Terrestrial ecosystems respire nearly 120-130 Gt carbon into the atmosphere every year. But how ecosystem respiration changes under global warming is not clear yet. Prof. NIU Shuli’s lab at the Institute of Geographic Sciences and Natural Resources Research of the Chinese Academy of Sciences found that ecosystem respiration shows a non-monotonic response to temperature, with maximum value of respiration at an optimum temperature and then decreases with the increasing temperature. The optimum temperature of ecosystem respiration is tightly correlated with the annual maximum daily temperature at the global scale. This work was published in Nature Ecology & Evolution.

Understanding of the temperature responses of ecosystem respiration (ER) remains limited since ER is a sum of complex processes of autotrophic and heterotrophic respiration affected by many confounding factors.

Under the guidance of Prof. NIU Shuli, CHEN Weinan analyzed the temperature response curves of ER at 212 sites from global FLUXNET. They found that the temperature optima of ER existed at 183 sites widely across different biomes over the globe. In addition, the temperature optima of ER also linearly increased with annual maximum daily temperature (Tmax) across sites and vegetation types, suggesting thermal adaptation.

This study provided the first evidence of the widespread existence of thermal optima of ER and its adaptation with Tmax across different biomes over the globe, advancing the traditional cognition on temperature response functions of ER. The widespread thermal optima of ER implied that the terrestrial ecosystem respiration rates might decline instead of continuing to rise at high temperatures.

The study was conducted in collaboration with colleagues from East China Normal University and Cornell University. 

The work was financially supported by the National Natural Science Foundation of China, National Key Technology R & D Program of China, and International Partnership Program of Chinese Academy of Sciences.