Soil microorganisms are adapted to temperature in global drylands

A study led by Marina Dacal, a PhD student from the Dryland Ecology and Global Change Lab at the Rey Juan Carlos University (URJC, Spain), has shown that CO₂ emissions into the atmosphere from the microbial respiration of the soil of  global drylands decrease according to increases in mean annual temperature of the place. The article, published in the prestigious journal Nature Ecology and Evolution, is the result of the collaboration of an international group of researchers from the URJC, the Institute of Agrarian Sciences (CSIC, Spain) and the Yale University (USA).

Global warming, which is a consequence of anthropogenic CO₂ emissions, increases natural CO₂ emissions through soil microbial respiration, which in turn contributes to accelerating global warming. Currently, there is a broad scientific consensus about the existence of this positive Carbon- Climate feedback, but recent studies question the magnitude of it. The reason is that the positive effect of temperature on soil microbial respiration can be smoothed over time thanks to various mechanisms, such as thermal adaptation of soil microorganisms. This global warming will have a particular impact on the dryland ecosystems as they cover more than 45% of the Earth’s land surface.  

In this study thermal adaptation of soil respiration was analyzed using a global network of 110 dryland sites distributed across all continents except Antarctica, spanning a gradient of mean annual temperature from -2 to 28 ° C. This network is the result of the BIOCOM project, led by Fernando T. Maestre, and funded by the Starting Grants program of the European Research Council (ERC). 

The results of this study suggest that soil microbial respiration in global drylands is adapted to temperature. Although the increase in temperature still supposes an increase in soil respiration, contributing to the positive Carbon-Climate feedback described above, the magnitude of this change in drylands may decrease as a consequence of the adaptation of microorganisms to temperature. This study has important implications for the climate models of the IPCC (Intergovernmental Panel on Climate Change), whose predictive capacity could be improved, including aspects related to microbial activity.