Higher Temperature Sensitivity Of Soil C Release To Atmosphere From Northern Permafrost Soils As Indicated By A Meta-Analysis

The loss of carbon from soils to the atmosphere resulting from climate change is projected to be large, but these projections exhibit significant uncertainty, largely due to insufficient knowledge of the patterns and controls of the temperature sensitivity of soil microbial respiration. Here we synthesized data from 52 soil incubation studies across the Northern Hemisphere to assess the spatial patterns of Q(10) and its key drivers in different soil layers and geographic zones. The mean Q(10) was 2.51 +/- 1.13 across the northern ecosystems, but it exhibited significant variability. After averaged by ecosystem types, the highest mean Q(10) value was observed in the northern permafrost soils, where the Q(10) values were nearly 18% higher than those in nonpermafrost regions. The temperature sensitivity was larger in subsoil than in topsoil layers, particularly in permafrost subsoils. Besides, the dominant factors that correlate with Q(10) values are the carbon input, described by satellite-derived net primary productivity (NPP) in the topsoil and the soil C:N ratio in the subsoil. Based on the main factors affecting Q(10), we provide a gridded Q(10) data set for the midhigh-latitude areas, which further indicates that northern permafrost regions are more sensitive to climate warming than others. These results highlight the key role played by the permafrost in the temperature sensitivity of soil C release, and the necessity of including depth-specific soil C release processes in models, if we are to make better predictions of the soil C dynamics in future climate change scenarios.