Deer Fence Allowed Forest Development
Bridget Paonessa and Stephen Jaquith
August 2014
Summary
We documented the effects of deer browsing by performing a transect study within an 18-year-old deer exclosure fence and then doing the same outside the fence. The mature trees and sunlight availability in both areas were similar. The counts revealed a large difference in numbers as well as species of young trees. The results clearly indicate that white-tailed deer cause low numbers and reduce the species variety of tree saplings.
Background
The area being documented is located in Eagles Mere, a small borough in Sullivan County, Pennsylvania that is heavily wooded, and adjacent to the large Loyalsock State Forest. In this area, there has been a white-tailed deer population that has exceeded its food supply since the 1920s. Now the forest is dominated by species that deer prefer not to eat: American beech, striped maple, and hay-scented fern. Most native herbaceous plants, shrubs, and trees are missing from the forest understory. Tree seedlings are very scarce.
Study Area
In 1996, a 2.7-acre deer fence known as The Catharine DeWeese Woodland Restoration Area was installed just off the rail trail, on property owned by the Eagles Mere Conservancy. The area was sprayed with glyphosate once, in August of 1996. A few desirable native trees and shrubs were planted in the fenced area for diversity. This study was conducted in August of 2014.
Method
Starting roughly 10 feet from the now closed gate’s entrance, a 100’-long transect was measured heading at an azimuth of 220 degrees. Using a tape measure opened to 5 feet, all live saplings over 4 feet in height that appeared to have developed after the installation of the fence were counted within the 100’ x 5’ foot plot. The same procedure was then performed outside the fence. Again starting about 10 feet from the fence’s gate and running in the opposite direction from the first transect, all saplings that met the requirements were counted in the 100’ x 5’ plot outside of the fence as well.
Results
Inside the fence, a total of 36 saplings were counted. Outside the fence, there were just four saplings.
The species inside the fence were black birch, black cherry, beech, and pin cherry. Outside the fence were only beech and striped maple.
The results are shown in the following tables and chart.
Number of Saplings Inside the Fence
Species / No.Black Birch / 21
Black Cherry / 7
Beech / 5
Pin Cherry / 3
Totals / 36
Number of Saplings Outside the Fence*
Species / No.Beech / 3
Striped Maple / 1
Totals / 4
*Deer had persistently browsed several young beech trees, creating low bushes that were not counted because they were less than four feet tall. They are not expected to develop into saplings.
Discussion
The results demonstrate that browsing by white-tailed deer strongly influences both the number and species of young trees that can become established naturally in this forest. Deer have allowed only non-preferred species, in this case beech and striped maple, to survive. The result is a young forest age class composed exclusively of species that deer seldom eat.
The deer exclosure fence around the Catharine DeWeese Woodland Restoration Area has protected young trees in this area of the Conservancy’s land. Naturally seeded saplings within the fence are thriving. An examination of land outside of the fence showed very few young trees. These results show that deer browsing strongly influences the number and species of trees in the future forest.
It is the intent of the Conservancy to maintain this fence and continue studying the changes that occur. An interpretive trail through this area is also planned for the future.