不同氮素形态对湿地小叶章氮吸收和N2O排放的影响

氮素生物地球化学循环和减缓温室气体排放已成为全球（气候）变化研究的热点问题,氮素有效性是调控全球变化反馈机制的重要因子。本研究以东北三江平原小叶章湿地为研究对象,采用¹⁵N示踪技术,通过野外原位控制实验,研究湿地植物小叶章对不同氮素形态(NH⁺₄、NO^-₃、NH⁺₄-NO^-₃)的吸收及小叶章N₂O排放通量特征。结果表明：(1)不同氮素形态处理下,小叶章叶生物量表现为处理A>NA>N>CK;A处理,茎生物量最大,比对照提高了35.7%;NA处理,地下生物量显著高于A和CK(P<0.05);NA处理,根冠比最大,是对照的1.82倍。(2)不同氮素形态处理下,小叶章叶、茎、地上以及根氮含量显著高于对照(CK)(P<0.05),不同处理之间氮含量差异不显著(P<0.05)。(3)不同氮素形态处理下,小叶章叶、茎以及地上部分Ndff和¹⁵N含量均表现为处理A>N>NA>CK,并且各处理极显著高于对照(P<0.01),各处理之间达到显著差异(P<0.05)。(4)不同氮素形态处理下,处理N湿地N₂O排放量最多,且显著高于处理A和处理NA(P<0.05),处理N、A、NA显著高于对照(CK)(P<0.05)。阐释了不同形态氮素在植物-土壤-大气系统中周转与分配策略,以及对N₂O排放的影响,为湿地氮生物地球化学和温室气体排放研究提供基础数据。

Effects of Different Nitrogen Forms on Nitrogen Uptake and N2O Emission of Calamagrostis angustifolia in Wetland

Nitrogen biogeochemical cycles and mitigation of greenhouse gas emission have become a hot topic in global climate change research. Nitrogen availability is an important factor in the feedback mechanism of global climate change regulation. This research used a small Calamagrostis angustifolia wetland in the Sanjiang Plain of northeast China as the research object and adopted ¹⁵N tracer technique to study the uptake of different nitrogen forms (NH₄⁺, NO₃^-, NH⁺₄-NO^-₃) by C. angustifolia and its N₂O emission flux through field in situ control experiments. The results showed as follows. (1) Under different nitrogen forms, the biomass of C. angustifolia leaf showed: A>NA>N>CK; the stem biomass of treatment A was the largest, which was 35.7% higher than that of CK; the underground biomass of treatment NA was significantly higher than that of treatment A and CK (P<0.05); the root-shoot ratio of treatment NA was the largest, which was 1.82 times that of CK. (2) Under different nitrogen forms, the nitrogen contents in leaf, stem, aboveground part and root were significantly higher than those of CK (P<0.05), but there was no significant difference in nitrogen contents among different treatments (P<0.05). (3) Under different nitrogen forms, the contents of Ndff and ¹⁵N in leaf, stem and aboveground part showed: A>N>NA>CK, and each treatment had significantly higher content than that of CK (P<0.01), and there was a significant difference among all the treatments (P<0.05). (4) Under different nitrogen forms, the N₂O emission was the highest in treatment N, significantly higher than that of treatment A and NA (P<0.05), and the N₂O emission of treatment N, A and NA were significantly higher than that of CK (P<0.05). This study discussed the cycling and distribution strategies of different nitrogen forms in the plant-soil-atmosphere system, as well as their effects on N₂O emission, it will provide basic data for the research on wetland nitrogen biogeochemistry and greenhouse gas emission.