Canada

As in the Russia, the forested area of Canada is dominated by the boreal forest zone, which extends in a broad belt from the Atlantic to the Pacific Oceans, and lies immediately to the north of the heavily populated region along the Canada/United States border. Over the past century the use of the boreal forest zone in Canada, for both industrial and recreational purposes, has increased dramatically, and this has resulted in a concurrent increase in both forest fire incidence and the fire management capability mobilised to deal with this problem. Provincial and territorial agencies in Canada have progressed to the point where state-of-the-art centralised and highly computerised fire management systems are common, yet forest fires continue to exert a tremendous influence on the forest resource in this country. Periods of extreme short-term fire weather, in combination with a recognition of both the ecological desirability of natural fire and the economic impossibility of controlling all fires, have resulted in the realisation that forest fires in Canada are a problem that cannot, and should not, be eliminated.

Detailed forest fire statistics have been archived since 1920 in Canada and, within limits, this extensive record permits a general analysis of trends in this country. It is recognised that the Canadian fire record prior to the early 1970s (when satellite coverage began) is incomplete, as various parts of the country were not consistently monitored during this period. It is expected that this problem increases as one goes back in time, likely being more of a problem in the earlier part of the century than during the mid-1900s. Keeping this uncertainty in mind, annual fire occurrence in Canada, without fluctuating greatly on a year-to-year basis, has increased rather steadily from approximately 6,000 fires annually in the 1930-1960 period, to almost 10,000 fires during the 1980s and 1990s. This is a reflection of a growing population and increased forest use, but is also due to an expanded fire detection capability. The area burned by Canadian forest fires fluctuates tremendously on an annual basis, with the 1980-96 period significant in this regard, due to major fire years in 1981, 1989, 1994 and 1995. While fire occurrence numbers were relatively constant over the 1920-1959 period, and have increased steadily since that time, area burned actually decreased over the first four decades of record only to increase over the last three decades. The most dramatic increase occurred during the 1980s, and 1990s, primarily due to periods of short-term extreme fire weather in western and central Canada. During the 1981-96 period an average of 9,246 fires annually burned over an average of 2,519,105 hectares in Canada, with annual area burned fluctuating by an order of magnitude (0.76 million to 7.28 million hectares). Lightning accounts for 35% of Canada's fires, yet these fires result in 85% of the total area burned, due to the fact that lightning fires occur randomly and therefore present access problems usually not associated with human-caused fires, with the end result that lightning fires generally grow larger, as detection and subsequent initial attack is often delayed.

A recent evaluation of Canadian fire statistics (Stocks 1991) also identified some of the reasons why Canadian fire impact varies significantly. Sophisticated fire management programs are largely successful at controlling the vast majority of forest fires at an early stage, such that only~2% of fires grow larger than 200 hectares in size, but these fires account for ~98% of the area burned across Canada. In addition, the practice of "modified" or "selective" protection in remote regions of Canada results in many large fires in low-priority areas being allowed to perform their natural function. Recent studies comparing fire sizes relative to levels of protection indicate that, on average, fires in the largely unprotected regions of the boreal zone are much larger than fires in intensively protected regions (Stocks 1991; Ward and Tithecotte 1993). An examination of the spatial distribution of all 1980-89 Canadian fires >200 hectares (Stocks et al. 1996) showed that by far the greatest area burned occurred in the boreal region of west-central Canada, and attributed this to a combination of fire-prone ecosystems, extreme fire weather, lightning activity, and reduced levels of protection in this region.

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