<p><UnorderedList Mark="Bullet"> <ItemContent> <p>Q₁₀ ranged from 1.56–4.80 and was higher in the top than deep soil.</p> </ItemContent> <ItemContent> <p>The total effect of microorganisms was higher than C quality on Q₁₀ of C decomposition.</p> </ItemContent> <ItemContent> <p>Microbial diversity, F:B, and qCO₂ were driving forces over the variation in Q₁₀.</p> </ItemContent> <ItemContent> <p>Q₁₀ was negatively associated with microbial diversity, positively with F:B and qCO₂.</p> </ItemContent> <ItemContent> <p>C quality changed microorganisms to indirectly mediate Q₁₀.</p> </ItemContent> </UnorderedList></p><p>Understanding the temperature sensitivity (Q₁₀) of soil carbon (C) decomposition and the driving forces is vital for projecting soil C dynamics under climate warming. However, it is unclear of the geographic patterns in Q₁₀ and its driving forces in water-limited regions. We measured Q₁₀ of C decomposition and multiple facets of both C quality and microbial properties, including microbial diversity, abundance, composition, activity, and trophic strategy from two soil depths (0–10 cm, 30–50 cm) collected at 38 sites along a 2000-km transect in northern China’s deserts. Q₁₀ ranged in 1.56–4.80 and was significantly higher in the top (3.21) than deep soil (2.61). The large variation in Q₁₀ is directly determined by microorganisms, rather than C quality which is the ratio of microbial C decomposition rate over soil organic C content. Microbial diversity, the ratio of fungi to bacterial abundance (F:B), and mass-specific respiration (qCO₂) were driving forces for spatial variation in Q₁₀. Microbial diversity negatively impacted Q₁₀, while higher F:B and qCO₂ stimulated Q₁₀. Higher C quality indirectly inhibited Q₁₀ by improving microbial diversity, and decreasing F:B and qCO₂. Our study demonstrates that microorganisms drive the geographic variations in Q₁₀.</p>