Converse effects of warming and reclamation on methane uptake in alpine meadows

Abstract

Climate warming will lead to changes in soil properties, which in turn will affect the uptake of methane (CH₄) in meadows. Currently there is artificial reclamation of alpine meadows, and the effect of reclamation on CH₄ uptake in alpine meadow ecosystems is still unclear. Therefore, we investigated the effects of warming, reclamation and their interactions on soil CH₄ uptake in alpine meadows on the Tibetan Plateau. From May to December 2021 and from March to May 2022, CH₄ uptake was determined under four treatments: control (CK), warming, reclamation and warming under reclamation. Soil C and N nutrient contents and three enzyme activities were determined in 2021, and their effects on CH₄ uptake were elucidated using the Mantel test as well as structural equation modelling. The results showed that warming significantly increased CH₄ uptake by 23.84 %, reclamation significantly reduced CH₄ uptake by 58.64 %, warming interacted with reclamation significantly reduced CH₄ uptake by 33.45 % in growing season, and warming interacted with reclamation significantly reduced CH₄ uptake by 21.46 % in the non-growing season, as compared to CK. Warming promoted CH₄ uptake by increasing soil nutrient content and increasing the activities of methane monooxygenase and soil sucrase. Reclamation reduced the content of soil soluble carbon and nitrogen and inhibited the uptake of CH₄. Therefore, in the context of global warming, the destruction of natural grassland should be avoided as far as possible and the area of cultivated land should be rationally planned, so as to maintain the higher CH₄ uptake capacity of grassland.