Abstract: The rise of Megafires in California is largely attributed to warming climate shifts, increasing drought events, and suppressive fire management practices. In 2020, California experienced the largest wildfire in its history, which resulted in hazy smoke conditions that persisted for months and enveloped the Central Valley. Smoke has the potential to affect both the quality and quantity of light that reaches plants, which could ultimately impact their productivity. However, limited evidence currently exists on the effects of smoke on plant physiology. By utilizing remote sensing techniques in conjunction with a long-term non-structural carbohydrate dataset, we can gain insight into these effects. Notably, the optical depth values observed in September 2020 were significantly different from the average values observed over the past 20 years, indicating an unusually high level of smoke in the atmosphere during that period. These anomalous optical depth values were found to be correlated with lower non-structural carbohydrate values in both October, November and December. The reduction in carbohydrate values was linked to reduced stomatal activity as indicated by an increase in δ13C. The relationship between smoke exposure and reduced plant productivity may have significant implications for ecosystems and agriculture in fire-prone regions like California. Therefore, understanding the effects of smoke on plant physiology is crucial in developing effective management strategies to mitigate the impacts of wildfires.
