Heterotrophic respiration does not acclimate to continuous warming in a subtropical forest

Authors: Wu C., Liang N., Sha L., Xu X., Zhang Y., Lu H., Song L., Song Q., Xie Y.
Journal: Scientific Reports, 6:21561
DOI: 10.1038/srep21561
Abstract: As heterotrophic respiration (RH) has great potential to increase atmospheric CO₂ concentrations, it is important to understand warming effects on RH for a better prediction of carbon–climate feedbacks. However, it remains unclear how RH responds to warming in subtropical forests. Here, we carried out trenching alone and trenching with warming treatments to test the climate warming effect on RH in a subtropical forest in southwestern China. During the measurement period, warming increased annual soil temperature by 2.1°C, and increased annual mean RH by 22.9%. Warming effect on soil temperature (WET) showed very similar pattern with warming effect on RH (WERH), decreasing yearly. Regression analyses suggest that WERH was controlled by WET and also regulated by the soil water content. These results showed that the decrease of WERH was not caused by acclimation to the warmer temperature, but was instead due to decrease of WET. We therefore suggest that global warming will accelerate soil carbon efflux to the atmosphere, regulated by the change in soil water content in subtropical forests.