Estimating organic carbon storage in temperate wetland profiles in Northeast China

Abstract Wetlands contain a large carbon (C) stock and play an important role in global C cycling. To improve knowledge on organic carbon (OC) storage in the temperate wetlands of China, sixteen profiles (0–200 cm) from peat fen (PF, six profiles), humus marsh (HM, five profiles), and marshy meadow (MM, five profiles) from the Sanjiang Plain region of Northeast China were sampled and investigated. The OC content in the upper part of the organic horizon (specific gravity, SG  − 1 for PF, from 180 to 450 g kg − 1 for HM, and from 40 to 110 g kg − 1 for MM, respectively. For all of three types of wetlands, the proportion of OC in the light fraction (SG ≤ 1.7), which is considered to be a more decomposable fraction, was significantly correlated with the content of OC in the organic horizon. In the lower illuvial horizon (SG > 1.0), the content of OC was considerably smaller ( − 1 ) and also little was presented in the light fraction, despite differences in wetland type. OC storage in temperate wetlands is significantly underestimated if only the top 1 m of the profile is considered, because the upper organic horizon could vary considerably in depth. We conclude that considering the organic horizon plus the top 1 m of illuvial horizon gives a more reliable estimate of OC storage in the temperate wetland profiles studied. Using this approach, it was estimated that the mean OC storage was 828 t ha − 1 for PF. The corresponding values were 274 t ha − 1 for HM, and 171 t ha − 1 for MM.