The frequent and massive megafires in places like Canada and the American west have led to a lot of research on the impact of smoke on humans but there has been less study of the effects of smoke on plant health. Researchers at the University of California, Davis have found that trees are just as vulnerable as humans are to the harmful effects of long-term exposure to smoke.
The Davis researchers studied almond, pistachio, and walnut trees at 467 orchard sites in California’s Central Valley from 2018 to 2022. In 2022, so-called megafires burned more than 4.2 million acres in California, pouring ash and smoke into the sky. The researchers had been studying how trees store carbohydrates to cope with heat and drought.
With the onset of the fires, they saw an opportunity to study how smoke affects carbohydrate levels. Trees use stored carbohydrates to sustain them through winter dormancy and spring growth. Trees produce carbohydrates via photosynthesis and thick smoke blocks the amount of light reaching the trees. Beyond that, there are other aspects of wildfire smoke, such as particulate matter and ozone that appear to affect photosynthesis.
The team found that the smoke not only reduced the amount of carbohydrates in trees but also caused losses that continued even after the fires were extinguished. This led to nut yield decreases of 15% up to 50% in some orchards. The researchers expected to see some impact on the trees during periods when smoke was really dense but were not expecting the smoke to have such a lingering effect and result in a significant drop in yield.
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Smoke From Megafires Puts Orchard Trees at Risk
Photo, posted October 1, 2008, courtesy of Suzi Rosenberg via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio
