: Interpolated rain-gauge data were compared to Meteosat-based precipitation estimates for sub-Saharan Africa. Validation was carried out using a dataset from a very dense gauge network in South Africa, on a point-to-pixel (PO-PI) as well as on a pixel-to-pixel (PI-PI) basis. Error criteria computed at the gauged pixels indicate that overall the interpolated estimates perform similarly to the satellite-based data: they provide good estimates of lower but underestimate larger precipitation amounts. It is concluded that the satellite estimates are more fitted for the operational modelling of processes such as surface runoff and soil erosion, especially in the developing areas where resources are scarce.

Abstract: A simulation model was used to determine the ecological and economic consequences of managing stocking rate on semi-arid savanna rangeland continuously stocked with livestock to achieve the alternate management goals: (1) maintaining current range condition, (2) maximizing profit, or (3) improving range condition over a 30-year time frame. We developed values for end of the year herbaceous standing crop and utilization required to attain these management goals for rangeland in poor to excellent condition. Based on extensive field research conducted in this region over 5 decades, range condition in this model is programmed to decline in response to three factors: excessive grazing pressure, below average precipitation, and an increase in woody plants. Earning capacity is four times higher for range in excellent condition than that in poor condition. For all initial range condition (RC) values, simulated stocking rates that maintained RC resulted in simulated mean weaning weights 93-94% of maximum. Maximum short-term and long-term profit is attained at higher stocking rates than would maintain long-term range condition and at much higher levels than would increase range condition levels. When stocked for maximum profit, individual animal performance was 90% of maximum. The model predicts that low stocking rates allow range condition to improve. At these recovery stocking rates, total 30-year profits were found to be 78%-87% of the stocking rates that would maintain range condition, and only 67%-75% of stocking rates that would maximize profit. Predictions of the end of year standing crop to maintain range condition were in broad agreement with the 1000 kg ha- 1 advised for this region. To improve range condition, the model predicts that an end of year standing crop of 1500-2000 kg ha- 1 is required, compared to the generally advised level of 1200-1500 kg ha- 1. The predicted end of year forage standing crops for the maximum profit goal are well below the advised 800 kg ha- 1 threshold required to prevent degradation for all of the initial range conditions that were simulated. To ensure maintenance of range in excellent condition, our results concur with the advised utilization levels of 20-25%. However, for range in poorer than excellent condition, the model predicted much lower utilization levels were needed to maintain or improve range condition.

Abstract: The adoption of conservation agriculture (CA), based on minimal soil movement, permanent soil cover with crop residues or growing plants and crop rotation has advanced rapidly in the Americas and Australia over the last three decades. One of the immediate benefits of CA in dryland agriculture is improved rainfall-use efficiency through increased water infiltration and decreased evaporation from the soil surface, with associated decreases in runoff and soil erosion. This paper focuses on the effect of CA techniques on soil moisture relations in two researcher-managed trials in Zambia and Zimbabwe. In 2005/2006 and 2006/2007, we found significantly higher water infiltration on both sites on CA fields compared to conventionally ploughed fields. At Henderson Research Station, Zimbabwe, on a sandy soil, a direct seeded CA treatments had a 49% and 45% greater infiltration rate than the conventionally tilled plots after a simulated rainfall in both seasons. At Monze Farmer Training Centre, Zambia, on a finer-textured soil, the same treatment had 57% and 87% greater infiltration rate than the conventionally tilled control treatment in both seasons. Treatments that included reduced tillage and surface residue retention had less water runoff and erosion on runoff plots at Henderson Research Station, Zimbabwe. On average, soil moisture was higher throughout the season in most CA treatments than in the conventionally tilled plots. However, the full potential of CA in mitigating drought was not evident as there was no significant drought period in either season. Results suggest that CA has the potential to increase the productivity of rainfall water and therefore reduce the risk of crop failure, as was apparent at the Monze Farmer Training Centre, Zambia, in 2005/2006 when a period of moisture stress at tassling affected CA treatments less than the conventionally tilled treatment.

Abstract: The complex interactions between human activity and natural processes determine non-linear dynamics in ecosystems that can difficult their management. Human settlements in arid lands contribute to the modification of disturbance regimes, including the introduction of new disturbances and the elimination of others. In consequence, they can alter the functional mechanisms that allow systems to overcome limiting factors, leading to desertification. In this revision, we evaluated the effects of the changes on disturbance regimes produced by the different forms of land transformation on the structure and function of ecosystems of the Monte Biogeographical Province, in Argentinean arid west. Two approaches were used: the analysis of land use history and the analysis of the effects of the main disturbances on the dynamics of different communities. We concluded that throughout the history of the Monte Desert, the joint action of natural and anthropic agents has resulted in complex dynamics that lead most area of the Monte to a moderate to severe status of desertification. The modification of the disturbance regime had strong consequences for several aspects of the dynamics of communities, such as species composition and diversity, water dynamics, soil conditions, trophic structure and productivity of Monte Desert ecosystems. However, disturbance regimes could be managed to promote favorable transitions in ecosystems and, therefore, could be a tool for optimizing productivity of agro-ecosystems, and recovering and conserving natural ecosystems.

Abstract: Leaf wax components of terrestrial plants are an important source of biomass in the geological records of soils, lakes and marine sediments. Relevant to the emerging use of plant wax derived biomarkers as proxies for past vegetation composition this study provides key data for C3 plants of tropical and subtropical Africa. We present analytical results for 45 savanna species and 24 rain forest plants sampled in their natural habitats. Contents and distribution patterns of long chain n-alkanes (n-C25 to n-C35) and n-alkan-1-ols (n-C24 to n-C34) as well as bulk and molecular carbon isotopic data are presented. The variations of the analysed parameters among different growth forms (herb, shrub, liana and tree) are small within the vegetation zones, whereas characteristic differences occur between the signatures of rain forest and savanna plants. Therefore, we provide averaged histogram representations for rain forest and savanna C3 plants. The findings were compared to previously published data of typical C4 grass waxes of tropical and subtropical Africa. Generally, trends to longer n-alkane chains and less negative carbon isotopic values are evident from rain forest over C3 savanna to C4 vegetation. For n-alkanols of rain forest plants the maximum of the averaged distribution pattern is between those of C3 savanna plants and C4 grasses. The averaged presentations for tropical and subtropical vegetation and their characteristics may constitute useful biomarker proxies for studies analysing the expansion and contraction of African vegetation zones.

Abstract: The effect of different grazing intensities on the semiarid grasslands of the southern Chihuahuan Desert was studied using a fence-line contrast between a moderately grazed cattle ranch, from which goats and sheep had been excluded for forty-five years, and an ejido, heavily overgrazed for at least the last century. Each plant species density and cover was quantified in three distinctive microhabitats on the ranch and on the adjacent common-use rangelands. The results indicated that three grass species were important in the dynamics of this rangeland. Hilaria belangeri, a stoloniferous, mat-forming grass species, was dominant on the heavily grazed ejido but is in the process of being replaced by two taller grasses, Bouteloua gracilis and Bouteloua curtipendula, on the more moderately grazed ranch. These data suggest that the dynamics of this system in the semiarid grasslands of the southern Chihuahuan Desert are based primarily on two functional groups of species. Members of the first functional group are stoloniferous and clonal. Their growth form slows the rate of surface water movement, thereby controlling erosion while building up the soil by entrapping debris. In contrast, the second functional group is comprised of non-stoloniferous grasses that are described variously as bunch, tufted or tussock grasses in the literature. These species have the capacity to invade, overtop and replace individuals of the first functional group. They are limited in their lateral growth by their rhizomatous growth habit, which is much less efficient in co-opting space. Finally, there is, at least, a third functional group of much taller grasses present that are limited in these rangelands to refuges by the heavy grazing. These species are usually obligate seed producers. Such species have the potential to replace members of the earlier functional groups by overtopping them. They are limited by their inability to reproduce vegetatively, once established by their seed bank. This research suggests that restoration of the heavily eroded, semiarid grasslands of the southern Chihuahuan Desert must begin with the re-establishment of members of the first functional group. These species have the ability to facilitate the entry of the later functional groups and, in turn, be replaced competitively by them.

Abstract: Two models, artificial neural network (ANN) and multiple linear regression (MLR), were developed to estimate typical grassland aboveground dry biomass in Xilingol River Basin, Inner Mongolia, China. The normalized difference vegetation index (NDVI) and topographic variables (elevation, aspect, and slope) were combined with atmospherically corrected reflectance from the Landsat ETM+ reflective bands as the candidate input variables for building both models. Seven variables (NDVI, aspect, and bands 1, 3, 4, 5 and 7) were selected by the ANN model (implemented in Statistica 6.0 neural network module), while six (elevation, NDVI, and bands 1, 3, 5 and 7) were picked to fit the MLR function after a stepwise analysis was executed between the candidate input variables and the above ground dry biomass. Both models achieved reasonable results with RMSEs ranging from 39.88% to 50.08%. The ANN model provided a more accurate estimation (RMSEr = 39.88% for the training set, and RMSEr = 42.36% for the testing set) than MLR (RMSEr = 49.51% for the training, and RMSEr = 53.20% for the testing). The final above ground dry biomass maps of the research area were produced based on the ANN and MLR models, generating the estimated mean values of 121 and 147 g/m2, respectively.

Abstract: Leaf gas exchange characteristics play a key role in carbon sequestration and water balance from site to regional scales, yet show differences among plant species with alternative adaptations to the environment. To investigate the influences of climate regimes on leaf gas exchange characteristics and the underlying mechanisms and adaptations, we analyzed the photosynthesis and stomatal conductance characteristics of dominant C3 and C4 species at wet and dry ends of Kalahari transect in southern Africa by fitting empirical and mechanistic models to field measurements of leaf gas exchange rates. Adaptations to different climatic moisture regimes greatly influenced the leaf gas exchange characteristics of the species with different photosynthetic pathways along the Kalahari transect via a variety of mechanisms. We found that the leaf of C3 species with higher leaf nitrogen concentration at the dry site had higher photosynthesis rates than those at the wet sites. Our analysis also indicated that Stipagrostis uniplumis had high sensitivities to both radiation and vapor pressure deficit (VPD), indicating that the species may have soft guard cell structure to conserve water. We also found that the relatively high soil-to-leaf conductance allowing efficient water supply from soil to plant leaves might contribute to the small sensitivities of stomatal conductance to VPD for the grasses of S. ciliata and S. obtusa. The results of leaf gas exchange characteristics and underlying mechanisms provide basic but crucial parameters for simulation studies of carbon sequestration and water balance at site to regional scales in the Kalahari region.

Abstract: Understanding changes in soil chemical and biological properties is important in explaining the mechanism involved in the yield increases of cereals following legumes in rotation. Field trials were conducted between 2003 and 2005 to compare the effect of six 2-year rotations involving two genotypes each of cowpea (IT 96D-724 and SAMPEA-7) and soybean (TGx 1448-2E and SAMSOY-2), a natural bush fallow and maize on soil microbial and chemical properties and yield of subsequent maize. Changes in soil pH, total nitrogen (Ntot), organic carbon (Corg), water soluble carbon (WSC), microbial biomass carbon (Cmic) and nitrogen (Nmic) were measured under different cropping systems. Cropping sequence has no significant (P > 0.05) effect on soil pH and Corg, while WSC increased significantly when maize followed IT 96D-724 (100%), SAMPEA-7 (95%), TGx 1448-2E (79%) and SAMSOY-2 (106%) compared with continuous maize. On average, legume rotation caused 23% increase in Ntot relative to continuous maize. The Cmic and Nmic values were significantly affected by cropping sequence. The highest values were found in legume-maize rotation and the lowest values were found in fallow-maize and continuous maize. On average, Cmic made up to 4.8% of Corg and Nmic accounted for 4.4% of Ntot under different cropping systems. Maize grain yield increased significantly following legumes and had strong positive correlation with Cmic and Nmic suggesting that they are associated with yield increases due to other rotation effects. Negative correlation of grain yield with Cmic:Nmic and Corg:Ntot indicate that high C:N ratios contribute to nitrogen immobilization in the soil and are detrimental to crop productivity. The results showed that integration of grain legumes will reverse this process and ensure maintenance of soil quality and maize crop yield, which on average, increased by 68% and 49% following soybean and cowpea, respectively compared to continuous maize.

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Abstract: Overgrazing has led to severe degradation and desertification of semi-arid grasslands in Northern China over the last decades. Despite the fact that vegetation is often heterogeneously distributed in semi-arid steppes, little attention has been drawn to the effect of grazing on the spatial distribution of soil properties. We determined the spatial pattern of soil organic carbon (SOC), total nitrogen (Ntot), total sulphur (Stot), bulk density (BD), pH, Ah thickness, and carbon isotope ratios ([delta]13C) at two continuously grazed (CG) and two ungrazed (UG79 = fenced and excluded from grazing in 1979) sites in Leymus chinensis and Stipa grandis dominated steppe ecosystems in Inner Mongolia, Northern China. Topsoils (0-4 cm) were sampled at each site using a large grid (120 m � 150 m) with 100 sampling points and a small plot (2 m � 2 m) with 40 points. Geostatistics were applied to elucidate the spatial distribution both at field (120 m � 150 m grid) and plant (2 m � 2 m plot) scale. Concentrations and stocks of SOC, Ntot, Stot were significantly lower and BD significantly higher at both CG sites. At the field scale, semivariograms of these parameters showed a heterogeneous distribution at UG79 sites and a more homogeneous distribution at CG sites, whereas nugget to sill ratios indicated a high small-scale variability. At the plant scale, semivariances of all investigated parameters were one order of magnitude higher at UG79 sites than at CG sites. The heterogeneous pattern of topsoil properties at UG79 sites can be attributed to a mosaic of vegetation patches separated by bare soil. Ranges of autocorrelation were almost congruent with spatial expansions of grass tussocks and shrubs at both steppe types. At CG sites, consumption of biomass by sheep and hoof action removed vegetation patches and led to a homogenization of chemical and physical soil properties. We propose that the spatial distribution of topsoil properties at the plant scale (<2 m) could be used as an indicator for degradation in semi-arid grasslands. Our results further show that the maintenance of heterogeneous vegetation and associated topsoil structures is essential for the accumulation of SOM in semi-arid grassland ecosystems.

Abstract: This study looks at the impact of subdivision and sedentarization of pastoral lands on wildlife numbers and production in a savanna ecosystem of southern Kenya. The study uses aerial counts over a period of 33 years to compare changes in wildlife populations on two adjacent and ecologically similar Maasai group ranches. During the period under study, one group ranch was subdivided and settled. The other remained communally owned under shifting seasonal use. Wildlife populations decreased sharply on the privatized ranch following subdivision and increased steadily on the adjacent ranch where pastoralists continued mobile pastoralism. The results of multivariate analysis show that sedentarization and settlement distribution accounts for wildlife declines on the subdivided ranch. Both the direct displacement of wildlife and the reduction in grass production following a switch from seasonal to permanent grazing associated with sedentarization are discussed as causes of wildlife loss. Given the demand for title deeds among pastoralists to counter land losses, the resulting sedentarization is likely to become the biggest threat to wildlife in the East African savannas.

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Abstract: In situ rainwater harvesting (RWH) belong to the promising practices to support sustainable development in sub-Saharan Africa facing climate change impacts. However, appropriate indicators for their long-term sustainability are missing. Here, impacts for different aspects of sustainability are reviewed: in situ RWH practices improve hydrological indicators such as infiltration and groundwater recharge. Soil nutrients are enriched. Biomass production increases, with subsequent higher yields. Higher biomass supports a higher number of plants and animals, although native species might be replaced by crops as the landscape might change as a whole. This might strengthen conflicts between a nomadic and a sedentary population. Farmers applying in situ RWH practices profit from higher food security and higher income. However, some aspects are only poorly covered within the scientific literature. More integrative research concepts are needed.

Abstract: Human land use such as pastoralism may be a key determinant of wildlife populations. We studied the influence of land use on wildlife and livestock in south-western Kalahari, Botswana, during the wet and dry seasons. We included two types of livestock areas and two types of wildlife protection areas. Wild and domestic mammals >0.2 kg were sampled by distance technique. Small mammals <0.2 kg were trapped and a vegetation survey was performed. Livestock and some medium-sized wildlife species were most abundant in livestock areas, while large-sized wildlife species were mainly restricted to wildlife areas. Most red-listed species were confined to the national park. The influence of land use on abundances changed moderately between seasons. However, cattle moved into wildlife areas during the wet season. Differences in species richness and diversity were most pronounced during the dry season. The trapping frequency of small mammals was highest in the national park. Differences in vegetation structure included sparser field layer and higher cover of an invasive shrub in livestock areas. Our study shows the importance of protected areas for many wildlife species in the Kalahari. It also shows the value of a multi-species approach for investigating the effects of land use on wildlife communities.

Abstract: Knowledge of the southern Africa soil carbon pool, its heterogeneity, sources (from trees or grasses), and potential response to climate is extremely limited. In this study the Kalahari Transect (KT) was used as a representative savanna ecosystem to quantitatively evaluate the spatial heterogeneity of the soil carbon pool and its contributing sources. The KT encompasses a dramatic aridity gradient on relatively homogenous soils. Two sites were chosen along the KT, representing dry and wet conditions. In February-March 2005, soil samples were collected at each site along a 300 m transect. Stable carbon isotope ([delta]13C) and organic carbon content (%C) of the soils were utilized in the assessment in conjunction with geostatistical analysis of the spatial patterns of soil [delta]13C and %C. At the dry savanna site, well-defined patterns in both [delta]13C and %C were observed that were related to the distribution of woody vegetation. At the wet savanna site, the spatial patterns of [delta]13C and %C were somewhat less pronounced, but still were impacted by the distribution of woody vegetation. The relative contributions from C3 and C4 vegetation to the soil carbon pool at the wet site were independent of tree locations, but dependent on woody plant locations at the dry site. At the dry site, ~ 40% of the soil carbon was derived from C3 vegetation, whereas at the wet site ~ 90% of the soil carbon originated from C3 vegetation. These results represent an important step in understanding the impact of regional climate change (e.g., rainfall variations) on carbon sequestration in southern Africa by providing quantitative information on soil carbon spatial distributions and sources under different climatic conditions (e.g., different rainfall regimes).

Abstract: In the past century, especially the past five decades, the grasslands of the West Songnen Plain, Northeast China, were rapidly converted into croplands and salinized wasteland, and experienced a fragmentation process that is still ongoing. Almost no information is available on the spatial-temporal changes of grasslands in this area. In this study, grassland cover change, agricultural reclamation and salinized wasteland expansion were investigated during the past five decades. Grassland fragmentation was studied based on four landscape metrics. The grassland cover change was detected from a time series of topographic maps from 1954, satellite images of Landsat TM in 1986, 1995, and 2000 using remote sensing and geographic information systems (GIS). In addition, the land use changes were analyzed using a transition matrix of land use types, while the driving forces were explored according to climatic changes and socioeconomic developments. The results indicated a significant decrease in grassland area. Of the 1 418 945 ha of native grassland in 1954, approximately 64% was removed by 2000, while the number of patches (NP) increased from 865 to 2035 and the mean patch size (MPS) decreased from 1640 ha to 252 ha. During the whole study period, the average annual decrease rate of grassland was 34 894 ha/year. Cropland and salinized wasteland were the two main land use types into which grassland converted. During the past decades, obvious climatic changes occurred, which supplied a favorable potential environment for agricultural development but damaged grassland productivity. On the other hand, population, GDP and livestock number increased significantly as grassland quality decreased. According to the results, the shrinkage and fragmentation of grasslands may well be explained by socioeconomic development and aided by changing climatic conditions.

Abstract: The dietary regimes of 15 ungulate species from the middle Pleistocene levels of the hominid-bearing locality of Elandsfontein, South Africa, are investigated using the mesowear technique. Previous studies, using taxonomic analogy, classified twelve of the studied species as grazers (Redunca arundinum, Hippotragus gigas, Hippotragus leucophaeus, Antidorcas recki, Homoiceras antiquus, Damaliscus aff. lunatus, Connochaetes gnou laticornutus, Rabaticerus arambourgi, Damaliscus niro, Damaliscus sp. nov., an unnamed "spiral horn" antelope and Equus capensis), one as a mixed feeder (Taurotragus oryx) and two as browsers (Tragelaphus strepsiceros and Raphicerus melanotis). Although results from mesowear analysis sustain previous dietary classifications in the majority of cases, five species were reclassified. Three species previously classified as grazers, were reclassified as mixed feeders (H. gigas, D. aff. lunatus and R. arambourgi), one previously classified as a grazer, was reclassified as a browser (the "spiral horn" antelope), and one previously classified as a mixed feeder, was reclassified as a browser (T. oryx). While current results broadly support previous reconstructions of the Elandsfontein middle Pleistocene environment as one which included a substantial C3 grassy component, the reclassifications suggest that trees, broad-leaved bush and fynbos were probably more prominent than what was previously thought.

Abstract: In quantitative phytolith analysis, chance error associated with insufficient counts can affect the robustness of the interpretation, whether it is vegetation reconstruction or taxonomic differentiation. It is therefore vital to choose a count size that will ensure statistically reliable results, while minimizing the time expended. Numerical statistical methods (bootstrapping) that have become available over the past few decades have made it possible to model even complex phytolith assemblages with relative ease. This study used bootstrapping as well as analytic statistical formulas to evaluate the influence of count size on vegetation reconstruction by means of two commonly used indices, D/P (tree cover index) and Iph (aridity index). The analysis indicates that the count size needed to ensure statistical precision depends on the question as well as the observed assemblage composition. Importantly, it is the count of specimens relevant to a specific ratio or other index ("index-specific" count) that matters, whereas the total count is less important. Based on these results, some general guidelines for choice of count size and for the use of statistics in phytolith analysis are suggested.

Abstract: The existing SEtHyS SVAT model was developed further to model heat and water fluxes over savannah landscapes with the final objective to use remote sensing for regionalization and monitoring at larger scale. This new development incorporates two vegetation layers (low and high covers) above the soil. The transfer of soil water was revised in order to improve the simulated hydrology over Sahelian and semi-arid regions, by incorporating a mulch representation in a three-layer soil scheme. The two versions of the model, original and modified, have been compared at local scale over two instrumented local sites of the AMMA-Niger supersite: a fallow and a millet field equipped with surface flux, soil moisture and vegetation measurements. After calibration of the model parameters using the Multiobjective Calibration Iterative Process (MCIP) methodology on the 2005 dataset, the simulations of the two versions of SEtHyS were compared to observations over 2006. Significant differences were found between the simulations, and a better agreement with in situ measurements was observed for the new model. These differences are discussed in relation to the parameterizations of the hydrological and vegetation processes.

Abstract: Summary The SEtHyS_Savannah model [Saux-Picart et al., submitted for publication. SEtHyS_Savannah: a multiple source land surface model applied to sahelian landscapes. Agricultural and Forest Meteorology] was developed as an extension of the SEtHyS land surface model to simulate the water and energy fluxes over dry savannah landscapes. The vegetation cover is represented by a two layer model and a mulch approach is used for the soil description. The SEtHyS_Savannah model was regionalized over the AMMA-Niger super-site (about 50 km by 40 km), with the help of remote sensing data. The model uses a regular 1km grid and each cell is divided in sub-grid patches in order to represent land cover and soil heterogeneities (tile approach). The vegetation cover parameters were prescribed according to the land cover map and the seasonal evolution of the Leaf Area Index (LAI), both derived from SPOT-HRV (Satellite Pour l'Observation de la Terre - High Resolution Visible) data imagery. The atmospheric forcing was assumed homogeneous over the area and provided by a meteorological station installed at the Fakara experimental site. The surface water and energy budgets were simulated over a one-year period (2005) at a 5-min time step and validated against MSG-SEVIRI (Meteosat Second Generation - Spinning Enhanced Visible and Infra-red Imager) land surface temperature and ENVISAT-ASAR (ENVIronnement SATellite - Advanced Synthetic Aperture Radar) soil humidity products. The results show realistic surface fluxes and good agreement with the MSG-SEVIRI temperature observations. The soil moisture comparison presents significant correlation but large root mean square errors. These discrepancies are the consequence of both the use of a non-spatialized atmospheric forcing and to residual vegetation effects on the radar signal. Despite these uncertainties, the results increase confidence in the model representation of Sahelian soil-vegetation processes and open new perspectives to quantify the effects of vegetation changes on evapotranspiration and runoff over the region.

