PREDICTING THE EFFECTS OF CLIMATE-CHANGE ON FIRE FREQUENCY IN THE SOUTHEASTERN CANADIAN BOREAL FOREST

Although an increasing frequency of forest fires has been suggested as a consequence of global warming, there are no empirical data that have shown climatically driven increases in fire frequency since the warming that has followed the end of the ''Little Ice Age'' (similar to 1850). In fact, a 300-year fire history (AD 1688-1988) from the Lac Duparquet area (48 degrees 28'N, 79 degrees 17'W) shows a significant decrease both in the number and extent of fires starting 100 years ago during a period of warming. To explore this relationship between climatic change and fire frequency we used daily data from the Canadian Atmospheric Environment Service's General Circulation Model to calculate components of the Canadian Forest Fire Weather Index (FWI) System for the 1xCO(2) and 2xCO(2) scenarios. The average FWI over much of eastern Canada, including the Lac Duparquet region, decreased under the 2xCO(2) simulation, whereas FWI increased dramatically over western Canada. According to these results, fire frequency would decrease over the southeastern boreal forest which is in agreement with the empirical data from the fire history. Our results stress the importance of large regional variability and call into question previous generalisations suggesting universal increases in the rate of disturbance with climate warming.