Although it has been realized that the maintenance of forest ecosystem structure and function and its response to environmental changes are closely related to root exudation, the effects of warming and soil nutrient availability on the root exudate carbon (C) inputs and soil nitrogen (N) transformation related microbial processes are still not well understood. In this study, a randomized block experiment with two temperatures (control and ambient + 3.5 °C) and two nitrogen treatments (control and 25 g N m⁻² a⁻¹) was conducted to collect the root exudates of P. tabulaeformis seedlings in situ and the microbial processes related to soil N transformation were simultaneously measured. We found that trees exposed to elevated temperature significantly increased their root exudate carbon input in unfertilized plots, and thus stimulating extracellular enzyme activity and enhancing N benefit. In contrast, the effect of warming on root exudate C input and associated soil N transformation greatly reduced after N addition, indicating that the effect of warming on root C cost and N benefit is regulated by the soil nutrient availability. Collectively, our results suggest that the variation in root C cost-N benefit induced by environmental changes is an important physiological regulatory mechanism for maintaining continuous forest growth. This study provides new insights into understanding nutrient maintenance mechanisms for forest productivity and functional stability under climate changes.

尽管已经认识到森林生态系统的结构和功能的维持及其对环境变化的响应与根系分泌物，升温和土壤养分有效性对根系分泌物碳（C）输入和土壤氮（N）的影响密切相关。与转化有关的微生物过程仍然不甚了解。在这项研究中，进行了一个随机分组实验，其中包括两个温度（对照和环境温度+ 3.5°C）和两个氮处理（对照和25 g N m ^-2 a ^-1），以收集油松根系分泌物。同时测量了原位幼苗和与土壤氮转化相关的微生物过程。我们发现，暴露于高温的树木在未受精的地块中显着增加了其根系分泌物的碳输入量，从而刺激了细胞外酶的活性并增强了氮的利用率。相比之下，添加氮后变暖对根系分泌物碳输入和相关土壤氮转化的影响大大降低，表明变暖对根系C成本和氮效益的影响受到土壤养分有效性的调节。总体而言，我们的结果表明，环境变化引起的根C成本-N效益的变化是维持森林连续生长的重要生理调节机制。