The effects of climate warming on microbe-mediated mechanisms of sediment carbon emission

Due to significant differences in biotic and abiotic properties of soils compared to those of sediments, the predicted underlying microbe-mediated mechanisms of soil carbon emis-sions in response to warming may not be applicable for estimating similar emissions from inland water sediments. We addressed this issue by incubating different types of sediments, (including lake, small river, and pond sediments) collected from 36 sites across the Yangtze River basin, under short-term experimental warming to explore the effects of climate warm-ing on sediment carbon emission and the underlying microbe-mediated mechanisms. Our results indicated that under climate warming CO2 emissions were affected more than CH4 emissions, and that pond sediments may yield a greater relative contribution of CO2 to to-tal carbon emissions than lake and river sediments. Warming-induced CO2 and CH4 in-creases involve different microbe-mediated mechanisms; Warming-induced sediment CO2 emissions were predicted to be directly positively driven by microbial community network modularity, which was significantly negatively affected by the quality and quantity of or-ganic carbon and warming-induced variations in dissolved oxygen, Conversely, warming -induced sediment CH4 emissions were predicted to be directly positively driven by microbial community network complexity, which was significantly negatively affected by warming -induced variations in pH. Our findings suggest that biotic and abiotic drivers for sediment CO2 and CH4 emissions in response to climate warming should be considered separately when predicting sediment organic carbon decomposition dynamics resulting from climate change. (c) 2022 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.