Effect of soil physical properties on carbon sequestration in created marsh wetlands of central Ohio

Created wetlands have been shown to contain significantly less soil carbon than natural wetlands. It is expected, that with time, the created wetlands will accumulate carbon and eventually reach levels observed in natural wetlands. However, the rate of carbon sequestration in the created wetlands may be hindered by changes in soil physical properties that occur during wetland construction. The purpose of this study was to evaluate the effects of soil structure, texture, and bulk density on the accumulation of carbon in created wetlands. Five created (ages 3-8 years) and four natural marsh wetlands in Delaware, Franklin, Knox, Marion, and Pickaway counties of Ohio, were selected for this study. Nine to fifteen soil cores were collected at each site and analyzed for soil carbon, water-stable aggregates, texture and bulk density. Peak standing plant biomass was also collected. The created wetlands contained significantly less soil organic carbon and plant biomass than the natural wetlands (MRPP, p = 0.009). The two carbon parameters were significantly correlated to the soil physical properties (Mantel, p = 0.004). Redundancy analysis showed that both soil organic carbon and plant biomass increased with an increase in 2-8 mm aggregates and a decrease in 0.25-1 mm aggregates, 0.053-0.25 mm aggregates, and bulk density. Wetland construction that preserves soil structure and bulk density will help increase the rate of carbon sequestration in created wetlands and decrease the time required to reach equivalence with natural wetlands.