Date of Award

1989

Degree Type

Thesis

Degree Name

Master of Science in Natural Resources

Department

Natural Resources Science

First Advisor

Frank C. Golet

Abstract

Reaching a consensus on wetland boundary determination criteria has been hampered by imprecise definitions of the distinguishing features of wetland and upland. Wetland transition zone research, of which this thesis project was a part, was undertaken in red maple swamps in Rhode Island to examine the relationships among hydrology, vegetation, and soils, and to develop field criteria for locating wetland boundaries using these parameters.

In this thesis, three years of hydrologic data were used in cluster and discriminant analysis to classify sampling stations as wetland or upland. In most cases, the wetland/upland hydrologic break fell on the border between very poorly drained and poorly drained soils. Variables describing the percent of the three growing seasons during which high soil moisture levels occurred within 30 cm of the ground surface were most useful in distinguishing between wetland and upland. The location of the hydrologic break varied between years, and suggested that the location of the break may move upslope to include more of the poorly drained soil zone in years of high precipitation.

Wetland/upland breakpoints based on hydrology, hydric soil status, and herb-layer vegetation were compared. The hydrologic break was lowest on the moisture gradient, and the vegetation-based break was highest. The break based on hydric soil status appeared to be the most reasonable location for the wetland boundary from both ecological and management perspectives. These results suggest that poorly drained soils should be considered wetland, and that hydric soil status is a useful and consistent parameter for wetland boundary determination in southern New England.

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