Abstract: In West Africa, policies for prescribed early fire, grazing and selective tree cutting in the savanna-woodlands are rarely based on long-term experimental studies. The purpose of this study was to provide scientific evidence based on field data from two case studies for an informed discussion on the long-term response of herbaceous abundance both at the community and individual species levels to fire, grazing, selective cutting and their interactions. A long-term factorial experiment was established in two State forest reserves in Burkina Faso that mainly differ in their soil attributes. Community abundance data recorded from line intercept sampling over 13 years were analyzed using a multivariate ordination technique known as principal response curves (PRC). The results indicate that disturbance regimes, independently or interactively, influenced species abundance over time with inter-site specificity. The dynamics of these disturbance regimes exhibited temporal variation which could be related, to some extent, to inter-annual variation in annual rainfall. The PRC ordination accounted for 38% and 34% of the variation within the data set for sites with deep and shallow soils, respectively. At the site with deep soils, more than one PRC axis was needed to summarize the community response sufficiently, suggesting that the species reacted in different ways to disturbances. The PRC method approach to the analysis of disturbance dynamics allowed us to distil the complexity of the community responses to those of individual species and to identify species that can serve as indicators of certain disturbance regimes.

Abstract: Summary Evaporation measurements using two Bowen ratio energy balance (BREB) systems in a remote high altitude montane grassland catchment of the Drakensberg Mountains, Cathedral Peak, South Africa are reported on. Various methods of data verification and rejection of inaccurate measured air temperature and water vapour pressure gradients are examined. A theoretical analysis, based on the equivalent temperature, results in data rejection procedures using the measurement of the air temperature profile difference. Data rejection is necessary whenever the Bowen ratio approaches -1, resulting in extremely inaccurate and impossibly large positive or negative sensible heat and latent energy fluxes. Using the simplified energy balance, it is shown that when the Bowen ratio approaches the limit of -1, for which the available energy flux density approaches 0 W m-2, conditions are pseudoadiabatic and isobaric and that such conditions can be depicted by the wet-bulb temperature isolines of the psychrometric chart. Disregarding evaporation estimates for which the Bowen ratio values are between arbitrarily chosen values remedies the problem to some extent. With this method, daily total evaporation may be reasonable but 20-min values unreasonable during mainly early morning and late afternoon periods. A more sensitive and dynamic approach is used to prevent BREB data from being excluded unnecessarily and to prevent rogue values escaping detection. Once the rejection procedures were applied, the 20-min BREB latent energy flux estimates compared well with measurements from a weighing lysimeter adjacent the site. Three methods were used to estimate the exchange coefficient K which allowed flux estimation for when BREB data are invalid or lacking. One method involved calculating K from wind speed only and the second method was based on the MOST-dependent temperature-variance method for which the 20-min standard deviation of 1-Hz air temperature data were used. From independent measurements of sensible heat H and latent energy LE, a time-invariant exchange coefficient K was also determined from measurements of the air temperature profile difference. These methods were used when there were invalid water vapour pressure data due to condensation in the hoses or problems with the cooled dew point mirror or when the fine-wire thermocouples were damaged or when there were unreliable estimates of the air temperature gradient. The time-invariant value for K used in one of the methods, 0.239 m2 s-1, was confirmed for a mixed grassland catchment using independent eddy covariance and surface-layer scintillometer measurements of H and Bowen ratio measurements of the air temperature profile difference.

Abstract: Abstract Recent IPCC projections suggest that Africa will be subject to particularly severe changes in atmospheric conditions. How the vegetation of Africa and particularly the grassland�savanna�forest complex will respond to these changes has rarely been investigated. Most studies on global carbon cycles use vegetation models that do not adequately account for the complexity of the interactions that shape the distribution of tropical grasslands, savannas and forests. This casts doubt on their ability to reliably simulate the future vegetation of Africa. We present a new vegetation model, the adaptive dynamic global vegetation model (aDGVM) that was specifically developed for tropical vegetation. The aDGVM combines established components from existing DGVMs with novel process-based and adaptive modules for phenology, carbon allocation and fire within an individual-based framework. Thus, the model allows vegetation to adapt phenology, allocation and physiology to changing environmental conditions and disturbances in a way not possible in models based on fixed functional types. We used the model to simulate the current vegetation patterns of Africa and found good agreement between model projections and vegetation maps. We simulated vegetation in absence of fire and found that fire suppression strongly influences tree dominance at the regional scale while at a continental scale fire suppression increases biomass in vegetation by a more modest 13%. Simulations under elevated temperature and atmospheric CO2 concentrations predicted longer growing periods, higher allocation to roots, higher fecundity, more biomass and a dramatic shift toward tree dominated biomes. Our analyses suggest that the CO2 fertilization effect is not saturated at ambient CO2 levels and will strongly increase in response to further increases in CO2 levels. The model provides a general and flexible framework for describing vegetation response to the interactive effects of climate and disturbances.

Abstract: Starting in 2005, we examined differences in vegetation for three consecutive years across an airport fence that separated heavily grazed areas from areas in which grazing had been excluded for 24 years in Mandalgobi, Mongolia. We performed repeated-measures analysis separately on two community types (dominated by Allium polyrrhizum and Achnatherum splendens, respectively) to compare the effects of fencing and year on the cover of different plant functional types. There was a significant fence � year interaction for grass cover in the Allium type (but not the Achnatherum type), due to greater cover of grasses inside the fence only when rainfall was sufficient during the growing season. The effect of grazing exclusion on perennial forb cover was confounded by a significant fence � year interaction in both types. In 2007, perennial forbs were found outside the fence, but had almost disappeared inside the fence, resulting in this interaction. Annual forbs only had much greater cover values inside the fence than outside in 2006, also resulting in a significant fence � year interaction in both community types. This study thus suggests that the high rainfall variability in arid and semi-arid rangelands may modify the effects of long-term exclosure on vegetation.

Abstract: Managing a watershed for satisfying the inhabitant's demand is a difficult task if one has to maintain a reasonable balance between usually conflicting environmental flows and demands. The solution to these complex issues requires the use of mathematical techniques to take into account conflicting objectives. Many optimization models exist for general management systems but there is a knowledge gap in linking practical problems with the optimum use of all land resources under conflicting demands in a watershed. In the present study, an optimization problem has been formulated for the Brimvand watershed, Iran, comprising ca. 9572 ha to find out the most suitable land allocation to different land uses, viz. orchard, irrigated farming, dry farming and rangeland targeting soil erosion minimization and benefit maximization. Soil erosion, net benefit and land capability maps were provided as inputs to formulate the objective functions and governing constraints in a multiobjectives linear optimization problem. The problem was then solved using the simplex method with the help of ADBASE software package and the optimal solution was ultimately determined. Additionally, sensitivity analysis was also conducted to recognize more effective land use in reducing soil erosion and increasing benefit. The results of the study revealed that the amount of soil erosion and benefit could, respectively reduce and increase to the tune of 7.9 and 18.6%, in case of implementing optimal allocation of the study land uses. The results of sensitivity analyses also showed that the objective functions were strongly susceptible to the constraint of maximum summation of irrigated farming and orchard areas.

Abstract: Pollen and charcoal data generated from a 1469 cm core, radiocarbon dated to 26,430 14C yr BP, recovered from Rumuiku Swamp on the southeast of Mount Kenya, are used to document changes in the distribution and composition of montane vegetation and fire regimes over the Late Quaternary. Throughout the transition from the Last Glacial Maximum (LGM), high resolution (sub-centennial scale) analysis documents a highly dynamic ecosystem and fire regime. The pollen record shows that under a cool, but rather moist LGM climate, Ericaceae and Stoebe species shifted down-slope more than 1000 m relative to the present day. Rather than simple altitudinal lowering of current vegetation zonation, these taxa formed a vegetation assemblage that mixed high altitude components with relatively lowland taxa; in particular Juniperus that is presently found at altitudes lower than the study site, but on the drier side of Mount Kenya. There is noticeable addition and co-dominance of Hagenia to the ecosystem from 20,500 14C yr BP, until around 14,000 14C yr BP when a mix of Ericaceous Belt and upper montane forest taxa, such as Artemisia, Polycias, Schefflera and Stoebe, dominated the initial development of montane forest. Reduced levels of Hagenia, Juniperus, Olea and Podocarpus are recorded about the time of the Younger Dryas with highly variable presence of more mesic taxa such as Polyscias and Schefflera. This development of montane forest over the Late Pleistocene to Holocene transition reflects a significant reorganization of the ecosystem composition that was heavily influenced by a variable fire regime. Shifts in vegetation composition reflect the onset of a warmer moist climate from the beginning of Holocene, as mixed montane forest became more established. The latter part of the Holocene registers human impact and forest clearance with increased anthropogenic impact marked by a transition to open vegetation and increased fire frequency.

Abstract: In this study, we asked the Ariaal herders of northern Kenya to answer "why, what and how" they classified landscape, and assessed and monitored the biodiversity of 10 km2 of grazing land. To answer the "why question" the herders classified grazing resources into 39 landscape patches grouped into six landscape types and classified soil as [`]warm', [`]intermediate' or [`]cold' for the purpose of land use. For the "what question" the herders used soil conditions and vegetation characteristics to assess biodiversity. Plant species were described as [`]increasers', [`]decreasers' or [`]stable'. The decreaser species were mostly grasses and forbs preferred for cattle and sheep grazing and the increasers were mostly woody species preferred by goats. The herders evaluated biodiversity in terms of key forage species and used absence or presence of the preferred species from individual landscapes for monitoring change in biodiversity. For the "how question" the herders used anthropogenic indicators concerned with livestock management for assessing landscape potential and suitability for grazing. The anthropogenic indicators were related to soils and biodiversity. The herders used plant species grazing preferences to determine the links between livestock production and biodiversity. By addressing these three questions, the study shows the value of incorporating the indigenous knowledge of herders into classification of landscape and assessment and monitoring of biodiversity in the grazing lands. We conclude that herder knowledge of biodiversity is related to the use as opposed to exclusive conservation practices. This type of knowledge is extremely valuable to conservation agencies for establishing a baseline for monitoring changes in biodiversity in the future.

Abstract: Termites concentrate nutrients in their mounds, which may reenter soil through leaching. We studied the effect of the grass-feeder and litter-forager termite Cornitermes silvestrii on soil solution chemistry. Free-draining lysimeters were installed below mounds of this primary termite, below mounds build by C. silvestrii but inhabited by secondary termites (mainly by Nasutitermes kemneri), and reference soils. The solution was regularly collected during a 1-year period and analyzed for dissolved organic carbon (DOC), phosphate, nitrate, ammonium and pH. The volume of drainage water was lower under the mounds than under the reference soil, and so was the flux of DOC and nutrients. Only nitrate concentrations were enhanced under secondarily inhabited termite mounds. Hence, an effect of the termite mounds on drainage water and soil nutrients through leaching is evident, but the latter only below older mounds with secondary termites.

Abstract: In order to maintain small ruminant grazing systems it is necessary to know precisely how they work and what actions can be taken to improve them. The objective of this paper was to characterize, classify, analyse and propose improvements for the dairy goat grazing systems in three countries from the western Mediterranean area: Spain, France and Italy. A multivariate analysis was conducted with 21 indicators obtained from the data collected from 45 farms. As a result of the multivariate analysis, 82.5% of variance was explained by two principal components. The first component included proportion of cultivated pasture area and cultivated pasture area per goat. The second included goats present and forage supply per goat. After conducting a cluster analysis based on these two principal components, farms were classified into four groups. Group 1 was made up of French and Italian farms, which had a smaller territorial base but a high cultivated pasture area per goat, contributing to greater self-sufficiency in feed. However the concentrate per goat was too high in relation to milk production, which was medium. The difference between milk income and feed cost is also medium. Group 2 was basically made up of Italian farms. The farms in this group had the most extensive management systems, with a low use of inputs. However, the milk production was low, meaning that the difference between milk income and feed cost was also low. Group 3 was mainly made up of Spanish farms. On these farms the concentrate supply was excessive and the forage supply was low. The milk production per goat was medium and the difference between milk income and feed cost was small. Group 4 was made up mainly of French farms. The farms of this group had a moderate supply of concentrate although the forage supply was very high. They had a high milk production, which lead to a large difference between milk income and feed cost per goat. The main weaknesses observed are related to feeding management, particularly grazing, and to the goat productivity. In the former case research on the nutritional utilization of rangelands and pastures and correct feed supplementation is to be encouraged. In the latter, the production capacity of the goats present in these systems should be improved, without forgetting the balance between hardiness and general productivity.

Abstract: ABSTRACT Physical and biological evidence supports the probable existence of an enclave of relatively warm climate located between the Southern Appalachian Mountains and the Atlantic Ocean in the United States during the Last Glacial Maximum. The region supported a mosaic of forest and prairie habitats inhabited by a �Floridian� ice-age biota. Plant and vertebrate remains suggest an ecological gradient towards Cape Hatteras (35°N) wherein forests tended to replace prairies, and browsing proboscideans tended to replace grazing proboscideans. Beyond 35°N, warm waters of the Gulf Stream were deflected towards the central Atlantic, and a cold-facies biota replaced �Floridian� biota on the Atlantic coastal plain. Because of niche diversity and relatively benign climate, biodiversity may have been greater in the south-eastern thermal enclave than in other unglaciated areas of North America. However, the impact of terminal Pleistocene megafaunal extinctions may also have been shorter and more severe in the enclave than further north. A comparison with biotic changes that occurred in North America approximately 55 million years (ma) ago at the Paleocene-Eocene Thermal Maximum suggests that similar processes of change took place under both ice-house and greenhouse climates.

Abstract: Grassland degradation due to over-grazing causes severe ecological and economical problems in the semi-arid grasslands of Inner Mongolia, PR China. The development of sustainable management systems is required, but basic information regarding the degradation process in its formation and development is rare. In 2004 and 2005 a cutting-frequency experiment was conducted in the Xilin River Basin, Inner Mongolia, subjecting a non-degraded grassland area to 3 different cutting frequencies: single defoliation at the end of growing season and defoliations every 6 and 3 weeks. It was hypothesised that the productivity of the S. grandis/L. chinensis community will be reduced by frequent defoliations. The cumulative dry matter yield increased with increasing defoliation frequency from 204 to 277 g DM m-2 in 2004 and from 87 to 158 g DM m-2 in 2005. The low aboveground biomass productivity in 2005 resulted from the low amount of precipitation, which was only 50% of the long-term mean. The nitrogen yield increased from 2.9 to 6 g N m-2 in the frequently defoliated treatments in 2004 and from 1.2 to 2.8 g N m-2 in 2005. Total leaf area was significantly reduced by frequent defoliation, but specific leaf area increased both in S. grandis and L. chinensis. Root mass (0-15 cm) was on average 929 g OM m-2 in 2004 and 882 g OM m-2 in 2005 and, as well as species composition, not significantly influenced by frequent defoliations. It was concluded that frequent defoliation positively affected the productivity of the S. grandis/L. chinensis community, and that the annual amount of precipitation essentially determined the biomass production of this grassland ecosystem. Because the community increased its productivity after frequent defoliation in the 2 experimental years, it was suggested that the community is resistant to defoliation stress in the short-term.

Abstract: Paleosols (fossil soils) are preserved throughout the geologic record in depositional settings ranging from alluvial systems to between basalt flows. Until recently, paleosols were studied using primarily qualitative methods. In recent years, paleopedology has shifted from a largely qualitative field based on comparisons with modern analogues to an increasingly quantitative endeavor. Some of this change has been a result of applying existing techniques to new materials, but many of the innovations have been the result of applying new techniques to new materials, including thermodynamic modeling of soil formation, isotope geochemistry, and applications of empirical relationships derived from modern soils. A variety of semi-quantitative and quantitative tools has been developed to examine past weathering and pedogenesis, and to reconstruct both paleoenvironmental and paleoclimatic conditions at the time that the paleosols formed. Though it is often not possible to achieve the same temporal resolution as with marine records for paleoclimatic reconstructions, proxies based on paleosols are potentially a much more direct means of making paleoclimatic reconstructions because soils form at the Earth's surface, in direct contact with the atmospheric and climatic conditions at the time of their formation. Paleoclimatic and environmental properties that may be reconstructed using the new proxies include provenance, weathering intensity, mean annual precipitation and temperature during pedogenesis, nutrient fluxes into and out of the paleosols, the atmospheric composition of important gases including CO2 and O2, the moisture balance during pedogenesis, the soil gas composition, reconstructed vegetative covering, and paleo-altitude.

Abstract: The expected outcome of weed control in natural systems is that the decline of a dominant weed will result in an increase in diversity of the plant community but this has seldom been tested. Here we evaluate the response of the plant community following the decline of diffuse knapweed (Centaurea diffusa) in six different pastures at White Lake, BC, Canada over five years. This period followed the establishment, spread and high levels of attack by the introduced European weevil, Larinus minutus, as part of a biological control program. Knapweed declined immediately before and during the study period, but, contrary to expectations, the species richness and diversity of the rangeland plant community did not increase. The absolute cover of native and introduced forbs and grasses increased following knapweed decline, but only the introduced grasses showed a consistent increase in cover relative to the other life-forms. However, unlike in other studies, the native plants dominated the study site. We conclude that the changes in plant communities following successful biological control are variable among programs and that the impact of replacement species must be evaluated in assessing the success of ecological restoration programs that use biological control to manage an undesirable weed.

Abstract: Abstract The ecogeomorphic processes occurring on semiarid rangelands are reviewed, with emphasis on the source-sink relations and positive feedback loops that existed between shrub patches and intershrub areas, and the way livestock presence affected these interactions. Compared with intershrub areas, the shrub patches had a higher soil porosity, infiltration capacity, water-holding capacity, hydraulic conductivity, structural stability, and organic matter content, and lower bulk density. These differences derived from a host of processes whose intensity was less in the shrub patches, including raindrop impact, mechanical crust formation, overland water flow, soil erosion, evaporative moisture loss, and flock trampling. There was also greater shading of the soil surface; soil and litter deposition; water accumulation; microbial, fungal, and mesofaunal activities in the shrub patches. The overland flow of water carried soil and litter from the intershrub areas to the shrub patches and resulted in microtopographic modifications that tended to strengthen these source-sink relations. Grazing had an impact on these processes, not only at the shrub-intershrub scale but also within the intershrub areas, through the creation of highly compacted trampling routes. The combined role of the above ecogeomorphic processes was to maintain the rangeland's functionality. Without these inter-relationships, water loss, soil erosion, and nutrient depletion would occur at the hillside scale, causing degradation of the landscape.

Abstract: Natural resource management may change local and regional ecosystems, especially in drought-prone environments. Livestock are commonly kept as a source of capital in agriculturally dominated communities in Southern Africa, but the mis-management of available forage and water resources has led to significant land and water degradation. In Northwest Zimbabwe, to reverse trends in environmental degradation a community-based conservation program was established that uses intensive Holistic Management Planned Grazing (HMPG) to restore lost habitat and re-establish natural vegetation. We examined riparian ecosystem structure and water quality to compare the environmental impact of this management to nearby communal lands during a drought. The results demonstrate that concentrating livestock on ephemeral stream standing pools results in reduced water quality and altered riparian ecosystem structure. These results were not significantly different from what was observed when wildlife utilized similar water resources without livestock influence. When water is scarce, as during extreme droughts, livestock usage of surface water resources must be weighted against community water needs. The long-term regional benefits of HMPG may prevail over short-term reductions in local water quality but more research is needed to assess all the consequences of such management.

Abstract: This paper explores Swaziland's National Action Programme (NAP) to combat desertification; the country's main strategy for implementing the United Nations Convention to Combat Desertification (UNCCD). It considers whether this policy tackles real problems supported by micro-level scientific evidence and local experiences, or whether it further reinforces popular orthodoxies about land degradation. Data from one case study chiefdom in Swaziland are used to test two key orthodoxies identified within the country's NAP: (1) the presentation of degradation as a neo-Malthusian problem resulting from population pressure and (2) the assumption that the poor are responsible for degradation of their environment, in particular, the over-use of forest areas and the degradation of soils. It is found that diverse rural livelihoods inherently deliver patches of degradation at the micro-level but it is not necessarily population pressure or poor people that cause the degradation. Households with varying assets simultaneously degrade and conserve different parts of the land resource through pursuing different livelihood activities. The data indicate that while the NAP focuses on mythical problems grounded in the orthodoxies, policy attention is directed away from the more serious land degradation issues affecting rural livelihoods. The findings of this study provide a more nuanced understanding of the gaps between land degradation policy, local conservation practice and environmental and livelihood outcomes, and suggest that policymakers need to evaluate more critically the outdated and simplistic degradation orthodoxies on which much current policy is based. Stronger links need to be made between scientific and policymaking communities, while more credence should be given to land users' own knowledges, perspectives, concepts and categories surrounding issues of soil conservation and degradation. It is suggested that steps need to be taken towards the development of broadly applicable benchmarks and indicators that bring together local and scientific knowledges across levels. Without this, popularised orthodoxies will continue to provide a basis for inappropriate land policy.

Abstract: The impacts of climate change, drought and desertification are closely interlinked, and most acutely experienced by populations whose livelihoods depend principally on natural resources. Given the increases in extreme weather events projected to affect the Southern Africa region, it is essential to assess how household and community-level adaptations have been helped or hindered by institutional structures and national policy instruments. In particular, there is a need to reflect on efforts related to the United Nations' environmental conventions to ensure that policies support the maintenance of local adaptations and help retain the resilience of socio-economic and environmental systems. This paper examines three interlinked drivers of adaptation: climate change, desertification and drought, assessing the extent to which international and national policy supports local adaptive strategies in three countries in southern Africa. We show that while common ground exists between desertification and climate change adaptations at the policy level, they are insufficiently mainstreamed within broader development approaches. Similarly, there are some overlaps between policy-driven and autonomous local adaptations, but the mutually supportive links between them are poorly developed. Further efforts to integrate local adaptation strategies within policy could increase local resilience to environmental change, while also contributing to wider development goals.

Abstract: The Global Assessment of Soil Degradation (GLASOD) has been the most influential global appraisal of land quality in terms of environmental policy. However, its expert judgments were never tested for their consistency and could not be reproduced at unvisited sites, while the relationship between the GLASOD assessments of land degradation and the social and economic impact of that degradation remains unclear. Yet, other methodologies that could respond to urgent calls for an updated assessment of the global environmental quality are not operational or, at best, in progress. Therefore, we evaluate the reliability and social relevance of the GLASOD approach and assess its candidacy for new global environmental assessments. The study concentrates on the African continent, capitalizing on new GIS data to delineate and define the characteristics of GLASOD map units. Consistency is tested by comparing expert judgments on soil degradation hazard for similar combinations of biophysical conditions and land use. Reproducibility is evaluated by estimating an ordered logit model that relates the qualitative land degradation classes to easily available information on explanatory variables, the results of which can be used to assess the land degradation at unvisited sites. Finally, a cross-sectional analysis investigates the relation between GLASOD assessments and crop production data at sub-national scale and its association with the prevalence of malnutrition. The GLASOD assessments prove to be only moderately consistent and hardly reproducible, while the counter-intuitive trend with crop production reveals the complexity of the production-degradation relationship. It appears that increasing prevalence of malnutrition coincides with poor agro-productive conditions and highly degraded land. The GLASOD approach can be improved by resolving the differences in conceptualization among experts and by defining the boundaries of the ordered classes in the same units as independent, quantitative land degradation data.

