A basin-based approach to the long-term history of forest fires as determined from peat strata

Abstract

Valid reconstruction of long-term forest fire histories from individual peat cores usually fails, for a number of reasons, even though visible charcoal horizons in peat are indisputable evidence of local or in-situ fires. Both the dating and reliability of fire records from peat can be improved by the means of a ‘basin-based approach’, in which the gradual lateral growth of the peat is studied carefully by means of numerous dated basal peat samples. Applying this principle, the frequency of forest fires in an esker landscape in southern Finland was elucidated over the past 7000 years. The results indicate that a period of active land use, but undeveloped fire control in the area, reduced the mean fire interval from the natural background from c. 130 years to c. 40 years.