The Caumsett Foundation

Fighting Invasive Species on Butterfly Hill

Courtyard GardenIn January of 2024, Governor Kathy Hochul announced the Caumsett Foundation along with 42 other groups statewide would receive a total $2.9 million as part of the Invasive Species Grant Program of the Department of Conservation. These projects will reduce the negative impacts of invasive species of plants and pests in our communities, waterways, fields and forests. On Long Island, all six projects awarded are in Suffolk County. The Caumsett Foundation received $65,470 for the removal of invasive vines on Butterfly Hill near the entrance of the Park.

Butterfly Hill encompasses 4-acres of meadow vegetated by warm and cool season grasses, forbs, and the invasive vine porcelain berry (Ampelopsis brevipedunculata). Reduction, suppression, and long-term management of porcelain berry on the site will restore its ability to support the rare Baltimore checkerspot butterfly colony in the Park. This past spring the colony had to be relocated to another area of the Park where the host plants could sustain the larvae. Butterfly Hill has the only known breeding colony of this species on all of Long Island, and also contains threatened native species of plants.

Treatment of this area will be carried out over a 3-year period and evaluated after each season so that treatment modifications can be made. Porcelain berry is a rapid-growing woody vine in the grape family that is able to spread vegetatively through fragments and by seeds dispersed through animal droppings of birds and small mammals. Its large root crowns and ability to re-root at nodes along the stems make manual removal difficult. Because this species is able to spread vegetatively, all fragments will be solarized in garbage bags and destroyed. Porcelain berry seeds may remain viable in the soil for several years making continued removals of newly germinated plants necessary to deplete the underground seed bank. Cutting and mowing needs will be repeated on a regular basis as well so the plants won’t resprout. Repeat cuttings will reduce porcelain berry’s energy, resulting in a less vigorous root systems at the season’s end and allow for more successful removal the following growing season. Areas with dense porcelain berry seedlings will be covered with a dark tarp for the entire growing season to augment the remediation of all the invasives. Ultimately, the area will be seeded with native varieties to support the butterfly colony.

The Foundation is thrilled to receive this grant and is looking forward to returning the Baltimore checkerspot butterflies back to their home on Butterfly Hill once the project is completed. The Caumsett Foundation’s environmental projects are a resource for all Long Island’s land managers interested in invasive species management.

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