A Critical Evaluation of Fire Suppression Effects in the Boreal Forest of Ontario

Although fire suppression is widely believed to have changed the “natural” fire regime in the boreal forest, empirical evidence for this effect is limited and usually involves a comparison of fire sizes, average annual area burned, and fire cycle between areas with and without fire suppression. We critically evaluate this empirical evidence and discuss problems with untested assumptions, data quality, statistical analyses, interpretations, and inferences. Furthermore, to test the hypothesis that fire suppression has changed the natural fire regime, we apply time-since-fire techniques to spatial fire data (1921–1995) for the western and eastern boreal regions of Ontario and compare temporal and spatial variation in fire cycle for areas with and without fire suppression. There is no detectable temporal change in fire cycle between 1921 and 1995 in areas with aggressive fire suppression; however, interpretation of the fire cycle in areas without aggressive fire suppression is confounded by insufficient data. Also, although the western region shows an increase in fire cycle from fully protected to less protected areas, the eastern region shows the shortest fire cycle in the most protected area. Thus, to date there is insufficient empirical evidence that fire suppression has significantly changed the fire cycle in the boreal forest of Ontario. FOR. SCI. 51(1):41–50.