Consideration of dissolved organic carbon flux reduces estimated wetland carbon losses in response to warming

摘要

Purpose Wetland gaseous carbon (C) emissions have been widely used to evaluate temperature sensitivity of soil organic carbon (SOC) decomposition (indicated byQ(10)). However, dissolved organic carbon (DOC) flux as an important pathway for soil solid-phase organic carbon losses has seldom been considered in such estimations, which may introduce bias in predictions of wetland soil C-climate feedback. Hence, this study aimed to explore whether and how the temperature sensitivity of wetland SOC decomposition is affected by DOC flux. Materials and methods We carried out an anaerobic microcosm experiment using diverse wetland soils to assess the feedback of wetland SOC decomposition to temperature change with and without considering DOC flux. Results and discussion The contribution of DOC flux to wetlands SOC decomposition at a low temperature was significantly (p 0.05) higher than that at a high temperature.Q(10)values of wetland SOC decomposition rates were significantly (p 0.05) overestimated, by an average of 8%, when DOC was not considered. However, this overestimation was not significant (p 0.05) for low-SOC wetland soils. In addition, the overestimation for alkaline wetland soils was much higher than that of acid wetland soils, with a significantly (p 0.01) positive correlation between the ratios ofQ(10)(gaseous C emissions) toQ(10)(SOC decomposition) and soil pH across all wetland soil samples. Conclusions Our finding suggested that the sensitivity of wetland SOC decomposition to temperature change might be overestimated if DOC flux is not considered, especially in alkaline or high-SOC soils. Thus, C-climate models should incorporate DOC flux when predicting wetland C loss in response to warming.