Abstract: In the Mongolian steppes, livestock and burrowing rodents are the main animal modifiers of the habitat. Although grazing lands and rodent habitats overlap, the combined effects of livestock and rodent disturbance on spatial heterogeneity of plants and soil have rarely been evaluated. We established study plots at each of four sites: sites heavily grazed by livestock, with and without marmots, and ungrazed sites, with and without marmots. We subdivided each plot into quadrats to survey the plant species composition and soil nutrient properties, and calculated the spatial heterogeneity of vegetation at three spatial scales using non-metric multidimensional scaling analysis. We also calculated the coefficient of variance among the soil samples. The vegetation's spatial heterogeneity did not differ significantly between grazed and ungrazed plots; however, it was higher under marmot disturbance than in the absence of marmots at a fine scale, but lower under marmot disturbance at a coarse scale, irrespective of livestock grazing. At a fine scale, unique habitats were formed by each combination of livestock grazing (presence/absence) and marmots (presence/absence). In addition, the plant species composition in the grazed plots was distinct from that in the ungrazed plots at the coarser scale. The occurrence of degradation-indicator plant species depended on the presence of grazing rather than on the additive effect of grazing and marmots. Marmots increased the abundance of degradation-indicator species only in the ungrazed plots. Each herbivore group increased the spatial heterogeneity of soil nutrients at coarser scales, but these influences were lost when both herbivore groups coexisted. These results show that the ecological roles of livestock and marmots are complementary, not functionally equivalent. That is, livestock modified the overall vegetation composition, and thereby modified spatial heterogeneity at the landscape scale, whereas marmots modified spatial heterogeneity at the local scale. Proper manipulation of the livestock grazing regime can maintain species-rich communities without serious land degradation in the Mongolian steppe.
Abstract: Burrowing by semi-fossorial rodents modifies soil properties and plant communities. The effects of this burrowing on plants, however, are typically evaluated only by assessing changes in photosynthetic or production traits, not pollination traits. Therefore little is known about the indirect effects of burrowing on pollinators through its effects on the emergence of insect-pollinated plants. We recorded the relative elevation, grass cover, and flower height of insect-pollinated plant species; the number of inflorescences; and the number of pollinators in a marmot colony on the Mongolian steppe. We compared these parameters on and off marmot mounds and searched for factors that might explain variations in pollinator biodiversity at the plot and individual-plant levels. Flower numbers and flower visitation frequency per plot were significantly higher in the on-mound plots. The number of pollinators at the plot level was positively correlated with the relative elevation and number of flowers. Species richness of the pollinators was negatively correlated with grass cover. These results demonstrate that mounds created by marmots attracted pollinators by increasing flower numbers and by making flowers more conspicuous by raising them above the surrounding vegetation or removing that vegetation.
Abstract: The global population of saiga Saiga tatarica, categorized as Critically Endangered on the IUCN Red List,
declined by .95% at the end of the 20th century, resulting in several conservation initiatives to protect the species. Previously used methods to monitor population trends were inadequate to assess numbers of saiga properly. We report findings from the first survey for Mongolian saiga S. tatarica mongolica to utilize statistically rigorous methodology, using line transect distance sampling in 2006 and 2007 to obtain population estimates in and around the Sharga Nature Reserve, the southern part of the species’ current range. We estimate a density of 0.54 and 0.78 saiga km-2 in 2006 and 2007, respectively. Our best models suggest that 4,938 (95% confidence interval, CI52,762–8,828) saiga occupied the 4,524-km2 study area in 2006 and 7,221 (95% CI54,380–11,903) occupied the 4,678-km2 study area in 2007. Although these estimates, with their large confidence intervals, preclude an assessment of the impacts of conservation initiatives on population trends, they suggest that the Mongolian saiga
population is larger than previous reports based on minimum counts, and adequate to support in situ population recovery. Modifications to the survey protocol hold promise for improving the precision of future estimates. Distance sampling may be a useful, scientifically defensible method for monitoring saiga population trends and assessing the effectiveness of conservation efforts to stabilize and recover populations.
