Climatically induced change in fire frequency in the southern Canadian Rockies

The fire frequency for the last 380 yr in the 495 km² Kananaskis Watershed, Alberta, showed a temporal change in fire frequency related to a change from a warmer and drier climate before 1730 to a cooler and moister climate since then. When the fire-frequency data were partitioned by a graphic technique, the two resulting fire frequencies fit negative exponential distributions. For 1730-1980 the fire cycle was 90 yr. Before 1730, the fire cycle was 50 yr. Data on fire behaviour in the Watershed indicated a short fire cycle, constant hazard, and lack of spatial fire-frequency differences, and suggest that the regional climate control of the temporal fire frequency is related to a characteristic synoptic weather pattern and the resulting high intensity and high rate-of-spread of fires. -from Authors