The General Effects Of Fire On Wildlife

Essay, Research Paper

The General Effects of Fire on Wildlife

Abstract:

Fire is an important part of many ecosystems and helps maintain the condition of habitats for wildlife. The effect of fire depends upon many factors, varying from the type of wildlife to their different habitats. Fire affects ungulates through positive, but often, short-lived improvements in diets by allowing ungulates to consume new plant growth. Fire mediates species interactions thereby reducing conflict. Birds are often positively benefited or unaffected by fire in the short-term. The beneficial role of fire on terrestrial ecosystems is contrary to the negative impact of fire on aquatic ecosystems. The long term effect of fire on wildlife is the maintenance of feeding areas by preventing succession of a habitat to its top state.

INTRODUCTION

Fire is an important part of many ecosystems, affecting wildlife populations in various ways, such as by changing habitat, affecting food supply or quality, or by altering interactions of species. Fire suppression has allowed forested areas to achieve a climax state which provides less forage for wildlife. While terrestrial wildlife is benefited by fire, aquatic ecosystems are negatively impacted by large fires through the increase in sediment flow. Fire is essential in maintaining biological diversity in the Northern Rocky Mountain forests.

NEGATIVE EFFECTS – AQUATIC ECOSYSTEMS

Contrary to the beneficial impacts of fire on terrestrial wildlife, aquatic ecosystems are negatively affected, such as the decrease in fish populations by fire. In the North Fork Shoshone River adjacent to Yellowstone National Park, fish died from increased sediment flow during a heavy rainstorm two years after the canyon had burned (Armbruster, 1996). Fish are sensitive to sediment both in concentration and length of exposure. When fire clears vegetation on slopes surrounding a river, runoff from rainstorms carries sediment into the river, killing portions of the fish population by obstruction of the gills.

REGROWTH

After a fire it takes many years for all trees and shrubs to grow back to their former levels; up to three-hundred years in the northern Rockies (Fuller, 1991). Burned forests show effects many years after the actual fire. Forests at lower elevations grow faster than those at high elevations. Fire and regrowth are part of a cyclic process like that of the seasons. Regrowth does not mean the fire caused the death of forest by only that it is at a different stage, as natural as that of an old forest.

FIRE DAMAGE AMONG TREES

Fire damages trees by a combination of crown, root, and cambium damage. Tress can lose twenty to thirty percent of crown before the fire affects its growth(Fuller, 1991. Thick growth of bark, like a ponderosa pine (Pinus ponderosa) and western larch (Larix occidentalis), protects against cambium damage. Cambium is a layer that produces new plant tissue. A tree s roots will only be damaged if the layer of duff burns away. Thick duff and deep roots are good protection. Thick trunked trees resist fire because their size prevents from heating quickly. Deciduous trees resist fire better that evergreen (Syngonium podophyllum) trees because foliage contains more moisture and fewer organic compounds (Harrison, 1969).

SUCCESSION

Fire prevents plant communities from succession to a climax condition, therefore maintaining the habitat in a state which provides greater forage. Woodland caribou (Rangifer tarandus caribou) are adversely affected by crown fires in the short-term due to major losses of forage and the avoidance of burned locations by the caribou. However, these fires provide the long term benefit of ensuring some of the habitat will remain as jack pine (Pinus banksiana) forest, which provides greater forage quantity for caribou(Patent, 19..).

Key deer (Odocoileus virginianus clavium) are also benefited by long term maintenance of habitat. Plant species used most often by the Key deer (Odocoileus virginianus clavium) are located in pine forests which are replaced by hardwood forests in the forest succession. Fire maintains areas of jack pine forest thus benefiting the Key deer. In oak-jack pine forests, white-tailed deer (Odocoileus virginianus) are found in greater numbers in burned areas eight years following a large fire. Fire acts as a disturbance creating a mosaic of patches that each undergo succession at different times.

BIRDS

Birds in Florida slash pine (Pinus elliotti) forests are relatively unresponsive in the short-term to ground fires; while in ponderosa pine (Pinus ponderosa) forests, bird populations increase after fire. Response of birds in slash pine forests varies depending upon the type of cover used by the species. Woodpeckers (Melanerpes formicivorus) and ground-dwelling birds use burned areas frequently because bare ground is rare in undisturbed slash pine forests and woodpeckers utilize the snags created in the fire. Other birds such as the Florida scrub jay (Aphelocoma coerulescens coerulescens) show no response to most fires because their range is much larger than the area affected by the fire. Cover and food are relatively unaffected by fire for most bird species in the slash pine forest. In the ponderosa pine (Pinus ponderosa) forests, bird populations increase following ground fires for a single year and then