Key Laboratory of Soil and Water Conservation and Desertification Combating in Hunan Province, College of Forestry, Central South University of Forestry and Technology, Changsha, China.
School of Atmospheric Sciences, Sun Yat-sen University, and Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, China.
Glob Chang Biol. 2022 Nov;28(21):6404-6418. doi: 10.1111/gcb.16365. Epub 2022 Aug 15.
Soil moisture (SM) is essential to microbial nitrogen (N)-cycling networks in terrestrial ecosystems. Studies have found that SM-atmosphere feedbacks dominate the changes in land carbon fluxes. However, the influence of SM-atmosphere feedbacks on the N fluxes changes, and the underlying mechanisms remain highly unsure, leading to uncertainties in climate projections. To fill this gap, we used in situ observation coupled with gridded and remote sensing data to analyze N O fluxes emissions globally. Here, we investigated the synergistic effects of temperature, hydroclimate on global N O fluxes, as the result of SM-atmosphere feedback impact on N fluxes. We found that SM-temperature feedback dominates land N O emissions by controlling the balance between nitrifier and denitrifier genes. The mechanism is that atmospheric water demand increases with temperature and thereby reduces SM, which increases the dominant N O production nitrifier (containing amoA AOB gene) and decreases the N O consumption denitrifier (containing the nosZ gene), consequently will potential increasing N O emissions. However, we find that the spatial variations of soil-water availability as a result of the nonlinear response of SM to vapor pressure deficit caused by temperature are some of the greatest challenges in predicting future N O emissions. Our data-driven assessment deepens the understanding of the impact of SM-atmosphere interactions on the soil N cycle, which remains uncertain in earth system models. We suggest that the model needs to account for feedback between SM and atmospheric temperature when estimating the response of the N O emissions to climatic change globally, as well as when conducting field-scale investigations of the response of the ecosystem to warming.
土壤湿度（SM）对陆地生态系统中的微生物氮（N）循环网络至关重要。研究发现，SM-大气反馈主导着陆地碳通量的变化。然而，SM-大气反馈对 N 通量变化的影响及其潜在机制仍高度不确定，这导致了气候预测的不确定性。为了填补这一空白，我们使用现场观测结合网格化和遥感数据来分析全球 N O 通量排放。在这里，我们研究了温度、水热气候对全球 N O 通量的协同影响，这是 SM-大气反馈对 N 通量影响的结果。我们发现，SM-温度反馈通过控制硝化和反硝化基因之间的平衡来主导陆地 N O 排放。其机制是大气水分需求随温度升高而增加，从而导致 SM 减少，这增加了主要的 N O 产生硝化菌（含 amoA AOB 基因），减少了 N O 消耗反硝化菌（含 nosZ 基因），从而可能增加 N O 排放。然而，我们发现，由于温度引起的水汽压亏缺对 SM 的非线性响应，土壤水分可用性的空间变化是预测未来 N O 排放的最大挑战之一。我们的数据驱动评估加深了对 SM-大气相互作用对土壤 N 循环影响的理解，这在地球系统模型中仍然不确定。我们建议，在全球范围内估计 N O 排放对气候变化的响应以及在进行生态系统对变暖的响应的现场调查时，模型需要考虑 SM 和大气温度之间的反馈。