Abstract: Understanding changes in hydrological characteristics of rangeland ecosystems with degradation is essential when making rangeland management decisions in arid and semi-arid areas to ensure sustainable animal production. The impact of rangeland degradation on root production, root/shoot ratio and water-use efficiency was therefore determined for a semi-arid rangeland, over a 7-year period (1999/00 to 2005/06 growing seasons). Water-use efficiency (WUE) is defined as the quantity of above- and/or belowground phytomass produced over a certain period of time per unit of water evapotranspired. Sampling was from rangeland artificially maintained in three different rangeland conditions, viz. good, moderate and poor. As much as 86, 89 and 94% of the roots for rangelands in good, moderate and poor conditions, respectively, occurred at a depth of less than 300 mm. Root mass was strongly seasonal with the most active growth taking place during March and April. Root mass appears to be greater than aboveground phytomass for this semi-arid area, with an increase in roots in relation to aboveground phytomass production with rangeland degradation. The mean monthly root/shoot ratios for rangelands in good, moderate and poor conditions were 1.16, 1.11 and 1.37, respectively. Rangeland degradation significantly lowered above- and belowground phytomass production as well as the water-use efficiency. The mean WUE (root production included) were 4.79, 3.54 and 2.47 kg ha-1 mm-1 for rangelands in good, moderate and poor conditions, respectively. These water-use efficiency observations are among the few also including root production in its calculation. As a proportion of annual phytomass, litter fall of 7.17, 4.64 and 3.41% was obtained for rangelands in good, moderate and poor conditions, respectively. Increasing rangeland degradation increased the replacement of total root system by about 10 months and decomposition time of litter by 6 months. The importance of a well-established root system for sustainable production in the semi-arid rangelands cannot be overemphasized.

Abstract: Fires threaten human lives, property and natural resources in Southern African savannas. Due to warming climate, fire occurrence may increase and fires become more intense. It is crucial, therefore, to understand the complexity of spatiotemporal and probabilistic characteristics of fires. This study scrutinizes spatiotemporal characteristics of fires and the role played by abiotic, biotic and anthropogenic factors for fire probability modelling in a semiarid Southern African savanna environment. The MODIS fire products: fire hot spots (MOD14A2 and MYD14A2) and burned area product MODIS (MCD45A1), and GIS derived data were used in analysis. Fire hot spots occurrence was first analysed, and spatial autocorrelation for fires investigated, using Moran's I correlograms. Fire probability models were created using generalized linear models (GLMs). Separate models were produced for abiotic, biotic, anthropogenic and combined factors and an autocovariate variable was tested for model improvement. The hierarchical partitioning method was used to determine independent effects of explanatory variables. The discriminating ability of models was evaluated using area under the curve (AUC) from the receiver operating characteristic (ROC) plot. The results showed that 19.2-24.4% of East Caprivi burned when detected using MODIS hot spots fire data and these fires were strongly spatially autocorrelated. Therefore, the autocovariate variable significantly improved fire probability models when added to them. For autologistic models, i.e. models accounting for spatial autocorrelation, discrimination was good to excellent (AUC 0.858-0.942). For models not counting spatial autocorrelation, prediction success was poor to moderate (AUC 0.542-0.745). The results of this study clearly showed that spatial autocorrelation has to be taken in to account in the fire probability model building process when using remotely sensed and GIS derived data. This study also showed that fire probability models accounting for spatial autocorrelation proved to be superior in regional scale burned area estimation when compared with MODIS burned area product (MCD45A1).

Abstract: The regeneration dynamics of South African subtropical thicket are poorly understood. This lack of knowledge hampers the development of appropriate restoration protocols in degraded landscapes. To address this we compared the magnitude of seed production and the frequency seedlings of canopy species in intact and browsing-degraded forms of Portulacaria afra-dominated thicket. Severe browsing had a negative impact on sexual reproduction of canopy species. Seed production for all species was lower in the degraded than the intact states of both vegetation types. In the case of seedlings, almost all individuals were associated with beneath-canopy microsites, irrespective of degradation status. Exceptions were P. afra, Putterlickia pyracantha and Grewia robusta. Of the 511 seedlings that we observed, 480 (94%) were found in the beneath-canopy microsite and 31 (6%) in the open. In both intact and degraded sites, there were significantly fewer seedlings (all species combined) in open microsites than would be expected on the basis of the aerial extent of this microsite. The results show firstly that preservation of remnant clumps of closed-canopy thicket in degraded landscapes is of paramount importance for restoration, and that for recruitment of a wide range of canopy species to occur outside of these remnant clumps, it is essential to restore closed-canopy conditions as speedily as possible.

Abstract: Abstract Aim Evidence is accumulating of a general increase in woody cover of many savanna regions of the world. Little is known about the consequences of this widespread and fundamental ecosystem structural shift on biodiversity. Location South Africa. Methods We assessed the potential response of bird species to shrub encroachment in a South African savanna by censusing bird species in five habitats along a gradient of increasing shrub cover, from grassland/open woodland to shrubland dominated by various shrub species. We also explored historical bird species population trends across southern Africa during the second half of the 20th century to determine if any quantifiable shifts had occurred that support an ongoing impact of shrub encroachment at the regional scale. Results At the local scale, species richness peaked at intermediate levels of shrub cover. Bird species composition showed high turnover along the gradient, suggesting that widespread shrub encroachment is likely to lead to the loss of certain species with a concomitant decline in bird species richness at the landscape scale. Finally, savanna bird species responded to changes in vegetation structure rather than vegetation species composition: bird assemblages were very similar in shrublands dominated by Acacia mellifera and those dominated by Tarchonanthus camphoratus. Main conclusions Shrub encroachment might have a bigger impact on bird diversity in grassland than in open woodland, regardless of the shrub species. Species recorded in our study area were associated with historical population changes at the scale of southern Africa suggesting that shrub encroachment could be one of the main drivers of bird population dynamics in southern African savannas. If current trends continue, the persistence of several southern African bird species associated with open savanna might be jeopardized regionally.

Abstract: Wild herbivore diversity and abundance have declined in African savannas for the past 20 years. Competition for forage resources between wild herbivore and livestock species might contribute to this decline, given habitat and diet overlap under conditions of resource limitation. Development of conservation and management strategies rely on understanding the spatial distribution of resources for livestock and wildlife, especially since the combination of transhumance pastoralism and wildlife conservation is common over Africa. We studied the distribution patterns of wild grazers in relation to cattle abundance, and distance to permanent and seasonal water bodies in semi-arid Kenya between 1983 and 2000. Cattle were abundant far from permanent water bodies during dry and wet years. Wild grazers less dependent on water also concentrated far from water during all years. Only wild grazer species more dependent on water remained concentrated close to water. Hence, wild grazers and cattle show spatial partitioning in the use of permanent and seasonal water bodies, but not in their forage resources. Our study provides no strong evidence of spatial displacement of wild grazers by cattle. We suggest that pastoralist decisions on cattle distribution do not need to negatively affect wildlife distribution and that coexistence can be possible through spatial partitioning. Our results show that pastoralist decisions play an important role in the interactions between livestock and wildlife in African savannas and that herd mobility is a key component in supporting sustainable use of resources for both wildlife and livestock.

Abstract: Summary The scientific and management perception of artificial surface-water provision has swung like a pendulum from being to the benefit of herbivores, to being to the detriment of many vegetation and herbivore species. Using simulations, this study explores in a GIS how the water-landscape may change for water-dependent grazers under different surface-water management policies and climatic conditions in the Kruger National Park, South Africa. The simulations revealed that the addition or removal of artificial water sources in Kruger will only significantly change the water-landscape during drought episodes, emphasising the importance of considering artificial water provision in a spatio-temporal context. More generally, this illustrates how climatic conditions and time-lags can often confound the effects of management intervention in highly variable systems, demostrating the importance of continuous and long-term monitoring for evaluating management actions. Furthermore, it was shown how the wide-scale provision of water suppressed variability in surface-water availability, reducing spatial and temporal heterogeneity that is important for coexistence in, and resilience of, naturally fluctuating, non-equilibrium systems. This was especially evident during drought periods. Considering the results, water provision policies of semi-arid conservation areas supporting large water-dependent herbivore species should explicitly recognise and consequently aim to mimic spatio-temporal variability in surface-water availability.

Abstract: A 4.5-m-long sediment core from a small basin in the Province of Misiones, NE Argentina, was analyzed in a multi-proxy geochemical approach (major and minor elemental composition, Corg, N, HI, OI, [delta]13Corg, n-alkanes and compound-specific [delta]13C analyses of biomarkers) in order to contribute to the reconstruction of the Late Quaternary environmental and climate history of subtropical South America. The results of the elemental analyses and radiocarbon dating indicate different sediment provenances for Unit A--the Holocene, Unit B--the Late Glacial and the Last Glacial Maximum (LGM), and Unit C--the [`]Inca Huasi' wet phase (before ~40 ka BP). A sedimentary hiatus after ~40 ka BP is interpreted as a pronounced pre-LGM dry phase with landscape erosion/deflation. Multi-proxy geochemical characterization of the soil organic matter (SOM) shows that especially (i) the stable carbon isotopic composition ([delta]13C) of the grass-derived alkanes nC31 and nC33, (ii) the alkane ratio nC31/nC27 and (iii) lacustrine-derived short- and mid-chain alkanes are valuable proxies for the reconstruction of the palaeoenvironment. A transition from C3-tree-dominance to C4-grass-dominance is recorded at the end of the [`]Inca Huasi' wet phase. In Unit B, the ratio nC31/nC27 documents forest expansion at the beginning of a Late Glacial wet phase. More positive [delta]13C values in Unit A reflect the increasing contribution of C4-grasses and/or CAM-plants to the SOM during the Holocene and a human impact on the formation of this unit may be possible. The results are in good agreement with other tropical/subtropical palaeoenvironmental records and highlight the importance and temporal variability of the palaeo-South American Summer Monsoon (SASM).

Abstract: Land degradation, the temporary or permanent reduction of land's productive capacity resulting from poor land management, has gained considerable attention as an environmental and development issue of global importance, in particular in the Earth's drylands. This study presents a global estimate of net primary production (NPP) losses caused by human-induced dryland degradation. Due to the large uncertainties related to international databases on dryland degradation, we compiled a world map of the extent and degree of desertification based on existing regional and global maps. Two distinct approaches were followed in order to estimate NPP losses due to degradation on drylands: in the first approach, we combined these maps with model results on global potential NPP, determined with the LPJ-DGVM, with a set of factors on NPP losses per degradation degree, derived from the literature. In a second approach, we made use of spatially explicit information on potential and current NPP of agricultural areas obtained from a global HANPP assessment [Haberl, H., Erb, K.-H., Krausmann, F., Gaube, V., Bondeau, A., Plutzar, C., Gingrich, S., Lucht, W. and Fischer-Kowalski, M., 2007. Quantifying and mapping the human appropriation of net primary production in earth's terrestrial ecosystems. Proceedings of the National Academy of Sciences of the United States of America, 104: 12942-12947.]. We used the difference between potential and current NPP on croplands situated in drylands in order to quantify the effect of dryland degradation on NPP. NPP losses were found to range between 799 and 1936 Tg C/yr in the first approach, and to amount to 965 Tg C/yr in the second approach. Overall, approximately 2% of the global terrestrial NPP are lost each year due to dryland degradation, or between 4% and 10% of the potential NPP in drylands. NPP losses amount to 20-40% of the potential NPP on degraded agricultural areas in the global average and above 55% in some world regions. The results reveal that the contributions of dryland degradation to the total HANPP in drylands is of similar dimension than the overall annual socioeconomic biomass harvest. Accordingly, strategies aimed at reducing dryland degradation could present promising options to sustain future population numbers without putting further pressures on dryland ecosystems.

Abstract: It has long been understood that as ephemeral landscape features sand dunes are highly sensitive to environmental change, and thus their distribution and the timing of their development may provide clues to past climate dynamics. The relationship between climate and dune activity, however, is neither simple nor straightforward, with a range of controls affecting the balance between erodibility (the availability of sediment for deflation) and erosivity (the potential for sediment transport). To explore such complex systems over large spatial and temporal scales, a number of dune activity indices (DAI) have been created that incorporate wind speed and moisture balances to calculate the potential for, and degree of dune mobilisation. Using modern weather station data, these indices have generally been shown to provide reasonable indications of dune activity potential. Until recently, however, the detailed quantitative data required to inform these equations has not been available for past climate scenarios, and attempts to determine the relative importance of the various controls of dune activity have relied on rough estimations of climatic parameters. This paper combines data from monthly general circulation model (GCM) outputs from the coupled Ocean-Atmosphere GCMs for 21 160;ka with the most detailed DAI equation presently available to calculate the potential for dune reactivation in southern Africa during the Last Glacial Maximum (LGM, 18-24 160;ka). Based on these data and calculations it is indicated that there was significantly less potential for dune activity across southern Africa at 21 160;ka. When compared to the aeolian sediment records from the region, this study poses serious and fundamental questions about: 1) the reliability of the model outputs, 2) the degree to which DAIs are able to account for the complexity and dynamics of aeolian systems, and/or 3) the interpretation of dune records as palaeoclimatic proxies at millennial time scales.

Abstract: The dominance of dryland environments in the Southern Hemisphere makes the study of these regions of critical importance for the development of regional, hemispheric and global models of environmental change. Unfortunately, the wetting and drying cycles associated with semi-hyperarid climates are not conducive to the preservation of traditional organic proxy data sources. The last decade, however, has seen the development of a number of alternative archives including the application of luminescence dating techniques to dunes and other aeolian deposits. In continental situations, the existence of relict dune fields has long been thought to be evidence of drier conditions during the Pleistocene, and direct ages from these features have been interpreted almost exclusively as indicating phases of aridity. However, an increasing number of ages from a broader range of environments are calling into question the assumption that aeolian activity can be simply equated with aridity. Presented here is a comparison of dune ages that have been obtained from across southern Africa with a range of proxies from both terrestrial and marine records. Taken as a whole, three primary phases of activity can be identified at 160;60-40, 35-20 and 17-4 160;ka. The frequent discordance with other terrestrial records indicating coeval increases in humidity and the close correlation of these phases with wind strength proxies suggest that aridity is unlikely to be the sole, or even primary, forcing mechanism for aeolian activity in the region, and the palaeoclimatic significance of these sedimentary archives needs to be reassessed.

Abstract: The Sneeuberg mountain complex (Eastern Cape) comprises one of the most prominent sections of the Great Escarpment in southern Africa but until now has remained one of the botanically least known regions. The Sneeuberg is a discrete orographical entity, being delimited in the east by the Great Fish River valley, in the west by the Nelspoort Interval, to the south by the Plains of Camdeboo, and to the north by the Great Karoo pediplain. The highest peaks range from 2278 to 2504 160;m above sea level, and the summit plateaux range from 1800 to 2100 160;m. Following extensive literature review and a detailed collecting programme, the Sneeuberg is reported here as having a total flora of 1195 species of which 107 (9%) are alien species, 33 (2.8%) are endemic, and 13 (1.1%) near-endemic. Five species previously reported as Drakensberg Alpine Centre (DAC) endemics are now known to occur in the Sneeuberg (representing range extensions of some 300-500 160;km). One-hundred-and-five species (8.8%) are DAC near-endemics, with the Sneeuberg being the western limit for most of these. Ten species (0.8%) represent disjunctions across the Karoo Interval from the Cape Floristic Region (CFR) to the Sneeuberg. In all, some 23 significant range extensions, eight new species, and several rediscoveries are recorded. We conclude by recognising the Sneeuberg as a new centre of endemism along the Great Escarpment, with floristic affinities with the Albany Centre and the DAC, and links to the CFR.

Abstract: Using a human security perspective, we investigate how the history of land tenure changes has driven sustainability in southern African savannas. The paper examines four countries�Botswana, Mozambique, South Africa and Zimbabwe. Two research questions are addressed: first, how has colonial land tenure and distribution affected people 039;s options and capacity to end, mitigate or adapt to risks to their human, environmental and social rights, and what have been the related effects on land uses and degradation? Second, to what extent have post-independence land reforms addressed threats to human security and political causes of land degradation? The inequitable distribution of land and colonial legacy of dual or pluralistic systems of tenure are found to be at the root of many agrarian and environmental problems. Post-independence land reforms have largely failed to address these fundamental issues, sometimes even reinforcing threats to social, economic and environmental sustainability. The skewed distribution of land and resources, insecure rights, and the marginalisation and restriction of savanna livelihood systems have persisted, undermining human security and environmental integrity in the region as well as leading to mounting conflict and insecurity.

Abstract: Abstract The advance of exotic tree and shrub species is one of the main threats to conservation of the last relicts of natural grassland in South America; however, control actions in the region are still scarce and there are almost no evaluations of the recovery of natural ecosystems after removing invasive plants. Monitoring of the vegetation during the years after removal of invasive trees is critical in order to decide whether an active restoration strategy is necessary. The recovery of montane grassland four years after the control of a dense invasion of Aleppo pine (Pinus halepensis) is described in this study. Experimental clearing areas were followed during four years and compared to grassland controls. Variation was seen in the levels of recovery in function of the proximity of sectors of grassland that are free of invasive species and/or the density of invasive trees before control. Native species slowly replaced many exotic herbs that had appeared as pioneers, there was low recruitment of pine seedlings in spite of the quantity of seeds from trees that surrounded the clearings, and species richness and diversity were restored, including cover of the typical grasses in the controls. Recovery of grassland after felling was shown to be successful and does not seem to be seed limited if tree removal occurs early in the invasion process.

Abstract: Savanna chimpanzees are useful as referential models for early hominins, and here potential differences between chimpanzee and early hominin ecology is the focus. Whereas chimpanzees inhabit only a handful of modern African savannas, there is evidence that early hominins occupied relatively more open and arid savannas than those in which chimpanzees live. In order to help expand potential models of early hominin palaeoecology beyond savanna chimpanzee-like scenarios, and to provide a basis for future modeling and testing of actual hominin diets, this study compares the types of plant foods available in modern semi-arid savannas of northern Tanzania to plant foods at savanna chimpanzee sites. The semi-arid savannas are not occupied by modern chimpanzees, but are potentially similar to environments occupied by some early hominins. Compared to savanna chimpanzee habitats, the northern Tanzania semi-arid savanna has a lower density and fewer species of trees that produce fleshy fruits. Additionally, the most abundant potential hominin plant foods are seasonally available Acacia seeds/pods and flowers, grass seeds, and the underground parts of marsh plants, as evidenced by vegetation surveys and by studies of the diets of baboons that forage in similar areas. The information from this study should be useful for framing hypotheses about hominin diets for sites with palaeoenvironmental contexts similar to those of the northern Tanzania semi-arid savannas and for contextualising tests of actual hominin diets (e.g., those based on dental microwear or isotopes).

Abstract: Soil erosion is an important process of land degradation in many rangelands and a significant driver of desertification in the world 039;s drylands. Dendrogeomorphology is an alternative to traditional methods for determining soil erosion rate. Specifically, the vertical distance between the upper portion of exposed roots and the actual soil surface can be used as a bioindicator of erosion since plant establishment. In this study, we determined (i) the soil erosion rate from exposed roots of the dwarf shrub Margyricarpus pinnatus [Lam.] Kuntze in two ecological sites in the northeastern rangelands of Patagonia and (ii) the relationship between shrub age and upper root diameter. We selected two ecological sites, a pediment-like plateau and a flank pediment, where the dominant soils were Xeric Haplocalcids and Xeric Calciargids, respectively. The soil erosion rates in the pediment-like plateau and in the flank pediment were 2.4 and 3.1 160;mm yr- 160;1, respectively. Data clearly indicate a high rate of soil erosion during the mean 8-year life span of the dwarf shrubs in degraded patches, which represent 160;10% of surface cover in the study area. Simple linear regression analysis yielded a highly significant predictive model for age estimation of M. pinnatus plants using the upper root diameter as a predictor variable. The measurement of ground lowering against datable exposed roots represents a simple method for the determination of soil erosion rates. In combination with other soil surface features, it was used to infer the episodic nature of soil erosion. This approach could be particularly useful for monitoring the effects of land management practices on recent soil erosion and for the establishment of records in regions where historical data regarding this process are scarce or absent.

Abstract: Accurate reconstructions of past hydrological variability are essential for understanding the climate history of the tropics. In tropical Africa, the relative proportion of vegetation utilizing the C3 vs. C4 photosynthetic pathway is mainly controlled by precipitation and thus past hydrological changes can be inferred from the vegetation record. In this study, biomarkers of terrestrial plants (lignin phenols and plant leaf wax carbon isotopes) are examined from a well-dated sedimentary record from Lake Malawi to provide a vegetation (aridity) record of the past 23 160;cal ka from southeast Africa. We suggest that the ratio of cinammyl to vanillyl (C/V) lignin phenols in Lake Malawi sediments mainly reflects inputs of C3 trees (woody tissue) vs. C4 grasses (non-woody tissue) and find that changes in the C/V ratio generally support variability noted in the n-alkane carbon isotope record. Together, these records provide evidence for increased C4 vegetation (grasses) surrounding Lake Malawi during Last Glacial Maximum (LGM), the Younger Dryas, in the early Holocene, and from 160;2 160;cal ka to the present, suggesting drier conditions at these times. Elevated inputs of C3 vegetation are noted in the intervals from 160;17-13.6 160;cal ka and 160;7.7-2 160;cal ka, indicating wet conditions in southeast Africa. A relationship is noted between the n-alkane average chain length (ACL) and temperature, with longer ACLs associated with higher temperatures. Higher n-alkane carbon preference index (CPI) values correlate with higher mass accumulation rates of biogenic silica and may result from periodic increased northerly winds over Lake Malawi, which enhance upwelling and diatom productivity while simultaneously increasing erosion and transport of plant leaf waxes to the lake. The molecular data produced in this study suggest that the carbon isotopic signature of bulk sediment ([delta]13CTOC) in Lake Malawi is primarily a reflection of terrestrial inputs (C3 vs. C4 vegetation) and may not mainly reflect changes in algal productivity, as previously thought.

Abstract: To restore China 039;s degraded environment, the government launched an environmental restoration project named the 34;Grain for Green 34; Project (GGP) in 1999. From 1999 to 2010, the government will spend US$ 40 billion to convert 147 million ha of farmland into forest and grassland and 173 million ha of wasteland (including abandoned farmland) into forest in 25 provinces. A primary focus is to replace farming and livestock grazing in fragile areas with reforestation and planting of forage crops. Given the project 039;s tremendous size and number of participants, the attitudes of the affected farmers will strongly influence the GGP 039;s success. To learn their attitudes, we surveyed 2000 farmers in 2005 to quantify their opinions of the GGP and how it has affected their livelihoods, and we discuss the concerns raised by these attitudes. Farmers appreciated the grain and financial compensation offered by the GGP, but few considered planting of trees (8.9%) or forage species (2.2%) to be a priority. Although only 19.1% felt that their livelihoods had been adversely affected by the GGP and 63.8% supported the project, a large proportion (37.2%) planned to return to cultivating forested areas and grassland once the project 039;s subsidies end in 2018. Therefore, much of the restored vegetation risks being converted into farmland and rangeland again, compromising the sustainability of the environmental achievements. To succeed, strategies such as the GGP must compensate farmers fairly for their costs, create new agricultural products and techniques for use on more suitable land, and create job and training programs that account for the needs and desires of farmers and give them alternatives to returning to old land-use practices.

Abstract: Manure disposal is a major challenge for the fast-growing dairy industry in New Mexico. There are currently over 355,000 milking cows in the state and limited cropland on which to use the manure generated by these cows. On the other hand, 80% of the state lands classified as rangelands are suffering from a lack of organic matter and nutrients. Application of dairy manure to rangelands could serve a dual purpose: (1) manure disposal from dairies and (2) soil amendment to improve soil characteristics and promote herbaceous production. Manure was applied at two rates according to phosphorus (P) content: (1) a recommended (light) rate (54 160;kg 160;P 160;ha-1) to enhance blue grama growth and (2) a gross over-application (heavy) rate (493 160;kg 160;P 160;ha-1) to determine the effects on runoff and soil properties. Light applications enhanced soil properties including decreased sediment runoff, increased soil organic matter, increased extractable P, and increased soil moisture, whereas heavy applications increased soil salinity, sodium adsorption ratio, and runoff water. Dairy manure can be safely applied at light rates to conserve and enhance rangeland soil properties and their herbaceous productivity. Manure disposal at heavy rates are unsafe. Further study is required to find out if other safe disposal exists between the light and heavy treatments.

