Enhanced response of soil respiration to experimental warming upon thermokarst formation
Guanqin Wang, Yunfeng Peng, Leiyi Chen, Benjamin W. Abbott, Philippe Ciais, Luyao Kang, Yang Liu, Qinlu Li, Josep Peñuelas, Shuqi Qin, Pete Smith, Yutong Song, Jens Strauß, Jun Wang, Bin Wei, Jianchun Yu, Dianye Zhang, Yuanhe Yang
Abstract
Abstract As global temperatures continue to rise, a key uncertainty of terrestrial carbon (C)–climate feedback is the rate of C loss upon abrupt permafrost thaw. This type of thawing—termed thermokarst—may in turn accelerate or dampen the response of microbial degradation of soil organic matter and carbon dioxide (CO 2 ) release to climate warming. However, such impacts have not yet been explored in experimental studies. Here, by experimentally warming three thermo-erosion gullies in an upland thermokarst site combined with incubating soils from five additional thermokarst-impacted sites on the Tibetan Plateau, we investigate how warming responses of soil CO 2 release would change upon upland thermokarst formation. Our results show that warming-induced increase in soil CO 2 release is ~5.5 times higher in thermokarst features than the adjacent non-thermokarst landforms. This larger warming response is associated with the lower substrate quality and higher abundance of microbial functional genes for recalcitrant C degradation in thermokarst-affected soils. Taken together, our study provides experimental evidence that warming-associated soil CO 2 loss becomes stronger upon abrupt permafrost thaw, which could exacerbate the positive soil C–climate feedback in permafrost-affected regions.