Soil Morphology and Pollen Distribution in Riparian Zones: Indices of Land Use Change.

Riparian zones are important components of the landscape that act as a buffer between upland and aquatic systems. These dynamic areas provide numerous functions including high rates of carbon sequestration, nutrient and sediment retention, denitrification, and flood abatement. Riparian zone functions may be impacted by land use changes within the associated watersheds. Understanding these effects is dependent upon development of approaches to assess changes in the riparian zone soils related to shifts in land use. Regional deforestation during an intense agricultural period (250-150 YBP), farm abandonment and forest regeneration (150-50 YBP), and recent urbanization (50 YBP-present) are the primary land use periods in southern New England. Traditional methods to establish site chronology utilize aerial photography, historical records, and radiometric dating (¹⁴C, ²¹⁰Pb, ¹³⁷Cs). These methods, however, have limitations; aerial photographs are only available since the 1930’s, historical documents can be highly inaccurate, and obtaining radiometric dates is expensive. The goal of my study is to develop a set of regional indicators for three major watersheds of southern New England: Narragansett Bay, Pawcatuck River, and Thames River. Eighteen representative study sites have been selected based on current land use activity within the region. These sites will be used to establish positive linkages between soil morphology characteristics, pollen assemblages, historical records, and calibrated radiometric dates. The stratigraphic markers obtained through this study will serve as the basis for further evaluation of the impact land use alteration has on the environmental functions provided by the riparian zone.