Structural characteristics of the cenopopulations of <i>Atraphaxis frutescens</i> (L.) C. Koch (Polygonaceae) in the territory of botanically valuable natural complexes of the Samara region

Abstract

The reduction in the area occupied by the petrophytic steppes of the European part of Russia, including in the Samara region, due to alienation under agricultural land and high anthropogenic pressure, led to a decrease in the total number of plant species in the steppe and mountain-steppe flora. The current state of the species of these phytocenotic groups in the regions also depends on the ecological and biological characteristics of the representatives.The object of study is Atraphaxis frutescens (L.) C. Koch (Polygonaceae). On the territory of the Samara Pre-Volga and Trans-Volga regions, the structure and current state of 21 coenopopulations were studied. In the course of the work, traditional population-ontogenetic techniques and recommendations were used. The heterogeneity of the ontogenetic spectra was revealed, the regional basic ontogenetic spectrum of Atraphaxis frutescens cenopopulations, the main demographic parameters (including the age-effectiveness criterion L. A. Zhivotovsky was used to determine the type of cenopopulations) were determined. Based on data on the population structure, the protection efficiency of Atraphaxis frutescens as part of nature monuments of regional significance is analyzed in comparison with other valuable natural complexes that do not have conservation status. It has been established that with low and medium load on the vegetation cover, natural monuments are able to ensure the preservation of the species in the region. Significant differences in the ontogenetic spectra of coenopopulations in and beyond protected areas were not noted. In the coenopopulations of A. frutescens in protected areas, there is a slight increase in the number of old generative plants (31.4 %) and a decrease in the proportion of subsenile individuals (7.1 %). The average area of the geographical population on the territory of protected natural complexes is 850 m2, the average number is 2011.7 generative individuals; outside the protected areas, the population area is 275 m2 and the number of individuals is 642.4.Thus, natural monuments contribute to better conservation of the area of the geographical population, ensure the stability of the number of individuals and spatial distribution, including the formation of large aggregations of individuals and a more even distribution of recorded aggregations.