Megafire smoke exposure jeopardizes tree carbohydrate reserves and yield

The global incidence of megafires is on the rise, leading to extensive areas being shrouded in dense smoke for prolonged periods, spanning days or weeks1. Here, by integrating long-term regional observations of non-structural carbohydrate content in trees across California’s Central Valley with spatiotemporal satellite data, we present compelling evidence that dense smoke plumes negatively impact carbohydrate stores in three tree species: Prunus dulcis, Pistacia vera and Juglans regia. Our findings show that the presence of smoke causes a significant decrease in total non-structural carbohydrates, with reductions in the accumulation of both soluble sugar and starch reserves. This decline in carbohydrate levels persists through the trees’ dormancy period into the next season’s bloom, culminating in a reduced yield. Our results highlight a previously unrecognized wildfire threat that could affect plant health and ecosystem stability in both agricultural and natural environments. The incidence and severity of megafires are increasing as a consequence of global change. While the impacts of fires on tree physiology and ecosystem functioning are well studied, how smoke affects these processes is less clear. Here Orozco et al. report that wildfire smoke significantly reduces tree carbohydrate reserves and yields, revealing an overlooked consequence of wildfires.