A thousand years of human impact in the northern Scandinavian mountain range: Long-lasting effects on forest lines and vegetation

The vegetation history has been examined by pollen, microscopic and macroscopic charcoal analyses in the vicinity of two alpine Stállo settlement sites and one forested ‘Reference area’ with no settlement remains in northwestern Sweden in the northern part of the Scandinavian mountain range. The acquired data provide indications of the effects of human activities on local vegetation during the settlement phase, and on ecological processes in both long- and short-term perspectives. The results show that one settlement site, Gieddeålge, was established just above the forest line in the Betula treeline zone, and the other, Varenodjukke, in the Betula forest. At Gieddeålge an increase in herbs and graminoids appears to have occurred c. 700 cal. BP (during the thirteenth century) suggesting that the vegetation was altered by nutrient addition, most likely related to human activities associated with the settlement. At Varenodjukke, the Betula trees around the settlement were cut down and the site developed into an alpine heath dominated by Betula nana, which still characterizes the site today. In the Reference area evidence of changes to the vegetation probably caused by human impact was also found from c. 3500 to 700 cal. BP. In conclusion, the vegetation currently present at Gieddeålge and Varenodjukke has been strongly influenced by previous human activities, which have clearly had profound effects, both short and long term, on the composition of the vegetation and the properties of the ecosystems in these areas. Further, when studying processes, such as anticipated global warming that will influence future patterns of vegetation in these forest-line areas, legacies of land use must be taken into consideration.