Variation and ecological characteristics of coarse woody debris in Lahemaa and Karula National Parks, Estonia

Abstract

The coarse woody debris (CWD) was inventoried in two boreal Estonian conifer-dominated forest landscapes/national parks, Lahemaa and Karula, with different forestry history and management intensity. The inventoried areas in both national parks consisted of a core with a strict nature reserve (unmanaged) and the surrounding protected special and restricted management zones (management activities in the past). Stands with no records of silvicultural activity since the 1920s (unmanaged) were compared with traditionally harvested stands. CWD was measured as standing dead trees, logs and snags >10 cm in diameter and >1.3 m in length in 304 circular plots (Lahemaa 134 plots, Karula 170 plots; r=11.28 m, 400 m²). The volumes of CWD varied considerably between individual stands. The mean volume of CWD (standing and down combined) in Lahemaa was 48.5 m³ ha⁻¹, ranging from 0.6 to 148.6 m³ ha⁻¹. The mean volume of CWD in Karula was 27.6 m³ ha⁻¹, ranging from 0.2 to 193.7 m³ ha⁻¹ from stand to stand. On average, 19.5 m³ ha⁻¹ (40.2%) of CWD in Lahemaa was standing dead wood and 29.1 m³ ha⁻¹ (59.8%) down dead wood. In Karula standing dead wood formed 15.2 m³ ha⁻¹ (55.7%) and down dead wood 12.2 m³ ha⁻¹ (44.3%). Variation in CWD volumes was clearly dependent on the management history of the stands. Stands with a documented history of management (e.g. cuttings and thinnings) had significantly lower CWD volume than natural stands found mainly in strict nature reserves. Stands selectively logged a long time ago (more than approximately 60 years) did not differ considerably from natural stands in the amount of CWD. The amount of CWD in managed stands (Lahemaa 14.1 m³ ha⁻¹ and Karula 10.6 m³ ha⁻¹) was comparable to other studies in silviculturally managed forests in the boreal zone. The study shows that CWD amounts in Estonian conditions are similar to previous studies in this region.

Keywords:

• Boreal forest
• coarse woody debris
• management history
• natural and selectively managed stands
• nature conservation

Acknowledgments

Kaisu Aapala is thanked for improving the manuscript and its scientific language. This study was supported by co-operation programme “Forest restoration in Estonian reserves” between Finnish and Estonian Environmental Ministries in 1999–2001 and by the Estonian Science Foundation (grants no. 4980 and 6008).