Abstract: Summary Among the three sites distributed along the West African latitudinal gradient in the AMMA-CATCH observation system, the experimental setup in the Niamey area of south-west Niger samples the cultivated Sahel environment, for hydrological, vegetation and land surface processes. The objective is to investigate relationships between climate, land cover, and the water cycle, in a rapidly changing semiarid environment. This paper first presents the main characteristics of the area, where previous research, including the EPSAT and HAPEX-Sahel experiments, had evidenced a widespread decadal increase in water resources, concurrently with severe drought conditions. The specifics of AMMA-CATCH research and data acquisition at this site, over the long-term ( 2001-2010) and enhanced ( 2005-2008) observation periods, are introduced. Objectives and observation strategy are explained, and the main characteristics of instrument deployment are detailed. A very large number of parameters - covering rainfall, vegetation ecophysiology, phenology and production, surface fluxes of energy, water vapour and CO2, runoff and sediment, pond water, soil moisture, and groundwater - were monitored at local to meso scales in a nested structure of sites. The current state of knowledge is summarized, connecting processes and patterns of variation for rainfall, vegetation/land cover, and the terrestrial hydrologic cycle. The central role of land use and of its spectacular change in recent decades is highlighted. This paper provides substantial background information that sets the context for papers relating to the south-west Niger site in this AMMA-CATCH special issue.

Abstract: The results from two climate model simulations are used to explore the relationship between North Atlantic sea surface temperatures and the development of African aridity around 100,000 years ago. Through the use of illustrative simulations with an Earth System Climate Model, it is shown that freshwater fluxes associated with ice sheet surges into the North Atlantic, known as Heinrich events, lead to the southward shift of the intertropical convergence zone over Africa. This, combined with the overall increased aridity in the cooler mean climate, leads to substantial changes in simulated African vegetation cover, particularly in the Sahel. We suggest that Heinrich events, which occurred episodically throughout the last glacial cycle, led to abrupt changes in climate that may have rendered large parts of North, East, and West Africa unsuitable for hominin occupation, thus compelling early Homo sapiens to migrate out of Africa.

Abstract: How to improve access to land and livestock production in synergy with ecosystem conservation? The paradigm occurring in natural grasslands of the Southern Brazilian Campos biome is used to illustrate the dilemma. This paper aims to contribute by addressing the technical bases being used by legislations concerning access to land and incentive to production and their consequences for natural grassland systems. Current policies have a production-oriented focus trying to promote livestock productivity by setting minimum stocking rates to be applied in grasslands. The unexpected results are overgrazing and reduction of natural grasslands, so the dilemma production versus conservation emerges. There is a need for adapting access to land legislations to the new environmental functions expected for natural grasslands, which warrant a conservation-oriented approach according to their multifunctional role. Integrated measures are proposed, which could be helpful in resolving the conflicting compromises regarding the inducement of production and the promotion of natural resources conservation.

Abstract: We compared seed banks between two contrasting anthropogenic surface disturbances (compacted, trenched) and adjacent undisturbed controls to determine whether site condition influences viable seed densities of perennial and annual Mojave Desert species. Viable seeds of perennials were rare in undisturbed areas (3-4 seeds/m2) and declined to 60;1 seed/m2 within disturbed sites. Annual seed densities were an order of magnitude greater than those of perennials, were one-third the undisturbed seed densities on compacted sites, but doubled on trenched sites relative to controls. On trenched sites, greater litter cover comprising the infructescences of the dominant spring annuals, and low gravel content, enhanced seed densities of both annuals and perennials. Litter cover and surface ruggedness were the best explanations for viable perennial seed densities on compacted sites, but litter cover and the presence of a common harvester ant explained annual seed densities better than any other surface characteristics that were examined. Surface disturbances can have a varied impact on the condition of the soil surface in arid lands. Nevertheless, the consistently positive relationship between ground cover of litter and viable seed density emphasizes the importance of litter as an indicator of site degradation and recovery potential in arid lands.

Abstract: Abstract Invasive plants have invaded swathes of grasslands in Lake Nakuru National Park thus necessitating the Park management to institute measures to control them. Despite this, information on the status and impact of invasive plants in these grasslands is lacking. Six grassland types were identified and assigned random numbers. Five study sites were then randomly selected from each grassland type. The Point-Centre Quarter method was used to determine the distribution and density of seven major invasive plants, whilst their impact was assessed by comparing biomass and crude protein content of important forage grasses in invaded and noninvaded grasslands. Results show that the distribution of invasive plants did not differ among the grasslands (F5, 30 160;= 160;1.47, P 160;= 160;0.229) but their densities differed among the plants (F6, 30 160;= 160;20.99, P 160; 60; 160;0.001). The mean biomass in invaded and noninvaded grasslands (22 160;g 160;m&minus;2 versus 37.2 160;g 160;m&minus;2) was significantly different (t-test, P 160; 60; 160;0.05), while crude protein content of grasses in invaded (7.73, % DM) and noninvaded (9.3, % DM) patches was not significantly different (t-test; P 160; 62; 160;0.05). Our results suggest that invasive plants lower grass production and hence might reduce food availability to grazers. xD;R 233;sum 233; Des plantes invasives ont envahi des 233;tendues de prairies du Parc National du Lac Nakuru, ce qui oblige la gestion du parc 224; instaurer des mesures pour les contr 244;ler. Malgr 233; cela, on manque toujours d&rsquo;informations sur le statut et l&rsquo;impact des plantes invasives sur ces prairies. On a identifi 233; six types de prairies et on leur a attribu 233; un num 233;ro au hasard. On a ensuite choisi au hasard cinq sites d&rsquo; 233;tude pour chaque type. La m 233;thode des quartiers par point centr 233; fut utilis 233;e pour d 233;terminer la distribution et la densit 233; de sept plantes invasives importantes, tandis que l&rsquo;on 233;valuait leur impact en comparant la biomasse et le contenu en prot 233;ine brute des herbes fourrag 232;res importantes dans les prairies envahies et non envahies. Les r 233;sultats montrent que la distribution des plantes invasives ne diff 233;rait pas selon les prairies (F 5,30 160;= 160;1,47, P 160;= 160;0,229), mais que leur densit 233; diff 233;rait parmi les plantes (F6, 30 160;= 160;20.99, P 160; 60; 160;0.001). La biomasse moyenne dans les prairies envahies et non envahies (22 160;g 160;m&minus;2 versus 37.2 160;g 160;m&minus;2) 233;tait significativement diff 233;rente (test de t 160;: P 160; 60; 160;0,05) alors que le contenu en prot 233;ine brute dans les 238;lots de prairies envahies (7,73, % DM) et non envahies (9,3, % DM) n&rsquo; 233;tait pas significativement diff 233;rent (Test de t: P 160; 62; 160;0,05). Nos r 233;sultats sugg 232;rent que les plantes invasives diminuent la production herbeuse et pourraient donc r 233;duire la disponibilit 233; de nourriture pour les animaux qui broutent.

Abstract: Monitoring cattle inflows and outflows over time is a good indicator of herd productivity. In this study, ninety households were monitored for a year to determine the effect of season, rangeland type and herd size on births, purchases, sales, deaths, off-take, cattle production potential (CPP) and cattle production efficiency (CPE) in the sweet and sour rangelands of South Africa. Most births were recorded in large herds in the sour rangelands during the hot-wet season (P 160; 60; 160;0.05). Farmers with large herd sizes purchased significantly more cattle compared to those with small herd sizes. Cattle sales were significantly high in the large herds in the cool-dry season. Mortality was significantly high in the hot-wet season in the sour rangeland and was mainly caused by gall-sickness (24%) and redwater (20%). The highest mortalities were observed in cows (45%). Households owning small herds in the sweet rangeland had the lowest CPP in the cool-dry season (P 160; 60; 160;0.05). The CPE was significantly high in the households owning large herds in the sweet rangeland. It was concluded that, although the CPP was low in the sweet rangeland, households in these areas had higher CPE compared to those in the sour rangelands.

Abstract: Fossil pollen grains extracted from sediments sampled from OGS-6a and OGS-7, two newly excavated Late Pliocene sites of Gona, in the Afar Depression of Ethiopia, indicate a high percentage of afromontane forest and highland taxa (36.8-43.3%), among which Podocarpus cf. gracilor is dominant (19.6-24.2%). Forest taxa typical of the afromontane phytogeographic region have also been identified in the samples. The overall pollen spectrum suggests a mosaic of open and closed habitats, with a considerable wooded environment present during the time associated with the beginnings of early hominid use of flaked stones at Gona. Here we provide details of the results from the pollen analyses. The two sites lie 4-8 160;m directly below a volcanic tuff dated by 40Ar/39Ar to 2.53 160; 177; 160;0.15 million years (Ma). The materials were recovered within fine-grained sediments located just above a geomagnetic polarity transition identified as the Gauss-Matuyama boundary dated close to 2.6 160;Ma, also corroborating the earlier age reported for the East Gona artifacts from EG-10 and EG-12. Thus, the stone artifacts, fossilized broken fauna and pollen grains from OGS-6a and OGS-7 represent archaeological materials from the world 039;s oldest securely dated sites, and offer insights on aspects of the palaeoenvironments around the time of the beginnings of ancestral hominid use of flaked stones, ca. 160;2.6 160;Ma.

Abstract: Image classification approaches are widely used in mapping vegetation on remotely sensed images. Vegetation assemblages are equivalent to habitats. Whereas sub-pixel classification approaches potentially can produce more realistic, homogenous habitat maps, pixel-based hard classifier approaches often result in non-homogenous habitat zones. This salt-and-pepper habitat mapping is particularly a challenge on images of savannas, given the characteristic patchy texture of scattered trees and grass. Image segmentation techniques offer possibilities for homogenous habitat classification. This study aimed at establishing the extent to which established, field surveyed and geology-related vegetation types in South Africa 039;s Kruger National Park (KNP) can be reproduced using image segmentation. Rain season Landsat TM images were used, selected to coincide with the peak in vegetation productivity, which was deemed the time of year when discrimination between key habitats in KNP is most likely to be successful. The multiresolution segmentation mode in eCognition 5.0 was employed, object classification accomplished using the nearest neighbour (NN) classifier, using object texture and training area mean values in the NN feature space. Compared to delineations of the vegetation types of KNP on a digital map of the vegetation zones that was tested, image segmentation successfully mapped the zones (overall accuracy 85.3%, K^ 160;= 160;82.7%) despite slight shifts in the location of vegetation zone boundaries. Maximum likelihood classification (MLC) of the same images was only 37% accurate (K^ 160;= 160;24.2%). Whereas the vegetation zones resulting from MLC were non-homogenous, with considerable spectral confusion among the vegetation zones, image segmentation produced more homogenous vegetation zones, comparably more useful for conservation management, because realistic and meaningful habitat maps are important in biodiversity conservation as input data upon which to base management decisions. Image segmentation appears to be a useful approach in mapping savanna vegetation.

Abstract: Throughout the Neogene, the faunas and floras in Africa recorded global climatic changes. We present an overview of Neogene desertification in Africa by tracing stable isotopes in eggshells and mammalian enamel, by faunal (changes in hypsodonty, etc.) and floral changes in sequences at the latitudinal extremities of the continent and the equator. This work reveals that desertification started in the southwest ca 17-16 160;Ma, much earlier than the region of the present-day Sahara (ca 8-7 160;Ma) and long before the deserts in East Africa (Plio-Pleistocene). A consequence of this history is that animals and plants inhabiting the South of the continent had a long period of time in which to adapt to arid, unstable climatic conditions. When parts of East Africa became arid during the Late Miocene and Plio-Pleistocene, several of these lineages expanded northwards and occupied developing arid niches before local lineages could adapt. Several of the latter became extinct, while others withdrew westwards as the tropical forest diminished in extent. It is proposed that the history of desertification in Africa was related to that of the polar ice caps (Antarctic, Arctic).

Abstract:

Abstract: There is limited knowledge about root morphological differences at the species level. Consequently, plant ecological groups are largely defined on aboveground traits. Our hypothesis was that roots of graminoid species differ in morphological and functional attributes. In field and greenhouse studies, we measured morphological and functional root traits of eight dominant graminoids. Multivariate analyses of root traits arranged species into two groups. Species were unequivocally classified by either discriminant analysis or a taxonomic key. Traits that contributed most to identification were diameter, colour, and branching. Species from one group had large root diameters, more branching, and lower tensile strength, specific length, rate of new root generation, and RGR than the other group. The grouping by root traits matched previous classifications: one group had been described as more xerophytic, less preferred by livestock, and more delayed in phenology than the second group. Our study shows that (1) a set of root morphological traits may be reliably used to recognize species, and (2) root traits reflect the major ecological grouping of species, even when they all belong to the same growth form. For Patagonia and similar sites, our work will open the way to more detailed, specific-level studies on community underground organization.

Abstract: Landscapes commonly comprise of mosaics, patches and boundaries. Riparian boundaries are complex to delineate and characterize, with a multitude of variables available for delineation. Multiple methods exist for boundary delineation such as two-dimensional wombling, constrained classification techniques and discontinuity detection. One method that has proven to be reliable in boundary delineation with one-dimensional transect data is the moving split window (MSW) analysis. This study demonstrates the efficacy of MSW to delineate grass species turnover and environmental boundaries across two geologically dissimilar riparian zones in the Kruger National Park, South Africa. There are few studies that have delineated riparian boundaries of Kruger National Park, and none that have used the MSW analysis. MSW detects significant changes in dissimilarity indices of variables along gradients. Significant shifts in dissimilarity designate boundaries at various spatial scales dictated by window sizes. Significant boundaries emerge by altering window sizes, increasing quadrat width and removing infrequent herbaceous species. By utilizing these three methods, MSW background variance was reduced and riparian and wetland/upland boundaries were sharper and more easily defined.

Abstract: Revegetation of disturbed land, particularly in arid environments, is often hindered by low seedling establishment. Information on seed biology and germination cues of keystone species is lacking, particularly in arid Australia; a major zone for mining developments. This study investigated seed characteristics and germination of 18 common species required for rehabilitation of disturbed areas at Shark Bay Salt in the Shark Bay World Heritage Area, Western Australia. Untreated seeds of seven species (Aphanopetalum clematideum, Atriplex bunburyana, Austrostipa elegantissima, Melaleuca cardiophylla, Pembertonia latisquamea, Rhagodia baccata, Salsola tragus) exhibited high germination percentages. Seeds of two species (Acacia tetragonophylla, Stylobasium spathulatum) had low imbibition, which increased with hot-water treatment, hence require scarification for germination. Gibberellic acid, smoke water and karrikinolide (a butenolide isolated from smoke) substantially increased germination percentages of three species (Anthocercis littorea, Diplolaena grandiflora, Solanum orbiculatum). Seeds of the remaining six species (Dioscorea hastifolia, Eremophila oldfieldii, Nitraria billardierei, Ptilotus exaltatus, Thryptomene baeckeacea, Zygophyllum fruticulosum) had low germination percentages regardless of treatment. Most species germinated equally well at 26/13 160; 176;C and 33/18 160; 176;C, however seven species had improved performance at 26/13 160; 176;C. This study is significant to land managers and conservation agencies with an interest in optimising germination of arid zone seeds for restoration.

Abstract: Improved agricultural productivity using conservation farming (CF) systems based on non-inversion tillage methods, have predominantly originated from farming systems in sub-humid to humid regions where water is not a key limiting factor for crop growth. This paper presents evidence of increased yields and improved water productivity using conservation farming in semi-arid and dry sub-humid locations in Ethiopia, Kenya, Tanzania and Zambia. Results are based on on-farm farmer and research managed experiments during the period 1999-2003. Grain yield of maize (Zea mays L.) and tef (Eragrostis Tef (Zucc)) from conventional (inversion) tillage are compared with CF with and without fertilizer. Rain water productivity (WPrain) is assessed for the locations, treatments and seasons. Results indicate significantly higher yields (p 160; 60; 160;0.05) for CF+ fertilizer treatments over conventional treatments in most locations, increasing from 1.2 to 2 160;t 160;ha-1 with 20-120% for maize. For tef in Ethiopian locations, the yield gains nearly doubled from 0.5-0.7 to 1.1 160;t 160;ha-1 for 34;best bet 34; CF+ fertilizer. WPrain improved for CF+ fertilizer treatments with WP gains of 4500-6500 160;m3 rainwater per t maize grain yield in the lower yield range from 0 to 2.5 160;t 160;ha-1. This is explained by the large current unproductive water losses in the on-farm water balance. There was a tendency of improved WPrain in drier locations, which can be explained by the water harvesting effect obtained in the CF treatments. The experiences from East and Southern Africa presented in this paper indicate that for smallholder farmers in savannah agro-ecosystems, conservation farming first and foremost constitutes a water harvesting strategy. It is thus a non-inversion tillage strategy for in situ moisture conservation, rather than solely aimed at minimum tillage with mulch cover. Challenges for the future adoption of CF in sub-Saharan Africa include how to improve farmer awareness of CF benefits, and how to efficiently incorporate green manure/cover crops and manage weeds.

Abstract: In large areas of the arid western United States, much of which are federally managed, fire frequencies and associated management costs are escalating as flammable, invasive cheatgrass (Bromus tectorum) increases its stronghold. Cheatgrass invasion and the subsequent increase in fire frequency result in the loss of native vegetation, less predictable forage availability for livestock and wildlife, and increased costs and risk associated with firefighting. Revegetation following fire on land that is partially invaded by cheatgrass can reduce both the dominance of cheatgrass and its associated high fire rate. Thus restoration can be viewed as an investment in fire-prevention and, if native seed is used, an investment in maintaining native vegetation on the landscape. Here we develop and employ a Markov model of vegetation dynamics for the sagebrush steppe ecosystem to predict vegetation change and management costs under different intensities and types of post-fire revegetation. We use the results to estimate the minimum total cost curves for maintaining native vegetation on the landscape and for preventing cheatgrass dominance. Our results show that across a variety of model parameter possibilities, increased investment in post-fire revegetation reduces long-term fire management costs by more than enough to offset the costs of revegetation. These results support that a policy of intensive post-fire revegetation will reduce long-term management costs for this ecosystem, in addition to providing environmental benefits. This information may help justify costs associated with revegetation and raise the priority of restoration in federal land budgets.

Abstract: The objective of this study was to clarify whether the changes in percent cover of plant functional types (i.e., life forms and growth forms) along a grazing gradient reflect the livestock number, which would reinforce the reliability of using a grazing gradient design and improve the management of rangeland. We selected two livestock camps that for many years have had different numbers of livestock, with approximately six times more sheep-equivalents at site 1 than at site 2. Vegetation was sampled in 10 quadrats on five transects along the grazing gradient at each site. In each quadrat, we recorded percent cover of each plant species. Our findings suggested that vegetation changes along the grazing gradient under different livestock numbers were characterized by changes in the cover of life forms: perennial species were replaced by annual species near the camps (10-50 160;m). However, we did not find growth form change that reflected the difference in the number of livestock.

Abstract: The objective of this study was to clarify whether the changes in percent cover of plant functional types (i.e., life forms and growth forms) along a grazing gradient reflect the livestock number, which would reinforce the reliability of using a grazing gradient design and improve the management of rangeland. We selected two livestock camps that for many years have had different numbers of livestock, with approximately six times more sheep-equivalents at site 1 than at site 2. Vegetation was sampled in 10 quadrats on five transects along the grazing gradient at each site. In each quadrat, we recorded percent cover of each plant species. Our findings suggested that vegetation changes along the grazing gradient under different livestock numbers were characterized by changes in the cover of life forms: perennial species were replaced by annual species near the camps (10-50 160;m). However, we did not find growth form change that reflected the difference in the number of livestock.

Abstract: In most parts of the world, pastoral societies are governed by internal rules or legal bodies and legal rules (institutions) at the regional and national scale. In the Large Scale Grazing Systems (LSGS) of the European Union (EU), institutional management is also dependent on EU regulations, which underpin a considerable part of total policy support. In this research we argue that the effectiveness of policy intervention should be determined 34;on the ground 34; and taking into account the structural and social features of particular LSGS. Under a community-based research approach, the main stakeholders (arable farmers and landless pastoralists) and organisations governing the cereal-sheep farming system in Castilla-La Mancha (South-Central Spain) were consulted with the aim of assessing the sustainability of the mixed cereal and sheep system. In this area, sheep farming is a secondary land use relying on the agricultural residues from arable farming, but representing some 35% of the total value of production farming per land unit. Our results showed that regional and EU regulations are uncoordinated and uncongenial for the continuity of the mixed cereal and sheep operation. They are supported by separate policy schemes, while operating on the same land units. Arable farming is more affected by EU regulations and corresponding policy support schemes, while sheep farming is more regulated by regional institutions. EU support was 32% and 13% of total farm income for cereal and sheep farmers, respectively. Arable farmers received a regulated non-market grazing fee. They abide by the law, but have no incentive to facilitate the sheep subsystem. The farming practices of sheep farmers are more market-driven as the value of production makes up the bulk of their total income. However, they are squeezed by strict regional regulations when implementing pastoral surviving strategies (mobility, accessibility, and diversity of land based resources). Both subsystems are following disconnected trends, with increasing cultivation intensity in arable farming and the abandonment of shepherding and a consequent consolidation of sheep flocks and an increase in indoor feeding. This research suggests that sensible institutional management should be derived from a proper knowledge of the social and structural features of particular grazing systems and the disentangling of their main constraints.

Abstract:

Abstract: Little is known about the grass species type, composition and nutritive value in the semiarid savannas that sustain most of Swaziland's cattle population through the seven-month-long dry season. This study was conducted to investigate the nutritional characteristics of grasses collected from two grazing areas (Big Bend and Simunye), which differed mainly in soil types. Mature grass species were harvested and evaluated for chemical composition (organic matter, neutral detergent fibre [NDF], acid detergent fibre [ADF], crude protein [CP] and minerals) and in vitro ruminal fermentation (in vitro gas production, in vitro organic matter degradability and partitioning factors). The most common grass species in the Big Bend grazing area were Bothriochloa insculpta, Cenchrus ciliaris and Urochloa mosambicensis. In the Simunye grazing area the most common species were B. insculpta, U. mosambicensis, Heteropogon contortus, Panicum deustum and P. maximum. For grasses harvested from Simunye, the most (P < 0.05) degradable (532 mg g?1 dry matter) was B. insculpta, which also had the least fibre (597 g kg?1 NDF and 351 g kg?1 ADF) and the highest CP content (79.8 g kg?1). The most common grass species harvested from the Big Bend area did not differ (P > 0.05) in their Mg, P, Cu, Fe, Zn, CP and NDF content. However, U. mosambicensis had the highest (P < 0.05) ADF content. The least fermentation efficiency (partitioning factor = 2.2 mg degradable organic matter [DOM] ml?1 gas) was observed for U. mosambicensis as a result of low DOM coupled with high cumulative gas production. It was concluded that all the grasses investigated in this study show a deficit for Ca, P and protein. Therefore, supplementation is needed to ensure maximum forage utilisation and to satisfy nutrient requirements of ruminant livestock.

Abstract: Livestock from communities bordered by dune mining, urban areas and commercial forestry in northern KwaZulu-Natal spend substantial time foraging in the coastal forest that the mining company is obliged to restore. A survey of livestock owners and an experimental study of impacts of cattle on restoration processes were conducted to develop better knowledge of the perceptions of livestock owners neighbouring the mine, and the impacts of their cattle on rehabilitating coastal dune forest. Shortages of grazing and livestock diseases were perceived to be the major constraints on livestock operations. Mitigation included grazing cattle in the rehabilitating forest and treating livestock diseases with available medicinal plant species. An exclosure experiment in one of the older stands undergoing restoration showed that cattle grazing reduced grass biomass and Acacia kosiensis seedling recruitment. A study of seeds collected from cattle dung showed that Psidium guajava, an important invasive alien woody species, was dispersed by cattle into the rehabilitating forest, but passage through cattle did not enhance germination of the invasive species. The study concluded that: (1) the proximity of livestock owners to large-scale commercial land uses influenced their perceptions and their resources, and (2) grazing and trampling by cattle in the rehabilitating dune forest may hinder the ecological restoration process.

