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Ecological Intelligence / Subject

wildlife habitat

Peer-reviewed North America

Frequent prescribed fire reduced shrub cover, but the wildlife-habitat tradeoff persisted

Evidence
Peer-reviewed
Geography
Dry ponderosa pine forests, Pacific Northwest United States
System
Dry pine forest understory; prescribed fire regimes

WHAT THE EVIDENCE SAYS

Researchers compared repeat burning at 5-, 10- and 20-year intervals with unburned controls. Five-year fires most consistently reduced litter and bitterbrush cover, but removing that shrub can also reduce forage and cover for wildlife. Longer intervals protected more bitterbrush in some periods yet sometimes favored snowbrush or brackenfern after overstory loss; species richness did not rise simply with repeated burning.

WHY IT MATTERS / OUR READ

Choose fire-return schedules from an explicit map of desired fuel, wildlife-forage and understory states rather than treating frequent burning as one universal prescription. A spatial mosaic of untreated patches and differently burned units may preserve habitat diversity while meeting fuels objectives.

CAVEATS / UNCERTAINTY

Results come from a particular long-term dry-forest experiment; fire severity, past stand structure, missed treatments and species composition matter. No fixed 5-, 10- or 20-year schedule is a site-independent recommendation.

SOURCE

Fire Ecology / USDA Forest Service — primary long-term experimental study
View original evidence ↗

A long-term ponderosa-pine experiment found 5-year burns kept fuels and bitterbrush low, while 10- and 20-year regimes allowed different shrub and herb-layer outcomes.

Read the Wild Lands assessment →
North America

Short burn intervals reduced fuels most—but also reduced some understory wildlife values

Evidence
Peer-reviewed long-term prescribed-fire experiment
Geography
Dry ponderosa pine forest, western United States
System
Fire-managed ponderosa pine forest

WHAT THE EVIDENCE SAYS

Long-term comparison of roughly 5-, 10- and 20-year prescribed-fire return intervals found the shortest interval most effective at keeping litter and shrub fuels low. Longer intervals retained more of some understory shrubs, including wildlife-useful browse, while plant richness was not strongly reduced across the treatments; longer gaps also allowed less desirable shrub and fern dominance in some settings.

WHY IT MATTERS / OUR READ

For managers, return interval is an objective tradeoff rather than a single optimum. Frequent fire can favor fuel-reduction goals, while somewhat longer or spatially varied intervals may preserve more understory habitat. A mosaic of burn histories may therefore be more useful than imposing one landscape-wide interval when fuels and wildlife objectives both matter.

CAVEATS / UNCERTAINTY

Results come from a dry ponderosa-pine system with its own fire history, soils and understory community. Longer intervals can accumulate fuels and competitive vegetation, and shorter intervals can suppress valued shrubs; the study does not establish one universally correct interval or eliminate the need to adjust timing and intensity to site conditions.

SOURCE

U.S. Forest Service
View original evidence ↗

A long-term ponderosa-pine experiment found five-year prescribed-fire intervals strongest for limiting litter and shrubs, while longer intervals retained more of some wildlife-useful understory structure.

Read the Wild Lands assessment →

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