During the past growing season, Wissahickon Valley Park has been the site of an experimental project with goats. Because of the ongoing problems associated with invasive plant species taking over many areas of our natural woodland, FOW and Philadelphia Parks & Recreation are always looking for new, successful ways of controlling these weeds.
“In some locations we have acres of knotweed or bamboo,” says FOW Executive Director Maura McCarthy. “Hand-weeding just won’t work.”
Thanks to Yvonne Post, a partner in Cooking for Real and owner of the goat herd, FOW has been able to expose six Angora goats to various species of invasive plants in three different months of the growing season. “Goats like to eat vertically and anything on the ground they will pull,” she maintains. This means that they are likely to remove the roots of the invasive plants they eat. The goat experiment will help FOW determine if there are alternatives to pesticides.
Goats are good foragers and eat a wide variety of weeds, woody plants, shrubs, briars, and grasses. In western states, goats have been used in many areas for plant removal. Often larger Boer goats, which will eat almost anything, are utilized with great success. Angora goats may be a bit more choosey, but they are easy to transport and manage—Post brings them from her farm in the back of her Subaru!
In previous years, Post has let her goats graze at the Tyler Arboretum and Longwood Gardens, but she did not know how these charming animals would like the Wissahickon. After installing a small, temporary fence, the goats were allowed to browse for one day in June, August, and September.
As the plant material matured over the growing season, the Friends were eager to learn if the goats would prefer early or late summer greenery. Before and after each visit, botanists from the Bowman’s Hill Wildflower Preserve, Janet Ebert and Jack Holt, surveyed the site and presented FOW with a complete list of the plants so that we could accurately identify what the goats had eaten. In June they loved poison ivy (Toxicodendron radicans), which is actually a native plant, although it can become quite a problem, and the invasives oriental bittersweet (Celastrus orbiculatus) and wing-stem burning bush (Euonymus alatus). In August they munched mainly on privet (Ligustrum obtusifolium) and English ivy (Hedera helix). We are still waiting for the results of their early September forage.
As a comparison, a similar sized 20’ x 20’ plot is being weeded by hand, and a third plot will be carefully sprayed with herbicide. The complete results will not be ready for at least another year. FOW will identify these specific plots with GPS and return next year to determine which species have returned and, hopefully, which species of invasive plants have been permanently extirpated or slowed down. If the goats have made a big impact, the project may be expanded.