长期氮沉降和地上凋落物处理对半干旱区沙质草地表层土壤碳氮组分的影响

Effects of Long-term Nitrogen Deposition and Aboveground Litter Treatment on Top Soil Carbon and Nitrogen Fractions in the Semi-arid Sandy Grassland

为揭示半干旱区沙质草地生态系统中表层土壤C、N组分对长期氮添加和地上凋落物处理的响应特征,以科尔沁沙地西南部国家野外科学观测研究站建立的长期(9年)氮添加和凋落物处理样地为平台,测定并分析该样地表层土壤环境因子、铵态氮、硝态氮、总有机碳、不同碳氮组分。结果表明:(1)持续9年的氮添加和地上凋落物处理对表层土壤环境因子和不同碳氮组分无交互作用;(2)氮添加处理显著降低土壤pH(p<0.01),增加土壤中硝态氮的含量(p<0.05),其增长幅度为37.57%,并显著增加溶解性有机氮(DON)和易变活性氮(LON)的含量(p<0.01,p<0.05);(3)地上凋落物去除显著降低土壤总有机碳(TOC)、易变缓性碳(IOC)、微生物生物量碳(MBC)和微生物生物量氮(MBN)含量(p<0.05);(4)经过9年氮添加和地上凋落物处理,半干旱区沙质草地表层土壤中不同碳氮组分与土壤环境因子间相关性并不密切。即长期氮添加和地上凋落物处理会改变表层土壤不同碳、氮组分的含量,但并未显著改变各碳、氮组分的比值。研究结果为揭示长期氮添加和地上凋落物处理对半干旱区沙质草地土壤C、N贮存和预测未来土壤生物地球化学元素动态研究提供参考资料。

In order to reveal the response characteristics of surface soil carbon(C)and nitrogen(N)components to long-term addition of N and aboveground litter treatment in semi-arid sandy grassland ecosystem,a long-term(9-year)N addition and litter treatment sample plot established by the National Field Scientific Observation and Research Station in the southwest of Horqin Sandy Land was taken as the platform.The surface soil environmental factors,ammonium nitrogen,nitrate nitrogen,total organic carbon(TOC)and different C and N components were measured and analyzed.The results showed that:(1)There was no interaction between surface soil biochemical factors and different C and N properties during 9 years of N addition and aboveground litter treatment.(2)The N addition treatment significantly reduced soil pH(p<0.01),significantly increased soil nitrate nitrogen content(p<0.05)by 37.57%,and the contents of dissolved organic nitrogen(DON)and labile organic nitrogen(LON)were significantly increased(p<0.01,p<0.05).(3)The treatment of aboveground litter removal significantly reduced the contents of TOC,intermediate organic carbon(IOC),microbial biomass carbon(MBC)and microbial biomass nitrogen(MBN)(p<0.05).(4)After 9 years of N addition and aboveground litter treatment,there was no close correlation between different C and N components and soil environmental factors in semi-arid sandy grassland.The above results showed that long-term addition of N and aboveground litter could change the contents of different C and N components in the surface soil,but did not significantly change the ratio of each C and N component.This study provides a reference for revealing the effects of long-term addition of N and aboveground litter treatment on soil C and N storage and predicting future soil biogeochemical element dynamics in sandy grassland in semi-arid region.