Soil carbon and nitrogen across wetland types in discontinuous permafrost zone of the Xiao Xing'an Mountains, northeastern China

Soil organic carbon (SOC) in high latitude ecosystems is potentially vulnerable to global climate change. However, the distribution of SOC and total nitrogen (N) is still unknown for the boreal wetlands. In this study, we collected soil samples from different wetlands in the discontinuous permafrost zone of the Xiao Xing'an Mountains, northeastern China. Permafrost was only present in the bogs and fens in this zone. Soil C concentrations were significantly correlated with total N concentrations and bulk density (P < 0.001). Wetland type, soil depth, and incidence of fire affected soil C and total N concentrations, suggesting that vegetation changes in wetlands could alter the soil C and nutrient sequestration processes under future global warming scenarios. However, soil C and total N storage in the 40 cm depth was not significantly different between wetland types (P > 0.05), suggesting that future global warming and vegetation change would not significantly affect soil C and total N storage in upper soil layers in wetlands. However, vegetation changes are likely to increase the depth of the permafrost active layer under permafrost degradation, release deep soil C, and add C to the atmosphere over the coming decades.

► The permafrost would only be existed in the bogs and fens in the discontinuous permafrost zone of Xiao Xing’an Mountains, China. ► The vegetation changes of wetlands could alter the soil C and nutrient sequestration processes under future global warming. ► The soil C storage and total N storage were not significantly difference in the upper soil layer for the wetlands types. ► The vegetation changing of bogs and fens would increase the depth of the permafrost active layer.