Köster, K., Ilisson, T., Tukia, H., Jõgiste, K. and Möls, T. 2009. Early Effects after Forest Disturbance in Decomposition of Trees in two Windthrown Areasin East Estonia.   Baltic Forestry, 15 (2): 143-150

Coarse woody debris (CWD), represented by logs and snags (>10 cm in diameter and >1.3 m in length/height), were sampled from two Eastern Estonian windthrow events (Tudu and Halliku), where storm occurred in the summers of 2001 and 2002. CWD was sampled to identify factors that affect early wood decomposition and changes in wood density. Tree species sampled included Norway spruce (Picea abies (L.) Karst.) and birch (Betula spp.). In total 944 subsamples were taken from sample trees on permanent sample plots located in totally damaged (TD), partly damaged (PD) and control areas with no damage (ND). Wood densities after the initial period of decomposition were different, depending on tree species, log or snag position (downed, leaning, standing), damage severity (TD area or PD area) and subsample position on sample disks (inner or outer layer of the disk). Most of the CWD was in the second class of decomposition (color of wood had changed and knife enters 1–2 cm into the wood), with mean CWD densities of 0.483 g cm³ to 0.571 g cm³ for spruce and 0.581 g cm³to 0.778 g cm³ for birch. Annual decomposition rates ranged from 0.78% to 5.57% for spruce and 2.19% to 7.42% for birch. Downed logs had lower density than leaning logs and standing snags. Snags/logs from TD area had a lower density than snags/logs from PD areas, thus they were decomposing faster.

Key words: dead wood, wood density, decay affecting factors, mixed models, windthrow