FOREST STANDS’ AND PEAT DEPOSITS STRUCTURE IN EUTROPHIC BOGS OF THE ZAPADNODVINSKY DISTRICT IN TVER REGION

A comparative assessment of the silvicultural characteristics of tree stands, peat deposits and the dynamics of the virgin lowland eutrophic black alder bogs development has not been previously carried out, which determined the choice of the purpose of this study. In the forests of the Zapadnodvinsk district of the Tver region. Lowland rain-groundwater black alder bogs were selected for analysis, one of which has variable circulating water supply, while the other was stagnant. Studied within the framework of the study were the age, dynamic, and renewal characteristics, the condition of trees and forest stands, indicators of tree mortality, and the infestation of forest stands with wood-decaying fungi. A comparative assessment of the peats characteristics was carried out regarding the pH of the salt extract, the ash content, the bulk mass (density) and the carbon content in soil horizons. Eutrophic black alder swamps have a large presence of Norway spruce in different proportions and an insignificant presence of downy birch. When edaphic conditions change, this feature determines the possibility of changing the alder formation to the spruce one. Using the exponential approximation, high values of the relationship between the presence of spruce in age generations of age series were shown for the biogeocenosis with circulating water – R₂ = 0.696. Under eutrophic growth conditions, downy birch can reach an age of 150 years. The soils of black alder forests are considered lowland peats, are high in ash content and composed of thick woody peats up to 2–4 m with a high degree of decomposition throughout the deposit (40–55%). The carbon content in peats with a fairly high ash content is different: 34–46 and 46–51% respectively in black alder forests with stagnant and flowing water. A comparative assessment of two black alder eutrophic bogs shows that Norway spruce occupies a subordinate position in relation to black alder. Under conditions of flow-through moisture, the productivity of black alder is 1-2 quality classes higher than that of European spruce. In more stagnant moisture conditions, Norway spruce actively replaces black alder both in the tree layer and in the undergrowth. In terms of the structure of age series, successional dynamics and tree mortality, indigenous eutrophic black alder bogs of different ages maintain the balance of biomass as climax stable forest communities.