青藏高原高寒草甸不同退化阶段植物氮利用速率变化  

Changes in nitrogen uptake rate of plant species in different degradation stages of an alpine meadow on the Qinghai-Tibet Plateau

作　　者：霍佳娟 宋明华[1] HUO Jia-juan;SONG Ming-hua(Key Laboratory of Ecosystem Network Observation and Modeling,Institute of Geographic Sciences and Natural Resources Research,Chinese Academy of Sciences,Beijing 100101,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院地理科学与资源研究所生态系统网络观测与模拟重点实验室,北京100101 [2]中国科学院大学,北京100049

出　　处：《草业学报》2025年第2期16-26,共11页Acta Prataculturae Sinica

基　　金：国家自然科学基金面上项目(32371664);第二次青藏高原综合科学考察研究(2019QZKK0302)资助。

摘　　要：氮(N)是植物生长繁殖的必需元素,以多种形式存在于生态系统中。高寒草甸位置特殊,气候严酷,土壤有效氮匮乏。过度放牧引起草甸发生退化演替,土壤速效养分流失严重,导致植物的氮素利用模式发生改变。以青海省黄南州泽库县高寒草甸为研究对象,选取轻度、中度、重度退化、侵蚀、严重侵蚀以及黑土滩6个退化阶段,利用稳定性同位素15N示踪的方法量化小嵩草对铵态氮(NH_(4)^(+)-N)和硝态氮(NO_(3)^(-)-N)吸收速率沿不同退化阶段的变化,以及草甸退化后期多度较高物种:小嵩草、橐吾、香薷对无机氮利用的差异。结果表明:沿退化序列,小嵩草对总无机氮的吸收速率呈波动下降趋势,其中对NH_(4)^(+)-N的吸收速率同总无机氮的吸收速率变化趋势一致,对NO_(3)^(-)-N的吸收速率呈波动上升趋势。除侵蚀和黑土滩阶段外,小嵩草对NH_(4)^(+)-N的吸收速率均为地下器官显著高于地上器官;除重度退化和黑土滩阶段外,其他阶段小嵩草对NO_(3)^(-)-N的吸收速率均为地下器官显著高于地上器官。退化后期,小嵩草在嵩草占优势斑块和杂草占优势斑块中对NO_(3)^(-)-N吸收方式无显著差异,而其在杂草占优势的斑块中对NH_(4)^(+)-N的吸收速率显著高于嵩草占优势的斑块。杂草斑块中的优势植物橐吾和香薷对NH_(4)^(+)-N和NO_(3)^(-)-N吸收方式差异显著,橐吾对NH_(4)^(+)-N的吸收速率显著高于NO_(3)^(-)-N,而香薷对二者的吸收速率无显著差异。综上,在高寒草甸不同退化阶段,植物物种采用不同的无机氮获取策略适应土壤养分状况,维持自身生存。深入认识草地不同退化阶段植物对土壤无机氮素的吸收利用能够深入理解物种共存机制,进而指导退化草地的合理恢复。Nitrogen(N)is an essential element for plant growth and reproduction,and it exists in various chemical forms in soils.The location of alpine meadows on the Tibetan Plateau is unique,where the climate is severe with low temperature.The low temperature restricts decomposition of soil organic matter and leads to scare available N in the soil,which further limits plant growth.Moreover,overgrazing causes grassland degradation and succession,resulting in severe loss of available nutrients in soil and changes in the N use patterns of plants.In this study,a 15N labeling experiment was conducted in an alpine meadow in Zeku County,Qinghai Province to trace plant utilization of ammonium nitrogen(NH_(4)^(+)-N)and nitrate nitrogen(NO_(3)^(-)-N)in plant communities exhibiting different degradation stages.Six degradation stages,including lightly,moderately,and severely degraded grasslands,and eroded,severely eroded grasslands,and bare black soil,were selected based on prior knowledge on plant community succession during the degradation of the alpine meadows.The uptake rates of NH_(4)^(+)-N and NO_(3)^(-)-N by the dominant sedge species Kobresia pygmaea were measured in the six degradation stages.Additionally,we also quantified the uptake rates of NH_(4)^(+)-N and NO_(3)^(-)-N by forb species Ligularia sibirica and Elsholtzia ciliata,the dominant species in patches in the later degradation stages.The results showed that along the degradation stages,the uptake rate of total inorganic nitrogen by K.pygmaea showed a fluctuating downward trend.The uptake rate of ammonium nitrogen was consistent with the trend of total inorganic nitrogen uptake rate,while the uptake rate of nitrate nitrogen showed a fluctuating upward trend.Except for the erosion and bare black soil stages,the uptake rate of ammonium nitrogen by K.pygmaea is significantly higher in underground organs than in aboveground organs.Except for the severe degradation and bare black soil stages,the uptake rate of nitrate nitrogen by K.pygmaea in underground organs was signif

关 键 词：高寒草甸 退化序列 无机氮的不同化学形态 氮吸收速率 15N示踪技术 

分 类 号：R28[医药卫生—中药学]