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GLACIER National Park |
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Fire Succession: Key to Continuity Most of Glacier's fires are lightning-caused. Strikes may flare up immediately; or fires may smolder in the forest duff for days until fanned into flame by wind. Ground fires may race through the forest understory, causing minor damage; or they may bridge the understory and reach the canopy, thus becoming rapidly spreading crown fires. Under certain conditions, uncontrollable infernos may develop, generating terrific winds and heat. These rare conflagrations are called fire storms. Every type of forest habitat has climax vegetation—trees and shrubs that are best suited to the site and thus maintain themselves indefinitely if not disrupted. After a major fire, habitat conditions are usually so altered that the site must pass through several seral stages before conditions are such that climax vegetation can return. A sere is a series of plant communities that follow one another in orderly fashion until climax conditions are again reached.  Lightning fires occur most often during the hot, dry weeks of late summer.  When the forest is dry, lightning often causes quick flare-ups.  The forest may continue to burn for days after the main conflagration has passed.  After a major fire, sun-loving grasses, shrubs, and wildflowers quickly invade the former forest. Deer and wapiti benefit from these new food sources.  Lodgepole pine, a pioneer species quick to take over burned areas at tower elevations, grows rapidly. These trees are five years old.  This is a Glacier National Park forest 80 years after a major fire. |
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Last Modified: Sat, Nov 4 2006 10:00:00 pm PST |