Bird communities follow alternate recovery trajectories two decades after wildfire

Abstract

Wildfires are altering forested landscapes across western North America. These wildfires are increasingly burning with high severity across large areas and driving the conversion of forest to non-forest. Understanding how longterm vegetation structure differs between low- and high-severity portions of burned landscapes, and how fire severity and post-fire vegetation structure relate to avian species and communities, is crucial for avian conservation efforts. We quantified vegetation structure and avian species composition in low- and high-severity portions of two wildfires - the 2002 Ponil Complex Fire in northern New Mexico and the 2002 Hayman Fire in southern Colorado - two decades after burning. We found long-term divergence in vegetation structure attributes, such as live overstory basal area, overstory canopy cover and 1000-hour fuel loads, between low- and high-severity sites, particularly at the Hayman Fire. We also found dissimilarities in avian species composition between low- and high-severity sites, and higher species richness associated with low-severity sites, higher live overstory basal area, and shorter distances to refugia, indicating that avian species are following alternate recovery trajectories at low- versus high-severity sites. Forest-associated bird species tended to occur at sites with greater overstory canopy cover and low fire severity. Meanwhile, grassland-, shrubland-, and desert-associated bird species were most commonly found in areas with lower overstory canopy cover and high fire severity. Our findings point to the importance of pyrodiversity on the landscape for providing suitable habitat for the greatest number of species, as well as the importance of low-severity patches for supporting forest-associated species that require intact overstory canopy cover. Large high-severity patches as the dominant component of the landscape will likely not support the most diverse or characteristic array of bird species 20 + years post fire.

Citation

Vicini, Maria; Stevens-Rumann, Camille S.; Vogeler, Jody C.; Fornwalt, Paula J. 2025. Bird communities follow alternate recovery trajectories two decades after wildfire. Forest Ecology and Management. 596: 123058.