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Soils

Effects of Wildfire on Soil and Water

Wildfire, n.d., US Fish and Wildlife Service.

Wildfire,US Fish and Wildlife Service

The effect of wildfire on soil is typically tied to the amount of heat transferred into the ground during a fire. This does not necessarily mean that high-intensity fires will have the greatest impact on the soil. In some cases, high-intensity fires can move quickly through the tree canopies and have less impact on the soil than low-intensity fires that smolder near the ground for longer periods. Looking at the severity of the burn rather than the intensity of the fire can be more useful in determining the impact of fire on soil. Fire severity describes the effects of fire on different components of the ecosystem, including its physical, chemical and biological properties. Disturbance of these properties can affect soil nutrients, cause soil erosion, or alter the water-retention capacity of the soil. The cumulative effects of these changes can modify the productivity of soil and biological diversity of an ecosystem.

The effect of wildfire on the hydrological processes within an area can also be substantial. For example, reduced vegetation cover can lead to significant flooding, soil erosion and sedimentation, pollution from chemicals that are no longer filtered by riparian vegetation, and changes in water temperature. All of these effects can have harmful impacts on aquatic life. Changes in hydrological processes are also likely to affect humans who depend on watersheds for municipal water supplies, as well as for their recreation and aesthetic value.

Sources

Wildland Fire in Ecosystems: Effects of Fire on Soil and Water. United States Department of Agriculture. Forest Service. Rocky Mountain Research Station. General Technical Report RMRS-GTR-42-volume 4, September 2005.

Authored by Dan Weston, Intern, Institute for Natural Resources (2010)