Current Status of Populations of Delphinium L. (Ranunculaceae, Magnoliópsida) Species in the Lower-Volga Region and Adjacent Territories

Abstract

30 populations of six Delphinium L. taxa (D. pubiflorum, D. litwinowii, D. duhmbergii, D. subcuneatum, D. sergii, and D. puniceum) were studied in the Ulyanovsk, Saratov, Samara, Volgograd, Astrakhan, Voronezh, Rostov, Penza and Tambov regions as well as in the Republics of Kalmykia and Mordovia in order to reveal features of their ontogenetic and vitality structures. Throughout the years of observation, the vitality of the populations of all studied species varied within rather wide ranges; individuals of medium or low vitality predominated in most populations. Also, the index of vitality of coenopopulation (IVC) varied in the populations of the same species. In over 50% of the populations, IVC was below 1. The indices of size plasticity of the species presented were rather low. The ratio of ontogenetic groups also varied substantially both among the species and among the populations of the same species. However, in most populations, generative individuals predominated; less often pre-generative or post-generative ones prevailed. According to the delta-omega criterion, most populations are mature with the only exception of D. puniceum populations being maturing at the time of observation. According to the recovery index, only few populations were capable of natural self-sustenance. Based on the results of our monitoring, it was concluded that both the number and abundance of populations of the taxa of the genus in the studied area have been dramatically decreasing in recent decades, all of them are in critical condition. This requires rigorous measures to preserve and restore the population of Delphinium species in the studied area. Without additional measures, most of the populations are doomed and can be eliminated in the near future.