Population Structure of Pyrola chlorantha (Family Ericaceae) at the Southern Range Margin (Samara Region, Russia)

The population structure of endangered species is one of the main criteria for assessing their state in their habitats. Representatives of the Ericaceae family are sensitive to environmental changes, including anthropogenic pressure; thus, they are considered the indicator species in assessing phytocenose stability. The population structure and density of the threatened species green-flowered wintergreen, Pyrola chlorantha Sw., have been described at the southern range margin (south-east of the European part of Russia, Samara Region). The observations were performed here in 2006–2021, and the main parameters of the age and spatial structure of P. chlorantha populations were revealed for the first time. Green-flowered wintergreen populations were studied at monitoring study sites and at temporarily established study plots. A bush part (ramet) was set as a counting unit. In total, 27 sub-populations were surveyed, with 1520 individuals registered. The age structure of populations was characterized using common demographic indicators: the recovery index and the population age index. The age structure of the population was associated with the efficiency of both vegetative and seed reproduction. Generally, the share of pre-generative individuals was 32.3%, generative, 66.9%, and senile, 1.8%. The studied populations were stable due to low anthropogenic impact at the growth sites.