Abstract: The study of mammals suffering intense poaching in remote areas poses an increasingly difficult conservation
challenge, in part because the extreme flightiness of such species complicates safe capture. The benefits of
handling (an opportunity to obtain biological information and attach radio collars) must be weighed against stress
to the animals and potential capture-related mortality. In parts of Central Asia this problem is not trivial, as
populations have been heavily harvested and opportunities for restraint are often limited. Mongolian saiga Saiga
tatarica mongolica, being both Endangered and poached, typifies these issues. Here we describe capture protocols for adult females handled quickly and without anaesthesia. Using multiple vehicles driven at high speed, individual saiga were isolated from groups and herded into nets. Chase time was linearly associated with rectal temperature (P,0.03), with maximum pursuits and temperatures of 9 minutes and 43.1C, respectively; time to release averaged, 7 minutes. Given that rural residents often chase saiga and other desert and steppe-dwelling ungulates, for photography or for amusement, our results offer conservationists and government officials an empirical basis for recommending prudence on chase times and/or for recommending that the practice be prevented.
Abstract: An understanding of the relationship between vegetation spatial heterogeneity and disturbance and its application to the management are important for maintaining biodiversity and functions of ecosystems. We examined the effects of disturbance by Siberian marmots on the spatial heterogeneity of vegetation at three spatial scales (fine, intermediate and coarse) in a Mongolian grassland. We established a 50 m × 50 m plot around five marmot mounds and another plot in an area with no mounds. Each plot was subdivided into 625 adjacent 4-m2 square quadrats and the plants in them were surveyed. Spatial heterogeneity was calculated as the mean dissimilarity in species composition among sample quadrats in each plot. The offcolony plant community was dominated by graminoids, but a variety of plants,
including graminoids, forbs and shrubs, were present in the on-colony plot. The slightly greater fine-scale heterogeneity in the on-colony plot compared to the offcolony plot reflected the presence of either disturbed or undisturbed patch within a single measurement unit, whereas the lower coarse-scale heterogeneity in the oncolony plot reflected the presence of both disturbed and undisturbed patches within a single measurement unit. Our results demonstrate the possibility of using the marmot as a conservation tool in our study site as far as a plant biodiversity is targeted.
Abstract: We investigated the effects of overgrazing on the foraging behavior of livestock on a Mongolian steppe, by quantifying some behaviors of cattle, sheep and goats foraging in a lightly and a heavily grazed area in summer and winter. All animal species showed higher walking velocity and tended to show higher step/bite ratio when they foraged in the heavily grazed area than in the lightly grazed area. The effect of overgrazing on the step/bite ratio was greater in sheep and goats than in cattle, and the effect on the walking velocity was stronger in winter than in summer. The results indicate that heavy grazing altered the foraging behavior of animals imposing higher foraging costs, which varied among the animal species and between the seasons. The declined quantity of preferred species in the heavily grazed area required high searching efforts and decreased the bite rate, for selecting acceptable plants and better feeding
sites. The stronger effects on sheep and goats than on cattle and in winter than in summer may reflect different foraging behavior potentials among the animals and different food availabilities between the seasons. We suggest that the ongoing increase in the number of goats in Mongolia is problematic not only from the viewpoint of grassland deterioration but also from feeding cost of whole livestock animals.
Abstract: Dogs (Canis familiaris) are recognized as one of the most numerous carnivores in the world. They have direct and indirect impacts on a diverse range of animal species. In Mongolia, there are shepherd families within Mongolia saiga (Saiga tatarica mongolica) range and shepherd dogs are suspected to cause saiga mortalities. However, quantitative information on the effects of dogs on saiga is lacking. In August 2008 and April 2009, we estimated abundance of dogs in Sharga Nature Reserve by compiling existing data and interviewing local people to understand public perceptions regarding impacts of dogs on saiga. Interviews revealed that the majority of local herders believed dogs have only a minor impact on saiga due to the low density of domestic dogs and the lack of feral dogs in the reserve. However, dogs are believed to have greater impacts on saiga in harsh winters, when saiga are in poorer health and are more likely to use areas where dogs are present. Thus, domestic dogs in the study area appear to have no regular detrimental impact on the local saiga population, but may act as a source of additive mortality in years with harsh winter conditions.
