Nonlinear microbial thermal response and its implications for abrupt soil organic carbon responses to warming

作者：Kailiang Yu, Lei He, Shuli Niu, Jinsong Wang, Pablo García‐Palacios, Marina Dacal, Colin Averill, Katerina Georgiou, Jian‐Sheng Ye, Fei Mo, Yang Lu, Thomas W. Crowther · 发表于：Nature Communications · 年份：2025 · DOI：10.1038/s41467-025-57900-9 · 被引用次数：27 · 研究领域：Soil Carbon and Nitrogen Dynamics、thermodynamics and calorimetric analyses、Plant Water Relations and Carbon Dynamics

Microbial carbon use efficiency (CUE) is a key microbial trait affecting soil organic carbon (SOC) dynamics. However, we lack a unified and predictive understanding of the mechanisms underpinning the temperature response of microbial CUE, and, thus, its impacts on SOC storage in a warming world. Here, we leverage three independent soil datasets (n = 618 for microbial CUE; n = 591 and 660 for heterotrophic respiration) at broad spatial scales to investigate the microbial thermal response and its implications for SOC responses to warming. We show a nonlinear increase and decrease of CUE and heterotrophic respiration, respectively, in response to mean annual temperature (MAT), with a thermal threshold at ≈15 °C. These nonlinear relationships are mainly associated with changes in the fungal-to-bacterial biomass ratio. Our microbial-explicit SOC model predicts significant SOC losses at MAT above ≈15 °C due to increased CUE, total microbial biomass, and heterotrophic respiration, implying a potential abrupt transition to more vulnerable SOC under climate warming. This study leverages the empirical datasets and microbial-explicit SOC model to show a thermal threshold of microbial CUE and heterotrophic respiration at 15 °C, implying a potential abrupt transition to more vulnerable SOC under climate warming.