<p>Natural forest conversion profoundly alters soil respiration, yet its differential effects on autotrophic and heterotrophic components and their temperature sensitivity (<i>Q</i>₁₀) remain unresolved globally. Here we synthesize 452 paired observations from 164 field studies, showing that soil respiration declines by 7.0% following forest conversion, primarily driven by a pronounced reduction in autotrophic respiration (−26.8%), whereas heterotrophic respiration exhibits no consistent response. Although <i>Q</i>₁₀ does not shift significantly across all conversions, it increases markedly following conversion to agriculture (+8.8%) and grassland (+11.8%). Both soil respiration suppression and <i>Q</i>₁₀ elevation are transient, converging toward adjacent forest levels within approximately 30 years. Variations in soil respiration reflect the opposing influences of soil organic carbon loss and post-conversion soil warming, whereas <i>Q</i>₁₀ responses are strongly modulated by initial soil clay content and pH. Our findings underscore the need to incorporate component-resolved and context-dependent soil respiration and <i>Q</i>₁₀ into Earth system models to improve projections of long-term carbon–climate feedbacks under land-use change.</p>