Quantifying thermal adaptation of soil microbial respiration

Abstract

Abstract Quantifying the rate of thermal adaptation of soil microbial respiration is essential in determining potential for carbon cycle feedbacks under a warming climate. Uncertainty surrounding this topic stems in part from persistent methodological issues and difficulties isolating the interacting effects of changes in microbial community responses from changes in soil carbon availability. To combat these challenges, we constructed a series of temperature response curves of microbial respiration (given unlimited substrate) using soils sampled from around New Zealand, including from a natural geothermal gradient, as a proxy for global warming. We estimated the temperature optima (Topt) and inflection point (Tinf) of each curve and found that adaptation of microbial respiration occurred at a rate of 0.29°C ± 0.04 1SE for Topt and 0.27°C± 0.05 1SE for Tinf per degree of warming. Our results indicate that thermal adaptation is demonstrably offset from warming and calculate the potential for both limitation and acceleration of soil C losses depending on specific soil temperatures.