Abstract. Climate warming perturbs ecosystem carbon (C) cycling, causing both positive and negative feedbacks on greenhouse gas emissions. In 2016, we began a tidal marsh field experiment in two vegetation communities to investigate the mechanisms by which whole-ecosystem warming alters C gain, via plant-driven sequestration in soils, and C loss, primarily via methane (CH₄) emissions. Here, we report the results from the first four years. As expected, warming of 5.1 °C more than doubled CH₄ emissions in both plant communities. We propose this was caused by a combination of four mechanisms: (i) a decrease in the proportion of CH₄ consumed by CH₄ oxidation, (ii) more C substrates available for methanogenesis, (iii) reduced competition between methanogens and sulfate reducing bacteria, and (iv) indirect effects of plant traits. Plots dominated by Spartina patens consistently emitted more CH₄ than plots dominated by Schoenoplectus americanus, indicating key differences in the roles these common wetland plants play in affecting anerobic soil biogeochemistry and suggesting that plant composition can modulate coastal wetland responses to climate change.

中文翻译：

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生物地球化学和植物性状机制推动了甲烷排放的增加，以应对整个生态系统的变暖

摘要。气候变暖扰乱了生态系统的碳（C）循环，导致对温室气体排放的正反馈和负反馈。2016年，我们在两个植被群落中进行了潮汐沼泽田间试验，以研究整个生态系统变暖通过植物驱动的固存土壤来改变碳增加以及主要通过甲烷（CH ₄）排放改变碳损失的机制。在这里，我们报告前四年的结果。不出所料，在两个工厂社区中，5.1°C的升温使CH ₄排放量增加了一倍以上。我们认为这是由以下四种机制共同导致的：（i）CH ₄消耗的CH ₄比例减少氧化；（ii）更多可用于甲烷生成的C底物，（iii）减少了产甲烷菌和硫酸盐还原菌之间的竞争，以及（iv）植物性状的间接影响。通过主导地块狐米草一贯发出更多的CH ₄比为主的地块Schoenoplectus美洲，表明在这些常见的湿地植物的影响厌氧生物地球化学土壤，并暗示植物成分可以调节滨海湿地应对气候变化方面发挥的作用主要区别。