Effects of forest harvesting technologies on the hydrology of compaction-prone soils

Stockholm

2024

972

Bandaufführung

40005283

Forest soils usually show high infiltration rates and thus, compared to other landuses, a quick recharge of the soil water storage, a reduced peak flow and a prolonged base flow.Soil structure is crucial for both, the infiltration rate as well as the plant available soil water storage capacity. Different mechanical stresses caused by different harvesting technologies as well as biological remediation measures have, however, a short- and long-term impact on the infiltration rate and the water storage capacity of forest soils. Analysing the effects of fully and highly mechanized timber harvesting practices on the hydrology of compaction prone soilsis one of the objectives of a project, funded in the framework of the Austrian Waldfonds. The project focusses, in general, on how to secure the sustainability of forest soil functions in hardwood forests. In course of this project, water infiltration, surface runoff, water storage as well as water availability are being investigated on different scales, before and after the timber harvesting intervention using two harvester-forwarder (HF) configurations‘(w/wo bogie tracks) or cable-yarding with motor-manual-felling (CCM)‘. This includes rainfall simulation experiments and continuous as well as discontinuous soil moisture measurements. Preliminary results, considering surface runoff, indicate a strong change in rainfall-runoff behaviour following timber harvesting operations. Rainfall events on recent, highly compacted skidtrails suggest a significant increase surface runoff. We further observe higher soil water content as a result of the lack of vegetation activity and the changed soil structure after harvesting. By linking the direct hydrological effects of timber harvesting with other affected soil functions, a holistic perspective is created, which will lead to recommendations for soil-conserving timber harvesting on soils at risk of compaction.