Responses of Methanogenic and Methanotrophic Communities to Elevated Atmospheric CO2 and 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 CO2 concentrations (500 ppm, CE), (2) canopy air warming (2°C above the ambient, WA), (3) combined CO2 enrichment and warming (CW), and (4) ambient conditions (CK). We analyzed the abundance of methanogens and methanotrophs, community structures, CH4 production and oxidation potentials, in situ CH4 emissions using real-time PCR, T-RFLP, and clone library techniques, as well as biochemical assays. Compared to the control under CE and CW treatments, CH4 production 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 CH4 oxidation potential at the ripening stage. Phylogenic analysis indicated that methanogens in the rhizosphere were dominated by Methanosarcina, Methanocellales, Methanobacteriales, and Methanomicrobiales, while methanotrophic sequences were classified as Methylococcus, Methylocaldum, Methylomonas, Methylosarcina (Type I) and Methylocystis (Type II). However, the relative abundance of Methylococcus (Type I) decreased under CE and CW treatments and the relative abundance of Methylocystis (Type II) increased. The in situ CH4 fluxes indicated similar seasonal patterns between treatments; both CE and CW increased CH4 emissions. In conclusion results suggest that methanogens and methanotrophs respond differently to elevated atmospheric CO2 concentrations and warming, thus adding insights into the effects of simulated global climate change on CH4 emissions in paddy fields.

Vegetation Influence and Environmental Controls on Greenhouse Gas Fluxes from a Drained Thermokarst Lake in the Western Canadian Arctic

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Diversity of methanogenic archaea in freshwater sediments of lacustrine ecosystems

“…The depth of the sediment layers shape the structure of the methanogenic communities and also determine the pathway of CH 4 production. The CH 4 produced from the freshwater lakes are the result of the microbial methanogenesis occurring there .…”

Long-term elevated atmospheric CO2 and warming affect the root-associated microbiomes of rice and wheat

“…Therefore, soil organic C quantity and quality changes due to elevated CO 2 could affect the fungal diversity indices. Our previous studies also reported that elevated CO 2 increased the SOC and microbial biomass C by stimulating the primary biomass production of rice and increasing the abundance of microorganisms (Liu et al 2014;Liu et al 2016).…”

“…Compared with the ambient conditions, elevated CO 2 and warming resulted in higher levels of organic C, root exudates, and microbial abundance and diversity. This results in more complex niches for microbial communities (Bhattacharyya et al 2013, Liu et al 2016Wang et al 2017), which may enhance the interactions among microbial communities in the crop root zone. Recently, a long-term warming experiment showed that warming enhanced the complexity and stability of the microbial network, which could be tightly related to ecosystem function processes (Yuan et al 2021).…”