Abstract: This study was aimed to study the response of soil nitrogen components of wet meadows in the Qinghai-Tibet Plateau to the degree of nitrogen addition,analyze the environmental and ecological problems that may occur after a large amount of nitrogen is input into the ecosystem,and contribute to the ecological construction,environmental protection and rational use of wet meadows Provide scientific basis. The wet meadow soil in the Gahai-Zecha National Nature Reserve in Luqu County,on the northeastern edge of the Qinghai-Tibet Plateau,were used as the research object. Four treatments including a blank control (CK),low concentration nitrogen addition (N₅),medium concentration nitrogen addition (N₁₀) and high concentration nitrogen addition (N₁₅) were set up to analyze the soil nitrogen composition under different nitrogen concentration treatments,and the vertical and seasonal changes of the content (ammonium nitrogen,nitrate nitrogen,soluble organic nitrogen). The results showed that nitrogen addition increased the content of soil nitrogen components in a dose dependent manner. In the vertical section of the soil,the nitrogen content of the soil decreased as the depth of the soil layer increased. During the plant growth season,the higher soil nitrogen content after nitrogen addition treatment appeared at the end of plant growth.This study shows that nitrogen addition can significantly promote the increase of soil available nitrogen in wet meadows on the Qinghai-Tibet Plateau.

Key words: Qinghai-Tibet Plateau, Wet meadow, Soil nitrogen component, Nitrogen added

摘要： 为研究青藏高原湿草甸土壤氮组分对氮添加程度的响应规律,分析氮素大量输入生态系统后可能产生的环境和生态问题,本研究以青藏高原东北边缘碌曲县尕海-则岔国家自然保护区境内的湿草甸土壤为研究对象,设置空白对照(CK,0 g·m^-2)、低浓度(N₅,5 g·m^-2)、中浓度(N₁₀,10 g·m^-2)和高浓度(N₁₅,15 g·m^-2)4种处理,分析不同氮添加下的土壤氮组分含量(铵态氮、硝态氮、可溶性有机氮)的垂直和季节变化。结果表明:不同氮添加处理均能增加土壤氮组分含量,其增加程度依次为N₅＞N₁₀＞N₁₅＞CK;在土壤垂直剖面上,土壤氮组分含量随土层深度增加而降低;在植物生长季内,氮添加处理后的土壤氮组分含量较高值出现在植物生长末期。本研究表明氮添加对青藏高原湿草甸土壤有效氮的增加具有显著促进作用。

关键词: 青藏高原, 湿草甸, 土壤氮组分, 氮添加