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Fire Adapted Forests  and Fire Ecology


A lodgepole pine forest is naturally adapted to fires. The pines' serotinous cones have a waxy coating which opens in response to the heat of the blaze, scattering seeds  onto soil newly fertilized by nutrients in the ash.

Some 85% of Yellowstone Park's forests are lodgepole pine. After the dramatic fires of 1988, this forest began the process of renewal built into it, a process which had been going on for thousands of years before man arrived.

    The importance of fire to natural systems is an obvious one often overlooked by modern man. Fire, initiated by lightning, rock slides etc. was a part of forests, grasslands, and other habitats long before man came along to care. In fact man probably used fire early on as a tool to drive game, provide warmth, and drive away predatory animals. But as humans proliferated and moved into the forests of Europe and Asia, they began to see fire as a threat, and as a force of nature to be controlled and often eliminated, along with various predators and other animals such as brown bears, wolves, beavers and anything else that man found disturbing, threatening, or tasty. The result is a Europe which has generally sterile, low diversity forests intensively managed by man. 

    When European man came to the New World he brought his prejudices and practices with him and began to clear the forests, suppress fire, and eliminate predators. The first school of forestry in the U.S., the Biltmore School, was established at Mt. Pisgah, North Carolina in 1898. Commodore Vanderbilt hired a German forester to handle his extensive land holdings using the principles of European forestry.  Based on this European model, forests were cut, fires were suppressed, and a second growth forest produced which satisfies the need for intensive use and occupation by man, but bears little resemblance to the original frontier forest encountered by the first settlers. Less than one percent of that original forest remains, and much of that is threatened by pollution and acid rain. 

    The European model drove forestry practice and forestry education for the next 75 years. It worked reasonably well for developed areas of the northeastern U.S., but for the pine forests of the southeast and the coniferous forests of the west this model ran into trouble. These forests are fire adapted, and depend on fire and biological legacy to sustain them and their diversity of wildlife. Slowly, an understanding of the role of fire and biology has overtaken  forestry. In many forests Smoky the Bear has given way to "prescribed burns" and clearcutting has been replaced by sustainable forestry. The value of frontier forests and biological legacy is finally recognized. Hopefully this comes before it is too Late.

Fire Adapted Forests

    Southeastern pine forest - a mixture of loblolly, yellow, slash, and longleaf pine forests. These pines resist fire as seedlings and as mature trees. Without fire a subclimax of oaks and various shrubs will eventually choke out the pine trees. Controlled burns are used to reduce fuel and to maintain productivity of the pines.

    Sand pine - a southeastern species which grows on ancient sand dunes, derivatives of the original shoreline. These pines have serotinous cones which automatically reseed after a blaze.

    Lodgepole pine - from the southern Rockies to Alaska. These pines are naturally adapted to fires due to the serotinous cones they possess.

    Ponderosa pine - the dominant pine of the southwest. These pines have thick bark and limbs far enough from the ground to resist surface fires.

    Chaparral - this is a scrub forest found in areas with a Mediterranean climate- hot dry summer and fall, cool, moist winters. These areas are found on the west coasts of the U.S., Chile, Australia, South Africa, and the Mediterranean. The evergreen oaks, manzanita, and other species are adapted to the fires which sweep across the chaparral in the late summer and fall.  Some have thick leaves, others burn quickly but regrow from the roots. Do not confuse the true chaparral with the "inland chaparral",  a savanna woodland composed of pinyon-juniper and oaks.

    Sequoia - The Sequoia gigantea or Sierra redwood grows to hundreds of feet tall, over 20 feet in diameter,  lives thousands of years, and requires fire to assure its dominance. Without fires sequoias slowly are replaced by competing spruce and fir. Controlled burns are being used in Sequoia National Forest to maintain the historic dominance of the big trees. 

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Many of the large sequoias survive with significant scars, attesting to the long-standing presence of fire.

 

 

 

 

 

 

 

In this way the forest replaces itself and maintains heterogeneity and diversity by constant turnover.

Soon young seedlings appear and in a few years begin to carpet the forest floor, along with fireweed, lupine and other early stages of succession.

Pine flatwoods in northern Florida. These longleaf pines grow in a variety of soils, with an understory of saw palmetto.

The seedling of the longleaf pine, called its "grass stage", is adapted to fire and may persist for up to 6 years.

Longleaf saplings are susceptible to fire. But within one to two years they reach a height at which its lowest branches will be high enough to survive routine ground fires.


Regular surface fires keep shrubs and oaks from choking out the pines. Controlled burns are used to maintain the pine forest dominance. Saw palmetto and wiregrass recover quickly.

A standing ponderosa displays a scar from earlier fire.

Written and prepared by Jim Swan, for BIO 111 at Albuquerque TVI Community College