Researchers from the Institute of Applied Ecology, Chinese Academy of Sciences, and the University of California, Riverside have investigated how forest soil gaseous nitrogen losses (NO, N₂O, and N₂) respond to climate warming, highlighting their critical role in regulating forest nutrient cycling and ecosystem functioning.

For decades, climate models have predicted that warming will accelerate nitrogen (N) cycling and increase gaseous N losses. However, most previous warming studies relied on manual or low-frequency sampling and often focused only on N₂O, overlooking NO and N₂. As a result, the full picture of gaseous nitrogen loss under climate warming has remained unclear.

To address this gap, the team conducted research at the Qingyuan Forest Warming Experiment in Northeast China—the world’s largest infrared forest-warming platform. This site offers an unparalleled opportunity to examine soil gaseous nitrogen emissions under controlled, long-term warming conditions.

Their study represents the first in situ quantification of warming effects on both NO and N₂O emissions in a forest ecosystem. Remarkably, the researchers collected more than 200,000 automated, real-time gas measurements over six years—far exceeding the temporal resolution of any previous study.

Contrary to longstanding expectations based on laboratory-derived temperature sensitivities (Q₁₀), experimental warming of 2°C reduced, rather than increased, soil gaseous nitrogen emissions. Annual NO emissions declined by 19%, while N₂O emissions decreased by 16%.

The reduction in N emissions could not be explained by enhanced microbial reduction to N₂, greater plant N uptake or leaching, or changes in N cycling gene abundance. Instead, the researchers found that warming-induced soil drying, although modest, was sufficient to suppress microbial N transformations that generate gaseous losses.

Overall, the study challenges key assumptions built into many ecosystem and climate models, which often rely on laboratory parameters that do not fully capture field conditions. The findings underscore the importance of high-resolution, long-term field observations for understanding how ecosystems respond to a warming world.

The findings address a critical knowledge gap with broad implications for climate science and ecosystem management, helping to promote a new wave of ecosystem modeling to account for these unexpected changes in N cycling.

The study entitled "Climate warming reduces soil gaseous nitrogen losses in a temperate forest" was published in Proceedings of the National Academy of Sciences.