By measuring N₂O fluxes along an elevation gradient from 313 to 2,901 meters above sea level, the team discovered that alpine grasslands may become increasingly important sources of this potent greenhouse gas under future climate scenarios.
Nitrous oxide is nearly 300 times more powerful than carbon dioxide over a 100-year period and is also a major ozone-depleting substance. Globally, soils account for more than 60% of atmospheric N₂O emissions, largely through microbial processes known as nitrification and denitrification. Arid and semi-arid ecosystems cover roughly 40% of the Earth’s land surface but have historically been considered minor contributors to global N₂O budgets due to limited water availability. However, northern China’s arid regions are experiencing warmer and wetter conditions under climate change, potentially stimulating microbial nitrogen cycling and greenhouse gas release. At the same time, agricultural intensification—including irrigation and fertilizer use—has dramatically altered soil nutrient dynamics. Yet little is known about how elevation and land use interact to control N₂O emissions in arid mountain landscapes.
A study (DOI: 10.48130/nc-0025-0022) published in Nitrogen Cycling on 23 January 2026 by Longfei Yu’s team, Tsinghua University, provides new insight into how both natural and managed soils in northwestern China could amplify climate feedbacks in a rapidly changing environment.
Using in situ chamber-based N₂O flux measurements combined with analyses of soil physicochemical properties, inorganic nitrogen substrates, nitrogen-cycling functional genes (amoA, nirK, nirS, nosZ), and multivariate statistics including regression, principal component analysis (PCA), and random forest modeling, the researchers investigated how vegetation type and elevation jointly regulate N₂O emissions. At low elevation, cropland soils exhibited N₂O fluxes two orders of magnitude higher than natural ecosystems (mean 181.32 µg N m⁻² h⁻¹), coinciding with greater soil moisture, relatively high inorganic N availability, and elevated functional gene abundance, indicating strong denitrification potential under irrigation and fertilization. In contrast, barelands showed negligible or even negative fluxes under extremely dry conditions despite inorganic N accumulation. Grassland soils emitted modest N₂O at low elevation but showed a clear increase with elevation, reaching 11.09 µg N m⁻² h⁻¹ at 2,901 m. This trend paralleled rising water-filled pore space (R² = 0.58, p < 0.001), declining pH, and increased abundances of AOA and nirK, while nosZ abundance declined, suggesting enhanced incomplete denitrification under wetter conditions. Forest soils displayed the opposite elevational pattern: higher emissions at low elevation (up to 10.21 µg N m⁻² h⁻¹) and sharp declines at higher elevations. Here, N₂O fluxes were strongly linked to soil temperature (R² = 0.46, p < 0.001) rather than moisture, and denitrification gene abundances decreased with elevation despite increasing soil carbon and nitrogen pools. PCA and random forest analyses consistently identified moisture and denitrification genes as dominant predictors in grasslands, whereas temperature and organic nutrient variables were the primary controls in forests, demonstrating contrasting regulatory mechanisms along the elevation gradient.
Overall, the study indicates that warming and increased precipitation in arid northern China may turn alpine grasslands into emerging N₂O hotspots by stimulating moisture-driven denitrification. It also underscores the dominant contribution of irrigated croplands, where fertilization and dry–wet cycles trigger strong emission pulses, highlighting the need for improved nitrogen management. Furthermore, expanding planted forests in desert oases may carry unintended greenhouse gas costs under shifting climatic conditions.
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References
DOI
10.48130/nc-0025-0022
Original Souce URL
https://doi.org/10.48130/nc-0025-0022
Funding information
This work was financially supported by the National Natural Science Foundation of China (NSFC Grant No. 42577331), and the Guangdong Basic and Applied Basic Research Foundation (Grant No. 2025B1515020013). Longfei Yu acknowledges support from the Scientific Research Start-up Funds (Grant No. QD2022010C) from Tsinghua Shenzhen International Graduate School, and the Tianchi Talent Programme of Xinjiang Uygur Autonomous Region.
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