Long-Term Effects of Silvicultural Practices on Groundwater Quality in Boreal Forest Environment

Logging disturbances in boreal forest watersheds alter strongly a forest ecosystem resulting in different light, moisture and temperature conditions (Kubin and Kemppainen, 1991, 1994) and new distribution of forest biomass (Kubin, 1977). The effects on watercourses depend on the regeneration method used. Clear-cutting and site preparation cause the greatest changes in site conditions and to the environment. The oldest research carried out within the boreal coniferous forest zone on the leaching of nutrients into watercourses was conducted in Sweden in the early 1970s (Tamm et al., 1974; Wiklander, 1974). In Finland, the effect of clear-cutting and site preparation on the quality of surface runoff has been monitored since 1974 (Kubin, 1995) and on the leaching of nutrients from entire catchment areas since 1983 (Ahtiainen, 1988). The leaching of nutrients into the groundwater after clear cutting and waste wood harvesting has been monitored since 1986 (Kubin, 1998).