Masters Theses

Date of Award

8-1996

Degree Type

Thesis

Degree Name

Master of Science

Major

Ecology and Evolutionary Biology

Major Professor

John Rennie

Committee Members

Cliff Amundsen, Hazel Delcourt

Abstract

A landscape ecosystem classification (LEC) is described for the 26,100 ha Mountain Highlands section (610 m to 1660 m in elevation) of the Tellico Ranger District of the Cherokee National Forest. An LEC is based on the integration of three ecosystem components: landform, soils, and vegetation. The primary objectives of this research were; (1) to understand the spatial patterns and functional relationships of these ecosystem components, and (2) to provide a practical system of classification for use by U.S. Forest Service personnel in the management of forest ecosystems. Vegetation, soils, and landform data were obtained from ninety 0.04 ha plots located in stands representing late successional stages. Vegetation data were summarized by species and size class in terms of percent cover of the plot area. Two techniques of indirect ordination were used to distinguish site units (plots with similar vegetation): detrended correspondence analysis using DECORANA, and polythetic divisive classification using TWINSPAN. Stepwise discriminant analysis was used to determine those environmental variables that contributed most to the classification of the vegetation. A technique of direct ordination, detrended canonical correspondence analysis, was also used to identify site types from vegetation, soils, and landform variables. Results of the direct and indirect gradient analyses were compared and evaluated in terms of their ability to predict site units. Five ecological site units were identified and found to be recurring across the landscape. These were: 1) Yellow pine/mixed oak forest, 2) Mixed oak/red maple forest. 3) Cove hardwood/mixed mesophytic forest, 4) Eastern hemlock/yellow birch forest, and 5) Beech forest. Each site unit represents an array of site types which are identifiable combinations of landform and soil features, associated with discrete vegetative communities. A four variable model consisting of elevation, aspect, slope position, and A horizon depth accurately predicted site unit membership over 60% of the time. The primary axial expression of these site units is interpreted as a complex moisture gradient, made up of a combination of all four variables. For the purposes of developing a management strategy, elevation and aspect appear to be sufficient for predicting the distribution of site units across the landscape of the Mountain Highlands.

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