Students Study Whitetail Deer impact on forest understory

Through the cooperation of Matthews State Forest and forester Zack Olinger, and along with Alan Webb (Ag teacher), and Rachelle Rasco (stem lab manager) from Carroll County High School, BRDC initiated a research project at one of the two deer exclosure sites on MSF. This project is expected to encompass not only this fall semester, but also a spring 2016 return visit or two for further comparisons.

On August 21st, Evan Worrell and Scott Jackson-Ricketts (from Blue Ridge Discovery Center) gave a brief introductory explanation to the students about the project and what to expect. We handed out a research model, and encouraged them to familiarize themselves with the steps involved.

On September 9th, the 13 students arrived on a bus and joined Evan and Scott for a day of plant investigations. We also had on hand Dr. William Dunson whose experience in plant identification and deer plot studies proved to be of great help.

The practice of establishing deer exclosures dates back to at least the 1930s, and has been used to study the long term effects of deer browsing on forests. The basic approach is to choose a site that includes room for both the exclosure and control plots. Size of the plots is determined by proper and available space. 25% direct sunlight is required for both plots. The exclosures are fenced off from deer but are accessible to the research teams.

Our research goals are to follow guidelines of scientific inquiry which include building hypotheses based on early discussions about forest habitat and successional growth. We separated the students into four teams and divided the 32 square foot plots into four sections, assigning one group to one section each both inside and outside the exclosures. 

The research process involves adhering to an agreed upon series of protocols. Mapping out both plots into grids for detailed studies is essential. Data collection and documentation are the driving components. Type of tree cover, living or dead, descriptions of overstory (canopy) and understory growth including stumps, measurements of trunk diameter at approximately three feet from ground level, as well as total height of trees have been noted. Types of vegetation are broken down into these categories: trees, woody shrubs, herbaceous, graminae (grasses) and miscellaneous. Cover percentage of each vascular plant species was determined by means of a sampling frame, and numbered on the grid. 

On our first field day, we spent some time going over the layout, measuring tree diameters and heights, describing the canopy and familiarizing ourselves with our field guide library. Then we went about attempting to identify all of the plants, and counting species populations. It was quickly noted that inside the exclosure, more plants were thriving compared to the control plot that was fully available to browsing deer.

Zach closed the day’s activities with a summation of Matthews State Forest’s management goals, processes and tied that to the issues facing foresters through the white tail deer’s expanding impact on tree seedling survival…especially our native oaks. 

For our second field trip, held on October 21st, (more than a month later), we concentrated on improving our ID skills as well as making a greater effort on securing an accurate population count. Evan directed the students to rotate, giving each quadrant a much more thorough investigation. This intentional redundancy proved to be a most valuable tool and led to a higher degree of accuracy. We did find differences between our two investigations, and surmised that some of the smaller plants might not have been visible under the leaf litter until fall winds blew the leaves away.

Through the encouragement of Dr. Dunson, (now in Florida), Evan employed the Simpson Index for cataloguing and assimilating our data…which were entered into a spread sheet from which graphic analysis became more available and easier to understand. The Simpson Index takes into account total species diversity. Evan and Scott returned to the high school on November 17th to share the results of the students’ hard work, and to explain our accumulative findings. There were some surprises.