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 ones) 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 to shift the dominant controls for Q₁₀ from microbial community to abiotic and plant-related factors, while enhancing greenhouse gas emissions from permafrost soils.