Background and aims <p>Tree diversity strongly regulates organic matter inputs by rhizodeposition for microorganisms and microbial communities, impacting soil carbon (C) dynamics and stability. Because of much larger organic C availability in the rhizosphere, it can respond differently to tree diversity compared to bulk soil. To explore soil C stability under global warming, we assessed the temperature sensitivity (Q₁₀) of organic matter decomposition in rhizosphere and bulk soil depending on tree diversity.</p> Methods <p>Q₁₀ of organic matter decomposition in rhizosphere and bulk soil in a subtropical forest were examined using short-term incubation under controlled conditions depending on tree diversity. Fine root traits and soil C and N availability were evaluated as related to microbial properties.</p> Results <p>With increasing tree diversity, Q₁₀ remained stable in the rhizosphere but decreased in the bulk soil. While greater tree diversity increased fine root biomass, soil C and N availability, microbial K/r strategy ratios in rhizosphere and bulk soil shifter towards the r strategists, with a reduced bacterial K/r strategy ratio. However, microbial gene copy numbers and Shannon diversity remained stable. Partial correlation and multiple regression analysis revealed that rhizosphere Q₁₀ remained stable because of C excess and larger microbial abundance. The Q₁₀ reduction in bulk soil correlated with increased C availability and a shift in microbial community towards a lower K/r strategy ratio.</p> Conclusion <p>The Q₁₀ decoupling between rhizosphere and bulk soil highlights a trade-off, where increasing tree diversity accelerates organic matter decomposition in rhizosphere to sustain nutrient supply, while maintaining bulk C pool stability under global warming.</p>