Rare keystone taxa drive soil microbial stability in low-temperature peatlands of China

Understanding microbial diversity-function-stability relationships is essential for elucidating microbial ecological roles and environmental adaptability. However, the contribution of abundant taxa (AT) versus rara taxa (RT) to nutrient cycling and community stability remain unclear in peatland. In this study, we investigated six low-temperature peatlands in China to assess abundant and rare bacterial assemblages impact community stability. The AT and RT subcommunities in this study differed more in taxonomic composition than in functional potential, and AT dominated more carbon and nitrogen cycling, both of which were significantly affected by soil depth. Deterministic processes primarily governed both AT and RT community assembly (MST: AT: 0.257 vs. RT: 0.459), with their influence intensifying at greater depths. Notably, soil depth negatively affected the stability of the AT sub-community but had no significant impact on the RT stability. Surprisingly, higher Shannon diversity in both AT and RT was associated with reduced overall community stability, while changes in relative abundance of keystone taxa were a major driver of stability. Our results suggest that in nutrient-limited peatlands, changes in the abundance of key functional taxa—rather than diversity alone—play a dominant role in driving microbial stability. These findings highlight the critical role of abundant and rare taxa in maintaining peatland ecosystem function and resilience, emphasising their ecological significance in wetland sustainability.