Decline of CO2 Release During the Evolution of the Thaw Slump on the Northern Qinghai-Tibet Plateau

Abstract

Abrupt permafrost thaw accelerates the decomposition of soil organic carbon and might double the warming caused by the carbon release. However, the influence of thaw slump evolution on carbon dioxide (CO₂) emission rates and its drives remains unclear, which induces large uncertainties in the prediction of permafrost carbon-climate feedback. Here we collected soil samples in the thaw slump landscapes that happened 1–23 years ago on the northern Qinghai-Tibet Plateau (QTP) and measured the CO₂ release rates using a 189-day aerobic laboratory incubation in the dark. The incubation results showed that thaw slump occurred 23 years ago reduced soil CO₂–C release by 57 ± 19% compared with the undisturbed area. The relative contribution of O-alkyl C and microbial abundance decreases with the thaw slump initiation time lengthens. We illustrate that soil carbon quality and microbial communities uniquely explained 41% and 13% of the variation in CO₂–C release, respectively. We preliminary estimate that the carbon release for thaw slump landscapes on the QTP may be overestimated by approximately 50% if the declining soil CO₂–C release is without consideration. Our study highlights the CO₂–C release would decrease with the stability of thaw slumps on the warming and wetting QTP, which may weaken the mountain permafrost carbon-climate feedback.