No signs of thermal acclimation of heterotrophic respiration from peat soils exposed to different water levels

In a mesocosm experiment, with bare peat soils exposed to different water levels (WL), we examined whether heterotrophic respiration (Rh) acclimated to a 3 °C temperature increase. Across all WLs, Rh at 15 °C was never lower in the heated treatment than in the unheated treatment, indicating that Rh did not acclimate to the warmer conditions. We hypothesize that this lack of thermal acclimation is due to the unlimited substrate availability in these organic soils. These results imply that peat soils may exhibit a sustained positive feedback to global warming.