forest communities
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The allelopathic regime of the phytogenic field of model middle-aged trees of seven forest formations in the zone of humid subtropics of the Sochi Black Sea region was evaluated with an admissible range of stages of recreational digression. The method of biotesting of water extracts from forest litter, soil and roots was used to determine the spatial gradient of allelopathic activity of the phytogenic field environ-ment. The share of participation of the allelopathic factor in the formation of the phytogenic field at certain stages of recreational digression was established. It was determined that the value of allelopathic intensity of the phytogenic field, depending on the stage of recreational digression, field zones and edifi-cator species, can characterize the degree of resistance to the introduction of new species, recreational resistance and community stability.

A detailed description of the forests of the northern and southern macroslopes of western part of the West Sayan Ridge has been performed and differences in their forest vegetation have been analyzed. Along the West Sayan Ridge watershed, the important botanical and geographical boundary of the Altai-Sayan Mountains occurs. Its northern macroslope belongs to the humid bioclimatic sector; bioclimatic conditions throughout the southern macroslope vary in its different parts: the central and eastern parts are resided in the semihumid sector, while the western one is settled in the «rain shadow», where vegetation is similar to the semiarid sector one. The West Sayan background vegetation type is forest. The work is based on 120 complete geobotanical relevés made by the authors in 2019 using standard methods on test plots of 20 × 20 m. These plots had been uniformly distributed on a 300-kilometer transect crossing the northern and southern macroslopes of West Sayan’s western part. After all, 9 basic units of forest communities have been revealed, 6 of them are found to be altitudinal zone forests. These plant community positions in ecological-phytocenotic and floristic classification hierarchy have been ascertained. The altitudinal allocation and areas of altitudinal zone forests have been characterized and analyzed; the scheme of altitudinal zonation has been specified; the pictures in the text illustrate those results. In West Sayan’s western part, the northern and southern macroslopes are shown to have different altitudinal zone boundary marks and a different set of forest communities: six types of forests follow each other from north to south throughout 300 km. The significant hierarchical level of syntaxonomic differences of altitudinal zone forests on northern and southern macroslopes supports the presence of a bioclimatic barrier. In ecological-phytocenotic classification hierarchy these differences are reflected by the rank of classes of formations (deciduous, dark coniferous, and light coniferous forests substitute each other); in floristic classification hierarchy – the rank of classes (the forests of Brachypodio–Betuletea, Asaro–Abitetea, Vaccinio–Piceetea, and Rhytidio–Laricetea substitute each other from north to south).

This article presents the results of the population studies of rare protected species Orchis punctulata (Orchidaceae). Based on analysis of local floras in eastern and southeastern Crimea and personal observations, we identified the three most numerous populations of O. punctulata: two in the steppe (on the Tepe-Oba mountain ridge) and one in forest communities (on the Kiziltash mountain ridge). The ontogenetic, demographic, and vitality structures of the populations were studied. We also assessed the life strategies of the species in different habitats. The populations in steppe communities were characterized by high number and density parameters. O. punctulate often formed large clusters and was dominated here. A small number and low density characterized the population in the forest community; the distribution of individuals within the population was scattered. The age spectra were also different. The populations in steppe communities had a left-sided spectrum with a maximum in immature individuals, while in forest communities, it had a bimodal spectrum with maximums in generative (with a predominance of mature and old generative) and immature individuals. Specimens from forest communities were more extensive than those of steppe communities, they had longer leaves and inflorescences, and their inflorescences had a more significant number of flowers. As a result, the population in the forest community had a higher vitality index. It included individuals of the highest and middle class of vitality. The populations in the steppe community consisted of all classes of vitality or only of middle and lower classes. Thus, optimal environmental conditions for the growth of species are in forests. At the same time, a low level of regeneration and competition from other plants hinder its wide distribution. As a result, the species exserts as a phytocenotic patient (S-strategy). In steppe communities, the species is characterized by a mixed patient-explerant-violant strategy (SRC strategy).

A new view of the position of oak in the successional processes of oak forests of the forest-steppe is presented, based on the population strategy of this species and the peculiarities of the conditions for the development of pregenerative stages. The preferable conditions for natural regeneration of oak in forest communities and their relationship with the dynamics of deciduous communities of the forest-steppe are analyzed.