LAUSR

BackgroundsIn arid grasslands, wells are subject to heavy trampling and grazing pressure, which can increase vulnerability to local land degradation. To investigate trampling and grazing, we surveyed plant communities at three well sites in the desert steppe of Mongolia, using 1600-m line transects from the wells. The sites (Bshrub, Sshrub, and shrubL) differed by concomitant shrub type (big shrub, small shrub, and shrub-limited) and livestock pressure (light, medium, and heavy). A plant classification scheme based on edibility and morphology (rosette or creeping type) was used to separate grazing and trampling effects on plant communities.ResultsEdible plants were dominant at all sites but a fraction of grazing- and trampling-tolerant plants increased in the order Bshrub, Sshrub, and shrubL, following livestock pressure. Clear transition zones from inedible to edible plant groups were recognized but at different locations and ranges among the sites. Trampling-tolerant plants explained 90% of inedible plants at Sshrub with camels and horses, but grazing-tolerant plants prevailed (60%) at shrubL with the largest livestock number. Plant coverage increased significantly along the transects at Bshrub and Sshrub but showed no meaningful change at shrubL. Herbaceous plant biomass showed significant positive and negative trends at Bshrub and shrubL, respectively.ConclusionsBoth grazing and trampling can produce larger fractions of inedible plants; in this, camel and horses can have considerable effects on desert-steppe plant communities through trampling.