Fuel loading after steep slope salvage logging in the southern Rocky Mountains

Recent bark beetle outbreaks in western North America have raised concerns due to their frequency, impact, and geographic extent. These outbreaks can pose a heightened risk of intense wildfires by increasing the fuel load. In the Southern Rocky Mountain region, bark beetle outbreaks have led to millions of standing dead trees, prompting consideration of salvage treatments. Many of these treatments would occur on steep slopes using innovative harvesting equipment, such as winch-assisted cut-to-length harvesters, to remove standing dead stems. While salvage treatments aim to recover economic value and reduce fire risk, the ecological impacts from these treatments remain understudied, including what impact they have on wildfire woody fuel loading. Our study examined the impacts of winch-assisted cut-to-length salvage harvesting on fuel loads in subalpine and montane forest in southern Colorado. We assessed fuel loads in nine forest stands in treated and untreated areas and found that salvage logging significantly increased most fine woody surface fuels in both montane and subalpine forests. We also recorded a reduction of the standing dead fuels in montane and subalpine canopies by over 90 %. We did not observe significant differences in coarse woody material (CWM) loads for either forest type. Our results indicate that winch-assisted salvage logging may reduce the probability of canopy fires, while potentially increasing the risk of ground fires.