Coupled forest growth-hydrology modelling as an instrument for the assessment of effects of forest management on hydrology in forested catchments

摘要

The type and intensity of forest management directly influences regionalcatchment hydrology. Future forest management must optimise the effects ofits practices to achieve sustainable management. With scenario analysis offorestry practices, the effects of different forest utilisation strategies onthe hydrology of forested catchments can be temporally and spatiallyquantified.The approach adopted in this study necessitated the development of aninteractive system for the spatially distributed modelling of hydrology inrelation to forest stand development. Consequently, a forest growth model wasused to simulate stand development assuming various forest managementactivities. Selected simulated forest growth parameters were entered into thehydrological model to simulate water fluxes under different conditions offorest structure. The approach enables the spatially differentiatedquantification of changes in the water regime (e.g. increasedevapotranspiration).The results of hydrological simulations in the study area, the Oker catchment(northern Harz Mountains), show that forests contribute to the protection ofwater systems because they have a balancing effect on the hydrologicalregime. As scenario simulations also suggest, however, forestry practices canalso lead to substantial changes in water budgets of forested catchments. Thepreservation of the hydrological services of forests requires a sustainableand long-term forest conversion on the basis of current management directivesfor near natural silviculture. Management strategies on basis of moderateharvesting regimes are preferred because of their limited impact on the waterbudget.