[Effects of elevated CO2 on forest soil CH4 consumption in Changbai Mountains].

Elevated atmospheric CO2 concentration may affect the oxidation rate of methane (CH4 ) in forest soil. In this study, the effects of a 6-year exposure to elevated CO2 concentration (500 micromol x mol(-1)) on the soil microbial process of CH4 oxidation under Quercus mongolica seedlings were investigated with open top chamber (OTC), and specific 16S rRNA and pmoA gene fragment primers were adopted to analyze the diversity and abundance of soil methanotrophs. Comparing with that under ambient CO2 and open-air, the soil methane consumption under elevated atmospheric CO2 during growth season was reduced by 4% and 22%, respectively. The specific 16S rRNA PCR-DGGE analysis showed that under elevated CO2, the community structure of methane-oxidizing bacteria (MOB) changed, and the diversity index decreased. Elevated CO2 concentration had no distinct effects on the abundance of Type I MOB, but decreased the amount of Type II MOB significantly. The pmoA gene copy number under elevated CO2 concentration decreased by 15% and 46%, respectively, as compared with that under ambient CO2 and open-air. Our results suggested that elevated atmospheric CO2 decreased the abundance and activity of soil methanotrophs, and the main cause could be the increase of soil moisture content.