Soil Organic Carbon Pools in Riparian Landscapes of Southern New England

Riparian zones are important catchment-scale depositional environments that receive episodic influx of sediment and C from watershed sources. The specific impacts of upland disturbances on riparian soil development and soil organic carbon (SOC) dynamics are still largely unknown. The goal of our study was to understand the role of riparian soils in retaining C at the landscape and catchment scales. We quantified SOC pools to a depth of 1 m at 29 headwater riparian sites in southern New England. Riparian SOC pools ranged from 117 to 495 Mg C ha(-1), with a mean pool of 246 Mg C ha(-1). On average, >50% of the total SOC was stored below 30 cm. Riparian SOC pools differed significantly between soils formed in relatively fast accreting environments (those that contain buried surface horizons; 277 Mg C ha(-1)) and those in slow accreting environments where buried horizons were absent (188 Mg C ha(-1)). Catchment-scale analysis of SOC distribution indicated that riparian zones, on average, occupy 8% of the total watershed area yet store as much as 20% of the total catchment SOC. These results suggest that even though riparian zones occupy a small percentage of the overall watershed, these areas are an important component of the landscape for storage of SOC deposited as a result of catchment-scale disturbances.