Is “Fuel Reduction” Justified as Fire Management in Spotted Owl Habitat?

Chad T Hanson

doi:10.3390/birds2040029

Abstract

The California Spotted Owl is an imperiled species that selects mature conifer forests for nesting and roosting while actively foraging in the “snag forest habitat” created when fire or drought kills most of the trees in patches. Federal agencies believe there are excess surface fuels in both of these habitat conditions in many of California’s forests due to fuel accumulation from decades of fire suppression and recent drought-related tree mortality. Accordingly, agencies such as the U.S. Forest Service are implementing widespread logging in Spotted Owl territories. While they acknowledge habitat degradation from such logging, and risks to the conservation of declining Spotted Owl populations, agencies hypothesize that such active forest management equates to effective fuel reduction that is needed to curb fire severity for the overall benefit of this at-risk species. In an initial investigation, I analyzed this issue in a large 2020 fire, the Creek Fire (153,738 ha), in the southern Sierra Nevada mountains of California. I found that pre-fire snag density was not correlated with burn severity. I also found that more intensive forest management was correlated to higher fire severity. My results suggest the fuel reduction approach is not justified and provide indirect evidence that such management represents a threat to Spotted Owls.

Highlights

The Creek Fire began on 4 September 2020 in the Big Creek drainage north of the town of Shaver Lake, California, with lightning identified by the U.S Forest Service as the most likely cause
There was a significant inverse correlation between intensity of fuel-reduction management and percent high-severity fire, with the fuel-reduction logging categories experiencing the highest fire severity and the lowest fire severity occurring in forests that had previous prescribed fire or wildfire
Within the forest types inhabited by California Spotted Owls, high-severity fire occurrence was not higher overall in unmanaged forests and was not associated with the density of pre-fire snags from recent drought in the Creek Fire, contrary to expectations under the fuel reduction hypothesis

Summary

Introduction

U.S federal forestlands is to implement widespread active management for the stated purpose of reducing fuels, primarily to curb fire severity. Such management includes commercial thinning, which involves substantial removal of small and mature live trees along with removal of many snags. It includes pre-commercial thinning of small trees [1]. Mixed-severity wildfires are often viewed as events that increase combustible fuel by creating many new snags [1].

Methods

Results

Conclusion