Invasive Species Control

european frogbit

Town Farm Bay is located in the southwest corner of Charlotte. At the eastern edge of Town Farm Bay, Thorp and Kimball Brooks enter into Lake Champlain and form a large and diverse wetland complex. This wetland provides valuable breeding habitat for over 41 species of birds, 11 species of fish, 10 species of amphibians and reptiles, and is home to several species of mammals. The Vermont Agency of Natural Resources, the Vermont Nature Conservancy, and the Town of Charlotte have recognized this wetland complex as a Vermont Natural Heritage site and premier wetland housing excellent examples of many natural communities. These wetlands of Town Farm Bay are particularly vulnerable to invasive plant introductions due to the high number of recreational fishing boats that access the area, potentially transporting invasive plant seeds and viable root matter. 

A population of exotic, invasive plants in Town Farm Bay wetland threatens to degrade the individual natural communities within the wetland complex and viability of the complex as a whole.

Invasive European frogbit was discovered in Town Farm Bay in the Spring of 2007 along with three other invasive plants. In 2009, a project team was assembled to remove frogbit from the bay. The first year, 7 tons of plant matter were pulled, reducing the bay to 45% frogbit cover. By year three, 42 total tons of plant matter were pulled, reducing the bay to less than 6% frogbit cover. 

Since 2011, a team of volunteers pulls frogbit each Spring to maintain a small population, so native species can fully utilize the wetland habitat. For 2019, interested volunteers can sign up for available volunteer slots:

-in Shelburne at https://www.signupgenius.com/go/8050c49adab28a7f58-european or

-in Charlotte at https://www.signupgenius.com/go/8050c49adab28a7f58-european1

or reach out to Kate Kelly, lewiscreekorg@gmail.com, or 802-488-5203.

Yellow iris

Yellow iris (Iris pseudacorus) is an emerging threat to Lake Champlain wetlands and flood plain forests of Champlain direct drainage streams.  It is designated by the Vermont Agency of Agriculture as a Class B Noxious Weed. LCA began a long-term project in 2015 to identify high concentrations of Yellow iris, and remove iris when possible. An August 2014 site visit to Thorp/Kimball wetlands by Ann Bove, DEC Environmental Scientist, identified Yellow iris, along with Purple loosestrife as serious threats to the diverse natural communities of the 53 acre wetland complex.  Iris clump growth rates season-to-season have been observed to exceed 100% (2015-16.)  Iris, like phragmites, will over time raise elevations of wetlands, effectively eliminating emergent plant communities.  Chapter 6 describes the loss of Lake Champlain wetlands and emphasizes the critical nature of holding on to what we have.  Keeping iris out of this wetland complex speaks directly to that imperative.  While established emergent clumps have been eliminated within the wetland, 2016 revealed significant iris stands in Lower Thorp Brook.  In addition to disrupting natural riparian communities in Thorp, these stands serve as the primary seed source for Thorp/Kimball wetlands. 

Lower Thorp Brook is diverse beaver-influenced corridor, and serves as the primary iris seed source for the wetlands at its confluence with Lake Champlain. These wetlands are considered state waters, comprising a fifty-three acre matrix of wetland natural communities, whose value has been acknowledged by VT DEC, VT FWD Natural Heritage Program and TNC experts.  The lake-influenced lower reaches of Lewis Creek contain important floodplain forests, buttonbush swamps and a range of state significant emergent communities.  Lands are state-owned (Little Otter WMA) and private.  While the extent and nature of the infestation is understood and mapped (LCBP 2015-16), a mutually agreeable management approach is needed to begin addressing this growing infestation in an ecologically significant area of high public value.

LCA received a grant from LCBP to continue this work in 2017, which:

1. Funded the preparation of a management plan and treatment of yellow iris in the lower Thorp Brook areas, with a targeted 90% reduction of iris.

2. Met with professional experts and 3 landowners in Lower Lewis Creek (a priority Natural Heritage area with increasing high yellow iris infestation levels) to discuss and identify mutually agreeable yellow iris control options.

LCA received an award from VT Fish & Wildlife to continue work on Yellow Iris in 2019-21. This award will allow us to study specific test plots and their response to various treatment options, including examining the possibilities of using volunteers to control yellow iris populations.

phragmites

Phragmites australis, also called Common reed, is a tall, perennial grass that can grow to heights of 15 ft. (4.6 m) or more. Broad, pointed leaves arise from thick, vertical stalks. Phragmites replaces native grasses, sedges, and herbaceous plants. It provides poor quality habitat for insects, birds and amphibians. Fish populations that reproduce in wetlands and marshes inundated with phragmites suffer higher egg and juvenile mortality. The plant also exudes toxic chemical compounds from its roots, causing root death of nearby native plants.

Lewis Creek Association co-sponsored a workshop with Habitat Restoration Solutions in March 2018 to discuss management strategies, which featured speaker Zachary Simek from Adirondack Park Invasive Plant Program (APPIPP). To view his presentation, see additional resources.

Flowering Rush

Flowering rush (Butomus umbellatus) is an aquatic perennial that grows along freshwater shorelines and in wetland areas with water as deep as 3 feet. Its leaves are three-angled, a unique distinguishing feature. Flowering rush is most conspicuous in later summer and early fall when its large, umbellate pink flowers are visible on tall stalks that can reach over 3 feet in height. Flowers produce dark brown beaked fruit that split open to release many seeds. Flowering rush has been observed displacing native species and sometimes is found in populations so thick that boat access is limited. Furthermore, this rush spreads by seed and rhizome fragments and has been noted to appear in floodplain forests.

Lewis Creek Association was awarded an LCBP grant in 2019 to study the best way to remove flowering rush. With the help of Habitat Restoration Solutions, we will be setting up test plots and using multiple removal methods, to determine which is most effective. This work will be occurring in the Thorp/Kimball area, and will involve volunteer labor in the removal treatments.