Masters Theses

Date of Award

5-1991

Degree Type

Thesis

Degree Name

Master of Science

Major

Botany

Major Professor

Edward E. C. Clebsch

Committee Members

H.R. Deselm, L.J. Gross

Abstract

Tennessee coneflower, Echinacea tennesseensis (Beadle) Small, is a rare endemic of the limestone cedar glades and barrens of Middle Tennessee. At the time this study was initiated there were only five native populations known. Due to its limited numbers, the federal government lists the species as endangered. There are two primary objectives, and therefore two main parts to this study. The first objective is to analyze the vegetation of the five coneflower sites; the second objective is to study the demography of the species. Vegetation data were collected using half meter square quadrats placed at defined points on a grid extending over the coneflower population at each of the five sites. The percent cover of each plant species was estimated within each quadrat. Approximately five percent of the total area occupied by the coneflower was sampled. Approximately 100 individuals were selected at random from each population, and these individuals were monitored for two growing seasons. Mortality and life history characteristics were recorded, and an initial stage class distribution was constructed. Percent cover of each species was estimated for each population, and the species composition was found to vary among sites. Plant communities were identified in order to classify the vegetation and to compare environmental factors, such as soil depth, among communities. Mortality and growth varied greatly between growing seasons, and mortality were highest among juvenile (non-flowering) plants both years. The stage class distribution is such that there are many more juvenile (non-flowering) plants than adult (flowering) plants. Six communities were identified from the plot data. Two of the communities are considered barrens habitat and are characterized by greater than 50 percent cover of perennial grasses and relatively deep soils. Four of the communities are considered glade habitat and are characterized by more than 50 percent cover of annual grasses and excedingly thin soils. Tennessee coneflower occupies all the communities and both types of habitat, however cedar glade is considered the primary habitat of Tennessee coneflower because the majority of the habitats sampled are glades. The obvious reason for high mortality the first season is the severe drought of the summer of 1988. High mortality among juvenile plants both years and the stage class distribution suggest that established (larger) plants have a better chance of surviving the summer drought.

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