高寒灌丛土壤温室气体释放对添加不同形态氮素的响应

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

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。

In order to understand the effects of N addition with different chemical forms on greenhouse gas（CO2,N2 O 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 N2 O emissions,the highest N2 O 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.