Increased annual methane uptake driven by warmer winters in an alpine meadow

Pronounced non-growing season warming and changes in soil freeze-thaw (F-T) cycles can dramatically alter net methane (CH4) exchange rates between soils and the atmosphere. However, the magnitudes and drivers of warming impacts on CH4 uptake in different stages of the F-T cycle are poorly understood in cold alpine ecosystems, which have been found to be a net sink of atmospheric CH4. Here, we reported a year-round ecosystem daily CH4 uptake in an alpine meadow on the Qinghai-Tibetan Plateau after a five-year warming experiment that included a control, a low-level warming treatment (+2.4℃ at 5 cm soil depth), and a high-level warming treatment (+4.5℃ at 5 cm soil depth). We found that warming shortened the F-T cycle under the low-level warming and soils did not freeze under the high-level warming. Although both warming treatments increased the mean CH4 uptake rate, only the high-level warming significantly increased annual CH4 uptake compared to the control. The warming-induced stimulati...显著的非生长季增温与土壤冻融（F-T）循环变化，可大幅改变土壤与大气间的甲烷（CH4）净交换速率。然而，在被证实为大气甲烷（CH4）净汇的高寒生态系统中，不同冻融循环阶段下增温对甲烷吸收的影响强度及其驱动因子，目前仍缺乏深入认知。本研究依托青藏高原高寒草甸开展了为期五年的增温实验，设置对照组、低水平增温处理（5cm土层温度升高2.4℃）与高水平增温处理（5cm土层温度升高4.5℃），并报道了该生态系统全年逐日甲烷吸收通量。研究发现，低水平增温下土壤冻融循环周期缩短，而高水平增温下土壤未发生冻结。尽管两种增温处理均提升了甲烷平均吸收速率，但仅高水平增温较对照组显著提升了全年甲烷吸收总量。增温诱导的刺激效应（原文内容未完整呈现）