Dependence of main flora taxa number of flora on climatic indicators in the central Volga basin

Background. The regularities of the relationship between the number of families, genera, and species with climate at the regional level have been insufficiently studied and require further research. Materials and methods. We used initial data on flora in 28 plots with an area of 400 km2 each in the central part of the Volga basin. Taxonomic parameters were determined by the algorithms of the FD SUR database. The required combination of lists of vascular plant species and the construction of family and generic spectra were carried out. We used long-term averages of monthly precipitation and temperatures, temperatures and total precipitation by season, as well as the values of 19 bioclimatic variables. Results. Negative relationships with temperatures and positive relationships with precipitation during the warm period were revealed, when a statistically significant effect on diversity was revealed. The closest relationship with climate is for the number of families, the least for the number of species. Changes in temperature and precipitation in four geographical directions are estimated. The northern cold-humid and southeastern thermo-arid trends are most pronounced. The northern one is characterized by a decrease in temperature by 0,34°С and an increase in precipitation by 17 mm for every 100 km; southeastern - by an increase in temperature by 0,27°С and a decrease in precipitation by 15 mm. Conclusions. The cold-humid trend provides the most favorable conditions for increasing diversity in the region. It is characterized by the fact that for every 100 km the number of species increases by 36, genera – by 17, families – by 6. This indicates the ecological plasticity of diversity with different responses to climate variations for different taxonomic levels, which generally contributes to diversity conservation.