Long-term fire frequency in the spruce-dominated forests of the Ulvinsalo strict nature reserve, Finland

The long-term fire history of the spruce-dominated forests of the Ulvinsalo strict nature reserve in Kuhmo, eastern Finland (63°58′N, 30°22′E), was studied by means of charcoal particle layer records and macroscopic charcoal particles in peat and by pollen analysis. The data suggest that spruce forest sites in the area burned at a mean interval of a few centuries over a period of almost 6000 years prior to the beginning of slash-and-burn cultivation in the area. This low forest fire frequency can be attributed to the fragmented landscape pattern, which restricted the spread of fires ignited by lightning. Because a similar landscape pattern predominates over large areas of boreal Fennoscandia, it is possible that natural fire frequencies may also have been considerably lower than expected in these areas. It may well have been the case that, at least in spruce forests located in fragmented landscapes, small-scale disturbances were more important for the forest dynamics than fires.