Age and vitality structure of natural and reintroduced populations of Calophaca wolgarica

The results of the analysis of ontogenetic and vitality structure of Сalophaca wolgarica (L. fil.) DC. – a rare relict plant species, a paleoendemic to South-Eastern Europe – are presented. As part of the monitoring of the condition of this species’ populations, 21 natural populations on the territories of Volgograd and Rostov regions, the Republic of Kalmykia, Stavropol Krai, as well as five reintroduced populations on the territory of Saratov region were studied in 2024. The ontogenetic conditions of the plants were determined. Based on age group ratio, the population types were stated by L. A. Zhivotovsky system. 14 morphological parameters of the plants were measured. The vitality structure of the individuals and the populations was assessed using IVC and Q indexes. Mature generative plants prevailed in most natural populations of C. wolgarica. Predominance of the other age groups in a few populations was related to impact of the external factors. All possible types of the ontogenetic structure were observed, except a transitional one. All the reintroduced populations were young, most natural ones were mature. Considering the large vitality values, it is stated that the large majority of the natural populations and all the reintroduced populations are prosperous, only two populations are evaluated as depressive. In some prosperous mature populations there is no self-reproduction, which can lead potentially to death of those populations in the following years. It is shown that, among the natural populations, those placed in the north-west of the species area are in the best condition, and a few south-eastern populations are in the worst condition. The negative influence of fire and overgrazing on some populations was noted.