Reindeer grazing is often considered as a threat against the biodiversity in arctic and alpine plant communities in the Nordic countries. However, there is almost no data on the effect of reindeer grazing on species richness in arctic and alpine regions. If we should understand how reindeer grazing influence species richness, it is important to distinguish between different spatial scales. Species richness on small plots is probably determined by local processes such as competition intensity, germination rate of seeds or nutrient availability, while species richness at larger spatial scales is probably determined by the heterogeneity and the size of the species pool. As different processes influence species richness at different spatial scales, the effect of reindeer grazing on species richness in small and large areas does not have to be similar. My hypotheses is that reindeer grazing sometimes increase and sometimes decrease species richness on small spatial scales, while it consistently increase species richness at larger spatial scales.