Abstract: Seed production, viability, dispersal, predation and seed banks of Themeda triandra were determined to assess the potential of the seeds of this indigenous species in the re-establishment of degraded grassland. Annual seed production of T. triandra increased with length of burning rotation, ranging from 21 seeds m?2 in the annual winter burn to 757 seeds m?2 in the five-year burn. High predation of seeds (70?98%) and low viability (37% in 15-month-old seeds) contributed to the poor representation of T. triandra in the seed bank (<1.2%) when compared to the above-ground vegetation (<29.2%). These attributes, together with its poor dispersal (<1.75 m), indicate that seed dynamics of T. triandra will play a limited role in the restoration of grasslands in degraded areas.

Abstract: Differences in land-use management may result in different rangeland condition (soil, vegetation and biodiversity) and productivity. Vegetation condition in contrasting land-use management systems is well documented in semiarid rangelands, but relatively little information is available on soil quality. This study explores soil quality indicators in contrasting land-use management systems (communal, commercial and game/conservation) to compare degradation status. Soil samples collected in all land-use management systems were analysed for chemical, biochemical and microbiological properties. Soils were acidic (pH = 6.33) and nutrients deficient (average organic C [Corg] 0.37%, available P 3.04 mg kg?1, cation exchange capacity [CEC] 2.99 cmol(+) kg?1). Significant differences (pH, p < 0.0001; Ca2+, p < 0.0001; Mg2+, p = 0.001; Na+, p = 0.014; CEC, p < 0.0001; Corg, p = 0.004; dehydrogenase, p = 0.003; acid phosphatase, p = 0.001; urease, p < 0.0001) were found between the conservation and both the communal and commercial land-use management. Only few indicators of soil quality showed significant differences between the commercial and communal management. No clear gradient of soil degradation could be detected. Results recommend caution when assessing degradation across contrasting land-use management systems, and within a specific management system. Further research across a wide range of sites within management and taking into consideration spatial soil and vegetation distribution is required to understand land-use management effects on rangeland condition.

Abstract: The effect of four fertiliser nitrogen (N) levels (0, 50, 100 or 150 kg N ha?1) applied as a single dressing in either autumn (late April), early winter (early June), late winter (mid July), early spring (late August) or late spring (early October) on fertiliser N recovery by a perennial ryegrass?white clover pasture five weeks after fertiliser N application was investigated. Herbage N yield (kg N ha?1 uptake) was determined for the pasture from herbage N yield of the perennial ryegrass fraction and the clover fraction. Increased fertiliser N rate resulted in increased perennial ryegrass N yields. Perennial ryegrass N yields tend to be lowest during winter (early as well as late winter). Pasture N yield responses were similar to the perennial ryegrass N yields. Except in 2001, higher clover N yields (kg N ha?1) were recorded when no fertiliser N was applied compared to treatments that received fertiliser N. Clover N yields did not differ in the 50?150 kg N ha?1 range and would therefore not influence pasture N yield in that range. Although season of application influenced N yields the response pattern was not consistent among the years covered by the study. Calculating the apparent N recovery rate (difference between N removed in fertilised plots and control plots) can serve as an important tool to evaluate the efficiency achieved with fertiliser N application. More research is needed to develop N removal as a management tool to be used in strategic N fertilisation programmes.

Abstract: Literature shows that at a global scale, fire activity increased from the Last Glacial Maximum to the present. There is incremental evidence indicating that climate defines the regional boundary conditions for fire. Human influence on ignitions depends on climate and has, since prehistoric times, resulted in significant changes on vegetation and soil, some of which require greater attention in the light of anthropogenic climate change. Climatic conditions have been used to identify regions where fire patterns are (i) human controlled, (ii) constrained by fuel and (iii) limited by rainfall seasonality. At regional and local scales, the fire-climate relationship is distorted by the interactions of fire, vegetation, and land use, and this, combined with annual to decadal climatic variability since late Holocene, results in high spatial and temporal variations in fire regimes.

Abstract:

Abstract: We used simple ecological sustainability simulator (SESS) [Díaz-Solís, H., Kothmann, M.M., Hamilton, W.T., Grant, W.E., 2003. A simple ecological sustainability simulator (SESS) for stocking rate management on semi-arid grazinglands. Agric. Syst. 76, 655-680. <http://dx.doi.org/10.1016/j.agsy.2005.07.008>], modified to represent each of five management strategies (sets of decision rules) for adjusting stocking rates, to identify strategies that could reduce effects of drought on cow-calf production systems in semi-arid rangelands. We parameterized the model to represent a region of extensive cow-calf production in the northeastern portion of the Mexican state of Coahuila, and evaluated animal performance (animal body condition, cow mortality, and calf production) and range condition resulting from each strategy under random precipitation conditions typical of the region. To evaluate the validity of the randomly generated precipitation, we conducted the simulations under an historical (1950-1994) precipitation regime. The five management strategies included one with no adjustments to stocking rate (CONTROL, most common current practice), one with stocking rate adjustment rules based on changes in animal body condition (BCS), and three with different stocking rate adjustment rules based on various comparisons of recent-year precipitation with long-term mean precipitation during the growing season (March-November) (REPLA, PPT 1Y, PPT 2Y). Each strategy was evaluated at each of three initial base-level stock cow stocking rates (125, 250 and 500 AUY · 5000 ha-1). Stocking rate adjustments consisted of partial or total de-stocking, with the re-establishment, or not, of the initial number of stock cows before the beginning of the subsequent breeding season. Results of 45-year simulations under both random and historical precipitation suggest CONTROL and PPT 2Y (based on comparison of current year and previous year precipitation with the long-term mean) strategies, combined with the high base-level stocking rate, are the worst and best, respectively. Under the historical precipitation regime, in the last period of time simulated (1980-1994) these two strategies resulted, respectively, in poor (0.5) versus good range condition (1.0), animal body condition scores of 2.6 versus 5.2, annual cow mortalities of 76 versus 5%, and calf production rates of 0.9 versus 10.6 kg ha-1 year-1 at weaning. The PPT 1Y strategy (based on comparison of current year precipitation with the long-term mean) produced results fairly similar to PPT 2Y, with BCS and REPLA strategies producing results intermediate between CONTROL and PPT 2Y. Our results suggest it is advantageous to adjust stocking rates based on precipitation during the current growing season since it improves cattle production without damaging range condition. Considering the practical feasibility of the strategies, we recommend the PPT 1Y strategy because it maintains range condition at moderate stocking rates, results in good animal performance and does not require total de-stocking of the ranch. The simple method we developed to stochastically generate monthly precipitation produces a time series of precipitation values that were representative of general historical precipitation patterns and provided realistic levels of uncertainty in simulated forage production to evaluate alternative management strategies.

Abstract: Summary Abundant information is available on West African drought and its hydrological and environmental impacts. Land-use and climatic changes have greatly modified the conditions of Sudanian and Sahelian hydrology, impacting the regime and discharge of the main rivers. Human pressure on the environment (significant increase in crops and disappearance of natural bushes and landscapes, for example) has led to severe soil crusting and desertification throughout Sahelian regions. Despite recent increases in rainfall, the drought has not ended, resulting in two different hydrological evolutions. In the Sudanian areas, stream flows have been reduced, sometimes as much as twice the rainfall reduction rate. In the Sahelian regions, runoff coefficients have increased to such a degree that discharges are increasing, in spite of the reduced rainfall. The main goal of this paper is to synthesize the recent advances in the Sahelian and Sudano-Sahelian West African hydrology. The other objectives are two fold: First, to discuss the "Sahelian Paradox" (the increase in runoff in most of the Sahel during the drought, at least during the 1968-1995 period, as described in the 1980s) and paradox of groundwater highlighted in the square degree of Niamey (the rise in water table levels in some endorheic areas during the same drought, evidenced in the 1990s), and second, to attempt to define the application of their respective geographical areas. The land-use changes act as a general factor of hydrological evolution of soils and basins, while some spatial factors explain the great variability in the response to environmental evolution, such as endorheism, geological context, latitudinal climate gradient, and local hydrodynamic behaviour of environment. This paper is literature-based, and incorporates current research advances in the field, as well as a prospective focused on resources and socio-economic impacts.

Abstract: Sustainability impact assessment tools aim at optimising the development of policy measures. Here, we present an approach to designing policies for multifunctional land use with application to Europe and its regions. After the 35 environmental, social and economic impact issues of the European Impact Assessment Guidelines were reviewed on the basis of spatiotemporal indicators at both the top-down Europe-wide and bottom-up intra-regional resolution level, cluster analysis identified classes with specific sustainability characteristics and thus regions most likely facing similar sustainability problems. Sensitive region types such as post-industrial zones, mountains, coasts and islands were analysed separately. The results of the cluster analysis were tested against evidence-based information such as UNEP priorities and regional stakeholder evidence. Stakeholder evidence was specifically explored for the land use policy [`]bioenergy promotion' in Lusatia, Germany. We concluded that these top-down and bottom-up spatiotemporal data classifications with cluster analysis represent useful ex-ante impact assessment tools and need to be supplemented by participatory assessments. This procedure with top-down and bottom-up data analysis, and also participatory evidence, provide a valuable three-step sustainability impact assessment approach in policy making.

Abstract: Data from the NASA'S MODIS (Aqua and Terra) and EUMETSAT'S MSG-SEVIRI satellite sensors is analysed to characterise the geographic and temporal (including diurnal) evolution of the July 2007 fire disaster in the Kingdom of Swaziland using a geographic information system (GIS). Significant fire activity was observed during a three-day period beginning on the 27th July 2007. A total of 1358 and 4365 active fire hotpots were detected by MODIS and MSG-SEVIRI, respectively, mainly concentrated in the Highveld (70.91% for MODIS, 89.89% for MSG) and Middleveld (11.27% for MODIS, 5.23% for MSG) with MSG/MODIS active fire count ratio ranging from a high of 3.69 in the Highveld to a low of 0.06 in the Lubombo Plateau. The results indicate complex differences in spatial fire distribution, behaviour and risk within the country and the effect of sensor differences. A pronounced fire diurnal cycle with a broad afternoon peak centred on 14:00 local time is observed, in general agreement with observations from the region. Despite their limitations, the study demonstrates the importance and usefulness of remotely sensed data and GIS technology for fire disaster and risk assessment for a developing country, where fire monitoring resources are scarce.

Abstract: The direct short-term impact of three rates of stocking (4, 8 and 16 small-stock units [SSU] ha-1) was quantified in terms of soil characteristics of arid Nama Karoo vegetation (subshrub/grass). Mature Merino wethers grazed in the experimental plots throughout May in 1995 and 1996 (the plots were not subjected to grazing at any other time). Stocking rate proved inversely related to initial infiltration rate. Light trampling (4 SSU ha-1) loosened the topsoil sufficiently to increase the initial infiltration rate: infiltration capacity of soil in fields stocked at 4 SSU ha-1 and 16 SSU ha-1 was 17% higher and 14% lower respectively than that of soil of ungrazed rangeland over the two grazing periods. Increased soil compaction and greater bulk density due to higher stocking rates significant decreased the infiltration rate. Compared to ungrazed rangeland stocking rates of 4, 8 and 16 SSU ha-1 over the two grazing periods increased bulk density respectively by 2.73%, 6.67% and 8.945% and compaction by 10.90%, 16.78% and 20.90%. No grazing also increased bulk density and soil compaction and decreased infiltration rate. Light stocking (4 SSU ha-1) influenced all soil parameters most favourably. From a hydrologic point of view, grazing levels and rotation schemes need to be tailored for sustainable utilization of arid subshrub/grass vegetation by livestock.

Abstract: In a pot experiment, we examined the response of Eragrostis curvula and Themeda triandra to 0, 15, 30 and 60 g m?2 of nitrogen (N) supplied either as a rapid-release fertiliser (Sasol Nitro NPK) or a slow-release fertiliser (Plantacote Plus). Both E. curvula and T. triandra increased linearly in biomass with increasing levels of the slow-release fertiliser, achieving similar maximum biomass (75 g vs 71 g, respectively) at the highest level of the slow-release fertiliser. However, only E. curvula peaked at the highest level of the rapid-release fertiliser, whereas T. triandra did not show any increase in biomass beyond 15 g m?2 of N supplied by the rapid-release fertiliser. This resulted in considerably less biomass achieved by T. triandra under the rapid- than slow-release fertilizer (29 g vs 71 g, respectively) and in comparison to the maximum biomass of E. curvula under the rapid-release fertiliser (29 g vs 87 g, respectively). Thus, T. triandra was intolerant of high concentrations of N. This has implications for choosing the correct type of fertiliser according to the objectives of an experiment and for understanding the response of these grasses to fire, mowing, grazing and fertilisation.

Abstract: This study evaluated the variation of the concentration of mimosine in Leucaena forage with season, the time of defoliation and dehydration. Fresh samples were collected randomly from Leucaena regrowth and sorted into four types of samples (primordial tips, young leaves, mature leaves and edible twigs). The samples were divided into two portions and handled as fresh or air-dried. Mimosine was extracted from the fresh and air-dried samples with dilute hydrochloric acid. Chemical analysis was done by indirect spectrophotometric methods. A General Linear Model procedure was used to determine the impact of the variables on the concentration of mimosine. The results showed that air-dried samples in both seasons contained significantly (P < 0.05) more mimosine than the corresponding fresh samples by an average of 34%. Fresh autumn samples collected at 12:00 contained more mimosine (15.43%) than samples collected at 15:00 (9.09%) and 9:00 (4.48%) in comparison with corresponding summer samples. Similarly, air-dried autumn samples collected at 12:00 contained more mimosine (47.15%) than samples collected at 9:00 (43.57%) and 15:00 (40.12%) in comparison with the corresponding summer samples. Dehydration of samples elevated the concentration of mimosine by 39.09%, 31.72% and 31.03% for samples collected at 9:00, 12:00 and 15:00, respectively. It was concluded that dehydration of samples had the most significant impact on the concentration of mimosine followed by the time of defoliation and the season.

Abstract: Foliage of Ziziphus mucronata (buffalo thorn) was collected during the spring, summer and autumn. The chemical composition and in vitro digestibility of organic matter (IVDOM) of these samples were determined. Crude protein concentration ranged between 123?262 g kg DM?1, and tended to be higher in spring than in the other seasons. The acid detergent fibre ranged between 175?312 g kg DM?1 and also tended to be higher in autumn than in either spring or summer. The IVDOM values in this study were high (>700 g kg DM?1) compared to values reported in literature for the same species and other browse species such as Cassia sturtii, Tripteris sinuatum and Sutherlandia microphylla. The concentrations of calcium (Ca), sodium, zinc and manganese (Mn) appear to be higher in autumn while the concentrations of phosphorus (P), magnesium (Mg), potassium and copper (Cu) tended to be lower at this time compared to other seasons. In spring, the concentrations of Ca and Mn appear to be low while those of P, Mg and Cu are relatively high compared to the other seasons. However, the P content of Z. mucronata foliage was deficient in summer and autumn, while Cu was deficient in all seasons.

Abstract: Transformation of natural landscapes can result in the local extinction of many plant species. If the new land use is discontinued, many original species will not recolonise the area, necessitating their reintroduction for rehabilitation purposes. One method is to fragment local grass tufts into tillers and plant these into the degraded area. This project determined the survival and growth rates of various grass species planted into a recently cleared pine plantation near Nottingham Road, South Africa. Tufts of twelve grass species were collected locally, fragmented, kept on a mist bed for four weeks, and planted. Plants from all species were alive after nine months, although the average survival rate varied between species (from 92% for Eragrostis curvula to 39% for E. racemosa). Tuft area differed between species. The often-invasive species E. curvula had the highest average survival rate and the largest tuft area. The often-dominant, unpalatable Aristida junciformis demonstrated surprisingly low survival and growth rates. Themeda triandra and Tristachya leucothrix, species often dominating good-condition native grasslands, had average survival rates of 82% and 65%, respectively. This study indicates that tuft fragmentation and replanting is a useful way to re-establish locally extinct grass species into transformed habitats, but that success rates are species-specific.

Abstract: There are few tests of the predicted decline of secondary productivity in desertified rangelands, despite this being one of the major concerns around desertification. Subtropical thicket, largely used for goat pastoralism, suffers extensive transformation typical of desertification. We measured body growth and mohair production of Angora goats in both untransformed and desertified thicket paddocks over one year. Body growth and mohair length and diameter did not differ between the two treatments. We interpret the lack of responses in terms of the above-average rainfall during the study. In contrast, mohair mass was lower in the untransformed paddock, resulting in a decline in mohair production. We suggest that this counterintuitive result reflects the combing out, and therefore loss, of hair in the densely vegetated site. This study failed to demonstrate a decline in secondary productivity in desertified thicket and highlights the importance of replicating such studies in space and time.

Abstract:

Abstract: While there is no consensus on a definition, it is widely recognized that the concept of sustainability has economic, environmental and social dimensions. We used fuzzy logic as a well-suited tool to handle the vague, uncertain, and polymorphous concept of sustainability. For recognizing the major important indicators in defining sustainability in range management, several semi-structured interviews with an open-ended questionnaire in three different areas of the Fars province in Southwest Iran were held. Pastoralists 039; experts recognized that sustainability in range management is a function of three major components (inputs) which are the stocking rate in a pasture, the amount of plantation density per hectare, and the number of pastoralists who live in a pasture where the output of the model is the Right Rate of Stocking. Based on pastoralists 039; insights we developed a model called Equilibrium Assessment by Fuzzy Logic (EAFL) which provides a mechanism for assessing sustainability in rangeland management. The EAFL model exhibits three important characteristics. First, it permits the combination of various aspects of sustainability with different units of measurement. Second, it overcomes the difficulty of assessing certain attributes or indicators of sustainability without precise quantitative criteria and, third, the methodology is easy to use and interpret. An important outcome of the EAFL model is that all the pastoralists 039; experts agree with this conclusion that the current, real stocking rates are much higher than the optimal stocking rates.

Abstract: This study examined intraspecific variation in mineral composition and rumen degradability of Atriplex nummularia plants and the influence on selection preferences of sheep. Individual plants were categorised into high, medium and least preference groups by assessing the order in which they were selected by sheep. Nine plants were selected from each group and the regrowth of these plants was analysed for neutral detergent fibre (NDF), crude protein (CP), mineral composition and rumen degradability of dry matter. The data was subjected to one-way and multivariate analyses of variance. Highly preferred plants had a higher concentration of CP, phosphorous (P) and magnesium (Mg) in their edible forage compared to the medium or least preferred plants. Individual preferences of sheep were not, however, associated with the rumen degradability parameters. Principal component analysis revealed that highly preferred plants had lower NDF, manganese (Mn) and zinc (Zn), and higher CP, calcium, P, Mg and potassium values compared to the least preferred plants. In contrast, medium preferred plants exhibited inconsistent patterns, with a tendency to have higher sodium chloride and sodium, and lower Mn, Zn and copper, concentrations in the forage.

Abstract: Primary energy extraction patterns by livestock under agropastoralism and ranching were investigated by the bite count method in semiarid south-eastern Kenya. Sward biomass for optimal energy intake by cattle was derived using intake-digestibility constraint curves and realised livestock productivity from the systems compared. Cattle and sheep, and goats primarily consumed herbaceous and woody plants, respectively. Enteropogon macrostachyus and Panicum maximum, E. macrostachyus and Blepharis integrifolia, and Combretum exalatum and Duosperma kilimandscharica accounted for 33.5% and 9.9%, 16.6% and 10.3%, and 11.7% and 10.7% of cattle, sheep and goats' total energy intake, respectively. Cattle optimised energy intake at 370-610gm?2 of sward biomass and 55.5-64.3% organic matter digestibility. Panicum maximum yielded the highest optimal sward biomass. The energy expenditure of the animals was generally lower under agropastoralism across seasons. During the dry season, more animals (33-50%) lost weight under ranching. Agropastoralism was an efficient system as animals were moved across quality grazing microenvironments that minimised feeding costs and enhanced energy intake. Therefore, mobile grazing strategies, plant diversity and complementary trophic interactions stabilise energy extraction patterns and enhance livestock productivity under agropastoralism. However, human activities that affect plant diversity and mobility will undermine sustainable livestock production in such environments.

Abstract: True intestinal digestibility of dry matter (DM), rumen-undegraded dietary protein (UDP) and amino acids of cowpea, silverleaf desmodium and Brachystegia spiciformis (musasa) were estimated. The true intestinal digestibility was calculated as the difference between the content of a bag that was preincubated in the rumen for 12, 24 and 48 h and was recovered in the faeces. Significantly higher DM and nitrogen disappearance rate in the rumen, postruminally and throughout the whole tract were found for cowpea than for silverleaf desmodium and musasa. Total amino acids or true nitrogen digestibility values of silverleaf desmodium and musasa tended to be higher than in cowpea. The true digestibilities for the individual amino acids in the different undegraded protein sources showed significant differences. The true intestinal digestibility of DM, nitrogen and amino acids in the mobile bags after 24 h and 48 h of preincubation in the rumen were higher for silverleaf desmodium and musasa, than in cowpea. Musasa and silverleaf desmodium provided little rumen-degradable nitrogen and supplied UDP to the intestines. The UDP supplied postruminally would be used for productive processes such as milk production and growth.

Abstract: Editorial

Abstract: Understanding how grass species' traits relate to their invasiveness and the invasibility of their monocultures can inform restoration of diverse grassland. We measured vegetative traits for 18 bunch grass species local to Pietermaritzburg (KwaZulu-Natal, South Africa) and measured their competitive effect on a phytometer. Using 3 m ? 3 m plots planted as monocultures 12 years earlier, we related principal components of these traits to how species had invaded other species' plots (invasiveness), and how their monocultures had been invaded (invasibility). Species with high total leaf mass, many tillers and low specific leaf area (SLA) were most invasive and most resistant to invasion by other grasses. Short, slow-growing grasses were most invasible by forbs. This was partly explained by linking traits to invasion through competitive effect: grasses with high total leaf mass, many tillers and low SLA showed the strongest competitive effect, which appears to be necessary but not sufficient for invasiveness. Thus, traits can predict species' ecological performance and provide insight into the processes structuring plant communities. Restoring grasses with short stature, slow growth, low leaf mass, few tillers, and high SLA may facilitate invasion by other native species, thereby increasing species richness.

Abstract: The nutritive value of four subtropical grasses (Panicum maximum, Anthephora pubescens, Digitaria eriantha and Chloris gayana) standing hay were compared in terms of qualitative intake and partial digestibility by sheep. The species differed significantly in terms of diet quality selected by sheep grazing the standing hay. The rumen ammonia nitrogen (NH3-N), total volatile fatty acid and propionic acid concentrations of sheep grazing P. maximum and A. pubescens were higher than those sheep grazing D. eriantha and C. gayana standing hay. Organic matter intake (OMI) (g kg?1 W0.75 d?1), nitrogen intake (g d?1), digesta flow, the total N flow, NH3-N flow, non-ammonia nitrogen (NAN) flow and NAN disappearance (g d?1) in the ileum were higher for sheep grazing P. maximum than for those grazing the other standing hays. The organic matter disappearance in the stomach and small intestine of sheep grazing P. maximum and D. eriantha standing hay was higher than for those sheep grazing either A. pubescens or C. gayana standing hay. The NAN flow/N intake were the highest for sheep grazing P. maximum and A. pubescens compared to C. gayana. The NAN digestibility was, however, not significantly different among the four species. The standing hays (except for C. gayana) seemed to have the capacity to meet the N requirement of the sheep for production, but the OMI (g kg?1 W0.75 d?1) was not sufficient to support maintenance requirement of the sheep.

