Environmental changes are anticipated to generate substantial impacts on carbon cycling in peatlands, affecting terrestrial-climate feedbacks. Understanding how peatland methane (CH₄) fluxes respond to these changing environments is critical for predicting the magnitude of feedbacks from peatlands to global climate change. To improve predictions of CH₄ fluxes in response to changes such as elevated atmospheric CO₂ concentrations and warming, it is essential for Earth system models to include increased realism to simulate CH₄ processes in a more mechanistic way. To address this need, we incorporated a new microbial-functional group-based CH₄ module into the Energy Exascale Earth System land model (ELM) and tested it with multiple observational data sets at an ombrotrophic peatland bog in northern Minnesota. The model is able to simulate observed land surface CH₄ fluxes and fundamental mechanisms contributing to these throughout the soil profile. The model reproduced the observed vertical distributions of dissolved organic carbon and acetate concentrations. The seasonality of acetoclastic and hydrogenotrophic methanogenesis—two key processes for CH₄ production—and CH₄ concentration along the soil profile were accurately simulated. Meanwhile, the model estimated that plant-mediated transport, diffusion, and ebullition contributed to ∼23.5%, 15.0%, and 61.5% of CH₄ transport, respectively. A parameter sensitivity analysis showed that CH₄ substrate and CH₄ production were the most critical mechanisms regulating temporal patterns of surface CH₄ fluxes both under ambient conditions and warming treatments. This knowledge will be used to improve Earth system model predictions of these high-carbon ecosystems from plot to regional scales.

中文翻译：

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土壤生物地球化学和甲烷过程的综合模型：I. 模型结构和敏感性分析

预计环境变化将对泥炭地的碳循环产生重大影响，从而影响陆地气候反馈。了解泥炭地甲烷 (CH ₄ ) 通量如何响应这些不断变化的环境对于预测泥炭地对全球气候变化的反馈程度至关重要。为了改进对 CH ₄通量的预测，以响应大气 CO ₂浓度升高和变暖等变化，地球系统模型必须增加真实性，以更机械的方式模拟 CH ₄过程。为了满足这一需求，我们采用了一种新的基于微生物官能团的 CH ₄模块进入能源百亿亿级地球系统陆地模型 (ELM)，并在明尼苏达州北部的一个嗜碱性泥炭地沼泽中使用多个观测数据集对其进行测试。该模型能够模拟观测到的地表 CH ₄通量和在整个土壤剖面中促成这些通量的基本机制。该模型再现了观察到的溶解有机碳和醋酸盐浓度的垂直分布。精确模拟了乙酰碎屑和氢营养产甲烷（CH ₄生产的两个关键过程）的季节性以及沿土壤剖面的CH ₄浓度。同时，该模型估计植物介导的运输、扩散和沸腾对 CH _{4 的}贡献约为 23.5%、15.0% 和 61.5%运输，分别。参数敏感性分析表明，CH ₄底物和CH ₄产生是在环境条件和变暖处理下调节表面CH ₄通量时间模式的最关键机制。这些知识将用于从地块到区域尺度改进对这些高碳生态系统的地球系统模型预测。