Dendrochronologically dated changes in the limit of pine in northernmost Finland during the past 7.5 millennia

Postglacial changes in the occurrence of Scots pine in northernmost Finland and adjacent areas are indicated in data sets of megafossils dated to an accuracy of 1 year using analysis of tree rings. After adjustment for land uplift, results in the altitudinal and latitudinal extent and in the structure of the pine limit are compared in the context of megafossil and pollen evidence from Fennoscandia, the Kola Peninsula and Scotland. Temporal changes in tree density at the forest limit are estimated from chronology sample size. The record from the subregion of Enontekio shows a long-term retreat of pine, corresponding to summer cooling caused by orbital forcing. This long-term trend is superposed by shorter-term fluctuations, which is consistent with other proxy evidence of pine. An abrupt decline in the forest limit occurred during the first millennium BC in two major steps, with no indication of high-altitude pine germination between 800 BC and AD 100. The subregions of Inari and Utsjoki show significant fluctuations at the forest limit in tree density only.