Abstract: Smallholder dairy farmers in Natural Region II, especially in Chikwaka Communal Area, adopted Acacia angustissima, Calliandra calothyrsus and Leucaena leucocephala in the 1995/96 season as alternatives for supplementing expensive commercial dairy feeds. Although several on-station trials have been done in the subhumid region of Zimbabwe, there have been no studies assessing on-farm yields of the introduced fodder species. This study evaluated productivity in a communal area under varying soil (pH, nitrogen, phosphorus and potassium) and management conditions (protection and tree density). Leaf productivity was high on farms with relatively higher soil P. Leaf yields ranged from 0.4?3.3 t DM ha?1 for A. angustissima, 0.8?5.6 t DM ha?1 for C. calothyrsus and 0.2-0.7 t DM ha?1 for L. leucocephala, with mean values of 2.2, 2.6 and 0.4 t DM ha?1, respectively. The low yields of L. leucocephala were associated with psyllid (Heteropsylla cubana) infestation. Decrease in tree density (low population) resulted in reduced yield. Poor performance was also attributed to uncontrolled browsing. Influence of soil characteristics could not be confirmed, but there were indications that low soil phosphorus may have adversely affected tree growth. The yields were generally lower than on-station, which implies that there is room for improving fodder tree yields in this subhumid region, through improving the availability of P, planting a high density of trees, and protecting them from uncontrolled browsing.

Abstract: Does the current global political economic framework, or more specifically, the cost-price squeeze associated with primary production, restrict the choices of Australian cattle graziers in moving to more sustainable practices? It has often been argued by primary producers and academics, alike, that current terms of trade have resulted in reduced profitability at the property level, and as such, have made it difficult for landholders to shift to practices which are environmentally sustainable. Whilst there is mounting evidence that this is case, there is also evidence that some graziers have been able to adapt to the prevailing market conditions through an ideological as well as [`]practice' shift. Findings from qualitative research in Central Queensland, Australia, has highlighted how [`]cell grazing' departs from the traditional or conventional aspects of grazing which can be described as productivist, to an approach closely approximating Lang and Heasman's (2004) [`]ecologically integrated paradigm' [Lang, T., Heasman, M., 2004. Food Wars: The Global Battle for Mouths Minds and Markets. Earthscan, London]. It is argued that cell grazing is, at present, a marginal activity that requires an ideological and cultural shift, as well as an investment in new infrastructure, however, current cell grazing activities may also demonstrate that beef grazing has the potential to be both economically and environmentally sustainable.

Abstract: Summary This paper presents an analysis of the coupled cycling of energy and water by semi-arid Sahelian surfaces, based on two years of continuous vertical flux measurements from two homogeneous recording stations in the Wankama catchment, in the West Niger meso-site of the AMMA project. The two stations, sited in a millet field and in a semi-natural fallow savanna plot, sample the two dominant land cover types in this area typical of the cultivated Sahel. The 2-year study period enables an analysis of seasonal variations over two full wet-dry seasons cycles, characterized by two contrasted rain seasons that allow capturing a part of the interannual variability. All components of the surface energy budget (four-component radiation budget, soil heat flux and temperature, eddy fluxes) are measured independently, allowing for a quality check through analysis of the energy balance closure. Water cycle monitoring includes rainfall, evapotranspiration (from vapour eddy flux), and soil moisture at six depths. The main modes of observed variability are described, for the various energy and hydrological variables investigated. Results point to the dominant role of water in the energy cycle variability, be it seasonal, interannual, or between land cover types. Rainfall is responsible for nearly as much seasonal variations of most energy-related variables as solar forcing. Depending on water availability and plant requirements, evapotranspiration pre-empts the energy available from surface forcing radiation, over the other dependent processes (sensible and ground heat, outgoing long wave radiation). In the water budget, pre-emption by evapotranspiration leads to very large variability in soil moisture and in deep percolation, seasonally, interannually, and between vegetation types. The wetter 2006 season produced more evapotranspiration than 2005 from the fallow but not from the millet site, reflecting differences in plant development. Rain-season evapotranspiration is nearly always lower at the millet site. Higher soil moisture at this site suggests that this difference arises from lower vegetation requirements rather than from lower infiltration/higher runoff. This difference is partly compensated for during the next dry season. Effects of water and vegetation on the energy budget appear to occur more through latent heat than through albedo. A large part of albedo variability comes from soil wetting and drying. Prior to the onset of monsoon rain, the change in air mass temperature and wind produces, through modulation of sensible heat, a marked chilling effect on the components of the surface energy budget.

Abstract: Quantitative estimation of fractional cover of photosynthetic vegetation (fPV), non-photosynthetic vegetation (fNPV) and bare soil (fBS) is critical for natural resource management and for modeling carbon dynamics. Accurate estimation of fractional cover is especially important for monitoring and modeling savanna systems, subject to highly seasonal rainfall and drought, grazing by domestic and native animals, and frequent burning. This paper describes a method for resolving fPV, fNPV and fBS across the ~ 2 million km2 Australian tropical savanna zone with hyperspectral and multispectral imagery. A spectral library compiled from field campaigns in 2005 and 2006, together with three EO-1 Hyperion scenes acquired during the 2005 growing season were used to explore the spectral response space for fPV, fNPV and fBS. A linear unmixing approach was developed using the Normalized Difference Vegetation Index (NDVI) and the Cellulose Absorption Index (CAI). Translation of this approach to MODerate resolution Imaging Spectroradiometer (MODIS) scale was assessed by comparing multiple linear regression models of NDVI and CAI with a range of indices based on the seven MODIS bands in the visible and shortwave infrared region (SWIR) using synthesized MODIS surface reflectance data on the same dates as the Hyperion acquisitions. The best resulting model, which used NDVI and the simple ratio of MODIS bands 7 and 6 (SWIR3/SWIR2), was used to generate a time series of fractional cover from 16 day MODIS nadir bidirectional reflectance distribution function-adjusted reflectance (NBAR) data from 2000-2006. The results obtained with MODIS NBAR were validated against grass curing measurement at ten sites with good agreement at six sites, but some underestimation of fNPV proportions at four other sites due to substantial sub-pixel heterogeneity. The model was also compared with remote sensing measurements of fire scars and showed a good matching in the spatio-temporal patterns of grass senescence and posterior burning. The fractional cover profiles for major grassland cover types showed significant differences in relative proportions of fPV, fNPV and fBS, as well as large intra-annual seasonal variation in response to monsoonal rainfall gradients and soil type. The methodology proposed here can be applied to other mixed tree-grass ecosystems across the world.

Abstract: Savannahs are highly dynamic ecosystems but many of their properties and the related balances of energy, carbon, nitrogen, and water are still poorly understood. A particular scientific issue is the quantification of trace gases emitted from the soil of savannah ecosystems and their interaction with regional and global climate and air chemistry. Therefore it is important to develop and evaluate land-surface models that on the one hand represent vegetation and soil dynamics and on the other hand provide energy and water fluxes in a temporal resolution suitable for the application in climate/air chemistry models. In this paper, we present a consistent coupling between a common land-surface model (OSU) and a widely used biogeochemical model (DNDC) that is a first step for a full coupling of climate/air chemistry and biogeochemical processes. For consistency reasons, both models are linked to a general physiologically based plant model to provide the physical boundary conditions as well as the carbon and nitrogen in- and output variables. Evaluation is carried out with measurements of soil temperature, latent heat flux, soil water content, and soil emission data from two vegetation periods collected at a natural grassland site in Bontioli Nature Reserve, Burkina Faso (Africa). The results demonstrate that simulations of biogeochemical processes based on soil environmental conditions, calculated either with the land-surface model or with the unchanged biogeochemical model, do not differ significantly from each other. The OSU model simulates more realistic day-to-day variation of soil temperature as DNDC but the sensitivity of the biogeochemical simulation to this variation is small. In contrast, the sensitivity to differences in soil water content is high, but simulation results of both models are very similar on the daily scale and hardly depend on spatial soil resolution.

Abstract: This article reviews and analyzes the available information on range and livestock production in the Monte Desert. Cow-calf operations, goats for meat, and sheep for wool are the dominant production systems under continuous grazing. Rest-rotational grazing systems improved the efficiency of the current cow-calf production. Forage resources are primarily composed of perennial grasses and woody species. Rain-use efficiency for the total vegetation ranged from 3.9 to 4.8 kg DM ha-1 year-1 mm-1. Carrying capacity showed a broad range: 18.7, 4.5-64.5, and 21.6-89.3 ha AU-1 in the north, central, and south portions of the Monte, respectively. Mean crude protein (CP) content of grasses varied from 8.4 to 10.3 (wet season) and 7.1-3.7% DM (dry season) in the central west and Patagonia, respectively. Grasses predominated in the cattle diet, while the sheep diet was highly diverse because they ate most of the available plant species, and there was no unanimity as to the fact that goats are strictly browsers. Livestock diseases have lower prevalence indices than those recorded in other areas of the country. The high variability in carrying capacity values could be attributed to differences in rangeland condition and to the different methods used for its estimation. The CP levels in forage could meet cattle requirements provided that a proper-stocking rate were used. The most promising species for land rehabilitation are Opuntia, Atriplex spp., Eragrostis curvula and Cenchrus ciliaris. Priorities for future research should include topics such as assessment of the carrying capacity for most of the areas and nutrient content of the components of livestock diet, the livestock intake values, the economic feasibility of the use of complementary feeds and the development of seeding technology for valuable forage resources as Trichloris crinita, among others.

Abstract: Gully erosion represents an important soil degradation process in rangelands. In order to take preventive or control measures and to reduce its environmental damages and economical costs it is useful to localize the points in the landscape where gullying takes place and to determine the importance of the different factors involved. The study is carried out in Extremadura, southwest Spain. The main objectives of this work are: (a) comparing two nonparametric schemes to model the potential distribution of gullies, (b) evaluating the importance of the different factors involved in gullying processes, (c) analyzing the role of prevalence in the success of the model and finally, (d) implementing and mapping the results with the help of a Geographical Information System (GIS). Two methods were used to model the response of a dependent variable (gullying) from a set of independent variables: Classification And Regression Trees (CART) and Multivariate Adaptive Regression Splines (MARS). Three different datasets were used; the first one for constructing the model (training dataset) and the others for validating the model (external datasets). These datasets are formed by a target variable (presence or absence of gullies) and a set of independent variables. The dependent variable was obtained by mapping the locations of gullies with the help of a GPS and high resolution aerial ortophotographs. A set of 32 independent variables reflecting topography, lithology, soil type, climate, land use and vegetation cover of each area were used. The performance of the models was evaluated using a non-dependent threshold method: the Receiver Operating Characteristic (ROC) curve. The results showed a better performance of MARS for predicting gullying with areas under the ROC curve of 0.98 and 0.97 for the validation datasets, while CART presented values of 0.96 and 0.66.

Abstract: Summary A map of temporary small water bodies (TSWB) at 1 km resolution was derived for the arid, semi-arid and dry sub-humid regions of sub-Saharan western Africa where the spatio-temporal distribution of actual surface water occurrence exhibits high inter- and intra-annual variability. Water bodies and humid areas have been mapped and characterized by the analysis of 10 daily small water bodies (SWB) maps based on SPOT VEGETATION (VGT) data spanning the period January 1999-September 2007. Further analysis of the SWB time series provided additional information about the seasonal recurrence of water bodies as well as their hydrological function. A map derived from a continuous time series assures the inclusion of temporary features, a clear advantage compared to other datasets, which are based on several single date observations. The method described in this paper targets at a rapid creation of TSWB maps based on the SWB time series for different time intervals and regions. An accuracy assessment has been carried out with a stratified random sampling approach and a one-stage cluster analysis that relies on high-resolution satellite data to verify the detected water bodies. The overall accuracy, considering only the commission error, is 95.4% for the whole study region, with best results in the arid and semi-arid climate zone. The method to map water bodies delivers satisfactory results, particularly for sparsely vegetated areas as well as flat areas of the study region. In more humid, more vegetated areas and in mountainous areas, the possibility of false detections increases due to surface characteristics.

Abstract: Buffelgrass (Pennisetum ciliare L. Link) is an African agamospermous grass that has been widely introduced into arid regions of the world to improve rangelands for cattle production and as a result, it has invaded adjacent habitats. In this study, ISSR markers were employed to assess genotypic variation in populations of P. ciliare from north-western Mexico. We sampled plants from pasture and from colonizing roadside populations in order to explore if invasion success is associated with greater levels of genotypic diversity. Three ISSRs primers produced 27 reproducible bands that were used to screen 480 plants from sixteen populations. Mean values of the proportion of distinguishable genotypes (G/N) were 0.29, Nei's genotypic diversity was 0.75 and multilocus evenness (E) was 0.50. Sixty-seven multilocus genotypes were detected among 480 plants, with 46 (69%) restricted to single populations and 21 (31%) found in two or more populations. Our results showed no significant differences in genotypic diversity between pasture and roadside populations, suggesting that in P. ciliare invasion success is not directly associated with greater levels of genotypic variation. Probably, other factors such as phenotypic plasticity and propagule pressure could be major determinants of the invasion success of buffelgrass in this region of Mexico.

Abstract:

Abstract: Vegetation cover and composition are two indicators commonly used to monitor terrestrial ecosystems. These indicators are currently quantified with a number of different methods. The interchangeability and relative benefits of different methods have been widely discussed in the literature, but there are few published comparisons that address multiple criteria across a broad range of grass- and shrub-dominated communities, while keeping sampling effort (time) approximately constant. This study compared the utility of three field sampling methods for ecological assessment and monitoring: line-point intercept, grid-point intercept, and ocular estimates. The criteria used include: (1) interchangeability of data, (2) precision, (3) cost, and (4) value of each method based on its potential to generate multiple indicators. Foliar cover by species was measured for each method in five plant communities in the Chihuahuan Desert. Line- and grid-point intercept provide similar estimates of species richness which were lower than those based on ocular estimates. There were no differences in the precision of the number of species detected. Estimates of foliar cover with line- and grid-point intercept were similar and significantly higher than those based on ocular estimates. Precision of cover estimates with line-point intercept was higher than for ocular estimates. Time requirements for the three methods were similar, despite the fact that the point-based methods included cover estimates for all canopy layers and the soil surface, while the ocular estimates included only the top canopy layer. Results suggest that point-based methods provide interchangeable data with higher precision than ocular estimates. Moreover these methods can be used to generate a much greater number of indicators that are more directly applicable to a variety of monitoring objectives, including soil erosion and wildlife habitat.

Abstract: On rangelands, uneven or unmanaged livestock distribution can adversely affect plant community composition, riparian function, or displace wildlife. These issues have historic precedents and are still a challenge for those managing rangelands. A thorough understanding of the mechanisms governing livestock distribution can help land and livestock managers avoid or ameliorate many deleterious effects. To that end, this research tested hypotheses that grazing cattle seek nutritionally superior portions of rangeland pastures. Global positioning system (GPS) collars were used to track cattle movement and activity in three, 800+ ha pastures where the spatial distribution of standing crop, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and forage digestibility (in situ dry matter disappearance (ISDMD)) were mapped in late spring. Four of five analyses implied grazing cattle spatially responded to forage quantity/quality attributes. Analyses indicated cattle favored higher than average CP (P = 0.006) and ISDMD (P = 0.078), and lower than average NDF (P = 0.003) and standing crop (P = 0.069) locales. No significant effect (P = 0.954) occurred with ADF analyses. Correlations among those variables imply cattle may simultaneously respond to more than one nutritional attribute as they select foraging locales. Stepwise regression, however, relating grazing distribution to geophysical and forage quantity/quality characteristics were extremely poor predictors of where cattle grazed. Listed in order of entry, the model implied elevation above or below stock water, horizontal distance to stock water, forage CP content, and degree of slope were the site specific attributes most associated with cattle distribution. We speculate that cattle interactions with landscape level nutritional dynamics may at least partially explain seasonal changes in distribution and forage use by cattle across the landscape. These findings should help land and livestock managers understand, explain, and manipulate livestock distribution on their holdings.

Abstract: It is becoming increasingly difficult to manage and expand statutory conservation areas (i.e., parks and formally protected areas). Therefore, alternative opportunities for land conservation merit closer attention. This paper examines the extent to which privately owned conservation areas contribute to biodiversity representation. Gap analyses were performed for a large semi-arid region in South Africa with a comprehensive database of private conservation areas. The distribution of private conservation areas was compared to statutory conservation areas using several landscape characteristics: biome and vegetation variant, elevation class, ecological process area, total area, and threat status (endangerment). Conservation target achievement for the vegetation variants was also assessed, as was the degree to which private conservation areas complemented statutory conservation areas by representing different landscape characteristics. The number of targets achieved nearly tripled if private conservation areas were considered in addition to statutory conservation areas. Further, private conservation areas significantly complemented statutory conservation areas in the types of biomes, elevation classes, and threat status classes conserved. Private conservation areas were especially important in conserving lower elevation habitat, and by association, endangered vegetation. This particular relationship is expected to be common worldwide. Our results indicate that private lands conservation deserves an increased allocation of resources for both research and implementation.

Abstract: Abstract Alpine grassland is a fragile ecosystem, and a large area of this grassland type has been severely degraded in Northern Tibet, to the extent that it has become the primary ecological problem in the region. Various levels of government, including the national central government, the Tibetan Autonomous Region government, and the Nagqu Prefecture government have worked together to achieve alpine grassland ecosystem protection and prevent grassland degradation. These efforts have resulted in significant ecological, social, and economic benefits in Northern Tibet.

Abstract: The Early to Middle Pleistocene Dandiero rift basin is located near the Buia village, 110 km south of Massawa (Eritrea), and is filled by about 1000 m of continental deposits bearing 1 My erectus-like human remains. The basin fill consists of six formations (from bottom up): Bukra sand and gravels (fluvial), Alat formation (fluvio-lacustrine), Wara sand and gravel (fluvial), Goreya formation (lacustrine), Aro sand (fluvio-deltaic) and Addai fanglomerate (alluvial fan). This paper is focused on the Homo-bearing deposits of the Alat formation. The Alat formation records several episodes of changing accommodation space, with repeated shifts from fluvial to lacustrine conditions. The first episode points to rapid lake formation followed by a progressive shallowing. The second episode records fluvial aggradation above a sequence boundary, followed by the development and progressive infill of a second lake. The third episode points to a rapid lake formation followed by deposition of deltaic and fluvial sediments. The last episode is characterised by fluvial deposition under low-accommodation conditions. The development of the lacustrine environments was probably controlled by tectonics, in accordance with its formation during regionally dry climatic conditions, although minor shifts toward wetter conditions cannot be excluded. Human remains occur in the upper Alat formation, where the transition from a deltaic to alluvial setting is characterised by high frequency, potentially millennial-scale, lake-level oscillations. The palaeoanthropological record in the Buia area seems to be correlated with water availability (lacustrine coastal plains and floodplains) in a relatively open and grassy environment (grassland- and savannah-dominated). The increase in fluvial discharge that occurred at the top of the Alat formation led to erosion and winnowing of the underlying fossil-bearing, fluvio-deltaic deposits. A large number of bones and artefacts were consequently accumulated at the base of channel fills, which represent a preferential horizon for fossil searching.

Abstract: Conservation agriculture is claimed to be a panacea for the problems of poor agricultural productivity and soil degradation in sub-Saharan Africa (SSA). It is actively promoted by international research and development organisations, with such strong advocacy that critical debate is stifled. Claims for the potential of CA in Africa are based on widespread adoption in the Americas, where the effects of tillage were replaced by heavy dependence on herbicides and fertilizers. CA is said to increase yields, to reduce labour requirements, improve soil fertility and reduce erosion. Yet empirical evidence is not clear and consistent on many of these points nor is it always clear which of the principles of CA contribute to the desired effects. Although cases can be found where such claims are supported there are equally convincing scientific reports that contradict these claims. Concerns include decreased yields often observed with CA, increased labour requirements when herbicides are not used, an important gender shift of the labour burden to women and a lack of mulch due to poor productivity and due to the priority given to feeding of livestock with crop residues. Despite the publicity claiming widespread adoption of CA, the available evidence suggests virtually no uptake of CA in most SSA countries, with only small groups of adopters in South Africa, Ghana and Zambia. We conclude that there is an urgent need for critical assessment under which ecological and socio-economic conditions CA is best suited for smallholder farming in SSA. Critical constraints to adoption appear to be competing uses for crop residues, increased labour demand for weeding, and lack of access to, and use of external inputs.

Abstract: Savannas are shaped by drought, herbivory, nutrient limitation, and fire. We assessed the interactions between two of these factors--nutrient limitation and fire--across a savanna landscape in Kruger National Park, South Africa, by quantifying increases in plant-available forms of soil phosphorus (P) following experimental or simulated burns. Plant-available pools of P were defined for granitic surface soils subjected to four experimental fire regimes (no fire, triennial fire in the wet season, triennial fire in the dry season, and annual fire in the dry season). To provide context for these results, we also fractionated surface soils from a granitic catena after simulating burning of these soils in a furnace. Burned soils showed comparable pyromineralization rates, with the experimental burn plot soils averaging 0.49 ± 0.04 g labile P m- 2 y- 1 and catena soils averaging 0.63 ± 0.12 g labile P m- 2 y- 1. Only soils from subplots burned triennially during the wet summer season with moderate fire intensities (~ 1.1 MW m- 1) showed significant increases in labile P relative to control soils. Soils from other burned subplots with greater fire intensities showed smaller gains in labile P, suggesting pyromineralization rates may peak at intermediate fire intensities. We estimated ash contributed up to 33% of pyromineralized P. For catena soils, simulated burning led to significant increases in pyromineralized P for the relatively P-rich footslope soils and smaller increases for sandy crest and midslope soils. These pyromineralization P fluxes are of the same order of magnitude as plant P demand estimated using foliar P levels, and about one-half microbial mineralization rates. In P-limited ecosystems where chemical weathering rates are slow, moderate-intensity fires could play a critical biogeochemical role in the supply of labile P.

Abstract: Fencing for conservation is an acknowledgement that we are failing to successfully coexist with and, ultimately, conserve biodiversity. Fences arose during the Neolithic revolution to demarcate resource-rich areas (food sources) and exclude threats (intruders). Fencing for conservation can be viewed as fulfilling a similar function. The aims of this paper were to identify when fencing can and is used to conserve biodiversity; highlight the costs and benefits of fencing for conservation; and make recommendations to ensure appropriate use of fencing for conservation in the future. The IUCN identifies ten major threatening processes and the impacts of eight of these can be mitigated via the use of fencing, however avoiding human-animal conflict and reducing the impact of introduced predators are the two most common uses. Fences implemented to achieve a conservation benefit are not necessarily physical barriers, but can also include [`]metaphorical' fences of sound, smoke and smell, or even actual islands. Fences provide defined units for managers and separate biodiversity from threatening processes including human persecution, invasive species and disease. Conversely, they are costly to build and maintain; they have ecological costs through blocking migration routes, restriction of biodiversity range use which may result in overabundance, inbreeding and isolation; restriction of evolutionary potential; management; amenity and ethical costs. Despite these problems, fencing for conservation is likely to become increasingly utilized as biodiversity becomes increasingly threatened and methods of ameliorating threats lag behind. In the long-term, fences may ultimately prove to be as much a threat to biodiversity as the threats they are meant to exclude, and a new research agenda should arise to ensure that conservation fences do not remain a permanent part of the landscape.

Abstract: Summary Twenty-five rangeland sites were monitored over two decades (1984-2006) first to assess the impact of the 1983-1984 droughts on fodder resources, then to better understand ecosystem functioning and dynamics. Sites are sampled along the south-north bioclimatic gradient in Gourma (Mali), within three main edaphic situations: sandy, loamy-clay and shallow soils. In addition, three levels of grazing pressure where systematically sampled within sandy soils. Located at the northern edge of the area reached by the West African monsoon, the Gourma gradient has recorded extremes in inter-annual variations of rainfall and resulting variations in vegetation growth. Following rainfall variability, inter-annual variability of herbaceous yield increases as climate gets dryer with latitudes at least on the sandy soils sites. Local redistribution of rainfall explains the high patchiness of herbaceous vegetation, especially on shallow soils. Yet spatial heterogeneity of the vegetation does not buffer between year yield variability that increases with spatial heterogeneity. At short term, livestock grazing during the wet season affects plant growth and thus yield in direction and proportions that vary with the timing and intensity of grazing. In the longer term, grazing also impinges upon species composition in many ways. Hence, long histories of heavy grazing promote either long cycle annuals refused by livestock or else short cycle good quality feed species. Primary production is maintained or even increased in the case of refusal such as Sida cordifolia, and is lessened in the case of short cycle species such as Zornia glochidiata. These behaviours explain that the yield anomalies calculated for the rangelands on sandy soils relative to the yield of site less grazed under similar climate tend to be negative in northern Sahel where the scenario of short cycle species dominates, while yield anomalies are close to nil in centre Sahel and slightly positive in South Sahel where the refusal scenario is more frequent. Because grazing promotes short cycle species, grazed rangelands respond faster to droughts. Year to year changes in species composition are abrupt as expected from the transient soil seed stock. However, some decadal trends in species composition are identified, with a wave of pioneer species following the 1983-1984 droughts, and a more progressive diversification and return to typical Sahel flora from 1992 onwards.

