Ontogenetic structure of natural populations of rare species of the genus <i>Hedysarum</i> L. in the Volga and Ural regions

The paper presents the results of studying the population structure of rare species Hedysarum argyrophyllum Ledeb., H. cretaceum Fisch., H. gmelinii Ledeb., H. grandiflorum Pall. and H. razoumowianum Fisch. et Helm in the Volga and Ural regions. The study area covers Volgograd, Samara, Saratov, the southern part of the Ulyanovsk and the western part of the Orenburg Regions and the Republic of Bashkortostan. 10 coenopopulations of Hedysarum argyrophyllum, 18 coenopopulations of H. cretaceum, 410 coenopopulations of H. gmelinii, 1800 coenopopulations of H. grandiflorum, 1400 coenopopulations of H. razoumowianum were examined. The work was carried out in 20002021 using population-ontogenetic methods. The studied representatives are rare, their population characteristics are subject to changes under the influence of anthropogenic factors. Species have sufficient potential for self-recovery of natural populations. The ontogenetic spectra of populations are similar in their parameters; the dominant fraction of individuals is the generative one. Common features are the fluctuation type of population dynamics and ontogenetic structure of model representatives, relatively low demographic characteristics, weak ability for self-maintenance and self-recovery of populations under anthropogenic load. Anthropogenic load leads to a decrease in the number of individuals, their density and the gradual aging of populations.