Date of Award

12-2011

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Forestry and Natural Resources

Advisor

Conner, William H

Committee Member

Krauss , Ken W

Committee Member

Shelburne , Victor B

Committee Member

Bridges, Jr. , William C

Abstract

A hierarchical approach to forest community assessment was conducted by first focusing on landscape associations to edaphic factors among major tidal freshwater forested wetland basins in the Southeast. Four general tree communities exist along coastal rivers in the southeastern United States, based on the most prominent species in each: Water Tupelo, Swamp Tupelo, Dwarf Palmetto, and Cabbage Palm. Microhabitat usage and preference by trees were then examined, both across all species and within species, as related to such factors as coast, presence on rivers with dams, tree community assemblage, relative distance from the river, specific river basin, and microsite availability. There are significant differences in the relative use of microsites in relation to most factors, both on a species-specific basis, and across all species. Twenty-one species use hummocks more than hollows, while only three species use hollows more. Finally, the processes driving these preferences in individual trees through dedicated water use studies on baldcypress trees in various settings (e.g., flooded vs. non, on hummocks vs. in hollows, in slightly saline vs. freshwater environments) were examined. While mature baldcypress trees increase rates of sap flow during flooded conditions, their rates of sap flow are not influenced by microsite position, and they have lower total sap flow in higher salinity environments. Sap flow rates are maximized at different radial depths into sapwood that differ with salinity. This study increases our understanding of tidal freshwater forested wetlands at the regional level, thereby providing a better base of knowledge from which future management goals can draw. A broad understanding of community composition, their associations with soil and hydrology, and usage of microtopography may help direct future restoration efforts. Learning the physiology associated with water transport in trees under differing environmental conditions will allow us to understand the specific physiological requirements of trees at different microtopographic and landscape positions.

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