Dynamics of ecosystems of fresh subor (pine woods on sandy soils) in the central part of the Volga Upland
The results of our study of the dynamics of fresh subor (B2), a widespread type of forest ecosystems in the central part of the Volga Upland, are presented. The study was carried out on the territory of the Upper Sura section of the Privolzhskaya Forest-Steppe Nature Reserve. The course of the process was studied in the age series identified in homogeneous forest conditions based on the principles of dynamic classification of forest types. As a result of processing the forest inventory data, the average values of forest stand taxation indicators were obtained for each age class. At the same time, analysis of changes in all the components of plantations was carried out. On its basis, the age series was divided into separate periods and phases. Trends in the share of participation of each forest-forming species in the forest stand at different age stages were described by nonlinear equations. The study showed the resulting age series to be a series of transformation of forest communities. Violation of the course of the forest formation process led to a large-scale change of indigenous plantations to derivative ones. After the beginning of the use of clear-cutting fellings, the area occupied by deciduous trees (primarily birch) has been constantly growing. The large-scale use of intermediate-use, sanitary and voluntary-selective cuttings resulted in the formation of sparse pine stands. At the same time, transformation of the lower tiers of communities took place. These factors caused deterioration of the conditions for natural pine regeneration (Pinus sylvestris L.). As a result, by now the possibility of forming pine forest stands through natural regeneration is almost completely excluded.