氮输入对滨海盐沼湿地碳循环关键过程的影响及机制

Effects of nitrogen input on carbon cycle and carbon budget in a coastal salt marsh

滨海盐沼湿地是缓解全球变暖的有效蓝色碳汇,但是近岸海域富营养化导致的大量氮输入对盐沼湿地稳定性和碳汇功能构成严重威胁。潮汐作用下大量氮输入对盐沼湿地植物光合碳输入、植物-土壤碳分配和土壤碳输出等碳循环关键过程产生深刻影响,进而影响盐沼湿地碳汇功能评估的准确性。该文从植物光合固碳、植物-土壤系统碳分配、土壤有机碳分解、土壤可溶性有机碳释放、盐沼湿地土壤碳库5个方面综述了氮输入对盐沼湿地碳循环关键过程的影响。在此基础上,针对当前研究的不足,提出今后的研究中,需要进一步探究氮输入对盐沼湿地植物光合固碳及碳分配过程的影响、盐沼湿地土壤有机碳分解的微生物机制、盐沼湿地土壤可溶性有机碳产生和横向流动的影响、以及氮类型对盐沼湿地土壤碳库的影响。以期为揭示氮输入对盐沼湿地碳汇形成过程与机制提供基础资料和理论依据,为评估未来近岸海域水体富营养化影响下滨海盐沼湿地碳库的潜在变化提供新思路。

Coastal salt marshes are an effective blue carbon sink to mitigate climate warming,but their ecosystem stability and carbon sink function are threatened by the large amount of nitrogen input caused by coastal eutrophication.Under the action of regular tides,the high nitrogen content in the coastal waters will have a profound effect on the key processes of carbon cycle such as plant photosynthetic carbon fixation,carbon allocation in plant-soil system,and soil carbon release in the salt marsh.This study reviewed the effects of nitrogen input on plant photosynthetic carbon fixation,carbon allocation in plant-soil system,decomposition of soil organic carbon,formation and release of soil dissolved organic carbon(DOC),and carbon sequestration in the salt marsh.Based on the shortcomings of current research,this review proposed the directions of future research,including the effects of nitrogen input on plant photosynthetic carbon fixation and carbon allocation in plant-soil system,the microbial mechanism of soil organic carbon decomposition,production and lateral exchange of soil DOC,and the potential impact of different forms of nitrogen input on soil carbon sequestration in the salt marsh.Overall,this study aims to improve the understanding of impacts of nitrogen input on the key carbon processes and the mechanisms of carbon sequestration in a salt marsh,and to provide new ideas for assessing the potential changes of carbon pools under the influence of eutrophication of coastal waters in the salt marsh wetlands.