图2. 氮(N)输入对盐沼湿地土壤有机碳分解的影响(参考Hester et al., 2018 )。微生物过程直接或间接受到氮输入的影响。植物主要吸收铵态氮, 它刺激植物生产力和根际有机质的沉积, 从而刺激根际物质循环, 有利于根际微生物代谢。植物源性碳输入和更高的氮利用性联合刺激微生物异养呼吸, 进而刺激有氧状态下CO₂的产生和排放; 而在厌氧状态下, 过量的硝态氮转化为铵态氮, 增加的铵态氮将抑制CH₄氧化。

Fig. 2. Effect of nitrogen (N) input on decomposition of soil organic carbon in a salt marsh (adapted from Hester et al., 2018 ). Microbial processes are directly or indirectly affected by N input. Plants mainly absorb NH₄⁺-N, which stimulates plant productivity and the deposition of organic matter from the rhizosphere, thus stimulating the material circulation of rhizosphere and the metabolism of rhizosphere microorganisms. Plant derived carbon input and higher N utilization jointly stimulate microbial heterotrophic respiration, and then stimulate the production and emission of CO₂ in aerobic condition. In anaerobic condition, excessive NO₃^--N is converted into NH₄⁺-N, which will inhibit CH₄ oxidation.