Bioclimatic Factors and Ecogeographical Patterns in the Distribution of the Rare Species Hedysarum grandiflorum Pall.

This paper discusses the distribution range of the rare species Hedysarum grandiflorum Pall. in European Russia and the gradient of environmental factors within it. Data on 387 species habitats located in 10 regions of the Russian Federation are analyzed. Climatic and soil indices are computed using BioClim raster data on 19 bioclimatic variables, the SoilGrids digital soil mapping system, and the SRTM 1arc_V3 digital elevation model. Annual mean temperatures in H. grandiflorum habitats, as well as mean temperatures of summer and winter months, decrease in a northeasterly direction from Rostov oblast to the Republic of Bashkortostan, while annual precipitation is lower in southern regions of the steppe zone and higher in regions of the forest-steppe zone; in summer, precipitation is higher than in winter. In most cases, marginal species habitats located at the edge of its distribution range feature extreme (either maximum or minimum) values of climatic parameters. In the northeastern part of the H. grandiflorum range, the spread of this species is limited by low temperatures in summer and winter months; from the south, its spread is limited by high summer temperatures and low precipitation in summer. The species is preserved in 19 strict nature reserves, wildlife refuges, natural parks, and national parks and in more than 80 natural monuments. Overall, this is sufficient for its conservation; however, small marginal H. grandiflorum populations require special attention.