氮输入对沼泽湿地碳平衡的影响

以小叶章沼泽化草甸为对象,利用静态箱-气相色谱法,在三江平原进行野外原位试验,研究氮输入对沼泽湿地碳平衡及其各分量的影响.氮素输入后,沼泽湿地生态系统总初级生产力提高,生物量增大,分别比对照处理增加了10%和26.8%.同时,CH₄和生态系统呼吸CO₂排放量提高,而生态系统CO₂净交换(NEE)和净碳(CO₂和CH₄都转化成对应的碳)交换降低,CO₂、CH₄和NEE的季节变化动态未改变.2004年整个生长季氮输入处理的CO₂和CH₄排放量分别比对照处理升高了34%和145%,NEE和净碳交换分别降低了70%和81.6%,但整个生长季2个处理仍然表现为碳的净吸收.氮输入没有改变沼泽湿地碳“汇”的功能,只是减弱了其作为碳“汇”的功能.

Effects of Nitrogen Fertilization on Carbon Balance in the Freshwater Marshes

To understand the influence of nitrogen fertilization on the carbon balance in the freshwater marshes,we measured the CO₂ and CH₄ emissions as well as net ecosystem exchange(NEE) of CO₂ using the static chamber and gas chromatogram technique in situ over Deyeuxia angustifolia wetland in Sanjiang Plain.Results from the field observed indicated that fertilization increased the biomass and gross primary productivity(GPP) as well as the CO₂ and CH₄ emissions,while decreased the net ecosystem exchange of CO₂ but not change the seasonal dynamics of CO₂ and CH₄ emissions as well as the NEE.Seasonal amount of CO₂ and CH₄ emission from the fertilization was respectively 34% and 145% higher than that from the control,while the NEE and net carbon exchange decreased 70% and 81.6% due to the nitrogen fertilization.During the whole growing season of 2004 the ecosystem still showed the net uptake of the carbon not only in the fertilization treatment but also control.Thus,it can be assumed that nitrogen fertilization decreased the net carbon uptake from the atmosphere but not changed the ecosystem from a carbon sink to a source.