Local-scale disturbance by Siberian marmots has little influence on regional plant richness in a Mongolian grassland

Our objective was to examine the relative importance of local-scale disturbance by Siberian marmots in increasing regional (landscape-wide) plant richness. We used an additive diversity partitioning framework and quantified species richness patterns of grassland plant communities affected by marmot disturbance across different spatial scales: within and among on- and off-marmot-mound subsites, among sites, and among landscape units (corresponding to alpha and three levels of beta richness). Values of beta richness among subsites and beta richness among landscape units were similar to those expected by chance. This suggests that plant species are randomly distributed among subsites and among landscape units, despite the prediction based on previous studies that local-scale disturbance by Siberian marmots and its interactive effects with landscape contexts disproportionately influence spatial patterns of plant species. Of the spatial components of regional richness, only the beta richness among sites was significantly different from the expected value, probably reflecting the differential spatial pattern of disturbance by marmots at a site scale. The beta richness among landscape units contributed the most to regional richness, whereas beta richness among subsites and among sites contributed less. Thus, our results suggest that local-scale disturbance by Siberian marmots has little influence on regional plant richness in a Mongolian grassland.