Palaeovegetation-model comparisons, climate change and tree succession in Scandinavia over the past 1500 years

1 We assess the robustness of a 1500-year palaeoclimate data base and fores t gap model in simulating northern Scandinavian boreal forest succession si nce AD 500. We also evaluate trends in species abundance in a nemoral woodl and in southern Scandinavia by comparing modelling results to palaeoecologi cal data. 2 Simulated biomass trends for Picea, Pinus and Betula growing at Penningho lmen (northern Sweden) are strikingly similar to those observed in the loca l pollen record, particularly in the replication of the early Little Ice Ag e (LIA) decline in Betula and the late-LIA dieback of Picea and Pinus. 3 LIA decreases in Betula may therefore be partly due to the effects of cli mate on its competitive interactions with Pinus, as well as the previously proposed effects of insect herbivory. 4 Simulations of Draved Forest (western Denmark), suggest that Tilia is und er-represented in modern-day Scandinavian nemoral woodlands, and consequent ly that the present dominance of Fagus probably reflects strong human-plant interactions from as early as the beginning of the 17th century. 5 This study highlights the importance, despite general limitations associa ted with vegetation models, of model-data comparisons for understanding mec hanisms and processes underlying past forest succession, and emphasizes the usefulness of forest models for reconstructing climate influences on past vegetation.