Abstract: Summary To document trends in land use and herbaceous production, 71 field sites sampled among cropped fields, fallow fields and rangelands in the Fakara region (Niger) were monitored from 1994 to 2006. The overall trend in land use confirmed the historical increase of the cropped areas since mid 20th century, at an annual rate of 2% from 1994 to 2006. This trend is the result of changes in the relative extent of fields permanently cropped and fields under shifting cultivation, and for the latter, the relative proportion of short (3 years) and long (10 years) duration fallows. Type of land use together with topography and soil type determine the herbaceous production and the resulting yield measured towards the end of the wet season. The variation in site yields between years is of the same order of magnitude as the variation in yields between sites within a year. There is an overall decreasing trend in site yields by 5% annually from 1994 to 2006 that is not explained by variations in rainfall. The decreasing trend is observed on fields under shifting cultivation, fallowed fields and rangelands, although not all sites are equally affected. Causes are likely to be multiple which might include changes in land use, decline of soil fertility and increased grazing pressure. Indeed, the remaining rangelands on marginal land and the fallows still accessible to livestock are subject to such a heavy grazing during the rainy season that the herbaceous standing mass measured at the end of the season reflects poorly the actual production. After the two first years of cropping, the herbaceous yield in fields under shifting cultivation with no fertilisation is negatively affected by the number of successive years of cropping. Moreover, clearing fallow after a decreasing number of years affects the mean herbaceous yield of fallowed fields by reducing the contribution of more productive old fallows. Changes in land use, grazing pressure and soil fertility also triggered changes in species composition with a strong reduction in diversity from rangelands to fallows, and again from fallows to cropland weeds. No correlations was found however between productivity and species composition. Cumulative rainfall does not explain between site or between year deviations in herbaceous yield even when sites are sorted by land use type or by soil type in the case of fallow and rangelands. Simulated production calculated with the STEP model does not explain herbaceous yields much better even when sites are grouped by land use and soil type. However, relative changes of herbaceous yields are reasonably predicted on sites that remained fallowed and were not heavily grazed for at least four consecutive years.

Abstract: Little is known about the sequence of climate and environmental change in southern Africa during the last glacial period, in spite of the intimations from records, such as Antarctic ice cores and archaeological sites, that very marked changes took place which would have had profound effects on vegetation and animal distributions across the sub-continent. High-resolution, (semi-) continuous climate and environmental records can be extracted from suitable cave speleothems. Speleothems are reasonably abundant in southern Africa, but their occurrence is patchy in time and space and the records can be difficult to interpret. Here we report our assessment of the stalagmite W5 from Wolkberg Cave in the northeastern part of South Africa, as an archive for glacial-period climatic and environmental shifts. The cave is located at 1450 m asl, in the dolomitic limestones of the Transvaal System in an area currently dominated by C4 grass vegetation. Nine U/Th dates show growth from 58 to 46 ka, and a second brief phase ca. 40 ka, indicating that the available moisture was sufficient to allow speleothems to form. The [delta]18O and [delta]13C values along the growth axis show variability in the order of 2[per mille sign] for the former, while variability in the latter is characterized by a shift from values near - 2[per mille sign] in the older section to + 2[per mille sign] or more in the younger part. These high [delta]13C values are probably the combined result of CO2 degassing of the percolating soil water prior to the carbonate precipitation in the cave chamber, the increasing dominance of C4 over C3 vegetation, and the high percentage of aragonite towards the stalagmite's top. The retrieved data point towards increasingly drier and colder conditions during the growth period of the stalagmite. Furthermore, the high-frequency variations of [delta]18O values indicate the presence of short term climate oscillations that are probably linked to shifts of the Intertropical Convergence Zone.

Abstract: Improper cropping and overgrazing have led to land degradation in semi-arid regions, resulting in desertification. During desertification, vegetation changes have been widely observed, and are likely controlled to some extent by soil water. The purpose of this study was to investigate changes in soil physical properties, organic C, and vegetation induced by land-use changes, with special reference to the dynamics of available soil water. We selected four study sites in a typical Mongolian steppe grassland: grassland protected from grazing, grazed grassland, abandoned cropland, and cultivated cropland. Grazing exclusion increased the cover of perennial grass, with little increase in the root weight. Since there was no difference in available water between the grasslands with and without grazing, there appears to be no serious soil compaction due to overgrazing. On the other hand, vegetation cover and the number of species were poor in both abandoned cropland and cultivated cropland. However, the root weight was greater in abandoned cropland. Although the abandonment of cultivation appeared to increase organic C, available water did not differ significantly in comparison with cultivated cropland. The silt contents were significantly lower in abandoned and cultivated cropland than in both grasslands, suggesting the effects of wind erosion. In addition, the silt contents were positively correlated with the volume fraction of storage pores for available water. Therefore, the lower silt contents may constrain the volume of available water in abandoned cropland. Moreover, the unsaturated hydraulic conductivity results indicated that the diameters of storage pores for available water at the present study sites were smaller than those suggested by previous studies. Although the differences in vegetation cover by different land-use types were observed at every site, differences in the volume of available water were observed at between abandoned cropland and cultivated cropland. The reason why the no differences in available water between grazed grassland and grasslands protected from grazing may be short time of grazing exclusion for 2 years for evaluating the effects of exclusion on soil properties.

Abstract:

Abstract: Livestock are a global resource of significant benefits to society in the form of food, income, nutrients, employment, insurance, traction, clothing and others. In the process of providing these benefits, livestock can use a significant amount of land, nutrients, feed, water and other resources and generate 18% of anthropogenic global greenhouse gases. The total demand for livestock products might almost double by 2050, mostly in the developing world owing to increases in population density, urbanization and increased incomes. Multiple existing trade-offs and competing demands for natural resources will intensify, but reducing livestock product demand in places and capitalizing on the positive aspects of livestock systems such as the potential for sustainable intensification of mixed systems, the potential of ecosystems services payments in rangeland systems and well-regulated industrial livestock production might help achieve the goals of balancing livestock production, livelihoods and environmental protection.

Abstract: In many parts of the world, it is inevitable that fire will return as a natural disturbance factor to vegetation restored on anthropogenically-disturbed lands. Therefore, assessment of the ultimate success of restoration programs should include the ways in which these ecosystems respond to such natural disturbances. We compared the response of vegetation to experimental fires on mature ([greater-or-equal, slanted]8 y) post-mine restored and nearby natural shrubland communities in a Mediterranean-climate region of Australia. Pre- and post-fire perennial plant species composition was assessed in 40 � 40 m plots at three shrubland sites restored after mineral sand-mining, and at five natural shrubland sites. Additional quadrats were monitored for seedling survival over the first summer after fire. Species richness fell by 22-41% after fire in restored sites, but increased by 4-29% in natural sites. Of the species present before fire, 44-60% persisted after fire is restored sites, and 88-96% in natural sites. Only 42-66% of resprouting species recovered in restored sites, whereas 96-100% recovered in natural sites. Nonsprouting species recruitment was also lower in restored (18-57%) than natural (67-85%) sites. Seedling mortality over the first summer after fire was higher in restored sites (59-86% death of individuals) than in natural sites (14-60%). PCoA ordination showed that fire altered the floristic composition of restored sites much more than that of natural sites, and their vegetation diverged further from the targeted properties of natural communities. Our study highlights the importance of including the ability of post-anthropogenically-altered lands to recover from natural disturbances in determining the success of restoration programs.

Abstract: Complex ecological issues like depredation and its management are determined by multiple factors acting at more than one scale and are interlinked with complex human social and economic behaviour. Depredation by wild herbivores can be a major obstacle to agricultural community support for wildlife conservation. For three decades, crop and fence damage, competition with livestock for native rangeland and tame pasture, and depredation of stored feed by elk (Cervus elaphus canadensis) have been the cause of conflict with agricultural producers in the Cypress Hills, Alberta and Saskatchewan. Tolerance of elk presence on private lands is low because few benefits accrue to private landowners; rather they largely perceive elk as a public resource produced at their expense. Government management actions have focused on abatement inputs (e.g., population reduction; fencing) and compensation, but incentives to alter land use patterns (crop choice and location) in response to damages have not been considered. Nor has there been information on spatial structure of the elk population that would allow targeted management actions instead of attempting to manage the entire population. In this study we analysed the spatial structure of the Cypress Hills elk population, the distribution of the elk harvest in relation to agricultural conflicts, developed models of the spatial patterns of conflict fields, and evaluated compensation patterns for damage by wild herbivores. We propose modifications to current abatement and compensation programs and discuss alternative approaches involving changes to agricultural land use patterns that may reduce the intensity of conflicts with elk, and increase the acceptance capacity of landowners.

Abstract: In this work we analyze the temporal stability of soil moisture at the field and watershed scales in the Little Washita River Experimental Watershed (LWREW), as part of the remote sensing Cloud and Land Surface Interaction Campaign (CLASIC07) during June 2007 in south-central Oklahoma. Temporal stability of surface and profile soil moisture data were investigated for 20 LWREW soil moisture measurement stations. In addition, daily surface and profile soil moisture measurements were obtained in four 800 m by 800 m fields (remote sensing footprint), including two rangeland sites and two winter wheat fields. The work aimed to analyze the temporal stability of soil moisture at the watershed and field scale and to identify stations within the watershed, as well as locations within each field, that were representative of the mean areal soil moisture content. We also determined the relationship between sites found to be temporally stable for surface soil moisture versus those determined stable for average profile soil moisture content. For the unusually wet experimental period, results at the watershed scale show that LWREW stations 133 and 134 provided stable underestimates, while stations 132 and 154 provided stable overestimates of the watershed mean at all depths. In addition, station 136 had very high non-zero temporal stability at the 25 cm and 45 cm depths indicating that it could be used as representative watershed site provided a constant offset value is used to acquire a watershed mean soil water content value. In general, the deeper depths exhibited higher soil moisture spatial variability, as indicated by the higher standard deviations. At the field scale, measured average profile soil moisture was higher in the winter wheat fields than the rangeland fields with the majority of the winter wheat depth intervals having high non-zero temporal stability. Field scale temporal stability analysis revealed that 4 of the 16 sampling sites in the rangeland fields and 3 of the 16 sampling sites in the winter wheat fields either under or overestimated the field means in the 0-5 and 0-60 cm depth intervals. Field sites considered temporally stable for the surface soil moisture were not stable for the profile soil moisture, except for the LW45 field where two sites were stable at both the surface and profile soil moisture. This finding is significant in terms of soil moisture ground-truth sampling for calibrating and validating airborne remotely sensed soil moisture products under extremely wet conditions. In addition, identification of temporally stable sites at the watershed and field scales in the LWREW provide insight in determining future measurement station locations and field scale ground sampling protocol, as well as providing data sets for hydrologic modeling.

Abstract: We quantified livestock (cattle, shoats, horses and donkeys) losses to lions (Panthera leo) and attitudes to lions, livestock losses and tourism among livestock owners, village residents and tourism workers around Makgadikgadi Pans National Park in Botswana. Losses were not correlated with the size or structure of livestock enclosures, numbers of dogs or herders. Rather losses increased with the amount of livestock owned. Most were stray animals preyed upon at night. Attitudes to wildlife, conservation and lions were also not consistently distributed within the society we studied. Negative attitudes to lions were almost ubiquitous among cattleposts but less widespread among people living in the more urbanized society of villages or among people working in tourism. Although four tourist camps were operating in the area, benefits from these operations were largely limited to employees. Despite considerable sums of money being paid to Botswana by local tourist facilities few respondents viewed tourism as valuable and most felt that the government and not they or their community was the main beneficiary of tourism. Tourism employees made up a small sub-section of the adult population drawn predominately from larger villages while the costs of livestock losses were spread among cattleposts near the park boundary. These same cattlepost respondents were not prepared to improve stock care to protect livestock, but indicated a willingness to kill lions instead. If tourism is to play a role in reducing human-wildlife conflict, communities must not be regarded as homogenous entities into which to distribute benefits evenly. Benefits might usefully be distributed in relation to the costs of coexisting with wildlife or used as incentives to better protect livestock or other human resources.

Abstract: The aim of the present study was to determine the effect of polyethylene glycol (PEG) supplementation on grazing behaviour of beef cattle and on utilization of the woody components of a Mediterranean shrubland. Two experiments were conducted on two different sites in Northern Israel, Ramat Hanadiv (RH) and Hatal. On each site, the study area was divided into two paddocks, in one cattle were supplemented with 50 g PEG day- 1 per cow, while the other served as a control, with no PEG supplementation. In RH site the cows had free access to Prolix and in Hatal to poultry litter, both serving as a nitrogen supplement during the experiment. In the RH site, the consumption of Pistacia lentiscus, a shrub whose leaves contain high concentration of tannins, was found higher (P = 0.001) in the PEG group diet than in the control group. In Hatal site PEG increased foraging time by 18%, daily foraging distance by 15% and reduced the use of supplementary feed (poultry litter) by 20%. However, PEG did not affect the average cow body weight or water consumption on either site. It is concluded that PEG influences grazing behaviour of beef cattle on shrubby rangeland and increases the use of woody species with high tannin concentrations.

Abstract: The African Wildlife Foundation (AWF) has developed and applied a landscape-scale conservation planning methodology in eight priority conservation landscapes in Africa, areas we call African Heartlands. The foundation of the African Heartland Program is a landscape-scale planning process that has been developed and applied as part of the overall Heartland Conservation Process. This process helps AWF and its partners develop intervention strategies that address critical threats to the ecological viability of these landscapes, and to specific biodiversity conservation targets, whilst also working to improve the livelihoods of local people. In applying this participatory planning process to eight conservation landscapes in Africa we have begun to document and learn about the benefits and limitations of planning and implementation at the landscape-scale with stakeholders. We draw out lessons on the challenges and successes from our experience. Central to this are the merits of balancing a systematic science-based and pragmatic approach to landscape-scale conservation planning while addressing the needs and aspirations of local people. This approach could be particularly useful for other large-scale conservation planning efforts in developing countries where conservation objectives and human livelihoods are inextricably linked.

Abstract: Herbicides have been applied extensively on rangelands to reduce forbs that were considered undesirable, which has been assumed to lead to an increase in grass production and ultimately to an improvement in livestock performance. While scores of research studies support the premise that forb suppression can increase desirable forage on plot-level studies, only a few studies have attempted to quantify the effect on livestock production within experimental units equivalent in area to production-scale pastures. We therefore tested the effect of herbicide on mixed prairie vegetation and on livestock gain on pastures typical in area, stocking rate, and composition to working ranches in the region. Picloram and 2,4-d at 0.15 and 0.56 kg/ha, respectively, were applied aerially in spring of 2001 and again in spring of 2004 to two pastures. Two untreated control pastures were managed identically, including grazing management, but were not treated with herbicide. Canopy cover by species and cover of bare ground and litter were estimated in permanently located plots, and stocker cattle performance (average daily gain per head; ADG) and total cattle gain (kg ha-1) were measured from 2000 to 2005. Forb cover was less (P < 0.05) in herbicide treated pastures than in control pastures in the year of herbicide application (2001 and 2004) and for second growing season following the treatment (2 YAT) in the 2004 application. Grass cover varied more with annual precipitation than with treatment. Livestock ADG and gain ha-1 did not differ between treatments in any year or across years. Livestock production varied among years, reflecting variation in growing-season precipitation that is characteristic of non-equilibrium rangelands. Herbicide altered the plant community by reducing forb cover and increasing grass cover, but livestock production was not altered either on an individual basis (gain/head) or on an area basis (gain/ha). Livestock production per area (gain/ha) might be increased if grass production after herbicide treatment could be predicted reliably. However, predicting grass production is notoriously difficult in rangeland ecosystems that have high inter-annual variation in precipitation. Reliable adjustments in stocking rate to harvest grass released from forb competition is unlikely and therefore fraught with risk.

Abstract: The effectiveness of water harvesting systems collecting surface runoff form rangeland hillslopes in semi-arid regions is difficult to predict, since the hydrological response at the outlet depends on the heterogeneity of hydrological processes. The lack of continuous runoff pathways, due to the irregular spatial patterns of soil properties and the variety of antecedent soil moisture conditions directly influence runoff generation and control discharge into the water harvesting cisterns. The aim of this paper is to evaluate the effectiveness of semi-arid hillslopes in generating runoff for water harvesting systems. Runoff was estimated by the STREAM expert-based model which was applied to three semi-arid hillslopes (0.4 to 6 ha). On the one hand the STREAM model rules were adapted to the regional conditions i.e. an antecedent precipitation index was adjusted to local soil moisture conditions and the rainfall duration was defined as the total rainfall event quantity and the effective rainfall duration (Ptot/teff). On the other hand, the distribution of rock outcrop and vegetation cover along the slopes was used to define homogeneous hydrological units. Final infiltration capacities were attributed to these hydrological units based on values found in the literature. The prediction performances are acceptable for the three water harvesting systems with an RMSE of 13.9 m3. It was shown that the rainfall/runoff model was more sensitive to the duration of the storm than to the antecedent soil moisture conditions. The use of a unique set of hydrological parameters for the three water harvesting systems on representative hillslopes allows the runoff prediction from any rangeland hillslope within the same region. Furthermore, the spatial patterns of soil surface characteristics are crucial for collecting runoff at the outlet of the system. Model runs demonstrated that degradation of vegetation and sealing of very small areas within flow paths can lead to an increase of annual runoff by as much as a factor two.

Abstract: Large sediment fluxes can have significant impacts on ecosystems. We measured incoming and outgoing sediment across a gradient of soil disturbance (livestock grazing, plowing) and annual plant invasion for 9 years. Our sites included two currently ungrazed sites: one never grazed by livestock and dominated by perennial grasses/well-developed biocrusts and one not grazed since 1974 and dominated by annual weeds with little biocrusts. We used two currently grazed sites: one dominated by annual weeds and the other dominated by perennial plants, both with little biocrusts. Precipitation was highly variable, with years of average, above-average, and extremely low precipitation. During years with average and above-average precipitation, the disturbed sites consistently produced 2.8 times more sediment than the currently undisturbed sites. The never grazed site always produced the least sediment of all the sites. During the drought years, we observed a 5600-fold increase in sediment production from the most disturbed site (dominated by annual grasses, plowed about 50 years previously and currently grazed by livestock) relative to the never grazed site dominated by perennial grasses and well-developed biocrusts, indicating a non-linear, synergistic response to increasing disturbance types and levels. Comparing sediment losses among the sites, biocrusts were most important in predicting site stability, followed by perennial plant cover. Incoming sediment was similar among the sites, and while inputs were up to 9-fold higher at the most heavily disturbed site during drought years compared to average years, the change during the drought conditions was small relative to the large change seen in the sediment outputs.

Abstract: Strong sustainability, according to the common definition, requires that different natural and economic capital stocks be maintained as physical quantities separately. Yet, in a world of uncertainty this cannot be guaranteed. To therefore define strong sustainability under uncertainty in an operational manner we propose to use the concept of viability. Viability means that the different components and functions of a dynamic, stochastic system at any time remain in a domain where the future existence of these components and functions is guaranteed with sufficiently high probability. We develop a unifying and general ecological-economic concept of viability that encompasses the traditional ecological and economic notions of viability as special cases. It provides an operational criterion of strong sustainability under a mild form of uncertainty and for medium spatial and temporal scales. We illustrate this concept and demonstrate its usefulness by applying it to livestock grazing management in semi-arid rangelands.

Abstract: In this paper, we re-interpret three cases of research previously carried out in Mali, Niger and South Africa in light of the recent debate about formalisation of land rights that has emerged since the publication of Hernando de Soto's [`]Mystery of Capital'. The Malian case shows that lack of broad access to formalisation processes in high-pressure areas may play into the hands of those with power, information, and resources. The case also demonstrates that timing of formalisation efforts in urban areas characterised by rapid expansion is crucial in terms of distributive outcomes. The Nigerien case demonstrates how impending formalisation led to a scramble for land and increased conflicts in a context of institutional competition and limited administrative capacity. The South African case shows that the very process of surveying and registering rights may also change the rights themselves. Formalisation procedures may also amplify the tension between individual and communal rights, and boost privatisation.

Abstract: In this review, we compiled published results on biological interactions at different spatial scales in the Monte desert of Argentina and identified gaps in current knowledge. We presented evidence of competitive and facilitative plant-plant conspecific and heterospecific interactions, and plant-soil-microbes interactions in relation to the abiotic environment at the fine patch-scale. We also showed evidence of animal-animal interactions and plant-animal interactions at the community scale through study cases involving both native and introduced herbivores. Moreover, we identified bottom-up and top-down forces governing the interactions between granivores (birds, ants, and small mammals) and seed availability/production at the community scale. At the landscape scale, we discussed feedbacks between domestic grazers and the spatial patterns of resources and their interrelationships with processes occurring at other scales. We concluded that research has steadily increased during the last 6 years but knowledge on biological interactions in the Monte desert is still scarce, particularly at a landscape scale.

Abstract: A sequence of paleosols in the Solo Basin, Central Java, Indonesia, documents the local and regional environments present when Homo erectus spread through Southeast Asia during the early Pleistocene. The earliest human immigrants encountered a low-relief lake-margin landscape dominated by moist grasslands with open woodlands in the driest landscape positions. By 1.5 Ma, large streams filled the lake and the landscape became more riverine in nature, with riparian forests, savanna, and open woodland. Paleosol morphology and carbon isotope values of soil organic matter and pedogenic carbonates indicate a long-term shift toward regional drying or increased duration of the annual dry season through the early Pleistocene. This suggests that an annual dry season associated with monsoon conditions was an important aspect of the paleoclimate in which early humans spread from Africa to Southeast Asia.

Abstract: Côte d'Ivoire's adoption of land privatization policies promoted by the World Bank and European Union is producing new land use patterns in the countryside. A centerpiece of these policies is the 1998 Rural Land Law that aims to restructure rural economic life along agrarian capitalist lines. The purported "development" objective of land privatization is to stimulate agricultural productivity based on the assumption that land titling will lead farmers and herders to make greater investments in their production systems. This paper argues that the mobile livestock raising system of immigrant FulBe pastoralists in Côte d'Ivoire is threatened by the new land law. Since mobility is crucial to animal health and fertility rates, I argue that reduced mobility will lead to lower livestock productivity. Although the land law has yet to be implemented, its very existence is leading prospective claimants to test their land rights by planting orchards and lending land to immigrant farmers. The monetization of land lending and grazing rights is increasingly common. Land disputes over who has the power to allocate land are also on the rise. I argue that this heightened interest in "tenure building" is constraining herd mobility, especially for herders with limited resources to negotiate access to rangelands. On the other hand, land privatization is strengthening the hand of local cattle-owning farmers who increasingly practice mobile livestock raising and compete with FulBe herders for grazing lands. Under these new conditions of land access, control, and competition, FulBe herd mobility and productivity are at risk of declining.

