Изменение видового разнообразия фитоценозов после сплошных рубок

Cuttings are one of the major disturbances of forest ecosystems. There are very few works studying the protection and changes of biodiversity at cutting. With the purpose of studying changes in floristic diversity, we carried out in 2007 a model clear-cutting in the linden pine forest of the Sorvizhi Forestry, Kirov Region. At the first site, the cutting was conducted without leaving any trees and undergrowth followed by artificial pine stands planting. At the second site, the cutting was conducted without leaving any trees but with undergrowth preservation. The third site was cut leaving separate deciduous trees (birch), pine, and young spruce trees. At each of the cutting sites we observed increased species richness, as compared to the control site, due to the weed and ruderal vegetation. But floristic diversity changes differently at model sites, logways, furrows and between them. The highest index of floristic similarity (Jaccard index 0.68) was observed at the control site and skidding trail with separate deciduous trees left. The minimal similarity to the control site was observed at the cutting site with artificial stands (Jaccard index 0.33-0.38). Having analyzed the species structure, we found that skidding trails with and without any trees left have similar typical forest flora, while skidding trails without any trees left and those with artificial stands have similar introduced flora that appeared after cutting. High similarity indices (0.52-0.57) were identified during pairwise comparison of species composition in furrows, between them and on logways where artificial stands were planted. Artificial stands planting caused the most considerable damage of ground and soil cover throughout the entire site. Therefore, similar floristic composition is formed on different site elements (logways, furrows and places between them). Thus, species diversity of vascular plants in cutting areas of linden pine forests increased due to introduction of new meadow and weed flora species. Besides, the more considerable the environmental changes in the cutting area, the higher the proportion of ruderal vegetation in the community. Floristic diversity, typical for the forest ecosystems under consideration, tended to be preserved at the sites with separate forest elements left.