California wildfires altering ecosystems, disrupting wildlife habitats: Study

Extreme wildfires that have been burning through the California landscape over recent decades are disrupting wildlife habitats within the state, new research shows.

In the past two decades, forest fires in the U.S. have become progressively more intense, frequent and widespread, according to climate scientists and wildfire experts. The fires that have burned large swaths of land in California are reshaping wildlife ecosystems, the study, published Monday in the Proceedings of the National Academy of Sciences, found.

Researchers assessed the impact of the wildfire seasons in 2020 and 2021 on California wildlife by comparing maps of habitats for 508 vertebrate species with indices of fire coverage and severity. Those two seasons are significant because about 58% of the area affected by wildfires in California since 2012 occurred in those years, the researchers said, describing the amount of fire activity during that period as "unprecedented."

The data shows that fires spanned up to 30% of ranges for 50 species, while another 100 species had at least 10% of their habitats burned, according to the paper. Five to 14% of these species’ ranges burned at high severity.

Species responded to the fires differently, the researchers said. Previous studies have found that the great grey owl may survive wildfires better than the long-toed salamander, despite both species experiencing a similar degree of severe habitat disruption during the study period.

The long-toed salamander experienced high-severity fire across a greater portion of its range than any other species examined and has been shown to decline in population one to two decades following severe burns, the researchers said.

The fires did not disproportionately affect species of conservation concern, the researchers said. However, species in the region are not adapted to high-severity megafires.

Of the more than 2.2 million acres that were burned at high severity in 2020 and 2021, 89% occurred in large patches that exceeded historical estimates of high-severity patch size, according to the study. When fire regimes rapidly change, wildlife may be unable to respond appropriately, the researchers said.

The findings show that effective forest management practices such as prescribed fires, managed wildfires and mechanical thinning are needed to help promote the resilience of wildlife habitats in the face of increasingly frequent wildfires.