Results/Conclusions While previous research shows that Dipodomys spp. at the Portal LTREB affect plant species composition, SAR slopes among treatments were not significantly different. Linear models of winter and summer annual species richness were best fit using only area and time, without the inclusion of treatment. Rather, other factors may be more important in determining the shape of plant SARs at the Portal site such as interannual variation in the environment and on-site habitat variation. Plant species composition varies significantly by treatment, suggesting that Dipodomys spp. influence the identity of plant species on patches in which they are present, but they do not appear to influence the number of plant species found within a site. This suggests that seed dispersal is high enough that the plant community can respond to changing predation pressure without a significant loss in the total number of species. Since predators are often disproportionately affected by habitat fragmentation, empirical work in open systems is essential to understanding community diversity patterns at a multi-trophic level and addressing conservation goals in rapidly changing landscapes.