模拟氮沉降对色季拉山高寒草地土壤养分的影响

Effects of Simulated Nitrogen Deposition on Soil Nutrients in Alpine Grassland in Sejila Mountains

草地作为我国最大的陆地生态系统,对我国的生态文明建设具有不可估量的价值,在发挥生态系统服务功能等方面具有十分重要的作用。本试验以西藏林芝市巴宜区色季拉山高寒草地为研究对象,共设置对照CK、低氮LN、中氮MN和高氮HN(0、10、15、20 kg N·hm^(-2)·a^(-1))4种处理,研究0~20 cm高寒草地土壤中养分含量变化,探讨不同程度的氮沉降量对土壤养分的影响。结果表明:(1)在LN、MN到HN的模拟氮沉降过程中,土壤有机质、有机碳、碱解氮和可溶性总氮含量相比于CK处理均有显著增加,增幅在28.59%~65.27%之间,可溶性有机碳含量仅在MN下显著增加,增加了35.35%,易氧化有机碳在LN处理下抑制效果最强,达到72.92%,pH值在LN与HN添加下显著下降了15.67%和17.48%;(2)模拟氮沉降下色季拉山高寒草地土壤不同理化性质之间呈现显著相关关系。结论说明,土壤有机质和碳氮相关养分含量对模拟氮沉降均比较敏感,不同氮沉降水平下对色季拉山高寒草地养分有显著影响,且多数养分之间均有显著相关系,表明高寒草地不同养分之间存在紧密联系。

As the largest land ecosystem in our country,grassland has the inestimable value to our country's ecological civilization construction,and has the vital role in play the ecosystem service function.In this study,four treatments including CK,LN,MN and HN(0,10,15,20 kg N•hm^(-2)•a^(-1))were set in the alpine grassland of Sejila Mountain in Nyingchi County,Tibet,to study the changes of soil nutrient content in 0~20 cm alpine grassland,and to explore the effects of different degrees of nitrogen deposition on soil nutrients.The results showed that in the simulated N deposition process from LN,MN to HN,the contents of soil organic matter,organic carbon,alkalihydrolyzed nitrogen and total soluble nitrogen increased significantly compared with CK treatment,with an increase of 28.59%to 65.27%.The content of soluble organic carbon only increased significantly under MN,with an increase of 35.35%.The inhibition effect of easily oxidized organic carbon under LN treatment was the strongest,reaching 72.92%,and the pH value was significantly decreased by 15.67%and 17.48%under the addition of LN and HN.There was a significant correlation between soil physical and chemical properties in the alpine grassland of Sejila Mountain under simulated N deposition.It was concluded that soil organic matter and carbon and nitrogen related nutrients were sensitive to simulated N deposition.Different N deposition levels had significant effects on nutrients in alpine grassland of Sejila Mountain,and most nutrients had significant correlation with each other,indicating that there was a close relationship between different nutrients in alpine grassland.