The structure of coenopopulations and the protection of the rare species <i>Dictamnus gymnostylis</i> Stev. (Rutaceae) in the Samara Region and the Republic of Bashkortostan

Abstract

The conservation of phyto-diversity should be based on original data on the structure and condition of natural populations, plant biology and ecology. The purpose of this study is to identify and compare regional features of the ontogenetic structure and state of coenotic populations of the rare species of the Southern Urals and Middle VolgaDictamnus gymnostylis(in the Samara Region and the Republic of Bashkortostan). In the Republic of Bashkortostan 20 geographical populations of the species are currently identified. In the Samara Region various published sources indicate 712 geographical populations ofD.gymnostylis. The demographic structure, density of coenopopulations and habitat characteristics were studied with the use of traditional research methods in 18 trial plots: 9 in the forest-steppe zone of the Samara Region (Zavolzhye) and 9 in the southern forest-steppe zone in the Republic of Bashkortostan. Populations of the species were recorded in various types of communities: mainly meadow and shrub steppes, at the edges and under the canopy of oak groves. The number of populations in Bashkortostan is different: they number from 70100 to 20005000 or even more. Presumably, the total number of species in the region is from 15 to 20 thousand copies. The total area of all known populations in the Samara Region is estimated by us at 5 hectares. The total number of individuals is approximately 20003000. Most of the coenopopulations ofD.gymnostylisin the region are normal, incomplete. The absence in the spectrum of regenerative stages (seedlings and juvenile), as well as senile plants is typical. The absolute maximum falls on middle-aged generative individuals (24,159,0%). Almost all cenopopulations in the Samara Region are mature, and in Bashkortostan they are young (with a large share of regenerative plants). The recovery index is equal to or close to zero in the Samara Region; seedlings and juvenile plants are often absent here. In cenopopulations of the Republic of Bashkortostan, the recovery index in most cases is opposite to unity, which indicates a good replenishment of the population by young individuals. The aging index throughout the territory is close to or equal to zero (does not exceed 0,05). The state of the examined populations in Bashkortostan does not cause concern for their safety, but in the Samara Region they are vulnerable and require protection.