SBC Researchers Investigate Impact of Deer on Native Flora

| November 13, 2008

Thanks to the keen observations of biology professors past, there is a suspicion among Sweet Briar’s current science faculty that grazing by too many white-tailed deer is diminishing the diversity of the native flora on campus.

Assistant professor of biology Janet Steven stakes a potential site for an “exclosure” to study the impact of deer grazing on native plants. Photo by Linda Fink.

Ernest P. “Buck” Edwards, who retired from Sweet Briar as Duberg Professor of Ecology in 1990, and his late wife, Mabel Thacher Edwards, compiled several lists of plants based on observations made from 1965 to his retirement. Their observations were added to previous compilations.

“While we have no record of the abundance of individual species in the past, Buck and Mabel Edwards’ plant list from the eighties has species I’ve never seen blooming on campus in the four years I’ve been here,” said assistant professor of biology Janet Steven.

To test the hypothesis that overgrazing by deer explains why some plant species — especially wildflowers — are disappearing, Steven, professor of biology Linda Fink, naturalist-in-residence Mike Hayslett and Sweet Briar biology students will build deer “exclosures” where data can be collected over time. There are plans to build the first exclosure — possibly near the base of Monument Hill — by the end of the semester.

Steven said the area has both high deer densities and good plant habitat, and it’s easily accessible for classes. In the spring, she and her students will take data on what plant species are growing in the exclosure as well as the number of plants of each species, and possibly plant size. The same observations will be recorded in a control plot outside of the fence.

“Deer are selective in what they eat, so it’s possible that some species will show more dramatic recoveries than others,” Steven said, noting exclosures are becoming common in many locations, and often show striking results.

“With an exclosure at Sweet Briar, we can quantify the effects the deer have on our plant populations, and the time it takes those populations to recover after the intense herbivory caused by high densities of deer,” she said.

– By Jennifer McManamay, SBC staff writer

Category: Biology