Abstract How methane (CH4) fluxes from alpine peatlands, especially during freeze-thaw cycles, affect the global CH4 budget is poorly understood. The present research combined the eddy covariance method, incubation experiments and high-throughput sequencing to observe CH4 flux from an alpine fen during thawing-freezing periods over a period of four years. The response of CH4 production potential and methanogenic archaea to climate change was analyzed. We found a relatively high mean annual cumulative CH4 emission of 37.7 g CH4-C m−2. The dominant contributor to CH4 emission was the thawing period: warmer, longer thawing periods contributed 69.1-88.6% to the annual CH4 budget. Non-thawing periods also contributed, with shorter frozen-thawing periods accounting for up to 18.5% and shorter thawing-freezing periods accounting for up to 8.8%. Over the course of a year, emission peaked in the peak growing season and at onset of thawing and freezing. In contrast, emission did not vary substantially during the frozen period. Daily mean emission was highest during the thawing period and lowest during the frozen period. Diurnal patterns of CH4 emission were similar among the four periods, with peaks ranging from 12:00 to 18:00 and the lowest emission around 00:00. Water table and temperature were the dominant factors controlling CH4 emissions during different thawing-freezing periods. Our results suggest that CH4 emission from peatland will change substantially as CH4 production, microbial composition, and patterns of thawing-freezing cycles change with global warming. Therefore, frequent monitoring of CH4 fluxes in more peatlands and in situ monitoring of methanogenesis and related microbes are needed to provide a clear picture of CH4 fluxes and the thawing-freezing processes that affect them.

中文翻译：

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青藏高原沼泽不同冻融期甲烷排放量：四年测量

摘要 来自高山泥炭地的甲烷 (CH4) 通量，尤其是在冻融循环期间，如何影响全球 CH4 收支尚知之甚少。本研究结合涡度协方差方法、孵育实验和高通量测序，观察了四年内在解冻-冻结期间来自高山沼泽的 CH4 通量。分析了 CH4 生产潜力和产甲烷古菌对气候变化的响应。我们发现年平均累积 CH4 排放量相对较高，为 37.7 g CH4-C m-2。CH4 排放的主要贡献者是解冻期：更温暖、更长的解冻期对年度 CH4 预算贡献了 69.1-88.6%。非解冻期也有贡献，较短的冻融期占 18.5%，较短的解冻期占 8.8%。在一年的过程中，排放量在生长高峰期以及解冻和冻结开始时达到峰值。相比之下，在冻结期间，排放量没有显着变化。日平均排放量在解冻期最高，在冻结期最低。四个时期的 CH4 排放日规律相似，峰值在 12:00 至 18:00 之间，最低排放在 00:00 左右。地下水位和温度是控制不同融冻期 CH4 排放的主要因素。我们的研究结果表明，随着 CH4 生产、微生物组成和解冻-冻结循环模式随着全球变暖而变化，泥炭地的 CH4 排放将发生显着变化。所以，