STRUCTURE OF LINDEN COENOSES ON THE NORTH-EASTERN BORDER OF THE BROADLEAVED-CONIFEROUS FORESTS AREA IN THE KIROV REGION

On the territory of 8 planning quarters of the state natural reserve “Bushkovsky forest”, located on the north-eastern border of hemiboreal broadleaved-coniferous forests, a structural description of four groups of plantations was performed: linden with spruce and birch, spruce-birch-linden, elm-linden and birch-linden stands. The multi-species composition was made up of small-leaved linden, spruce, pine, fir, elm, Norway maple, ash, birch, aspen and grey alder. Linden was found to have a high ontogenesis polyvariance under conditions of low insolation and high humidity of the environment. The following life forms were described: single-trunk, coppice-forming, clump-forming, multi-trunk trees and facultative trailing shrub. The categories of tree vitality were defined and indices of forest stand condition were established. The average index value was found to be 0.9: individuals were described as “healthy”, although with values close to the lower limit. Most of the stands were two-storey with promising specimens of broadleaved species, such as maple and elm, gradually entering the first storey. Natural regrowth was assessed in different communities. The most resource-intensive in terms of development was the elm and maple undergrowth. The vitality index of the elm undergrowth never went lower than 91%; all individuals were sustainable and evenly distributed. In 71% of the coenoses, the undergrowth of this category had medium density values. Maple undergrowth was sustainable and healthy, with a vitality index surpassing 87%. It was evenly distributed in 62% of stands, 67% of coenoses had average density of its regrowth. Regarding spruce, the undergrowth was found to be weakened in 86% of cases, the minimal vitality index was 33%. Only in 10% of all stands has this species reached medium undergrowth density. The linden undergrowth was determined to be the most unreliable in terms of development: 71% of individuals had questionable vitality, while 29% were wilting. Only in 10% of the coenoses, linden trees grow in quantities slightly exceeding two thousand per hectare; in other cases, it was defined as scarce, numbering up to one and a half thousand. The data obtained can be used to analyse the dynamics of coenoses development and their transformations monitoring near the borders of their natural distribution area.