Submitted to: Environmental Pollution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 20, 2001
Publication Date: N/A
Interpretive Summary: The influence of soil erosion and redistribution on terrestrial C storage is poorly understood. Some assessments have indicated that soil erosion has an overall negative influence on C storage in the terrestrial ecosystem. However, recent work has led to a new concept that soil erosion and terrestrial sedimentation may promote carbon (C) sequestration within landscapes by establishing ecosystem disequilibrium. We explored the implications of this new concept on carbon sequestration and storage in a small agricultural watershed. We found evidence that soil movement within the watershed promoted carbon sequestration and increased the carbon storage capacity of the watershed. This indicates that agricultural activity may have a positive influence on carbon dynamics in the environment. This work will lead to a better understanding of the role agriculture plays in production and consumption of greenhouse gases.
Technical Abstract: Recent modeling studies indicate that soil erosion and terrestrial sedimentation may establish ecosystem disequilibrium that promote carbon (C) sequestration within the biosphere. Movement of upland eroded soil into wetland systems with high net primary productivity may represent the greatest increase in storage capacity potential for C sequestration. The capacity of wetland systems to capture sediments and build up areas of deposition has been documented as well as the ability of these ecosystems to store substantial amounts of C. The purpose of our work was to assess rates of sediment deposition and C storage in a wetland site adjacent to a small first-order stream that drains an agricultural area. The soils of the wetland site consist of a histosol buried by sediments from the agricultural area. Samples of deposited sediments in the riparian zone were collected in 5 cm increments and the concentration of 137 Cs was used to determine the 1964 and 1954 deposition layers. Agricultural activity i the watershed has caused increased sediment deposition to the wetland. The recent upland sediment is highly enriched in organic matter indicating that large amounts of organic C have been sequestered within this zone of sediment deposition. Rates of sequestration are much higher than rates that have occurred over the pre-modern history of the wetland. These data indicate that the increased sedimentation rates in the wetland ecosystem are associated with increased C sequestration rates.