Wetlands represent the most significant natural greenhouse gas (GHG) source and their annual emissions tightly depend on climatic and anthropogenic factors. Biogeochemical processes occurring in wetlands are still poorly described by mechanistic models and hence their dynamic response to environmental changes are weakly predicted. We investigated wetland GHG emissions, relevant electron acceptors and donors concentrations, and microbial composition resulting from changes in temperature, CH₄ plant uptake efficiency, and deposition using a mechanistic biogeochemical model (here called BAMS3) that integrates the carbon (C), nitrogen (N), and sulfur (S) cycles. Parameters constraining the coupled C‐N‐S cycles were retrieved from controlled experiments and were validated against independent field data of CH₄ emissions, and CH₄ (aq) and concentration profiles in a wetland in southern Michigan, USA (Shannon & White, 1994). We found that +1.75°C increase in temperature leads to 22% and 30% increment in CH₄ and N₂O emissions, respectively. A decrease in the CH₄ plant uptake efficiency causes the prevalent CH₄ emission pathway to become diffusion‐mediated and resulted in 50% increase in the daily average CH₄ emissions. Finally, a decreasing deposition rate can increase CH₄ emissions up to 5%. We conclude that the increasing GHG emissions from wetlands is a result of both environmental and anthropogenic causes rather than global warming alone. An increase in model complexity does not necessary improve the estimation of GHG emissions but it aids interpretation of intermediate processes to a greater detail.

中文翻译：

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响应温度，植被和养分输入变化的湿地生物地球化学机理分析

湿地是最重要的天然温室气体（GHG）来源，其年排放量紧密取决于气候和人为因素。用机理模型仍然不能很好地描述湿地中发生的生物地球化学过程，因此，人们对它们对环境变化的动态响应的预测是微弱的。我们调查了湿地温室气体排放，相关的电子受体和施主浓度以及温度变化，CH ₄植物吸收效率和使用整合了碳（C），氮（N）和硫（S）循环的机械生物地球化学模型（这里称为BAMS3）进行沉积。从受控实验中获得了约束耦合C-N-S周期的参数，并根据美国密歇根州南部湿地的CH ₄排放，CH ₄（aq）和浓度分布的独立现场数据进行了验证（Shannon＆White，1994） ）。我们发现，温度升高+ 1.75°C，分别导致CH ₄和N ₂ O排放增加22％和30％。CH ₄植物吸收效率的降低导致普遍的CH ₄排放途径成为扩散媒介，导致每日平均CH ₄排放增加50％。最后，降低的沉积速率可使CH ₄排放增加至5％。我们得出的结论是，湿地温室气体排放量的增加是环境和人为原因的结果，而不仅仅是全球变暖的结果。模型复杂性的增加并不一定会改善温室气体排放的估算，但有助于更详细地解释中间过程。