APPLICATION OF A FOREST SUCCESSION MODEL TO A CONTINENTALITY GRADIENT THROUGH CENTRAL EUROPE MARCUS LINDNER, PETRA LASCH and WOLFGANG CRAMER Potsdam Institute for Climate Impact Research, P.O. Box 601203, D-14412 Potsdam, Germany Abstract. The forest succession model FORSKA was applied to a west-east transect across Central Europe using points from a global climate data set. Climate change experiments were undertaken for two general circulation model scenarios and two different site classes. The simulated climate changes lead to reduced forest productivity and a changed species composition on most sites. Under current climate, the broad scale pattern of the climatically driven distribution of forest communities is quite realistically reproduced. However, the resolution of climate data imposes limitations on the simulation of forest dynamics in subcontinental climate, because climate variability and extreme events are not well represented. Introduction Forest succession models have been applied to study possible impacts of climate change on forests in the transition zone from maritime to subcontinental climate in Central Europe. Initially we compared the two forest succession models FORECE (Kienast 1987) and FORSKA (Prentice et al., 1993), which had been developed in Europe for alpine or boreal forests, respectively. In the FORSKA model, the formulation of a number of processes is more mechanistic than in traditional gap models (Bugmann et al., 1996). Therefore this model seemed to be more appropriate to simulate impacts of changing climate on forest dynamics and it was chosen for further development and applications. Some model modifications have been made, in order to realistically simulate species composition and forest productivity of the major natural forest communities in northeastern Germany. Among other changes, establishment rates were increased, some environmental response parameters were adjusted, and the function to account for resource depletion was altered (Lasch and Lindner, 1996). In this study, some points from the global climate data set of Leemans and Cramer (1990) were used to run the modified FORSKA model on an extended west-east transect across Central Europe from The Netherlands to Poland. The objective was to test the model performance on a larger regional scale than before. We also wanted to discuss the results with emphasis on limitations imposed by the resolution of climate data as well as by the representation of environmental factors in the model. The transect from maritime to continental climate coincides in Europe with a moisture availability gradient. It was chosen because forest dynamics in temperate continental climate usually are strongly influenced by water limitations, Climatic Change 34: 191-199, 1996. (~) 1996 Kluwer Academic Publishers. Printed in the Netherlands.