Abstract: With the intensification of global climate change, the area, intensity, and frequency of droughts continue to increase. The content and composition of root exudates (such as sugars, amino acids, and organic acids) will change, thereby affecting carbon and nitrogen cycling in forests. However, how the content and composition of root exudates vary with drought intensity and tree species, as well as the mechanisms of root exudates in mediating carbon and nitrogen cycles under drought conditions, remain unclear. Therefore, we first summarized the effects of drought intensity on the content and composition of forest root exudates and the responses of root exudates across different tree species. Secondly, the mechanisms of root exudates on soil carbon and nitrogen cycles under drought conditions were analyzed from two aspects of soil carbon and nitrogen. Finally, it is suggested that future research should focus on strengthening the following four aspects: (1) the effects of different drought intensities and recovery on the composition and content of forest root exudates; (2) the soil priming effect mediated by root exudates; (3) the microbial regulation mechanisms of carbon and nitrogen cycles mediated by root exudates; (4) the intra and inter-specific interactions mediated by root exudates.

Key words: drought, forest ecosystem, root exudate, carbon cycling, nitrogen cycling