Carbon and Nitrogen Cycles Continually Adjust Under Global Change

This study is led by Dr. Shuli Niu (Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences). The study revealed that processes of both carbon and nitrogen cycles continually adjust under global change, leading to dynamic coupling in carbon and nitrogen cycles.

The study made a comprehensive review of ecosystem carbon and nitrogen processes under global change. The review shows that nitrogen input mostly stimulates plant primary productivity, decreases microbial activities, hardly increases soil carbon sequestration but considerably increases nitrogen loss by nitrogen leaching and nitrogenous gas emissions. Carbon input under rising atmosphere CO₂ concentration, climate warming, or along ecosystem succession stimulates nitrogen fixation and mineralization but decreases nitrogen leaching to support plant growth and ecosystem carbon sequestration. The carbon and nitrogen processes continually adjust under global change to couple with each other under a new dynamic equilibrium.

The shifts in carbon-nitrogen coupling have important implications for modeling ecosystem carbon sequestration under global change. The ecosystem carbon sequestration may be overestimated under nitrogen input and be underestimated under elevated CO₂ when the ecosystem models fail to simulate these dynamic adjustments of carbon and nitrogen cycles.