Effect of atmospheric nitrogen deposition and its components on carbon flux in terrestrial ecosystems in China.

Long-term atmospheric nitrogen (N) deposition increases bioavailable N in terrestrial ecosystems, thereby influencing ecosystem productivity. However, how N deposition and its components (i.e., NO-N and NH-N) influence the spatial pattern of productivity in terrestrial ecosystems in China remains unknown. Here, we utilize published data including carbon (C) fluxes from eddy flux tower (gross ecosystem productivity, ecosystem respiration, and net ecosystem productivity) and the corresponding climate and N deposition data for 60 typical ecosystems in China. The objective was to investigate the effect of N deposition on ecosystem productivity and explore the variations of N use efficiency (NUE). Our results reveal that atmospheric total N deposition is significantly correlated with C fluxes of terrestrial ecosystems in China. Ecosystems respond variably to different components of N deposition. In detail, forest ecosystem marginally correlated with NO-N and wet deposition, while grassland ecosystem significantly correlated with NH-N and dry deposition. NUE of productivity induced by N deposition in Chinese terrestrial ecosystems was 53.95 ± 40.30 g C g N, and it was influenced by precipitation and aridity index. This study quantifies the contribution of total N deposition and its associated components to productivity in terrestrial ecosystems in China, offering vital information for regional C and N management.