Abstract: Relations between phytolith occurrences, taxonomy, and habitat are assessed for 184 East African grass species through the re-analysis of two qualitative surveys of phytolith types in leaf epidermis. This is done in conjunction with data on grass subfamily, photosynthetic pathway, and requirement for light and moisture compiled from floras and the literature. This survey includes ca 79% of the grass genera listed in the flora of tropical East Africa. It aims to further investigate the potential for grass short cell phytoliths to characterize the environment, and therefore improve reconstructions of past vegetation and climate in Africa. In this analysis, we identified ca 60 phytolith types (within the main categories Rondel, Trapeziform Short Cell, Bilobate, Cross, Polylobate, Saddle, and Trapeziform Sinuate) reported to occur in 10 grass subfamilies (Pharoideae, Bambusoideae, Ehrhartoideae, Pooideae, Danthonioideae, Arundinoideae, Chloridoideae, Centothecoideae, Panicoideae, and Incertae Sedis Streptogyna). These subfamilies include hydrophytic, helophytic, mesophytic and xerophytic species, with C3 or C4 photosynthetic pathways, and with affinities for shade, open, or semi-shade habitats. Analysis of phytolith occurrences shows that few morphotypes are restricted to some species only. However, there are morphological variations (of size and number of lobes) within the main phytolith categories Rondel, Bilobate, and Cross, which could additionally be considered to improve environmental and taxonomical interpretation of phytolith assemblages. The Rondel phytolith with a base diameter > 15 [mu]m was only reported in C3-Pooideae, while the Rondel with a base diameter of < 15 [mu]m occurs in several grass subfamilies (including Pooideae). Bilobates with long shanks between the two lobes are most frequently reported in xerophytic species, while Bilobates with short shanks are most frequently reported in mesophytic grass species. Finally, three-lobed crosses are reported only in Panicoideae and Chloridoideae, all being C4, light-loving species. A correspondence analysis confirms already known relationships between 1) Saddle forms, C4 pathway, open and xeric habitats, 2) Bilobates, Crosses, Polylobates, shaded and hydric habitats, 3) Trapeziform Sinuates and Pooideae. Of major implication for palaeoenvironmental reconstructions in East Africa, we found that the Trapeziform Sinuate phytoliths mark the presence of C3-grasses in the Afromontane zone, whereas the Rondels alone do not because they also occur in many C4 species of the Chloridoideae subfamily. We also establish that collapsed saddles are not diagnostic for Bambusoideae closed-habitat grasses since they occur in xerophytic species of the Chloridoideae, characteristic of several open habitats. In conclusion, this study contributes to better characterize Afromontane vegetation and better discriminate mesic and xeric vegetation types in East Africa. It also brings caution for future phytolith studies that rely on the presence of diagnostic types instead of phytolith assemblage analysis to trace the presence of particular taxa and/or environments in East Africa.

Abstract: The study examines the changes in sub-Saharan's natural land cover resources for a 25 year period. We assess these changes in four broad land cover classes - forests, natural non-forest vegetation, agriculture and barren - by using high spatial resolution Earth observing satellites. Two sets of sample images, one [`]historical' targeted at 1975 and a second [`]recent' targeted at the year 2000, have been selected through a stratified random sampling technique over the study area, targeting a sampling rate of 1% in each of the strata. The results, presented at eco-region level and aggregated at sub-Saharan level, show a 57% increase in agriculture area at the expense of natural vegetation which has itself decreased by 21% over the period, with nearly 5 million hectares forest and non-forest natural vegetation lost per year. The impacts of these changes on the environment on one site and on the socio-economy on the other site are discussed and possible pressures on human well being are highlighted.

Abstract: Summary This paper analyses the dynamics of vegetation and carbon during the West African monsoon season, for millet crop and fallow vegetation covers in the cultivated area of the Sahel. Comparing these two dominant land cover types informs on the impact of cultivation on productivity and carbon fluxes. Biomass, leaf area index (LAI) and carbon fluxes were monitored over a 2-year period for these two vegetation systems in the Wankama catchment of the AMMA (African monsoon multidisciplinary analyses) experimental super-site in West Niger. Carbon fluxes and water use efficiency observed at the field scale are confronted with ecophysiological measurements (photosynthetic response to light, and relation of water use efficiency to air humidity) made at the leaf scale for the dominant plant species in the two vegetation systems. The two rainy seasons monitored were dissimilar with respect to rain patterns, reflecting some of the interannual variability. Distinct responses in vegetation development and in carbon dynamics were observed between the two vegetation systems. Vegetation development in the fallow was found to depend more on rainfall distribution along the season than on its starting date. A quite opposite behaviour was observed for the crop vegetation: the date of first rain appears as a principal factor of millet growth. Carbon flux exchanges were well correlated to vegetation development. High responses of photosynthesis to light were observed for the dominant herbaceous and shrub species of the fallow at the leaf and field scales. Millet showed high response at the leaf scale, but a much lesser response at the field scale. This pattern, also observed for water use efficiency, is to be related to the low density of the millet cover. A simple LAI-based model for scaling up the photosynthetic response from leaf to field scale was found quite successful for the fallow, but was less conclusive for the crop, due to spatial variability of LAI. Time/space variations in leaf distribution for the dominant species are key to scale transition of carbon dynamics. Results obtained for the two vegetation covers are important in light of the major land use/cover change experienced in the Sahel region due to extensive savanna clearing for food production.

Abstract: Little is known about the effects of grazing on vegetation composition on the Arabian Peninsula. The aim of this study therefore was to analyse the vegetation response to environmental conditions of open woodlands along an altitudinal and a grazing gradient in the Jabal al Akhdar mountain range of Oman. The species composition, vegetation structure, grazing damage and several environmental variables were investigated for 62 samples using a nested plot design. Classification analysis and a Canonical Variate Analysis (CVA) were used to define vegetation types and to identify underlying environmental gradients. The relationship between environmental variables and diversity was analysed using correlation coefficients and a main-effects ANOVA. The plant species richness followed a unimodal distribution along the altitudinal gradient with the highest number of species at the intermediate altitudinal belt. The cluster analysis led to five vegetation groups: The Sideroxylon mascatense-Dodonaea viscosa group on grazed and the Olea europaea-Fingerhuthia africana group on ungrazed plateau sites at 2000 m a.s.l., the Ziziphus spina-christi-Nerium oleander group at wadi sites and the Moringa peregrina-Pteropyrum scoparium group at 1200 m a.s.l, and the Acacia gerrardii-Leucas inflata group at 1700 m a.s.l. The CVA indicated a clear distinction of the groups obtained by the agglomerative cluster analysis. The landform, altitude and grazing intensity were found to be the most important variables distinguishing between clusters. Overgrazing of the studied rangeland is an increasing environmental problem, whereas the plant composition at ungrazed sites pointed to a relatively fast and high regeneration potential of the local vegetation.

Abstract: Summary Soil moisture is widely recognized as a key parameter in environmental processes mainly for the role of rainfall partitioning into runoff and infiltration. Therefore, for storm rainfall-runoff modeling the estimation of the antecedent wetness conditions (AWC) is one of the most important aspect. In this context, this study investigates the potential of scatterometer on board of the ERS satellites for the assessment of wetness conditions in three Tiber sub-catchments (Central Italy), of which one includes an experimental area for soil moisture monitoring. The satellite soil moisture data are taken from the ERS/METOP soil moisture archive. First, the scatterometer-derived soil wetness index (SWI) data are compared with two on-site soil moisture data sets acquired by different methodologies on areas of different extension ranging from 0.01 km2 to ~60 km2. Moreover, the reliability of SWI to estimate the AWC at a catchment scale is investigated considering the relationship between SWI and the soil potential maximum retention parameter, S, of the Soil Conservation Service-Curve Number (SCS-CN) method for abstraction. Several flood events occurred from 1992 to 2005 are selected for this purpose. Specifically, the performance of the SWI for S estimation is compared with two antecedent precipitation indices (API) and one base flow index (BFI). The S values obtained through the observed direct runoff volume and rainfall depth are used as benchmark. Results show the great reliability of the SWI for the estimation of wetness conditions both at the plot and catchment scale despite the complex orography of the investigated areas. As far as the comparison with on site soil moisture data set is concerned, the SWI is found quite reliable in representing the soil moisture at layer depth of 15 cm, with a mean correlation coefficient equal to 0.81. The characteristic time length parameter variations, as expected, is depended on soil type, with values in accordance with previous studies. In terms of AWC assessment at catchment scale, based on selected flood events, the SWI is found highly correlated with the observed maximum potential retention of the SCS-CN method with a correlation coefficient R equal to -0.90. Besides, SWI in representing the AWC of the three investigated catchments, outperformed both API indices, poorly representative of AWC, and BFI. Finally, the classical SCS-CN method applied for direct runoff depth estimation, where S is assessed by SWI, provided good performance with a percentage error not exceeding ~25% for 80% of investigated rainfall-runoff events.

Abstract: SummaryOver 1,200 Important Bird Areas (IBAs) have been identified in Africa, each meeting at least one of four objective criteria that identify it as an area of high conservation importance for birds. Despite their biodiversity value, many IBAs are threatened by habitat degradation and a high proportion lack legal protection. We integrate an inventory of these IBAs with remote sensing data to identify patterns that could be used to assess priorities for monitoring and conservation. Land cover composition in IBAs differed significantly from that in buffer zones of the same area immediately surrounding them and was significantly more homogeneous. Agriculture and deforestation were the most prevalent threats to IBAs, particularly in IBAs containing a high proportion of dense forest or shrub. Human population density within IBAs was no lower than that immediately outside IBAs, and was around three times higher than the average for sub-Saharan Africa. However, projected human population growth was lower than the average for sub-Saharan Africa, with the projected increase greatest in IBAs with a high proportional cover of dense forest and mosaic woodland and lowest in IBAs with a higher grassland component. Fifty seven percent of IBAs fell within or overlapped Protected Areas, though this percentage differed between different categories of IBA. IBAs that were included within Protected Areas supported a greater number of globally threatened bird species and contained proportionally more dense forest, woodland and shrub than IBAs falling outside Protected Areas. IBAs outside Protected Areas contained a high proportion of mosaic woodland and open water, suggesting that such habitats are under-protected in Africa. We suggest that because the most prevalent threats to IBAs involve changes in land cover that could be detected from satellites, remote sensing could play an important role in the monitoring of African IBAs. This would permit monitoring of a wider range of sites than is possible solely by conventional, ground-based approaches.

Abstract: Ecosystems services sustain humans all over the world. The unsustainable use of ecosystem services around the world has led to widespread degradation which now threatens human health and livelihoods. Although the maintenance of ecosystem services is often used to justify biodiversity conservation actions, it is still unclear how ecosystem services relate to different aspects of biodiversity and to what extent the conservation of biodiversity will ensure the provision of services. The aim of this study was to find out whether biodiversity priorities, biomes, species richness and vegetation diversity hotspots co-occur in space with ecosystem services. The distribution of the ranges and hotspots of five ecosystem services (surface water supply, water flow regulation, carbon storage, soil accumulation, and soil retention) was assessed in South African biomes. Coincidence, overlap, and correlation analyses were used to assess spatial congruence between ecosystem services and species richness (plants and animals) and vegetation diversity hotspots. The grassland and savanna biomes contained significant amounts of all five ecosystem services. There was moderate overlap and a generally positive but low correlation between ecosystem services hotspots and species richness and vegetation diversity hotspots. Species richness was mostly higher in the hotspots of water flow regulation and soil accumulation than would be expected by chance. The water services showed varying levels of congruence with species richness hotspots and vegetation diversity hotspot. These results indicate that actions taken to conserve biodiversity in South Africa will also protect certain ecosystem services and ecosystem services can be used to strengthen biodiversity conservation in some instances.

Abstract: Since the mid-1980s, sagebrush rangelands in the Great Basin of the United States have experienced more frequent and larger wildfires. These fires affect livestock forage, the sagebrush/grasses/forbs mosaic that is important for many wildlife species (e.g., the greater sage grouse (Centrocercus urophasianus)), post-fire flammability and fire frequency. When a sagebrush, especially a Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis (Beetle & A. Young)), dominated area largely devoid of herbaceous perennials burns, it often transitions to an annual dominated and highly flammable plant community that thereafter excludes sagebrush and native perennials. Considerable effort is devoted to revegetating rangeland following fire, but to date there has been very little analysis of the factors that lead to the success of this revegetation. This paper utilizes a revegetation monitoring dataset to examine the densities of three key types of vegetation, specifically nonnative seeded grasses, nonnative seeded forbs, and native Wyoming big sagebrush, at several points in time following seeding. We find that unlike forbs, increasing the seeding rates for grasses does not appear to increase their density (at least for the sites and seeding rates we examined). Also, seeding Wyoming big sagebrush increases its density with time since fire. Seeding of grasses and forbs is less successful at locations that were dominated primarily by annual grasses (cheatgrass (Bromus tectorum L.)), and devoid of shrubs, prior to wildfire. This supports the hypothesis of a "closing window of opportunity" for seeding at locations that burned sagebrush for the first time in recent history.

Abstract: Relationships between fire history, vegetation structure and composition, and invasion by introduced plant species have received limited attention in Australian woodlands. A study in a Mediterranean, fire adapted urban Banksia woodland remnant in the biodiversity hotspot of southwest Australia investigated: (1) Have significant changes occurred in the woodland tree canopy between 1963 and 2000? (2) Do correlations exist between fire frequency and canopy cover? (3) If there is a difference in the vegetation composition of Banksia woodland invaded by the South African Ehrharta calycina (PCe) and Pelargonium capitatum (PCp) compared to largely intact remnants (GC)? and (4) Do correlations exist between vegetation condition, composition, fire frequency and invasion? Aerial photography, processed in a Geographical Information System, was used to establish fire history and changes in canopy cover over time (1963-2000). PCe and PCp sites experienced the greatest number of fires, with a net reduction in canopy cover in all areas experiencing four or more fires (60% of all woodlands). Frequent fire corresponded with a decline in native cover, richness and diversity, a shift from native to introduced species, changes in the relative importance of fire response categories, and loss of native resprouting shrub cover. Life forms of introduced species, which included no trees, shrubs and perennial sedges, contrasted strongly with those of native species, which had poor representation of annual and perennial grasses. Clear ecological and conservation consequences due to the loss of species diversity, changes in fire ecology and invasion have occurred in the Banksia woodlands. This study provides an understanding of the invasion process, enhancing conservation knowledge to improve the adaptive management of the key threatening process of invasion in biodiverse communities.

Abstract: This study has compared the phytolith production and soil phytolith assemblages of two native grass communities typical in Argentina, namely the monospecific Paspalum quadrifarium community or "pajonal", and the Stipa-Piptochaetium community or "flechillar". Five sites - three of which had been unmanaged while other two had been submitted to fire and fire-grazing management activities - were selected for study. The results show that in these sites a) phytolith production of the plant communities differed due to their diverse floristic composition, b) it was possible to define the type of management or the type of community based on soil phytolith assemblages, c) there were differences between plant communities and soil phytolith assemblages. These results suggest that modern phytolith assemblages are composed not only of local and present vegetation but also of extralocal/regional and probably past vegetation. Hypotheses about the probable processes involved in phytolith incorporation to soil have emerged during the investigation.

Abstract: Relationships between plant invasion and the soil seed bank in highly diverse fire adapted mediterranean woodlands are poorly understood, yet critical for that ecosystem's conservation. Within the biodiversity hotspot of southwest Australia we investigated the composition and diversity of the Banksia woodland soil seed bank in good condition (GC), medium condition (MC) and poor condition invaded by the South African perennial species Ehrharta calycina (PCe) and Pelargonium capitatum (PCp). The investigation assessed three questions: (1) Do soil seed banks of invaded sites have fewer germinants of native species and more germinants of introduced (non-native) species than sites with minimal invasion? (2) Do soil seed banks show shifts in ecological functional types with invasion? (3) Is the soil seed bank of introduced species persistent? Native species germinants, mainly shrubs and perennial herbs, were highest in GC sites and least in poorer condition sites suggesting a reduction in their numbers had occurred over time. Introduced germinants were dominated by perennial and annual grasses, and annual herbs. E. calycina had the greatest seed density (8328 germinants m-2). More introduced than native germinants occurred in the litter. Rapid germination of introduced species (30% in week 1) compared to native species (4% in week 1) provides the capacity for their early dominance. A limited native soil seed bank and dominant persistent introduced soil seed bank represent great challenges for the structural and functional conservation and restoration of woodland ecosystems. This study provides key new knowledge, applicable to a wide range of ecosystems, to help formulate conservation protocols to control dominant introduced species and conserve and restore biodiverse-rich woodlands.

Abstract: The north-west Tibetan Plateau in China is currently undergoing development-related changes in land use that illustrate a significant mismatch between national/international conservation objectives and national livestock and other rangeland development goals for the region. Areas designated as nature reserves are being subjected to the same livestock development policies as elsewhere on the Plateau, including interventions that are detrimental to the supposedly protected wildlife populations. Unintended effects of some livestock development activities, such as the fencing of winter grazing areas and resultant enhancement of illegal hunting, have been little considered in overall development actions inside the nature reserves. We address these issues within the 300,000 km2 Chang Tang Nature Reserve, covering much of the north-west Plateau, and concentrate on Gertse County in the western part of the Reserve. There are still tens of thousands of Tibetan antelope Pantholops hodgsonii, Tibetan gazelle Procapra picticaudata, kiang Equus kiang and other species in the north-west Chang Tang, and long-distance antelope calving migrations are still relatively intact. However, increasing human and livestock populations, new rangeland management initiatives, effects of mining activity and continued hunting have the potential to counter conservation initiatives even in the most critical areas for wildlife in the region. Within the nature reserves livestock carrying capacity determinations that allow for wildlife needs and recognize the variable climate are essential. Livestock fencing amenable to wildlife movement, a ban on fencing in areas critical to wildlife, and other actions that mitigate negative effects on wildlife are needed in nature reserves where antelope and other species are still abundant.

Abstract: Woody plant encroachment is a threat to savanna ecosystems worldwide. By exploiting differences in the physiology and seasonality of herbaceous species and encroaching hardwoods, herbicides can be used to control woody shrubs in savannas without causing lasting harm to desirable vegetation. We applied three herbicides and one tank mix to control shrubs following removal of the slash pine (Pinus elliottii Engelm.) canopy and replanting with container-grown longleaf pine (Pinus palustris Mill.) seedlings in a mesic-wet savanna in the southeastern USA. The herbicides tested were imazapyr, sulfometuron methyl, hexazinone, and a hexazinone + sulfometuron methyl tank mix. 4 years after application, no negative effects on understory species richness, diversity, evenness, or community composition were evident in any of the herbicide treatments. Oaks (Quercus spp.), one of the dominant shrub genera on the study site, were resistant to sulfometuron methyl, and this herbicide was therefore ineffective both as a pine release treatment and for enhancing herbaceous species cover. Imazapyr was the most effective treatment overall, leading to significant improvements in longleaf pine seedling growth and also enhancing herbaceous species cover. Both hexazinone and the hexazinone + sulfometuron methyl tank mix provided some seedling growth and understory enhancement as well. In particular, the tank mix significantly increased wiregrass cover relative to the control. Shrubs resprouted quickly following a dormant-season prescribed fire in the fifth year after treatment, indicating that herbicide-related increases in herbaceous cover may be lost if an aggressive prescribed fire program is not implemented.

Abstract: Summary Post-1994 land reform policies have had limited effects on land use in the communities surrounding Dwesa-Cwebe Nature Reserves in South Africa's Transkei region. Likewise, prior state interventions have largely been resisted and ignored. Instead, community-driven processes, influenced by the regional political economy, have shaped diverse patterns of changes in land use. These relate to the diverse livelihood styles in the area: different patterns of education, labor migration, and consumption have affected local use of land and forest products. Activities planned under land reform, however, may threaten local control of land tenure and use.

Abstract: Abstract This study investigated the utilization of mist-belt grassland habitat by the threatened blue swallow and was conducted over three successive breeding seasons in the Blue Swallow Natural Heritage Site at Kaapsehoop, Mpumalanga, South Africa. Blue swallows significantly preferred wetlands over grasslands for foraging. Sufficient foraging habitat must be within a 1.5 km radius from an active nest site. The minimum size of a pair of blue swallows home range should be 333 ha, consisting at a minimum of grasslands (243 ha or 73%) and wetlands (90 ha or 27%). In order to conserve this threatened species, habitat transformation should not take place within a minimum radius of 1.5 km of any blue swallow nest. Due to the critical dependence of the blue swallow on wetland habitat for foraging, any development outside the 1.5 km radius that would affect hydrology and water quality within this range would need to be considered, and any adverse effect mitigated. Rehabilitation of areas to a grassland/wetland mosaic would rather quickly support foraging, and eventually breeding. Although a better understanding of the dynamics between wetlands and adjacent grasslands regarding blue swallow habitat requirements is needed, action can already be taken, based on our results. Résumé Cette étude a examiné l�utilisation de l�habitat de prairie mist-belt par l�hirondelle bleue qui est une espèce menacée et elle s�est poursuivie pendant trois saisons de reproduction successives dans le Site du Patrimoine naturel de l�Hirondelle bleue, à Kaapsehoop, Mpumalanga, en Afrique du Sud. Les hirondelles bleues préféraient de façon significative les zones humides aux prairies pour se nourrir. Il faut qu�il y ait un habitat suffisant pour se nourrir dans un rayon d�1,5 km autour d�un site de nidification actif. La taille minimale pour le domaine vital d�un couple d�hirondelle bleue serait de 333 ha, composé au minimum de prairies (243 ha soit 73%) et de zones humides (90 ha ou 27%). Afin de conserver cette espèce menacée, il faudrait qu�il n�y ait aucune transformation de l�habitat dans un rayon d�au moins 1,5 km de tout nid d�hirondelle bleue. �tant donné que l�hirondelle bleue dépend de façon critique d�une zone humide pour se nourrir, tout développement prenant place à l�extérieur d�un rayon de 1,5 km et qui affecterait l�hydrologie et la qualité de l�eau dans le domaine vital devrait être reconsidéré, et tout effet négatif devrait être atténué. La réhabilitation de zones de mosaïque prairie/zone humide favoriserait assez vite le nourrissage et, peut-être, la reproduction. Bien qu�il soit nécessaire de mieux comprendre la dynamique entre zones humides et prairies adjacentes en ce qui concerne les exigences de l�hirondelle bleue en matière d�habitat, on peut déjà prendre des mesures en se basant sur nos résultats.

Abstract: Camel grazing plays a crucial role in the desert ecosystems of the UAE. In this study, we compare areas grazed by small antelope (Al Maha Resort - the AMR) with areas grazed by both camels and small antelope (Dubai Desert Conservation Reserve - the DDCR). A total of 126 plots were selected during the growing season 2006/07 on three soil substrates: gravel plains, sand flats and sand dunes. In each plot, several vegetation parameters were assessed: density, frequency, percent cover and diversity indices. The replacement of camels with wild antelope has significantly increased the number of species on gravel plains, vegetation density on sand dunes and diversity indices on both sand flats and sand dunes, but significantly decreased plant cover on sand flats and sand dunes. The increase in species diversity in the AMR was attributed to moderate grazing by antelope. Replacement of camels by antelope in the AMR has resulted in change in plant community composition of the three substrate types. Species recovered after protection from camel grazing are palatable, especially for camels, except Heliotropium kotschyi and Aerva javanica. The absence of most of the palatable species from the DDCR was attributed to both selective foraging and overgrazing by camels.

Abstract: Domestic grazing animals that congregate around watering points in arid rangelands create clearly-defined trampling-induced grazing gradients. Grazing and trampling alter soil and vegetation condition, often leading to substantial reductions in ecological function. We measured foraging pits and mounds created by native soil foraging animals over 12 months at three watering points in a Chihuahuan Desert grassland, and hypothesized that the density and cover of their disturbances would increase with increasing distance from water. We recorded an average of 3756 disturbances ha-1 and cover of 34.18 m2 ha-1 across the grazing gradients, which comprised mainly pits (43%) and mounds (25%) of heteromyid rodents, ants and spiders. Soil turnover was estimated at 1.43 m3 ha-1. We detected no differences in density, cover, soil volume or composition of disturbances in relation to distance from water, but there were significant, though ill-defined, differences across the five sampling periods, with generally more activity in the warm-wet months. Small animal-created mounds and pits are important sources of soil and sinks for litter within grazing gradients, and may represent the only sites where plants can establish given a relaxation in grazing pressure.