PA Environment Digest

The Friends of the Wissahickon have launched a pilot project to explore the possibility of using goats to control the growth of invasive plants in Wissahickon Valley Park.

This small, informal study compares invasive plant control results using three mechanisms: goats; herbicide; and human hand-clearing. “I am not aware of this type of scientific experiment ever having been done in the area,” says FOW Conservation Chair Susan Wilmerding. “It will be interesting to see the results.”

(Photo: Yvonne Post, a partner in Cooking for Real and owner of the goat herd, with Wyeth and Rodin as they enjoy some English Ivy, an invasive plant in the Wissahickon.)

Six test sites in close proximity have been chosen with comparable terrain/conditions for the five year study. Every site consists of 400 square feet with 100 percent or close total coverage of target invasive plant species. They have been flagged, assigned GIS (Geographic Information System) coordinates, and evaluated for plant values using the Plant Stewardship Index.

Botanists have documented the type and quantity of the species growing in the six plots, and will return and identify what remains.

The three invasive plant control mechanisms have each been assigned two test sites at random. After each site visit, a botanist returns to identify the remaining species and their quantity. Possible alterations may be made to the test site protocols after the first year.

The herbicide glyphosate will be applied during one mid-summer clearing by 6-10 volunteers with varied background in invasive plant control, repeated with a late summer (August/September) application.

Hand-clearing is also being completed by volunteers, who will visit their two sites three times in groups of 6-10 throughout the summer and early fall. Control methods will vary based on targeted species.

A herd of six Angora goats will visit their two sites three times throughout the summer and early fall. Goats are good foragers and eat a wide variety of weeds, woody plants, shrubs, briars and grasses. According to Yvonne Post, a partner in Cooking for Real and owner of the goat herd, “Goats like to eat vertically and anything on the ground they will pull.” This means that they are likely to remove the roots of the invasive plants they eat.

“FOW is excited about this project,” says FOW Executive Director Maura McCarthy. “It’s important for the Friends to explore all options for removing invasive plants.”

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