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

Valid reconstruction of long-term forest fire histories from individual pea t cores usually fails, for a number of reasons, even though visible charcoa l horizons in peat are indisputable evidence of local or in-situ fires. Bot h the dating and reliability of fire records from peat can be improved by t he means of a 'basin-based approach', in which the gradual lateral growth o f the peat is studied carefully by means of numerous dated basal peat sampl es. Applying this principle, the frequency of forest fires in an esker land scape in southern Finland was elucidated over the past 7000 years. The resu lts indicate that a period of active land use, but undeveloped fire control in the area, reduced the mean fire interval from the natural background fr om c. 130 years to c. 40 years.