Mapping the growth potential of Douglas-fir in Austria and Germany.
Maps of the growth potential for the non-native coastal Douglas-fir (Pseudotsuga menziesii var. menziesii) are presented for Austria and Germany. The regional growth potentials were derived using a site-sensitive statistical model which determines productivity as the dominant-height at age 60 (SI60). The model was calibrated using data from 28 Douglas-fir stands in Austria and Germany growing on silicate and carbonate bedrock. The model is based on non-linear relationships between SI60 and ten climatic, soil physical and soil chemical parameters. Model predictions were calculated for a 1 km × 1 km grid for Austria and Germany. The results revealed that the Northern Alpine foothills in southern Germany are an area with a particularly high growth potential under current climatic conditions (mean 1970-2000). Applying two climate change scenarios (RCP 4.5 and RCP 8.5) to assess the future productivity of Douglas-fir, we see that the changing growth conditions will have a positive impact on Douglas-fir growth at higher altitudes, whereas the productivity may decline in areas where the current growing conditions are dry and highly productive.