Microbes in Cold Soil: How They Change When the Ground Thaws

Scientists studied 125 samples taken from five deep cores that reach 15 meters below the surface on the Qinghai‑Tibet Plateau. The samples spanned from the top active layer, where plants grow, down to the frozen permafrost below. Using DNA sequencing they looked at the bacteria living in each depth and how their communities shift as the ground warms. The results show that bacterial diversity drops when you go deeper, while random changes and how tightly the community sticks together both rise. In the upper layer, as thaw progresses, these patterns change noticeably; in the frozen layer they stay fairly steady. The key players – a few bacterial groups that appear everywhere – help keep the community stable, but their influence differs between layers.When permafrost thaws, bacteria that are usually linked to carbon storage become less common. The link between how stable the bacterial community is and how much carbon remains in the soil becomes stronger, especially near the surface. This suggests that as the ground melts, microbes may speed up carbon release, feeding back into global warming. The study highlights that the way microbes respond to thaw varies with depth. Understanding this vertical difference is vital for predicting how much carbon will escape from permafrost in the future.