模拟海平面上升和氮负荷增加对河口感潮沼泽湿地CO2垂直交换的影响

海平面上升和氮负荷增加是入海河流河口面临的两个主要全球性环境问题.揭示河口潮滩沼泽湿地CO₂垂直通量对二者及交互作用的响应，对于科学评估全球变化背景下的河口潮滩沼泽湿地生态系统蓝碳功能具有重要的科学意义.本研究以闽江河口鳝鱼滩中潮滩短叶茳芏湿地为研究对象，在野外原位实施模拟海平面上升、氮负荷增加及二者交互作用的实验处理近1年后，在2019年冬季各月的大潮日白天涨潮前、平潮期及落潮后3个阶段，运用透明静态箱（或遮光布遮光）+Li-6800光合作用仪对短叶茳芏湿地生态系统净CO₂交换（NEE）和生态系统呼吸（ER）进行测定.结果发现，与对照处理相比，冬季尺度3种处理下短叶茳芏湿地生态系统NEE均显著增加；模拟海平面上升影响下短叶茳芏湿地生态系统ER无显著变化；氮负荷增加及二者交互作用下，短叶茳芏湿地ER均显著增加.模拟海平面上升、氮负荷增加及二者交互作用情景下，短叶茳芏湿地生态系统总初级生产力（GPP）均明显增加.研究表明，在未考虑甲烷排放的情景下，即使在冬季，海平面上升、氮负荷增加及二者交互作用将可能增加亚热带河口潮滩半咸水沼泽湿地的碳汇功能.

Effects of simulated sea level rise and nitrogen enrichment on net ecosystem exchange of CO2 of Cyperus malaccensis marsh in the Min River estuary

Sea level rise and nitrogen enrichment are two major global environmental issues facing estuarine wetlands. It is important to reveal response of net ecosystem exchange of CO₂ and blue carbon sink of estuarine tidal marshes to the above two environmental issues under the background of global change. This study applied in-situ experimental manipulations of sea-level rise (SR), nitrogen enrichment (NE) and SR+NE within a tidal brackish marsh (the Min River estuary, southeast China) dominated by Cyperus malaccensis over one year. Using transparent static chamber (or black cloth shading)+Li-6800 method, we measured the net ecosystem CO₂ exchange (NEE) and the ecosystem respiration (ER) at three stages during the spring tide days:exposed prior to before flooding, slack water period and exposed-after ebb. Compared with the control treatment, the NEE of the C. malaccensis marsh all significantly increased in the three treatments (SR, NE and SR+NE) at winter scale; however there was no significant change in the ER in the SR treatment. Under the three treatments, the GPP of the C. malaccensis marsh significantly increased. The results suggested that during the winter, without considering methane emissions, sea level rise, nitrogen enrichment, and the interaction between them may increase the carbon sink function of sub-tropical estuarine brackish tidal marshes.