Genetic Linkage of Soil Carbon Pools and Microbial Functions in Subtropical Freshwater Wetlands in Response to Experimental Warming |
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| Authors: | Hang Wang Zhili He Zhenmei Lu Jizhong Zhou Joy D. Van Nostrand Xinhua Xu Zhijian Zhang |
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| Affiliation: | aCollege of Environmental and Resource Science, Research Center of Water and Watershed Sustainability, Zhejiang University, Hangzhou, China;bInstitute for Environmental Genomics, Department of Botany, University of Oklahoma, Norman, Oklahoma, USA;cInstitute of Environmental Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, China;dDepartment of Earth and Environmental Engineering, Columbia University, New York, New York, USA |
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| Abstract: | Rising climate temperatures in the future are predicted to accelerate the microbial decomposition of soil organic matter. A field microcosm experiment was carried out to examine the impact of soil warming in freshwater wetlands on different organic carbon (C) pools and associated microbial functional responses. GeoChip 4.0, a functional gene microarray, was used to determine microbial gene diversity and functional potential for C degradation. Experimental warming significantly increased soil pore water dissolved organic C and phosphorus (P) concentrations, leading to a higher potential for C emission and P export. Such losses of total organic C stored in soil could be traced back to the decomposition of recalcitrant organic C. Warming preferentially stimulated genes for degrading recalcitrant C over labile C. This was especially true for genes encoding cellobiase and mnp for cellulose and lignin degradation, respectively. We confirmed this with warming-enhanced polyphenol oxidase and peroxidase activities for recalcitrant C acquisition and greater increases in recalcitrant C use efficiency than in labile C use efficiency (average percentage increases of 48% versus 28%, respectively). The relative abundance of lignin-degrading genes increased by 15% under warming; meanwhile, soil fungi, as the primary decomposers of lignin, were greater in abundance by 27%. This work suggests that future warming may enhance the potential for accelerated fungal decomposition of lignin-like compounds, leading to greater microbially mediated C losses than previously estimated in freshwater wetlands. |
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