Nitrogen allocation in PM 2.5 smoke-exposed plants: implications for ecosystem nitrogen cycling and stress response

Background With the increase in forest fire emissions, an increasing amount of nitrogen is released from combustibles and taken up by plant leaves in the form of PM 2.5 smoke deposition. Concurrently, the stress from PM 2.5 also disrupts the physiological processes of plants. This study aims to reveal the migration paths of N in combustibles in smoke and plants during forest fires and the stress response of plant leaves to smoke particle deposition. This study conducted a simulated smoke deposition treatment on Schima superba and Cunninghamia lanceolata , analyzing the changes in plant 15 N content and stress-related products. Results The main findings include the following: (1) Nitrogen in combustibles can be transported to plant leaves via PM 2.5 smoke during combustion and can be allocated and assimilated in various parts of the plant after being absorbed by the leaves. (2) The stress response of Schima superba to PM 2.5 is less pronounced than that of Cunninghamia lanceolata . (3) Under PM 2.5 stress, the correlation between nitrogen accumulation in the leaves of Schima superba and Cunninghamia lanceolata and their respective stress responses differs. Conclusions In forest fires involving different tree species, there are variations in the migration pathways of nitrogen and the stress effects of PM 2.5 on leaves, with a significant correlation observed between leaf nitrogen accumulation and stress response. Graphical Abstract