Nitrous oxide (N₂O) is one of the most important greenhouse gases and has the potential to aggravate global warming. Arbuscular mycorrhizal (AM) fungi form mutualistic associations with most terrestrial plants, which can help plant nitrogen (N) uptake and have also been shown to reduce soil N₂O emissions. However, the development and species community composition of AM fungi are influenced by warming and N deposition. To date, the mechanism by which warming, N deposition, and AM fungi interactively affect soil N₂O emissions in the field is still poorly understood. We implemented elevated temperature and N addition treatments in a 5-year experiment in a semiarid temperate meadow to examine the impact of AM fungi on soil N₂O fluxes under the treatment conditions. Both elevated temperature and N deposition and the combination of the two significantly increased soil N₂O emissions. AM fungi reduced soil N₂O emissions under elevated temperature and N deposition. The decrease in soil N₂O emissions by AM fungi was lower under elevated temperature than N deposition. Under elevated temperature, the AM fungal decrease in soil N₂O emissions was mainly determined by the abundance of the functional genes ammonia-oxidizing bacteria (AOB) and nosZ, while the AM fungal reduction in soil N₂O emissions was mainly affected by soil microbial biomass carbon under N deposition. These results indicate that although AM fungi could reduce soil N₂O emissions the pathway by which AM fungi regulate soil N₂O emissions might vary under different global change contexts with elevated temperature or nitrogen deposition. Our results highlight the negative effect of AM fungi on soil N₂O emissions under elevated temperature and N deposition and show that the influence of AM fungi on N₂O emissions might be simultaneously determined by warming, N deposition and ecosystem types. The results of the study help to evaluate the potential role of AM fungi in reducing N₂O emissions from grassland ecosystems in the context of future global change and provide a theoretical basis for sustainable grassland management.

一氧化二氮 (N ₂ O) 是最重要的温室气体之一，有可能加剧全球变暖。丛枝菌根 (AM) 真菌与大多数陆生植物形成共生关系，这有助于植物吸收氮 (N) 并已显示可减少土壤 N ₂ O 排放。然而，AM真菌的发育和物种群落组成受变暖和氮沉降的影响。迄今为止，变暖、N 沉积和 AM 真菌相互作用影响田间土壤 N ₂ O 排放的机制仍知之甚少。我们在半干旱温带草甸的 5 年试验中实施了高温和 N 添加处理，以检查 AM 真菌对土壤 N _{2 的影响}处理条件下的 O 通量。升高的温度和N 沉积以及两者的结合显着增加了土壤N ₂ O 排放。AM 真菌在升高的温度和 N 沉积下减少了土壤 N ₂ O 排放。AM 真菌对土壤 N ₂ O 排放的减少在升高的温度下低于 N 沉积。在升高的温度下，AM 真菌减少土壤 N ₂ O 排放主要取决于功能基因氨氧化细菌（AOB）和nosZ的丰度，而 AM 真菌减少土壤 N ₂O排放主要受氮沉降下土壤微生物生物量碳的影响。这些结果表明，虽然AM真菌能减少土壤氮素_2个O排放通路通过该AM真菌调节土壤氮素₂ O排放可能根据与升高的温度下或氮气沉积不同的全局变化的上下文而变化。我们的研究结果强调了 AM 真菌在升高的温度和 N 沉积下对土壤 N ₂ O 排放的负面影响，并表明 AM 真菌对 N ₂ O 排放的影响可能同时由变暖、N 沉积和生态系统类型决定。研究结果有助于评估 AM 真菌在减少 N ₂方面的潜在作用未来全球变化背景下草原生态系统的O排放，为可持续草原管理提供理论基础。