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Extramural Research

Grantee Research Project Results

NCER Grantee Research Project Results

Individual Growth Rates and Population Demography of White-Flowered Trillium (Trillium grandiflorum) Across Gradients of Light, Fertility, and Deer Browsing Pressure

EPA Grant Number: U915650
Title: Individual Growth Rates and Population Demography of White-Flowered Trillium (Trillium grandiflorum) Across Gradients of Light, Fertility, and Deer Browsing Pressure
Investigators: Rooney, Thomas P.
Institution: University of Wisconsin - Madison
EPA Project Officer: Manty, Dale
Project Period: August 1, 1999 through August 1, 2002
Project Amount: $93,147
RFA: STAR Graduate Fellowships (1999)
Research Category: Fellowship - Terrestrial Ecology and Ecosystems , Academic Fellowships , Ecological Indicators/Assessment/Restoration

Description:

Objective:

The objective of this research project is to determine the effects of deer browsing on the forest herb, the large white-flowered trillium (Trillium grandiflorum). The investigator proposes to: (1) determine if trillium growth reflects an overcompensatory or undercompensatory growth response to browse damage, and how this response is mediated by soil fertility, light availability, and the reproductive history of the plant; (2) find the determinants of plant selection by browsers; (3) determine how browsing, relative to other environmental factors, affects the population structure and growth of trillium; and (4) determine the impacts of the loss of populations on genetic diversity.

Approach:

In 1997, the investigator established 27 study plots throughout northern Wisconsin and the western portion of Michigan's upper peninsula. In each study plot, the spatial location and height of all three-leafed, white-flowered trilliums and the location of all one-leafed trilliums were recorded. The 2000 plants in these plots have been monitored every year. Soil and light measurements were taken in each study plot, and local browsing pressure was assessed. Four additional study plots were added in 1998 for artificial defoliation experiments.

Supplemental Keywords:

fellowship, Trillium grandiflorum, white-tailed deer impacts, plant population decline.

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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