Reconciling carbon quality with availability predicts temperature sensitivity of global soil carbon mineralization
Shuai Zhang, Mingming Wang, Liujun Xiao, Xiaowei Guo, Jinyang Zheng, Biao Zhu, Zhongkui Luo
Abstract
Soil organic carbon (SOC) mineralization is a key component of the global carbon cycle. Its temperature sensitivity Q 10 (which is defined as the factor of change in mineralization with a 10 °C temperature increase) is crucial for understanding the carbon cycle-climate change feedback but remains uncertain. Here, we demonstrate the universal control of carbon quality-availability tradeoffs on Q 10 . When carbon availability is not limited, Q 10 is controlled by carbon quality; otherwise, substrate availability controls Q 10 . A model driven by such quality-availability tradeoffs explains 97% of the spatiotemporal variability of Q 10 in incubations of soils across the globe and predicts a global Q 10 of 2.1 ± 0.4 (mean ± one SD) with higher Q 10 in northern high-latitude regions. We further reveal that global Q 10 is predominantly governed by the mineralization of high-quality carbon. The work provides a foundation for predicting SOC dynamics under climate and land use changes which may alter soil carbon quality and availability.