Soil Moisture Threshold of Methane Uptake in Alpine Grassland Ecosystems

作者：Peiyan Wang, Jinsong Wang, Song Wang, Ludovica D’Imperio, Bo Elberling, Per Ambus, Zhen Zhang, Akihiko Ito, Yang Li, Junxiao Pan, Lei Song, Ning Liu, Ruiyang Zhang, Weinan Chen, Shuli Niu · 发表于：Global Change Biology · 年份：2025 · DOI：10.1111/gcb.70062 · 被引用次数：13 · 研究领域：Atmospheric and Environmental Gas Dynamics、Climate change and permafrost、Peatlands and Wetlands Ecology

ABSTRACT Methane (CH 4 ) uptake in alpine ecosystems is an important component of the global CH 4 sink. However, large uncertainties remain regarding the magnitude and spatial patterns of CH 4 uptake, owing to its extensive spatial variability, diverse controlling factors, and limited regional‐scale observations. Here, we investigated field ecosystem CH 4 uptake along a 3200‐km transect across various alpine grasslands on the Qinghai–Tibetan Plateau (QTP). We found a substantial spatial variation in in situ CH 4 uptake among alpine grasslands, with the highest rates in drier regions of the mid‐western QTP. Soil moisture was the most important factor controlling CH 4 uptake, exhibiting a remarkably low threshold of 6.2 ± 0.1 v/v %. Below this threshold, CH 4 uptake was constrained by soil moisture, moisture‐induced nitrogen limitation, and high temperatures. Above this threshold, CH 4 uptake was mainly limited by gas diffusion and low temperatures. By integrating grid predictors with a random forest model trained on 1851 field measurements encompassing both our observations and a regional synthesis across the QTP, we estimated a regional CH 4 uptake of 0.88 ± 0.020 Tg CH 4 year −1 from all alpine grasslands on the QTP. This higher estimate, primarily driven by alpine steppes, was significantly greater than current regional estimates from global CH 4 models. Our findings highlight the importance of CH 4 sink in dry alpine ecosystems characterized by low soil moisture, suggestin...