Effects of Fire on Forest Soil

A look at soil after the 2000 Blodget Fire, Montana
The "dirt" of the forest floor is actually a mixture of minerals, air, water, and decomposing plant and animal matter, teeming with microbes and insects. This soil is the lifeblood of the forest. It supplies mechanical support, nutrients, water, and air to the roots of forest plants (DeBano et al. 1998). In addition, the soil acts like a giant sponge, soaking up snowmelt and rainfall and regulating the flow of water into nearby streams. If forest soil is altered by fire, both terrestrial and aquatic plants and animals can be affected.

The effects of fire on forest soils can be direct, from heating, or indirect, due to fire's consumption of organic matter atop and within the soil. We detail each in the following sections:

During the fire: the direct effects of fire on forest soil
After the fire: the indirect effects of fire on forest soil

Then, we describe how ecologists rate the severity of fires from the perspective of forest soil heating.


DeBano, L.F., D. G. Neary, and P. F. Ffolliott. 1998. Fire's Effects On Ecosystems. John Wiley & Sons, New York, New York, USA.

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