<b>Tree diversity alters CUE thermal response</b>

In the context of global warming, understanding microbial responses to temperature changes is crucial for predicting soil carbon dynamics, but whether soil microbial carbon use efficiency (CUE) are adaptive to warming remains unclear. Here, we assayed thermal responses of microbial respiration, growth rates and CUE using soils across a natural plant species diversity gradient in a subtropical mature forest, southwest China. We found that higher tree species diversity strengthened both thermal compensation adaptation of microbial respiration and growth, and the thermal enhancement adaptation of microbial CUE. These adaptations were mainly attributed to reduced temperature responsiveness of bacterial K:r ratio, and amplified temperature responsiveness of enzymatic activity, and intensified competitive interactions within fungal taxa. Our findings suggest that restoring and conserving plant species diversity can enhance soil’s capacity to mitigate climate change, not only by reducing respiratory losses but also via increasing soil organic carbon stability.