Global warming-adapted target forest types for Germany

This research report provides tools for the initialization of near-natural forests adapted to global warming. The key idea is that target forest communities could naturally migrate from countries south of Germany—where the climatic conditions expected in Germany’s future have already existed for centuries. These specific forest communities have the unique ability to recreate their characteristic biocenosis in Germany and develop their typical biodiversity. The target forest types (TFT) thus serve as essential components in establishing forest development targets for ecological forest conversion. The BERN database serves as the basis for the modeling. In total, 1,143 plant communities (including 543 natural wood communities) were evaluated from data collections of largely undisturbed sites, preferably those dating before 1980. For this investigation, 498 phytosociological publications have been evaluated up to now, containing a total of 143,000 relevés with corresponding descriptions of the ecoclimatic and edaphic site factors from Central and Southern Europe. The oldest available published synoptic table serves as a reference for a community. Each community is characterized by ranges for fuzzy limits of pH value, base saturation, carbon to nitrogen ratio, volumetric soil water content, continentality index, climatic water balance, growing season length and photosynthetically active radiation from reference measured data.For the regionalization of global warming-adapted TFTs, a climatic classification for Germany is proposed, taking projected global warming into account. The parameters growing season length (period of days with > 10°C) and climatic water balance in the growing season are sufficient to establish a significant correlation to the occurrence of forest community groups (compiled according to main tree species).The evaluation of the measurement data (time series 1991–2020) and a simulation run of the RCP8.5 scenario (time series 2051–2080) resulted in a range of the growing season length from 55 to 246 d a ^-1 and a range of the climatic water balance in the growing season from − 47 to + 291 mm/month. The resulting 38,200 edaphic/climatic combination types (=”habitat types”) were assigned a total of 147 different TFTs. If multiple communities were possible at a single site type, an alternative assessment was conducted using 10 additional site factors. The mapping of the TFT for Germany was conducted using the 1:200,000 soil map, intersected with the climate class map. A factsheet with the reference site parameters and the vegetation structure was created for each TFT (Supplement 1).The results may help to support forestry decision-makers in forest conversion with regard to selection and structuring of tree species. The map, the factsheets and the ecograms form an essential basis for determining suitable climate- and site-adapted tree species proposals for entire Germany.