It is clearly evident in the pair of images above that the landscape of Sheep Hill has changed over the past century. The early 20th C. farms on Stone Hill, in the middle distance, have become almost entirely forested, and the then active Sheep Hill pasture at the base of Bullock’s Ledge, on the left middle distance, has also been invaded by woody vegetation. For thousands of years before European settlement of the indigenous landscape, Bullock’s Ledge has supported a highly diverse biological community that included species that are now considered to be rare, endangered, and of special concern. The south and east sides of the marble outcrop of Bullock’s Ledge was far too steep to be of interest to the first, or even subsequent, farmers that occupied the landscape to consider for cultivation or pasturage, so its forest and woodland cover remained largely intact. The tract was owned by the Rosenburg family as part of their Sunnybrook Farm until they sold it to the MA Division of Fish & Wildlife in 1997, creating the 15+/- acre Bullock’s Ledge Wildlife Management Area.
Starting in the late 19th Century, the residents of the region started to import and plant shrubs that they considered to be decorative or useful species such as barberry, European honeysuckles, buckthorn, privet, burning bush, multiflora rose and others which later have become invasive. Then, in the late 1980s, the wide-open pasture at the western base of Bullock’s Ledge was abandoned when livestock operations ceased on Sunnybrook Farm. The result was that the native white pines were overly successful in filling the now un-grazed real estate with seeds that formed an extremely dense invasion of their own.
The coincidence of exotic and native species invading Bullock’s Ledge from Sunnybrook Farm on the west created a situation in which rare native plants on the ledge are in jeopardy of becoming locally extinct. While these species are adapted to periodic disturbances, such as storms and even fires, they are not well-adapted to the environment that has been created by the invasions of the exotic shrubs and the old-field white pines. The invasion of both exotic plants and native pine are products of past human activities. In the absence of human landscape alterations, the disturbance cycle would have been quite different, and the light, hydrology, and soil environments more conducive to maintaining a wider diversity of species, especially for those now on the rare and endangered species list. There is a high probability that if the populations of invasive species are not reduced, the species of special concern will disappear from the site, resulting in true losses in local and regional biodiversity, and of our greater biological heritage.
Williamstown Rural Lands is collaborating with the Massachusetts Division of Fisheries and Wildlife to restore the functional ecology of the site. The work is being supervised by Chris Buelow, Senior Restoration Ecologist of the MA Natural Heritage & Endangered Species Program. On 24 August 2021 the first phase of invasive species control was undertaken with precision application of herbicides to the smaller sized individuals of the target species. Later in the fall there will be further cutting and removal of exotic shrubs and trees such as multiflora rose, buckthorn, barberry, and honeysuckles. The cutting and removal of the invading white pine trees will occur during the winter of 2021-2022 when the meadows will be dormant and the soils less prone to disturbance.
The management of the Bullock’s Ledge Wildlife Management Area is a balancing act between preserving the capacity for rare organisms to survive and respecting natural processes of native biological communities. Though a relatively small property, Bullock’s Ledge is a statewide priority for the preservation of vulnerable biodiversity in Massachusetts. The State purchased this property to preserve high priority, rare biodiversity elements, and considering the main threat to those elements (invasive species and a dramatic shift away from the supporting specialized natural communities), the main restoration objectives of Williamstown Rural Lands and the Natural Heritage and the Massachusetts Endangered Species Program remain invasive species control and natural community restoration.
By Hank Art, WRL Interim Director