尕海湿地不同退化阶段土壤氮转化的关键微生物功能基因

The key microbial functional gene of soil nitrogen transformation in different degradation stages of Gahai wetland

明确湿地退化对土壤氮素转化微生物基因丰度的影响,为认识湿地的退化机理以及科学治理高寒退化湿地提供重要依据。以尕海湿地未退化、轻度退化、中度退化和重度退化4种不同退化程度土壤为研究对象,用实时荧光定量PCR技术检测固氮菌(nifH)、氨氧化古菌(AOA-amoA)、氨氧化细菌(AOB-amoA)和反硝化菌(nirK)基因丰度,分析功能基因丰度在不同退化阶段的变化特征。结果表明:0~10 cm土层4种功能基因丰度均显著高于10~20 cm土层,nifH、AOA、AOB和nirK基因丰度的变化范围为10^(6)~10^(8)、10^(7)-10^(8)、10^(5)~10^(6)和10^(7)-10^(8)copies·gsoil,且AOA丰度显著高于AOB丰度;4种基因丰度均在轻度退化阶段达到最大值,中度和重度退化阶段显著降低;土壤理化性质对微生物功能基因的解释率达到了87.9%和91.2%,但不同月份关键驱动因子不同;在6月,土壤含水量是功能基因丰度变化的关键因子,而在8月,氮素是基因丰度变化的关键因子。

Clarifying the effects of wetland degradation on nitrogen-transforming gene abundance of soil microorganisms provides an important basis for understanding wetland degradation mechanism and scientific management of degraded alpine wetlands.We detected the gene abundance of nitrogen-fixing bacteria(nifH),ammonia oxidizing archaea(AOA-amoA),ammonia oxidizing bacteria(AOB-amoA)and denitrifying bacteria(nirK)in Gahai wetland soils under four different degrees of degradation(non-degraded,lightly degraded,moderately degraded and severely degraded),by real-time fluorescent quantitative PCR technology.We further analyzed the characteristics of functional gene abundances under different degradation stages.The results showed that the abundances of the four functional genes were significantly higher in the 0-10 cm soil layer than that in the 10-20 cm soil layer.The gene abundance of nifH,AOA,AOB and nirK ranged 10^(6)~10^(8),10^(7)-10^(8),10^(5)-10^(6)and 10^(7)-10^(8)copies·gsoil,respectively,while the abundance of AOA was significantly higher than that of AOB.The abundances of the four genes peaked in the lightly degraded stage,and significantly decreased in the moderately and severely degraded stages.The interpretation rates of soil physical and chemical properties for the variations of soil microbial functional genes were 87.9%and 91.2%,respectively,with the key drivers differing in different months.Soil water content was the key factor affecting gene abundance in June,while nitrogen content was the key factor driving the variations of gene abundance in August.