German forest sector under global change: An interdisciplinary impact assessment

The assessment of potential impacts of climate change on forests and forestry requires an interdisciplinary approach. This paper introduces the collaborative,German Forest Sector under Global Change" study, which was designed to demonstrate the potential of such an analysis. The objective of the study was to investigate the nature and extent of possible impacts of global climate change on forests and the forest sector in Germany. Our paper describes the overall project philosophy, as well as the scenarios for changing climate and forest management that were used in the research network. The assessment was based on inventories of national forest resources as well as on several simulation models: the forest growth simulator SILVA 2.2, the forest patch models FORSKA-M and 4C, the forest scenario model ActioSilva, a forest estate model and the forest product market model FPMM. From forest inventory data 200 forest stands were selected to represent structure and composition of forests in Germany Stand development was projected 30 years into the future under both current and changed climatic conditions. For each forest inventory plot, climate data were generated corresponding to current climate (1961-1990) and two climate change scenarios based on the projections of the HadCM2 and ECHAM4 global circulation models for the years 2041-2070. For Germany, both climate change scenarios show an increase of 2.9-3.6 degreesC in mean temperature, but rainfall differed markedly between scenarios. While the HadCM2 model projects on average a 20% increase in annual precipitation in this region, the ECHAM4 model projects reduced precipitation, along with a greater temperature increase during the summer months. Three prototypical management strategies are used for the assessment, spanning a triangle including pure economical orientation, optimised timber volume yield, and priority to ecosystem services from the forest. These extreme management strategies were devised to encompass the great variety of different management objectives that are encountered in German forestry. The paper ends with an outlook on the remaining papers of this journal supplement, which presents the results of three years of work of the research network, documenting significant progress in quantitative forest science and global change research in Germany.