Prolonged exposure to wildfire smoke may be depleting energy reserves in California orchards, reducing nut production by up to half, a new study finds.
After a large fire, smoke can affect such trees for months, with widespread effects on seasonal flowers and subsequent harvests, according to research published Wednesday.natural plants.
“While many studies have focused on the effects of smoke on humans, there are fewer studies on the effects of smoke on plant health,” said lead author Jessica, a postdoctoral fellow in plant sciences at the University of California, Davis. Orozco said in a statement. .
“Our research suggests that trees are just as vulnerable as humans,” she added.
Orozco and his colleagues studied almond, pistachio, and walnut trees in 467 orchards in California's Central Valley, the state's agricultural heartland, from 2018 to 2022.
Scientists initially focused on how trees store energy in the form of carbohydrates during heat and drought. But after massive wildfires in 2020 burned 4.2 million acres across the state, they expanded their efforts to study how smoke affects carbohydrate levels.
The authors pointed out that smoke particles not only block some of the sun's rays, but can also affect the photosynthesis process by reflecting light.
The new light source actually helps trees produce more carbohydrates, but dense smoke prevents the light from making up for the significant loss, according to the study.
Instead, the authors found that smoke can interfere with carbohydrate storage in trees, both during a fire and in its aftermath. Making matters worse is the fact that wildfires are typically most active during the time when trees begin to store carbohydrates for winter sustenance.
“Photosynthesis produces carbohydrates, which are essential for tree survival,” Orozco said. “Trees need carbohydrates not only to grow, but also to store energy when they are under stress or when photosynthesis is not occurring.”
The researchers found that fruit yields in orchards affected by large-scale fires decreased by 15 to 50 percent, depending on location.
The authors characterized the effects of these large fires as “clear evidence that sustained exposure to high levels of smoke leads to widespread reductions in energy reserves.”
Although it remains unclear which components of smoke cause its depletion, the researchers noted that ozone and particulate matter are known to affect photosynthesis.
“We expected some impact, especially in the months when the smoke was so thick, but we didn't expect the smoke impact to last this long and lead to such a significant reduction in yield,” Orozco said. he added.
