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Research article - Peer-reviewed, 2007

Long-term fire frequency not linked to prehistoric occupations in northern Swedish boreal forest

Carcaillet C, Bergman I, Delorme S, Hornberg G, Zackrisson O


Knowledge of past. re regimes is crucial for understanding the changes in. re frequency that are likely to occur during the coming decades as a result of global warming and land-use change. This is a key issue for the sustainable management of forest biodiversity because. re regimes may be controlled by vegetation, human activities, and/or climate. The present paper aims to reconstruct the pattern of. re frequency over the Holocene at three sites located in the same region in the northern Swedish boreal forest. The. re regime is reconstructed from sedimentary charcoal analysis of small lakes or ponds. This method allows. re events to be characterized, after detrending the charcoal influx series, and allows estimation of the time elapsed between. res. The long-term. re regime, in terms of fire-free intervals, can thus be elucidated. At the three sites, the mean fire-free intervals through the Holocene were long and of similar magnitude (similar to 320 years). This similarity suggests that the ecological processes controlling. re ignition and spread were the same. At the three sites, the intervals were shorter before 8600 cal yr BP ( calibrated years before present), between 7500 and 4500 cal yr BP, and after 2500 cal yr BP. Geomorphological and vegetation factors cannot explain the observed change, because the three sites are located in the same large ecological region characterized by Pinus sylvestris-Ericaceae mesic forests, established on morainic deposits at the same elevation. Archaeological chronologies also do not match the. re chronologies. A climatic interpretation is therefore the most likely explanation of the long-term regional pattern of. re. Although recent human activities between the 18th and the 20th centuries have clearly affected the. re regime, the dominant factor controlling it for 10 000 years in northern Sweden has probably been climatic

Published in

2007, Volume: 88, number: 2, pages: 465-477