Comparative study of relationships between richness of species, genera and families of vascular plants on climate and topography in the Middle Volga region

The influence of climate features, topography and solar radiation on richness of different taxonomic ranks of vascular plants is studied. A result unknown earlier in the literature is that taxonomic richness exhibit not only different sensitivity to the same environmental factors, but can also have opposite links to them. For example, as the variability of precipitation increases, richness of species decreases, that of genera increases, and that of families does not change; species richness is positively related to slope insolation, while richness of genera is negatively. Such facts indicate the presence of distinguishable adaptation mechanisms for different taxonomic ranks including inverse reactions in response to environmental changes. Incoherent responses of taxonomic levels may contribute to the conservation of plant community diversity in a changing climate.