System-Specific Complex Interactions Shape Soil Organic Carbon Distribution in Coastal Salt Marshes

Abstract

Coastal wetlands provide many critical ecosystem services including carbon storage. Soil organic carbon (SOC) is the most important component of carbon stock in coastal salt marshes. However, there are large uncertainties when estimating SOC stock in coastal salt marshes at large spatial scales. So far, information on the spatial heterogeneity of SOC distribution and determinants remains limited. Moreover, the role of complex ecological interactions in shaping SOC distribution is poorly understood. Here, we report detailed field surveys on plant, soil and crab burrowing activities in two inter-tidal salt marsh sites with similar habitat conditions in Eastern China. Our between-site comparison revealed slight differences in SOC storage and a similar vertical SOC distribution pattern across soil depths of 0–60 cm. Between the two study sites, we found substantially different effects of biotic and abiotic factors on SOC distribution. Complex interactions involving indirect effects between soil, plants and macrobenthos (crabs) may influence SOC distribution at a landscape scale. Marked differences in the SOC determinants between the study sites indicate that the underlying driving mechanisms of SOC distribution are strongly system-specific. Future work taking into account complex interactions and spatial heterogeneity is needed for better estimating of blue carbon stock and dynamics.

Characteristics of soil organic carbon fractions in four vegetation communities of an inland salt marsh

“…Carbon sequestration in the salt marsh is an important part of the wetland carbon sink. The carbon capacity of salt marsh is stronger than that of other vegetation ecosystems in arid areas, and it is very sensitive to regional and global climate change [ 5 ]. To study the influencing mechanism of carbon sequestration in the vegetation-soil system of inland salt marsh wetlands, and to provide a scientific basis for revealing the mechanism of soil organic carbon accumulation in wetlands under the background of global change.…”