Divergent terrestrial responses of soil N2O emissions to different levels of elevated CO2 and temperature

Understanding soil nitrous oxide (N2O) emissions responses from terrestrial ecosystems to future CO2 enrichment and warming is critical for the development of mitigation and adaptation policies. The continuous increase of elevated CO2 (EC) and elevated temperature (ET) effects on N2O emissions are not fully known. We synthesized 209 measurements from 70 published studies and carried out a meta-analysis to examine individual and interactive effects of EC and ET on N2O emissions from grasslands, croplands, and forests. On average, a significant increase of 23% in N2O emission was observed under EC across all case studies. A sharp increase in the N2O emissions was noticed in the response to EC under less than 150 ppm enrichment levels. Nonetheless, a significant but weak negative response of N2O emission to EC was examined. Compared with non-significant responses of grassland and forest, EC resulted in the highest increase (38%) in N2O emission of cropland. The extent of ET effect on N2O e...探明陆地生态系统（terrestrial ecosystems）土壤一氧化二氮（N₂O）排放对未来二氧化碳富集与气候变暖的响应机制，对于制定温室气体减排与适应政策至关重要。目前学界对于二氧化碳富集（elevated CO₂, EC）与温度升高（elevated temperature, ET）对N₂O排放的持续影响效应尚未完全明晰。本研究整合了70项已发表研究中的209组观测数据，通过荟萃分析（meta-analysis）探究了EC与ET单独及交互作用对草地、农田与森林生态系统N₂O排放的影响。综合所有案例研究结果，EC处理下N₂O排放平均显著提升23%。当CO₂富集水平低于150 ppm时，EC处理会引发N₂O排放的急剧升高。但研究同时发现，EC对N₂O排放存在显著但微弱的负向调控效应。相较于草地与森林生态系统的无显著响应，EC处理对农田N₂O排放的提升幅度最大，达38%。而温度升高（ET）对N₂O排放的影响程度……