Mineral protection explains the elevational variation of temperature sensitivity of soil carbon decomposition in the Eastern Himalaya

The pace of climate warming increases with elevation, quantifying the temperature sensitivity of soil carbon (C) decomposition (Q10) along the "natural temperature gradient" consequently can provide a better understanding for soil C-climate change feedback. Here, we collected soils from five well-protected forest ecosystems across an elevational gradient ranging from 841 m to 3445 m in the Eastern Himalaya and quantified the Q10 by a continuous-flow incubation approach. We aimed to explore the regulations of climate factors, soil properties (pH, bulk density, and texture), C-quality (proportion of recalcitrant C and C to nutrients ratios), mineral protection (mineral-associated C and iron/aluminum oxides), and microbial attributes (microbial biomass, enzymes, and microbial metabolic quotient) on the variation of Q10 along the elevation. We found that Q10 decreased as increased elevation. Negative correlations between Q10 and C to nutrients ratios or proportion of recalcitrant C suggested that soil C-quality can't explain the variation of Q10. Q10 was positively related to soil pH, bulk density, and microbial metabolic quotient, but negatively related to clay plus silt content, mineral-associated C, reactive iron and aluminum oxides, and microbial biomass. Overall, the complex interactions between mineral protection and microbial attributes masked the kinetic theory of chemical reactions, leading to a more complex soil Cclimate feedback than that was previously considered in mountain forest ecosystems.