Ratio and factors of continuity and discreteness of vegetation cover on the example of southern taiga landscapes of the Valdai hills

The article considers the ratio of continuity and discreteness of vegetation cover in the southern taiga landscapes of the South of Valdai hills on the example of a 1.72 km long transect (87 points with a description step of 20 m) located in the core of the Central forest state natural biosphere reserve (Tver region, Russia). On the territory of the study, quite large areas of forests that have not experienced anthropogenic impact and reproduce the course of natural ecosystem processes have been preserved. Descriptions of forest communities are grouped based on ecological and phytocenotic classification, and syntaxones are analyzed using diagnostic species (species with IndVal > 25 %). Morphometric parameters of the relief (relative height and steepness of slopes), relative humidity of the upper soil horizon, and granulometric composition of the soil were evaluated as differentiating factors from the ecotope conditions. The results of cluster analysis of the composition of selected syntaxons contributed to the recognition of discrete boundaries between individual classes. In general, on transect in question, discrete boundaries (61%) dominated, mainly associated with sharp changes in landforms and, consequently, the humidity of the upper soil horizon. Continuous boundaries were observed at insignificant height gradients for transitional successional states of communities. It ocuured in the process of overgrowth of dumps, as well as due to changes in the capacity and nature of organoaccumulation of the upper part of the soil profile and the granulometric composition of its middle and lower parts. The analysis showed that for swampy poorly drained spruce forests of the southern taiga landscapes of the South of Valdai hills, the relief and granulometric composition of soils can be attributed to the main differentiating factors of ground tiers of vegetation cover.