Soil Survey Investigations of Freshwater Subaqueous Soils: Carbon Accounting and Invasive Species.

Subaqueous soils are those that occur under permanently flooded or ponded environments. In this study, we are examining subaqueous soils of three natural and three created fresh water-bodies in Rhode Island. Bathymetric data were collected and topographic maps of the lake bottom were constructed. Data were used to delineate subaqueous landscapes. Ground-penetrating radar (GPR) transects were run across landscape units to test the effectiveness of this technology to identify soil types at the order level. The location and abundance of aquatic vegetation was mapped during peak flowering, paying close attention to aquatic invasive species and related to geographic, bathymetric, and soil type data. The primary landscape units identified from the bathymetric maps include submerged shorelines, coves, lake plains, and shoals. GPR was able to identify the presence of stones and boulders, stratified mineral layers, and the thickness of organic soil materials. These data were used to identify and map subaqueous Histosols (Frassiwassists) and Entisols (Frassiwassents). Two of the natural ponds were entirely free of aquatic invasive species while Variable milfoil (Myriophyllum heterophyllum) and Fanwort (Cabomba caroliniana) were the most common invasive species in the created ponds. Work is continuing to relate soil properties to the presence and abundance of invasive species and inventory carbon stocks in these soils.