Abstract: We conducted a carcass census of Mongolian gazelles (Procapra gutturosa) along the Trans-Mongolian railroad in June 2005. We counted 241 gazelles that had died within the previous 12 months. Carcass numbers were greater on the southwestern side in the northern 3 zones, but we found carcasses only on the northeastern side in the southernmost zone. It suggests that impact of the railroad was stronger on one side and that the strength of this impact varied among regions.
Abstract: Land bridges once assured transcontinental connectivity, but climate-induced habitat loss resulted in the extinction of numerous North American large mammals. Using GPS technology on the formerly widespread but now endangered saiga in Mongolia, we identified a fine-scaled 5-km wide critical corridor, whose protection is critical for maintaining migration and meta-population structure.
Abstract: Widespread degradation of Mongolian grasslands by overgrazing is of global concern. The
objective of this study was to reveal the effects of grazing on pollination as an example of
interaction biodiversity in Mongolian grasslands. We established three plots according to
grazing intensity on the eastern steppe of Mongolia. In each plot, we recorded the numbers
of insect-pollinated plants and observed the foraging behavior of pollinators in June and
August. The richness of insect-pollinated species was high and these species were most
abundant in lightly grazed plots, and formed complex relations with diverse pollinators.
But, frequency of flower visitation and pollination index were greater in heavily grazed
plots. All pollination properties were poorest in intermediately grazed plots. These results
suggest that the forb-biased foraging of sheep and goats reduces the floral diversity of
insect-pollinated species, and consequently reduces pollinators in the intermediately
grazed plots. In the heavily grazed plots, only limited ruderal species could survive under
heavy cattle grazing, and such simple vegetation formed unbalanced but strong bonds with
pollinators. Removal simulation showed that the mutual network was more fragile with
respect to the extinction of certain species.
Abstract: With our enhanced understanding of the factors that determine biodiversity and assemblage structure has come increasing acknowledgment that the use of an appropriate disturbance regime to maintain spatial heterogeneity is an effective conservation technique. A herbivore’s behavior affects its disturbance regime (size and intensity); this, in turn, may modify the associated spatial heterogeneity of plants and soil properties. We examined whether the pattern of spatial disturbance created by the Siberian marmot (Marmota sibirica) affects the spatial heterogeneity of vegetation and soils at a colony scale on the Mongolian steppe. We expected that the difference in management between two types of area (protection against hunting marmots vs. hunting allowed) would result in different behavioral patterns; therefore, we estimated the patterns of spatial disturbance separately in protected and unprotected areas. We then surveyed plant communities and soil nutrients in these areas to assess their spatial heterogeneity. We found that disturbance of both vegetation and soil was more concentrated near marmot burrows in the unprotected area than in the protected area. In addition, the degrees of spatial heterogeneity of vegetation and soil NO3-N were greater in the unprotected area than in the protected area, where disturbance was more widely distributed. These results indicate that the spatial pattern of disturbance by herbivores affects the spatial heterogeneity of vegetation and soil properties through changes in the disturbance regime. Our findings also suggest that the intensity of disturbance is more important than its size in determining community structure in Mongolian grasslands.
Abstract: An understanding of the relationships between spatial heterogeneity and disturbance regime is important for establishing the mechanisms necessary to maintain biodiversity. Our objective was to
examine how the configuration of disturbance by burrowing rodents (Siberian marmot) affected the
spatial heterogeneity of vegetation and soil nutrient properties. We established three 2500-m2
(50 m 9 50 m) isolated-burrows plots and three 2500-m2 clustered-burrows plots in a Mongolian grassland. Each plot was subdivided into 4-m2 quadrats, and the plant species richness, percent
coverage, and soil nutrient properties in the quadrats were surveyed. Spatial heterogeneity was calculated for vegetation using the mean dissimilarity of species composition among sample quadrats, and geostatistical analysis was used to calculate soil properties. Heterogeneous patches of plants such as Achnatherum splendens and higher nutrient concentrations were found only near the clustered burrows. As a result, spatial heterogeneities of vegetation and soil nutrient properties were higher in the clustered colony than those in the isolated colony. The configuration of disturbance patches affected the
spatial heterogeneity at the landscape level through the spatial pattern of disturbance frequency.
