Responses of Soil N2O Emission and CH4 Uptake to N Input in Chinese Forests across Climatic Zones: A Meta-Study

Abstract

Enhanced nitrogen (N) deposition has shown significant impacts on forest greenhouse gas emissions. Previous studies have suggested that Chinese forests may exhibit stronger N2O sources and dampened CH4 sinks under aggravated N saturation. To gain a common understanding of the N effects on forest N2O and CH4 fluxes, many have conducted global-scale meta-analyses. However, such effects have not been quantified particularly for China. Here, we present a meta-study of the N input effects on soil N2O emission and CH4 uptake in Chinese forests across climatic zones. The results suggest that enhanced N inputs significantly increase soil N2O emission (+115.8%) and decrease CH4 uptake (−13.4%). The mean effects were stronger for N2O emission and weaker for CH4 uptake in China compared with other global sites, despite being statistically insignificant. Subtropical forest soils have the highest emission factor (2.5%) and may respond rapidly to N inputs; in relatively N-limited temperate forests, N2O and CH4 fluxes are less sensitive to N inputs. Factors including forest type, N form and rate, as well as soil pH, may also govern the responses of N2O and CH4 fluxes. Our findings pinpoint the important role of Southern Chinese forests in the regional N2O and CH4 budgets.

Four decades of full-scale nitrous oxide emission inventory in China

“…S8 ). Previous studies based on a meta‐analysis [ 44 ], a conceptual model [ 29 ], and an ensemble of terrestrial biosphere model showed that atmospheric N deposition enhances natural soil N 2 O emissions [ 45 ], which was consistent with our results. Apart from the effect of atmospheric N deposition, climate change leaded to an increase of 1.6 Gg N 2 O yr −1 for soil N 2 O emissions ( Fig.…”

The Responses of N2O, CO2 Emissions, and Bacterial Communities to Nitrogen Addition in Saline–Alkaline Wetlands of Northeast China

“…In this study, N addition significantly positively affected soil N 2 O emissions in three points, with similar phenomena observed in irrigated maize in a Mediterranean agroecosystem [27]. N addition tends to promote N 2 O emissions, and it has been found that among the various factors affecting soil N 2 O emissions, the amount of N application is the most decisive [28,29]. The nitrification process gradually depletes the soil of energy materials and easily decomposable organic N, so the gas emissions gradually stabilize in the later stages [30].…”