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Climate change poses new challenges to forest management and the necessary spatial information on nutrient status and water availability of forest soils. Digital Soil Mapping techniques allow to update spatial data sets for forest planning and to provide them for previously unmapped areas. The potential and uncertainties were demonstrated using the example of the forest site mapping system of Hesse, Germany. The six soil nutrient index classes (poor, moderate-weak, moderate, moderate-good, rich, carbonatic) were updated to better reflect the soil nutrient availability observed by the second National Forest Soil Inventory (NFSI II). The frequency distribution generated by the model shows a significantly higher correspondence of the individual nutrient index classes with the distribution of the nutrient index classes derived from the nutrient availability observed at the spatially representative soil profiles of the NFSI. Furthermore, corresponding information could also be provided for the more than 20 % previously unmapped forest area in Hesse. Through the use of a Random Forest Model (RF), spatial information on terrain water regime classes could also be provided for unmapped areas. The RF model shows overall a "considerable" agreement between the modeled terrain water regime classes and those of the forest site mapping in the evaluation process. However, higher uncertainties exist in the modeling of "fresh" forest sites. Based on the terrain water regime classes, now available for the entire area of Hesse, a statistical model for estimating available soil water capacity was parameterized and evaluated with the soil profiles from the NFSI. The model for the available soil water capacity represents a clear improvement compared to the approaches used in forest planning in the past. [ABSTRACT FROM AUTHOR]

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]