Reduced microbial stability in the active layer is associated with carbon loss under alpine permafrost degradation

Climate warming has led to extensive permafrost degradation, potentially inducing massive soil carbon loss. However, microbially mediated mechanisms responsible for carbon loss from the active layer in degraded permafrost remain unclear. Thus, we investigated how soil microbial communities in the active layer respond to permafrost degradation and influence carbon storage in alpine ecosystems of the Qinghai-Tibet Plateau. Our results reveal that severe degradation of permafrost increased bacterial and fungal dissimilarities and reduced bacterial and archaeal community richness. Microbial community stability also declined, as evidenced by increased microbial community sensitivity to environmental change and a prevalence of destabilizing properties of microbial networks. It was estimated that the increase in microbial dissimilarity was associated with amplified soil organic carbon loss in severely-degraded permafrost. Overall, our study implies significant changes in microbial diversity and stability of the active layer in alpine ecosystems under permafrost degradation, with potential implications for carbon-climate feedbacks.