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 forest gap model in simulating northern Scandinavian boreal forest succession since AD 500. We also evaluate trends in species abundance in a nemoral woodland in southern Scandinavia by comparing modelling results to palaeoecological data. 2 Simulated biomass trends for Picea, Pinus and Betula growing at Penningholmen (northern Sweden) are strikingly similar to those observed in the local pollen record, particularly in the replication of the early Little Ice Age (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 climate 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 under-represented in modern-day Scandinavian nemoral woodlands, and consequently 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 associated with vegetation models, of model-data comparisons for understanding mechanisms and processes underlying past forest succession, and emphasizes the usefulness of forest models for reconstructing climate influences on past vegetation.