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青藏高原高寒草甸退化对土壤氮素转化微生物基因的影响
王向涛1,2,3, 张超4, 廖李荣3,4, 王杰4, 喻岚辉3,4, 张宪洲2,3,5
1.西藏农牧学院 动物科学学院, 西藏 林芝 860000;2.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, 拉萨高原生态试验站, 北京 100101;3.中国科学院大学, 北京 100049;4.西北农林科技大学 水土保持研究所, 陕西 杨凌 712100;5.中国科学院大学 资源与环境学院, 北京 100190
摘要:
[目的] 深入分析高寒草甸退化过程中土壤氮素转化特征,明确草甸退化对土壤氮素转化微生物基因丰度的影响,为认识高寒草甸的退化机理以及科学治理高寒退化草甸提供重要依据。[方法] 以青藏高原不同退化程度高寒草甸(未退化、轻度退化、中度退化、重度退化)为研究对象,利用实时定量PCR法分析退化过程中土壤理化性质及与氮素转化相关基因(nifH,amoA-AOA,amoA-AOB,narG,nirK,nirS和nosZ)丰度的变化,明确影响高寒草甸氮素转化基因的关键因子。[结果] ①随退化程度的加剧,高寒草甸土壤有机碳、全氮、硝态氮及铵态氮含量逐渐降低;②高寒草甸退化降低了与氮素转化相关的固氮nifH基因、氨氧化amoA-AOA和amoA-AOB基因丰度,但增加了反硝化narG,nirS和nirK基因丰度,且在重度退化草甸丰度最高;③nifH,amoA-AOA和amoA-AOB基因与土壤有机碳、硝态氮、铵态氮及水分呈显著正相关,narG,nirS和nirK基因与土壤有机碳、硝态氮及铵态氮含量呈显著负相关,与pH值呈显著正相关。[结论] 高寒草甸退化对氮素转化微生物具有重要影响,土壤有机碳、pH值及水分是影响土壤氮素转化微生物基因的主要因素。
关键词:  高寒草甸  功能基因  土壤性质  氮素
DOI:10.13961/j.cnki.stbctb.2020.03.002
分类号:S812.2
基金项目:国家自然科学基金项目“藏北高寒草地土壤种子库与植物多样性的关联及对草地恢复的作用机制”(41761008);国家重点研发计划“西藏退化高寒生态系统恢复与重建技术及示范”(2016YFC0502001)
Effects of Degradation of Alpine Meadow on Soil Microbial Genes in Nitrogen Transformation in Qinghai-Tibet Plateau
Wang Xiangtao1,2,3, Zhang Chao4, Liao Lirong3,4, Wang Jie4, Yu Lanhui3,4, Zhang Xianzhou2,3,5
1.College of Animal Science, Tibet Agriculture and Animal Husbandry College, Linzhi, Tibet 860000, China;2.Lhasa National Ecological Research Station, Key Laboratory of Ecosystem Network Observation and Modelling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China;3.University of Chinese Academy of Sciences, Beijing 100049, China;4.Institute of Soil and Water Conservation, Northwest A&F University, Yangling, Shaanxi 712100, China;5.College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100190, China
Abstract:
[Objective] The characteristics of nitrogen (N) transformation in degraded alpine meadows and identify the effects of meadow degradation on the gene abundance of soil nitrogen-transforming microorganisms were studied thoroughly, in order to provide a basis for understanding the degradation mechanism and scientific management of alpine meadows.[Methods] A soil survey along a degraded gradient, including undegraded, lightly degraded, moderately degraded, and severely degraded meadows, in the Qinghai-Tibetan alpine region was conducted. The changes in soil physicochemical properties and genes in N transformation (including nifH, amoA-AOA, amoA-AOB, narG, nirK, nirS, and nosZ) were investigated by using real-time quantitative PCR method, and the drivers of these functional genes were clarified.[Results] ① The contents of soil organic carbon (SOC), total N, nitrate N, and ammonium N decreased along the degradation gradient. ② Degradation led to a significant reduction in the abundance of nifH, amoA-AOA, and amoA-AOB genes, whereas it caused an increase in the abundance of narG, nirS, and nirK genes, which was the maximum in the severely degraded meadow soils. ③ The abundance of the nifH, amoA-AOA, and amoA-AOB genes was significantly positively correlated with the contents of SOC, nitrate N, ammonium N, and soil moisture. The abundance of the narG, nirS, and nirK genes was significantly negatively correlated with the contents of SOC, nitrate N, and ammonium N, whereas it was positively correlated with the pH value.[Conclusion] The degradation of the alpine meadows had an important influence on the microorganisms involved in N transformation. The SOC, pH value, and moisture were the significant drivers of the functional genes in soil nitrogen-transforming microorganisms in alpine meadow soils.
Key words:  alpine meadow  functional gene  soil property  nitrogen