California is counting on its forests for carbon dioxide reduction. This element of California’s climate change solution may be in danger, according to University of California Irvine research. The University of California Irvine has reported that California’s mountains and open spaces are suffering from wildfires, and that fewer trees are being planted.
James Randerson (the Ralph J. Cicerone Professor Earth system science at UCI) said that the forests aren’t keeping up with large fires. In the state, the tree area has dropped 6.7 percent from 1985 to 1985. He said, “These are significant changes in less than forty decades.”
This is the first time researchers have been able measure the declines of tree populations in California.
UCI’s team used satellite data from NASA and the USGS to study changes in vegetation between 1985 and 2021. They discovered that Southern California had the most severe declines in tree coverage. In this region, 14 percent disappeared from the tree population of local mountain ranges. This could be a permanent loss.
Jonathan Wang, a Randerson postdoctoral researcher, said that the ability of forests to recover after fire seems to be declining in the south. He was the lead in the study published in AGU Advances. “At the exact same time, the state’s cover of shrubs, grasses, and trees is increasing, which could indicate more permanent ecosystem shifts.”
The state’s rate of decline and the extent of it vary. For instance, tree cover in Sierra Nevada was stable until about 2010, after which it started dropping rapidly. The 8.8% Sierra Nevada tree death coincided in severe drought that lasted from 2012 to 2015. This was followed by the worst wildfires of state history, including Creek Fire in 2020.
Wang said that “in the North, there’s plenty recovery after fire”, perhaps due to the region’s cooler temperatures and higher rainfall. Even so, the visible effects of high-fire years in 2020 and 2021 are evident.
Randerson stated that the tree loss has also affected the state’s carbon storage capabilities. Randerson added that the next step will be to accurately quantify the forest’s ability to absorb anthropogenic Carbon dioxide. Michael Goulden (a UCI professor in Earth system science and the director of the Center for Ecosystem Climate Solutions) is the co-author. He uses the data to study how changes in forest cover affect water resources, carbon storage, and fire behavior throughout the state.
Wang stated, “This threat to California’s climate solutions isn’t going away anytime soon.” “We may be entering a new era of extreme fire and fragile forests.”
Clarke Knight, UC Berkeley’s John Battles are co-laborators. The California Strategic Growth Council, the UC National Laboratories Grant Program and NASA long-term funding were all part of the support for the research.