Dredging Impacts on Soil Properties of the Kankakee River System 150 Years after Perturbation

Freshwater marshes provide ecosystem services such as improving water quality by storing water and filtering nutrients from upland runoff, minimizing erosion and flooding by reducing stream and river velocity and peak flows, and carbon sequestration by storing organic matter for long extended periods of time. These ecosystem services have increased interest in the protection and restoration of marshes and soil properties and are an important consideration for successful restoration. This study was conducted in Indiana, USA, within the historical extent of the Grand Kankakee Marsh that once encompassed 202,343 ha, until the dredging of the Kankakee River from 1852 to 1917 to convert the marsh to cropland. Current (in 2019) soil properties (organic matter mass and concentration, bulk density, moisture content, and carbonate concentration) were compared between (1) marshes that were dredged and presently in other land-use categories such as cropland and forests, and (2) remnant marshes that were not impacted by dredging. On average, organic matter mass and concentration were not significantly different between dredged areas and marshes (p > 0.05). However, marshes tended to have lower bulk densities, greater moisture contents, and greater carbonate concentrations compared to dredged areas. The soil properties of remnant marshes in this study can be used to evaluate the success of marsh restoration efforts in regions with similar soils, climate, and land-use history.