Soil nitrogen regulates root carbon secretion in the context of global change: A global meta-analysis

The secretion of root exudates plays a crucial regulatory role in the process of soil carbon cycling. It is also significantly affected by global change factors (GCFs), yet the general patterns of these changes have not been fully explored, which greatly limits the accurate establishment of carbon cycling models under the background of global change. To address this, we conducted a meta-analysis that included 1926 data pairs to examine the effects of global variability on root exudates. Furthermore, we performed multi-model inference using Akaike's information criterion (AIC) to assess the relative importance of multiple factors such as annual average temperature (AAT), type of ecosystem, intensity of treatment, duration and more. The findings revealed that GCFs generally improved the production of root exudates. While the addition of nitrogen and its interaction with increased temperature significantly reduced the rate of root carbon secretion, all other factors significantly promoted it. Interestingly, as the intensity of warming increased, the rate of root carbon secretion caused by warming displayed a downward trend, with a threshold of 3.6 degrees C. Furthermore, the influence of GCFs on root carbon secretion was found to be regulated by soil nitrogen, confirming the importance of nutrients from the rhizosphere in this process. These results underscore the importance of GCFs in root exudates and emphasize the crucial role of soil total nitrogen in the regulation of root carbon secretion. They also provide valuable scientific parameters for the development of more accurate models for the global-change carbon cycle.Read the free Plain Language Summary for this article on the Journal blog. Read the free Plain Language Summary for this article on the Journal blog.image