Fire history and tree species composition in managed Picea abies stands in southern Finland: Implications for restoration

We studied the fire history of 24 managed Picea abies-dominated stands in southern Finland using dendrochronological dating of fire scars in old stumps. Forests in the study area have been heavily utilized in many ways for centuries for swidden cultivation, tar burning, forest pasturage and pasture burning. Old charred stumps of Pinus sylvestris were found in every stand although in nine of them the stumps were too decayed to provide a sample that could be dated. In the 17th and 18th centuries, forests burned at intervals of ca. 50 years on average. The last fires in the study plots occurred in the latter half of the 19th century. Based on the presence of the old Pinus stumps, past frequent fires and historical documents, it can be judged that forests were Pinus-dominated in the 17th and 18th centuries. Around the middle of the 19th century a gap occurred in the annual tree ring chronologies of all study plots. This suggests that large coniferous trees were absent at that time. The currently dominating Picea populations regenerated at the beginning of the 20th century. Our results demonstrate that in an area where human impact on forests has been variable, pervasive and long-lasting, the goal of forest restoration can be very different depending on the choice of reference period. We conclude that for defining restoration goals, knowledge of local forest history is needed.