Asiya Zagidullina Preliminary estimation of parameters of big disturbances in pristine forests of northern dvina-mesen landscape province

Saint Petersburg Forest Research Institute, Saint-Petersburg Russia

e-mail: azagidullina@gmail.com

In the north-eastern region of European Russia, commercial harvesting executes usually by extensive clearcuts (one~50 ha). The result of their contiguity are a many kilometers of clearcuts and secondary young aspen and birch stands. It is evident that in such areas that have been so strongly affected by forestry a dramatic simplification of forest structure, degradation of biodiversity and ecosystem services take place. Preservation and emulation of natural heterogeneity of forest ecosystems is important condition for biodiversity and ecosystem services.

Natural mosaic of intact forest is a result as well of site conditions diversity, as disturbance pattern. Disturbance shape forest structures to create their natural range of variability. It follows that an adequate forestry operations should rely on the quantification of natural disturbance
dynamics, taking into consideration adequate spatial scale and time perspective. However, the development of adequate dynamics emulation model for forestry is prevented by largely lacking scientifically based data. The estimation of the intensity and amplitude of past disturbances can be obtained within landscapes covered by predominately intact forests. This information is important to advice forestry and conservation planning on the historically justified stand age structures and maximum levels of landscape transformations.

The preliminary estimation of parameters of big disturbances was obtained for some pristine boreal forest areas of Nortern Dvina and Verhnyaa Vashka watersheds using special statistics , forest inventory information et al. It was shown that frequency and period of big disturbances have not been constant for the last 300-400 year, but characterized by some change points.