Half-Century Dynamics of Primary and Secondary Tree Stands in the Veps Forest Natural Reserve

In view of the ongoing discussions of forestry intensification, declining areas of natural forests, and the resulting decrease in biological diversity, it has become increasingly important to understand the mechanisms of recovery of disturbed natural biogeocenoses. The purpose of this study is to investigate features of the recovery of middle taiga forest communities after a clear-cutting of primary forest stands in comparison with the natural dynamics of primary forest communities on control plots. The study addressed the following tasks: (1) determine the timber stock volume for both primary and secondary forest stands (including total values, distribution by forest-forming species, and changes over the observation period); (2) identify the features of the distribution of the number of trees and the timber stock by diameter classes; (3) evaluate the productivity indicators (annual growth increment) of primary and secondary forest stands; and (4) describe the dynamics of tree species composition in secondary forests. This was achieved thanks to long-term observations conducted on permanent sample plots. Natural disturbances caused by strong winds contributed to significant fluctuations in the number of trees and the timber stock in primary stands. In many cases, the timber stock of forest stands that recovered after clear-cutting became comparable to that of primary stands, when they reached the age of 50 years. During certain periods, some primary and secondary stands exhibited similarities in the distribution of timber stock and the number of trees by diameter classes. This similarity was caused by external disturbances of similar intensity (clear-cutting or severe windfall). The productivity of the majority of secondary stands was significantly higher than that of primary forest communities. Deciduous species were predominant in most first-generation secondary stands, though the presence of coniferous species was also significant. The findings of this study can be used to address issues in the forest management practices, the development of optimal scenarios for forest keeping in various stands, and the preservation and/or restoration of the environment-forming functions of the managed forests.