TheState of California is depending on its forests to help cut down planet-warmi-组卷网

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The State of California is depending on its forests to help cut down planet-warming CO₂. But that climate-change strategy may be risky, as new research from the University of California, Irvine(UCI)reports that trees in California’s mountains and open spaces are dying from wildfires and other pressures — and fewer new trees are filling the blank.

“The forests are not keeping up with these large fires,” said study co-author James Randerson, the Ralph J. and Carol M. Cicerone Professor of Earth system science at UCI. Acrossthe whole state, tree cover area has dropped 6.7% since 1985. “These are big changes in lessthan forty years,” he said. It’s the first time that researchers have been able to measure tree population fall in California, and find out the reasons(wildfires and woodcutting).

For the study, the UCI-led team used satellite data from the USGS and NASA’s Landsat mission to study plant changes between 1985 and 2021. They found that one of the most obvious falls in tree cover was in southern California, where 14% of the tree population in local mountain had disappeared, maybe everlastingly.

“The ability. of forests to recover(恢复)from fire appears to be dwindling in the south,” said Jonathan Wang, a researcher in Randerson’s research group, who led the study coming out in AGU Advances. “At the same time, the state’s coverage of bushes and grasses is rising, which could mean more everlasting ecosystem shifts(生态系统转化).”

“The speed and scale of fall in tree cover is different across the state. Tree cover in the Sierra Nevada, for example, stayed relatively unchanged until around 2010, then began dropping suddenly. Fortunately, in the north, there’s plenty of recovery after fire,” said Wang, perhaps because of the area’s higher rainfall and cooler temperatures. “This threat(威胁) to California’s climate solutions isn’t going away anytime soon,” Wang said. “We might be entering a new age of bigger fire and vulnerable(易受损的) forests.”

【小题1】What mainly helped California cut down CO₂?