Effects of abrupt and gradual increase of atmospheric CO2 concentration on methanotrophs in paddy fields

• DOI: 10.1016/j.envres.2023.115474
• Publication Date: 2023-02-10T12:00:22Z
• Authors: Lidong Shen; Bingjie Ren; Yuhan Jin; Xin Liu; Jinghao Jin; Hechen Huang; Maohui Tian; Wangting Yang; Yuling Yang; Jiaqi Liu; Caiyu Geng; Yanan Bai; Zhenghua Hu
• Keywords: 0301 basic medicine; Soil; 03 medical and health sciences; Oryza; Carbon Dioxide; Oxidation-Reduction; Methane; Ecosystem; Soil Microbiology

The simulation of abrupt atmospheric CO2 increase is a common way to examine the response of soil methanotrophs to future climate change. However, atmosphere is undergoing a gradual CO2 increase, and it is unknown whether the previously reported response of methanotrophs to abrupt CO2 increase can well represent their response to the gradual increase. To improve the understanding of the effect of elevated CO2 (eCO2) on methanotrophs in paddy ecosystems, the methane oxidation potential and communities of methanotrophs were examined via open top chambers under the three following CO2 treatments: an ambient CO2 concentration (AC); an abrupt CO2 increase by 200 ppm above AC (AI); a gradual CO2 increase by 40 ppm each year until 200 ppm above AC (GI). Relative to AC treatment, AI and GI treatments significantly (p < 0.05) increased the methane oxidation rate by 43.8% and 36.7%, respectively, during rice growth period. Furthermore, the abundance of pmoA genes was significantly (p < 0.05) increased by 62.4% and 32.5%, respectively, under AI and GI treatments. However, there were no significant variations in oxidation rate or gene abundance between the two eCO2 treatments. In addition, no obvious change of overall community composition of methanotrophs was observed among treatments, while the proportions of Methylosarcina and Methylocystis significantly (p < 0.05) changed. Taken together, our results indicate similar response of methanotrophs to abrupt and gradual CO2 increase, although the magnitude of response under gradual increase was smaller and the abrupt increase may somewhat overestimate the response.