Short-term effects of post-fire salvage logging intensity and activity on breeding birds in the Sierra Nevada Mountains, USA

Abstract

Background: Salvage logging of fire-killed trees in western US conifer forests has been shown to negatively affect many wildlife species, but there are few quantitative studies from the Sierra Nevada, CA. Salvage intensity (i.e., the proportion of fire-killed trees removed during logging activities) has also rarely been measured; instead, most studies track the presence/absence of salvage activities. We explored the effects of post-fire salvage on the breeding bird community following the 2012 Chips and 2013 Rim fires using a before-after control-impact sample design, and modeled species responses to salvage including a test of whether species responded to salvage intensity or the presence of salvage activities as a whole. Results: Salvage operations removed an average of 71% of the snag basal area in the Chips Fire and 64% in the Rim Fire within 50 m of our salvaged survey locations. Bird species responses to salvage in both fires were largely non-significant or negative (Chips: 11 negative, 4 positive, 19 non-significant; Rim: 13 negative, 4 positive, 20 non-significant). Statistical support for the salvage intensity vs. salvage activity models was split evenly among all species. Positive salvage responders in both fires included species adapted to open habitats and seed consumers, while a wide variety of species, including woodpeckers, species associated with open and dense mature forest, and some shrub nesters, responded negatively to salvage. We also evaluated five salvage prescription scenarios based on snag basal area, salvage intensity, and area treated to determine whether any combination could minimize the negative effects on the salvage-sensitive species yet retain the same salvage yield. The scenarios with the smallest area targeted with high-intensity salvage saw the smallest declines in abundance and diversity, but nearly all scenarios reduced both measures. Conclusions: No combinations of salvage intensity and distribution from among the scenarios we explored were able to fully mitigate the negative effect on the bird community; however, the magnitude of declines in abundance and diversity was smaller than expected, and the majority of the species analyzed had a non-significant response. We recommend targeting salvage activities in the Sierra Nevada to those locations where snags pose a safety issue or where reforestation is most needed to conserve this fire-adapted bird community.