Resources and ontogenetic structure of cenopopulations of the genus Viola (Violaceae, Magnoliópsida) in the Right Volga bank of the Saratov region

The results of our studies of resources and the state of coenopopulations of three species from the genus Viola, namely, V. canina L., V. tricolor L., and V. arvensis Murray, conducted in Romanovsky, Balashovsky and Kalininsky districts of the Saratov region in 2016–2021 are presented. Descriptions of the species’ habitats with geographic coordinates are given. The species V. canina, V. tricolor, and V. arvensis have medicinal, honey-providing and decorative value. Populations of the species are confined to meadow-steppe grass-forb phytocenoses. The phytocenoses with the participation of the studied species differ in dominant and codominant species. As a result of our study of the ontogenetic structure of V. canina cenopopulations (CP), it was found that both CPs have unimodal spectra with a maximum on plants of the virginal group. The cenopopulation type according to the «delta-omega» criterion is transitional. The CP of V. tricolor and CP 2 of V. arvensis are characterized by average reproduction efficiency. The CP 1 of V. arvensis has low reproduction efficiency; the value of the recovery index of its age spectrum is less than one. Regeneration processes in CP 1 of V. arvensis are difficult and unstable. Our analysis of the age structure of CPs using the delta-omega classification has shown that the CP of V. tricolor and CP 1 of V. arvensis are maturing, while CP 2 of V. arvensis is transitional by its position in the delta-omega coordinate system. The yield of the species depended on the degree of moisture in the year. On average, over 5 years of the study, the yield of V. arvensis, V. canina and V. tricolor was 21.51, 19.09 and 27.2 t/ha, respectively. In order to restore the populations, the exploitation of thickets of all species of the genus Viola should be carried out once every three years on 1/3 of the area of thickets.