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大气CO2浓度升高可能对森林土壤的甲烷(CH4)氧化速率产生影响.本文采用开顶箱技术,对连续6年高浓度CO2(500μmol·mol-1)处理的长白山森林典型树种蒙古栎树下土壤CH4氧化速率进行研究,并利用CH4氧化菌的16SrRNA特异性引物以及CH4单加氧酶功能基因引物分析了土壤中CH4氧化菌的群落结构与数量.结果表明:CO2浓度增高后,生长季土壤甲烷氧化量与对照和裸地相比分别降低了4%和22%;基于16SrRNA特异性引物的DGGE分析表明,CO2浓度增高导致两类甲烷氧化菌的多样性指数降低;CO2浓度增高对土壤中Ⅰ类甲烷氧化菌数量无显著影响,而使土壤中Ⅱ类甲烷氧化菌数量显著减少,功能基因pmoA拷贝数与对照和裸地相比分别降低了15%和46%.CO2浓度增高导致森林土壤甲烷氧化菌数量与活性降低,土壤含水量的增加可能是导致这一现象的主要原因.
Atmospheric CO2 concentration may have an impact on the methane (CH4) oxidation rate in forest soils.In this study, open-top box technology was used to study the effects of high CO2 concentration (500μmol · mol-1) Soil CH4 oxidation rate was studied and the structure and amount of CH4 oxidizing bacteria in soil were analyzed by 16SrRNA specific primers of CH4 oxidizing bacteria and CH4 monooxygenase functional gene primers.The results showed that after CO2 concentration increased, Methane oxidation decreased by 4% and 22% respectively compared with control and bare soil. DGGE analysis based on 16SrRNA specific primers showed that the diversity index of two kinds of methanotrophs decreased with the increase of CO2 concentration. The number of methanotrophic bacteria in class I was significantly reduced, while the number of methanotrophs in class II significantly decreased, while the copy number of functional gene pmoA was reduced by 15% and 46% respectively compared with control and bare land. The quantity and activity of methanotrophs decreased, and the increase of soil water content may be the main reason for this phenomenon.