Habitat Mosaics Stop Fires

photograph of clouds above a beaver dam in a river

Biological Strategy

American beaver

AskNature Team

Image: NPS/Adams / Flickr / Public Domain - No restrictions

Manage Disturbance in a Community

When environmental conditions change, they can disrupt an ecosystem’s equilibrium. Excessive rain can cause flooding and drought can cause forest fires. An ecosystem must be resilient to such disturbances. Disturbances are unpredictable in location, size, and intensity, so ecosystems must be able to regrow and must have a variety of duplicate forms, processes, or systems that are dispersed in location. For example, a forest ecosystem can recover from fire because diverse organisms play different roles in different ways and in different locations. Many organisms can resprout or grow from seeds triggered by fire, and their dispersed distribution ensures that an entire population isn’t decimated. Though the recovered ecosystem may look totally different from the pre-fire one, the ecosystem as a whole remains healthy.

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Mammals

Class Mammalia (“breast”): Bats, cats, whales, horses, humans

Mammals make up less than 1% of all animals on earth, but they include some of the most well-known species. We know first-hand some of the characteristics that make mammals unique, like having hair, being able to sweat, and producing milk through mammary glands. Another critical shared feature is a set of highly-specialized teeth. Unlike sharks or alligators, for example, whose teeth are generally all the same size and shape, mammals have differently shaped teeth in different areas of the jaws to target specific foods or foraging strategies.

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Beavers reduce fire impacts in spruce stands by creating a mosaic of habitats that act as natural firebreaks.

Image: Sam Beebe/Ecotrust /

This photos title on Flickr was Beaver Dam on the Teton. The full-size photo shows a number of beaver dams, and the vegetation mosiac that results.

“Not only do the appetites of moose and beavers help determine when a northern forest will reach this flammable spruce stage, but beavers also indirectly affect the extent of the burn. The mosaic of aspen and willow stands, meadows, ponds, and wetlands they maintain amid the flammable spruce forests can serve as natural firebreaks, keeping fires smaller than they would be in homogeneous landscapes. Both the moose and beaver then benefit from the effects of fire because it clears the way for the regrowth of aspen and willows in the nutrient-laden ash.” (Baskin 1997: 168)