高寒灌丛土壤温室气体释放对添加不同形态氮素的响应

为探索不同形态氮素输入对青藏高原高寒灌丛土壤CO₂、N₂O和CH₄排放的影响，采集青藏高原东部金露梅高寒灌丛土壤，设置1个对照(CK)和3个添加不同形态氮素的处理(NH₄Cl，NH₄NO₃，KNO₃)，在实验室恒温15℃下进行培养，分析了土壤CO₂、N₂O和CH₄的释放量以及土壤NH₄⁺，NO₃^-和可溶性有机碳(DOC)含量。结果表明:1)所有氮素处理抑制了高寒灌丛土壤CO₂的排放，土壤CO₂排放量与DOC浓度呈显著正相关关系;2)所有氮素处理显著增加了土壤N₂O的排放，而且以添加NO₃^--N增加的N₂O最为显著;3)高寒灌丛土壤N₂O的产生过程以反硝化作用为主;4)添加不同形态氮素对高寒灌丛土壤CH₄吸收没有显著影响。5)不同形态氮素施入后，高寒灌丛土壤温室气体全球增温潜能(GWP)顺序:KNO₃>NH₄NO₃>NH₄Cl>CK。

Response of soil greenhouse gas emissions to different forms of nitrogen in alpine shrub ecosystems

In order to understand the effects of N addition with different chemical forms on greenhouse gas (CO₂, N₂O and CH₄) emission from the alpine shrub meadow on Qinghai-Tibetan Plateau. Four treatments including a control (CK), no nitrogen plus three forms of nitrogen (NH₄Cl, NH₄NO₃, KNO₃) were applied in Hongyuan County, eastern Qinghai-Tibetan Plateau. A composite sample of the top 15 cm of soil taken from each treatment was incubated at the lab at 15℃. Emissions of CO₂, CH₄ and N₂O from the incubated soil and the soil mineral nitrogen (NH₄⁺ and NO₃^-) and dissolved organic carbon (DOC) were determined. The results showed that all the nitrogen addition treatments inhibited soil CO₂ emission which was significantly, positively correlated with soil DOC concentration. Addition of nitrogen significantly increased soil N₂O emissions, the highest N₂O emissions were found with NO₃^--N addition. There were no treatment differences in soil CH₄ absorption. The results suggest that application of NH₄⁺-N rather than NO₃^--N will reduce greenhouse gas emissions in Tibetan alpine shrub ecosystems.