Following megafires fishes thrive and amphibians persist even in severely burned watersheds

https://doi.org/10.1038/s43247-025-02893-y

Communications Earth & Environment, November 2025

Authors
Allison G. Swartz, Oregon State University
Ashley A. Coble, NCASI
Brooke E. Penaluna, United States Forest Service (USFS) Pacific Northwest Research Station
Rebecca L. Flitcroft, United States Forest Service (USFS) Pacific Northwest Research Station
Joseph L. Ebersole, United States Environmental Protection Agency
Meg A. Krawchuk, Oregon State University

Abstract
Wildfires are increasing in severity, frequency and size, potentially threatening freshwater species that adapted under different disturbance regimes. However, few wildfire studies have comprehensively evaluated freshwater populations and assemblages following wildfire over broad spatial scales while accounting for post-fire salvage practices in the watershed. We reveal that stream vertebrate assemblages across thirty 4th order streams, spanning a range of both watershed fire severity and post-fire forest management extent, were minimally influenced by immediate effects of fire alone (absent of channel reorganization events). Greater total taxa, total fish, and adult trout densities were associated with streams draining more severely burned watersheds, whereas sculpin, amphibian and crayfish densities appeared uninfluenced by burn severity. Greater extent of post-fire watershed salvage practices was negatively associated with frog densities and positively with young-of-year trout and crayfish densities. Our findings indicate fishes thrive, and amphibians and crayfish persist despite experiencing high-severity megafires in the western Cascades of Oregon.

Keywords: Fire ecology, Forest ecology, Freshwater ecology