Sixteen stands of dry alvar grassland in Estonia, representing the samevegetation type in similar ecological conditions, were investigated in order tostudy a considerable variation in species richness within and between stands.Alpha diversity and within stand beta diversity (spatial turnover of species)were negatively correlated. The distribution of species frequencies across thestands was clearly U-shaped, which made it possible to distinguish core species(occurring in more than 75% of stands) and satellite species (occurringin less than 25% of stands), including most of species from the totalspecies pool. Species richness showed significant nestedness – scarcespecies occurred more often in species-richer stands. Both mean alpha diversityand the size of the community species pool were significantly positivelycorrelated with the number of core species found in a stand, while betadiversity was correlated with the number of satellite species. Speciesfrequencies across the stands were negatively correlated with species averageheight, seed mass and requirement for soil fertility. These differences werealso evident in comparison of core and satellite species by 14 PhylogeneticallyIndependent Contrasts. Also, satellite species had a significantly highervariation in average height and seed size than core species. It was concludedthat the community matrix is made up of core species, which are better suitedtodry oligotrophic conditions. Beta diversity is largely caused by satellitespecies, the optimum conditions of which may be found in other neighbouringcommunities. Further studies have to show whether stands with higher richnessand thus a higher number of satellite species are those which were or aresurrounded by communities which may potentially act as sources of satellitespecies.