Entwicklung von mischbeständen mit komplexer struktur im klimawandel

Close-to-nature silviculture is emphasizing mixed-species, multi-layered stands. Dynamic models are appropriate tools for estimating their future development. Specifically, the fam-ily of gap models, which originate from ecology, renders such analyses possible. We use the example of the ForClim model to illustrate how these models are structured, how they can be used, and where their limits lie. Based on a stratification of the Swiss forest area, 71 typical stands (strata) were de-rived, differentiated according to location region, elevational level, structure and tree species composition. For each stra-tum, simulations were carried out with four climate scen arios, two different assumptions about soil properties and eight model variants. The latter was done because it was largely unknown to what extent the uncertainties in the model formulations affect the simulation results. Simulation results show a regionally and elevationally differentiated picture, partly with strong changes of stand basal area and species composition. Depending on the stratum, increases or de-creases were recorded. Soil properties proved to be quite im-portant, surprisingly also in the subalpine and upper sub-alpine zones. Uncertainties in the model formulations do not considerably influence simulation results, i.e. model behav-iour is robust. The results of the individual strata can be used for forest management planning at the operational or regional level. Although they do not provide any firm recommenda-tions for the future management of specific stands (i.e., they should not be taken literally), they deserve to be taken ser-iously as they are able to show trends of future forest devel-opment.