Dying Trees from Frequent Wildfires in California Might Not Grow Back, Scientists Warn

Scientists have calculated the rate of dying trees in California and how it changed over time, providing previously unheard-of detail about the deteriorating trees over 37 years.

In a recent study that was published in AGU Advances, the co-authors used LANDSAT satellite data to show how the tree cover in California changed between 1985 and 2021 as a result of logging, wildfires, and droughts.

California has lost about 6.7% of its tree cover over that time, with the majority of the loss occurring as a result of "mega-fires" since 2010, according to a study co-author, Jonathan Wang.

He wrote that despite a brief period of growth in the 1990s brought on by more rainfall and less tree-cutting. He also said that a lot of the loss happens in the scorching, dry summer. Additionally, he stated that "climate warming" might increase the vulnerability of forests.

Wildfires

James Randerson, another co-author of the study, said that with such large fires, the forests are unable to keep up. Randerson is from the University of California-Irvine. He added that the past forest fires have caused significant changes in less than four decades, referring to the loss of trees.

One of the sharpest decreases in forest cover was seen in Southern California, where 14% of the local mountain range's tree population disappeared, possibly permanently.

Wang emphasized that the southern region of California is significantly drier and hotter than the northern Sierra Nevada mountains, and the trees there are already at the very edge of their viability.

Lower Rate of Successful Regrowth

Wang claimed that rapidly rising temperatures and protracted droughts are impeding forests' ability to recover from disturbances by, for instance, making it more difficult for seeds to germinate after a fire.

Wang, a post-doctoral researcher who led the study, pointed out that in the south, forests' capacity to recover from fire seems to be declining. At the same time, the growth of grasses and shrubs in the state may portend longer-lasting changes to the ecosystem.

In terms of the research's next steps, Wang wrote that he and his associates were surprised by the insufficiency of recovery in Southern California's forests, which raises doubt in his mind about the ability of the Golden State to sequester carbon and achieve net-zero emissions targets.

The research team is working to develop an extensive map of above-ground biomass to better understand the weakness and dispersion of the state's forest carbon stocks, according to Wang, who also noted that California is relying on its forests to help it meet its climate action goals.

A history of fire suppression has resulted in a dangerous buildup of fuels in California's forests, which is causing even more catastrophic wildfires, according to Wang. As a result, Wang wrote, they also look to use these datasets to better understand how prescribed fire and forest management are affecting the severity of wildfire throughout the state.

Even though the mega-fires of 2018, 2020, and 2021 severely damaged some areas, Wang confirmed that the northern part of the state has recovered well from the fires. He attributed this to its cooler temperatures and higher rainfall patterns.

The threat to California's climate solutions, he continued, is not going away any time soon. It's possible that California is about to enter a period of intense fires and threatened forests, Newsweek reports.