Fire Effects on Wildlife Foods

Fire’s influence on wildlife food is probably the most thoroughly researched aspect of the relationship between fire and fauna. It has generated a vast literature showing a great variety of results. In general, the literature regarding fire effects on wildlife food indicate that the factors that affect postfire changes in vegetation quantity and nutritional quality include:

• soil,
• vegetation type,
• age and structure of vegetation prior to burning,
• rainfall before and after burning,
• fire severity,
• season of burning,
• time since fire, and
• presettlement disturbance regime.

Also, the following general effects of fire on wildlife foods have been found across regions:

• Burning sets back plant development and succession, often increasing or improving forage for wildlife from a few years to more than 100 years, depending on vegetation type.
• Fires usually increase habitat patchiness, providing wildlife with diversity of vegetation conditions from which to select food and cover.
• The biomass of forage plants usually increases after burning in all but dry ecosystems.
• The production of seeds by grasses and legumes is usually enhanced by annual or biennial fires. Mast production is usually enhanced by a 5-year or longer burning cycle.
• Burning sometimes, but not always, increases the nutritional content and digestibility of plants. This effect is short-lived, typically lasting only one or two growing seasons.
• Some wildlife species select more nutritious diet from burned areas even though the average nutrient content of burned plants does not differ from that of unburned plants.

The literature on fire effects on wildlife foods is not balanced among faunal classes or geographic regions, since most studies focus on a species of concern to managers in a particular geographic area. In the following sections, we summarize what is known about changes in quantity and quality of forage following fire for specific regions of the United States. In addition, where information is available, we summarize changes in availability of seeds, mast, and insects.

• Southeastern forests
• Eastern deciduous forests
• Prairie grasslands
• Northern forests (Boreal and Laurentian)
• Western forests (Rocky Mountain, Sierra, and Pacific Coast Maritime)
• Western woodlands, shrublands, grasslands, and desert (Pinyon-juniper, chaparral, sagebrush, deserts)

It is impossible to generalize about fire effects on wildlife foods that apply throughout all of North America. Furthermore, while improving and increasing food for particular wildlife species may be an important objective, it is important that these goals not be accomplished at the expense of ecosystem sustainability (Provencher and others 1998).