Extensive atmospheric methane consumption by alpine forests on Tibetan Plateau

Abstract

The uptake rates of methane (CH4) in alpine regions remain highly uncertain. Southeast Tibet holds one of the highest alpine forest ecosystems worldwide, which provides us with an ideal experimental site for CH4 uptake rates observation. Therefore, we conducted a two-year observation from August 2019 to July 2021 at an alpine forest site to collect CH4 uptake data with minute time resolution. Our findings showed that alpine forest ecosystem consumed 5.06 kg ha−1 yr−1 CH4 which was higher than previous estimations made by the process-based models. Soil temperature was an important positive controller of CH4 consumption when soil volumetric water content (% VWC) remained lower than 15% but had no effect on CH4 consumption when VWC exceeded 15%. Soil moisture exerted strong negative control on CH4 consumption when soil temperature was greater than 2 °C. Our results underscore the crucial role that alpine forest CH4 uptake plays in maintaining the CH4 balance of the Tibetan Plateau and the environmental tipping point with this minute scale observation, which imply the alpine forest to be a CH4 sink with rising temperature in the future.