title: Responses of Methanogenic and Methanotrophic Communities to Elevated Atmospheric CO2and Temperature in a Paddy Field.
abstract: Although climate change is predicted to affect methane (CH4) emissions in paddy soil, the dynamics of methanogens and methanotrophs in paddy fields under climate change have not yet been fully investigated. To address this issue, a multifactor climate change experiment was conducted in a Chinese paddy field using the following experimental treatments: (1) enrichment of atmospheric CO2concentrations (500 ppm, CE), (2) canopy air warming (2°C above the ambient, WA), (3) combined CO2enrichment and warming (CW), and (4) ambient conditions (CK). We analyzed the abundance of methanogens and methanotrophs, community structures, CH4production and oxidation potentials,in situCH4emissions using real-time PCR, T-RFLP, and clone library techniques, as well as biochemical assays. Compared to the control under CE and CW treatments, CH4production potential, methanogenic gene abundance and soil microbial biomass carbon significantly increased; the methanogenic community, however, remained stable. The canopy air warming treatment only had an effect on CH4oxidation potential at the ripening stage. Phylogenic analysis indicated that methanogens in the rhizosphere were dominated byMethanosarcina, Methanocellales, Methanobacteriales, andMethanomicrobiales, while methanotrophic sequences were classified asMethylococcus, Methylocaldum, Methylomonas, Methylosarcina(Type I) andMethylocystis(Type II). However, the relative abundance ofMethylococcus(Type I) decreased under CE and CW treatments and the relative abundance ofMethylocystis(Type II) increased. Thein situCH4fluxes indicated similar seasonal patterns between treatments; both CE and CW increased CH4emissions. In conclusion results suggest that methanogens and methanotrophs respond differently to elevated atmospheric CO2concentrations and warming, thus adding insights into the effects of simulated global climate change on CH4emissions in paddy fields.
authors.affiliation: Department of Bioengineering, College of Life Science, Huaibei Normal University Huaibei, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Institute of Resources, Ecosystem and Environment of Agriculture, Nanjing Agricultural University Nanjing, China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Liu
authors.affiliation: Institute of Resources, Ecosystem and Environment of Agriculture, Nanjing Agricultural University Nanjing, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Cheng
authors.affiliation: Institute of Resources, Ecosystem and Environment of Agriculture, Nanjing Agricultural University Nanjing, China.
authors.forename: Lianqing
authors.initials: L
authors.lastname: Li
authors.affiliation: Institute of Resources, Ecosystem and Environment of Agriculture, Nanjing Agricultural University Nanjing, China.
authors.forename: Xuhui
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Institute of Resources, Ecosystem and Environment of Agriculture, Nanjing Agricultural University Nanjing, China.
authors.forename: Jufeng
authors.initials: J
authors.lastname: Zheng
authors.affiliation: Institute of Resources, Ecosystem and Environment of Agriculture, Nanjing Agricultural University Nanjing, China.
authors.forename: Jinwei
authors.initials: J
authors.lastname: Zheng
authors.affiliation: Institute of Resources, Ecosystem and Environment of Agriculture, Nanjing Agricultural UniversityNanjing, China; Zhejiang Provincial Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration, School of Environmental and Resource Sciences, Zhejiang A & F University, Lin'anHangzhou, China.
authors.forename: Genxing
authors.initials: G
authors.lastname: Pan
keywords: elevated CO2; methanogen; methanotroph; paddy field; warming