Warming-induced carbon vulnerability in permafrost forests: a shift in Q10 from continuous to discontinuous zones

Permafrost forests harbor vast, climate-sensitive carbon (C) reservoirs whose vulnerability largely depends on temperature sensitivity of microbial respiration (Q10). However, substantial uncertainties persist in predicting Q10 patterns due to complex interactions among multiple ecological factors. Here, we conducted a standardized field survey with controlled incubations across a regional gradient from continuous permafrost (CP) and discontinuous permafrost (Dis-CP, including sporadic and isolated one) in the Greater Khingan Mountains to quantify Q10 values and identify their main ecological controls. We found that the Q10 values were significantly higher in CP than Dis-CP forests, indicating a stronger microbial respiratory response to warming in the coldest permafrost regions. Statistical analysis revealed that the soil microbiome was the most important factor explaining Q10 values in CP forest (47.8%), whereas a distinct set of factors (plant production, fine texture, substrate quality, and mean annual ground temperature) explained the largest proportion (63.2%) of Q10 variation in Dis-CP forests. Our findings suggest that warming-induced permafrost degradation is likely shift the dominant controls for Q10 from microbial community to abiotic and plant-related factors, while enhancing greenhouse gas emissions from permafrost soils.