As if California’s natural habitat hadn’t already been through enough over the last few years, a recently published aerial survey of its vast forests by a federal agency has estimated that millions of trees died in 2022 because of drought, high temperatures, insects, disease and overcrowded forests.
The survey, conducted by the U.S. Forest Service from July to October, estimated that 36 million trees had died across a 2.6 million acre area, which is about the size of Rhode Island and Delaware combined.
In 2021, the same survey counted 9.5 million dead trees in the state.
The report details the latest ecological setback for a state in perpetual drought and at constant risk from wildfires. New threats have also emerged, like the atmospheric rivers that brought torrential rain and flooding over the winter.
Researchers surveyed more than 40 million acres of federal, state and private land.
Of the 36 million dead trees, approximately 77% were true firs, according to the report.
However, Douglas firs showed the biggest mortality rate increase. Around 3 million were found to be dead, an increase of 1,650% over the previous year. They were primarily seen in the central Sierra Nevada Range.
Aside from being a valuable resource for the furniture industry, Douglas firs provide food for small mammals, including chipmunks, mice, shrews and red squirrels. Bears eat the sap and songbirds consume the seeds direct from the cones. Raptors also use old-growth Douglas firs for cover.
Of the true firs, red and white make up the largest casualties in 2022, combining for a total of 28 million dead trees. Most of the dead trees were found in Northern California, close to the city of Redding, including the Shasta-Trinity National Forest and surrounding areas.
The severe drought has exacerbated disease and bark beetle infestations, which typically attack weakened, dying or dead spruce, fir and hemlock.
Healthy trees can usually fight off beetle infestations, but with greater competition for scarce water, trees become weakened, according to one California-based expert.
“The real problem here is that our forests are far too dense,” Ryan Tompkins, a forester and natural resources advisor at the University of California Cooperative Extension, told the Los Angeles Times. “And when these forests are really dense, trees are competing for a finite amount of water, particularly in a dry year. While we see these periodic droughts and these periodic tree mortality events, some of this is driven because we’ve normalized these very dense forests.”
Tompkins also said that aside from drought and beetles, extinguishing wildfires allowed trees to survive and grow stronger and bigger - making the competition for water far worse.
California’s wildfires burned 4.3 million acres in 2020 and 2.5 million in 2021, according to CalFire stats. Last year saw less than 500,000 acres burned in the state.
But there have been far worse years for dead trees in California.
At the height of California’s drought in 2016, the U.S. Forest Service counted 100 million dead trees. By 2017, the figure had dropped to 27 million; by 2019, it had fallen to 15 million.
Unfortunately, many of California’s forests are not coming back, according to Jon Wang, assistant professor at the University of Utah.
“The way climate change affects these forests, primarily, is by making the atmosphere hotter,” he told NPR, referring to research he published last year about California’s forest regrowth. “The warmer it gets, the more water that each of these trees needs.”
Without enough water, the trees are more susceptible to disease and wildfires. That’s when the beetles strike.
California has proposed spending billions on wildfire resilience and forest health to combat the issue. The $2.7 billion multiyear spending package through 2026 will help thin out dense forests in strategic areas, spray insecticide on barks of high-value trees, remove trees hazardous to public safety, and monitor landscape conditions.
“Forest health is a top priority for the Forest Service,” said Jennifer Eberlien, Regional Forester for the Pacific Southwest Region, in a press release. “The agency’s 10-year strategy to address the wildfire crisis includes removal of dead and dying trees in the places where it poses the most immediate threats to communities. Working together, we can mitigate the risks of tree mortality and high-intensity wildfire by reducing the overabundance of living trees on the landscape.”