Coarse woody debris in the forests of the St. Petersburg region, Russia

The significance of coarse woody debris (CWD) for biodiversity, carbon budgeting, and nutrient cycling in forest ecosystems is widely acknowledged, however the lack of comprehensive and representative data hinders the progress in understanding dead wood dynamics in forest landscapes and regions. To assess the regional stores of CWD in the St. Petersburg region of northwestern Russia we combined data collected as part of the forest inventory with measurements in 384 sample plots and results of bulk density sampling of 128 dead trees. Forest inventory data for 7 forests with a total area of 1.1million ha (216 000 forest stands) was processed using a system of ratio estimators derived from measurements in sample plots. The amount of CWD declined with age among young forests and reached the minimum in stands 20-30 yr old. In older forests the amount of CWD increased with age to a level ranging from 30 to 50 m3 ha-1(7.0 to15.3 Mg ha-1) depending on the dominant tree species. The store of CWD in the recently disturbed forests depended on the type of disturbance: the clearcuts stored 24m3ha-1 (9.5 Mg ha-1), while after natural disturbance the store of dead wood reached 145 m3 ha-1 (57 Mg ha-1). The average store of CWD in the seven selected forests ranged from 5.15 to 7.39 Mg ha-1 and mature and older stands contributed the largest proportion of the overall store of CWD.