The distribution of terrestrial plants and animals of this region is largely a consequence of past forest fires. The frequency, intensity, and extent of these fires determines vegetation patterns which, in turn, play a major role in determining the composition and distribution of the animal populations. It appears that any given site in the ELA will probably be subjected to a forest fire on the average of every 50 to 100 years. If intense, these fires may completely kill the existing forest cover and an entirely new sequence of revegetation will begin. When fires are less intense, many of the older trees may survive and only partial regeneration will occur. Moist areas at lower elevations, particularly Sphagnum bogs and lake shorelines, are relatively resistant to fires. Ridge tops, because of their exposure to higher winds and their much dryer conditions, are particularly susceptible to intense fires. Fire intensity on these ridges may be such that layers of rock are actually spalled from the bedrock surface by the heat. This may, in fact, be a primary agent in the initial phase of soil formation for this region.
At the time of its designation, in the late 1960's, the Experimental Lakes Area had not experienced a significant forest fire in recent memory. While there was evidence of old fire scars on some of the larger trees, the entire area was covered by mature forest. During the first few years of the ELA operations, these conditions persisted as cool damp summers were the norm. In July of 1973, a violent windstorm blew down extensive areas of the forest cover, both within the ELA and to the south and east of the ELA. Later that summer, a tiny forest fire started in some blown down timber within the Lake 262 drainage basin but was quickly extinguished. In late June, 1974, following a period of relative drought, two forest fires started within areas of blown down trees to the southeast of the field station. The first may have started from human sources, but the latter was lightening-caused. Over the next few weeks, these fires (Dryden 16 and 18 - 1974) burned over several hundred km2 of forest, both within and adjacent to ELA watersheds. Over 50% of the Lake 239 (Rawson) and Lake 240 (Boundary or Hayes) watersheds were burned. Perhaps 5% of the Lake 305 (Hutchinson) watershed was burned. Most of the ELA watersheds designated in the original 1968 agreement and lying to the east of Lake 228 (Teggau) were completely burned over. These included Lakes 229, 230, 241, 268, 296, 297, 298, 309, 310, 311, 312, 314, 315, 316, 317, 320, 383, 385, 703, 704, 705, and 934.
The second half of the 1970's brought a number of dryer than normal years to the region. Several sizeable forest fires occurred locally in 1976, but none directly impacted any ELA watersheds. In 1978, a fire was started inadvertently when DFO staff left a campfire burning at a temporary campsite on Lake 382. This fire burned approximately 5% to 10% of the Lake 382 watershed plus a tiny portion of the Teggau Lake drainage basin. Later that summer, a larger fire northeast of Teggau Lake burned over 1000 ha, including approximately half of the Lake 265 watershed. In 1979, the Ontario Ministry of Natural Resources (OMNR) conducted a prescribed burn in a previously logged area immediately east of Lake 259 (Burton). Unfortunately, this fire escaped OMNR control and burned more than a hundred hectares of unlogged forest, including the northwest half of the Lake 226 experimental watershed and small portions of the Lakes 221 and 222 watersheds.
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