ALBERT, M., LEEFKEN, G., NUSKE, R. S., AHRENDS, B., SUTMÖLLER, J., and SPELLMANN, H.
The presented study shows the effects of climate uncertainty, characterized using three different climate projections, on growth and yield in four regions of the north German lowlands (tab. 1). We examine whether climate uncertainty affects forest management or whether different silvicultural concepts might eviscerate the climatic effects in forest development. Three silvicultural concepts are applied: the reference scenario defined by the principles of close-to-nature silviculture, the biodiversity strategy indending to increase the area of natural vegetation, and the climate protection path trying to maximize CO2 sequestration (tab. 3). The simulation system WaldPlaner with site- and climate- sensitive growth functions projects forest development in the four regions from 2011 to 2070 applying the three silvicultural concepts as well as three climate projections (fig. 1). Climatic and silvicultural effects are directly comparable as the projection excludes any tree or forest losses due to risk factors, i.e. no interaction of mortality and forest development is simulated. The starting conditions in the four regions, i.e. site and climate characteristics (tab. 2, fig. 2), age class distribution (fig. 3) and species proportions (tab. 5) heavily influence the projected forest development. The scenario study shows the clear effects of climatic uncertainty on standing and harvested volume (fig. 4, tab. 6), on periodic annual increment (fig. 5) and on the prescribed yield index (fig. 6, tab. 8). Climatic uncertainty increases with time. Nevertheless, we show that silvicultural measures are capable to control forest development to a much stronger degree. A subsequent risk analysis is indispensable to recommend management options or to derive adaptation strategies. Here, we show the effect of climate uncertainty and silvicultural practices on risk factors using drought vulnerability as an example (tab. 5, fig. 6). Obviously the climate effect is much stronger on drought vulnerability than the silvicultural effect. This result is contrary to the effects on growth and yield. Keeping in mind the strong influence of climatic uncertainty on climate-sensitive risk factors forest management needs to plan responsibly and forest conversion must not be in stereotypes. A flexible formulation of adaptation strategies continuously acknowledging progress in climate change research is necessary. The results of the presented scenario study help to evaluate the climate effects, the degree of uncertainty and silvicultural alternatives on forest development in order to recommend management options and to derive adaptation strategies. [ABSTRACT FROM AUTHOR]