Mid Sweden University

Forest fires are historically one of the dominant disturbances in boreal forest landscapes. The last 150 years of fire suppression have basically removed this disturbance from Fennoscandia. To remediate this, restoration fires are commonly used in protected areas as a conservation method. However, their application require understanding of past fire intervals in both inhabited and uninhabited areas of importance. In this study, fires of the past 700 years are dated in both space and time in a 15800 ha boreal forest landscape in the middle of Sweden. In total 222 wood samples have been analyzed representing 632 individual fire scars. Standard dendrochronological methods were used for the construction of a ring width chronology used for cross dating the fire scared wood samples. The spatial and temporal patterns of these fires are combined with information on historical human activities, such as local slash and burn settlements, armed conflicts and forest management. The earliest dated fire occurred in 1232 A.D. The frequency of fires increased in the 1600s, approximately at the same time as human population and activity increases. In the second part of 1800s, detected forest fires decreases significantly. Together with historical information, the results indicate links between size and frequencies of fires and human land use during most of the studied time period. However, in the early phases of the time sequence studied (1400s to 1500s), fire regime may be considered controlled by natural dynamics and climate. The fire interval in an average point in space at that time was 40 years, and an area approximately equal to the studied area burned each century.