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.
You can view the above presentation in PDF form, with notes attached, by downloading it here.
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, volunteers pull frogbit each spring to maintain a small population, so native species can fully utilize the wetland habitat. Contact Kate Kelly, lewiscreekorg@gmail.com or 488-5203, to sign up to help out! We provide all the equipment, and you provide a few hours of your time to weed on the water.
Boat Launch Stewards
LCA’s boat launch steward inspects kayaks before they launch into Bristol Pond
Boat launch stewards are responsible for interacting with recreational boaters, anglers, and the general public to educate them about aquatic invasive species threats to the watershed and the proper cleaning methods for their recreational equipment (in particular focusing on cleaning, draining, and drying equipment). While educating the public, the boat launch stewards also collect survey data on boater behaviors, and identify and remove invasive species from watercraft. In 2020, LCA began a boat launch steward program at Bristol Pond, which was expanded in 2021 and later to include Monkton Pond. Read more about our boat launch steward program and results on our Boat Launch Steward Program page.
Japanese Knotweed
Japanese knotweed on the bank of Lewis Creek in Starksboro. Photo credit: Kate Kelly
Japanese knotweed can be a particularly tough non-native invasive species to remove. It was introduced from East Asia in the late 1800s, and was planted as an ornamental and for erosion control (but ironically, can actually increase streambank erosion). It spreads primarily by its roots/rhizomes, which can break off during a flood then resprout and form a new colony downstream. LCA hopes to engage the community to undertake a long-term project controlling knotweed (without herbicides) in our watershed, and we need your help!
A prior grant to LCA documented that knotweed is present in the Lewis Creek watershed, but with a patchy distribution, and that it has not yet spread prevalently across streambanks (unlike in many other Vermont watersheds where it covers nearly every space along streambanks!). LCA is excited to demonstrate a non-chemical removal method to the public at a site in North Ferrisburgh, where our technicians will be present weekly to lead removal efforts, and to display these methods to the public (who can help if they wish!). LCA is partnering with Mike Bald (Got Weeds?) to guide this work and demonstrate effective methods for knotweed removal without herbicides – it can be done!! You can also get involved in a project that uses community scientists to help us understand the distribution of knotweed in the watershed using iNaturalist. LCA would love to have your involvement in one or both portions of the project. If you’re interested in learning more, sign up at https://bit.ly/lca-knotweed or reach out to Kate Kelly, Program Manager for Lewis Creek Association, at lewiscreekorg@gmail.com or 488-5203. This work is funded by the Lake Champlain Basin Program/NEIWPCC/US EPA.
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:
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.
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 in the Little Otter Wildlife Management Area. This award allowed us to survey yellow iris from the Falls in North Ferrisburgh to the mouth of Lewis Creek, and to study specific test plots and their response to various treatments, including the possibility of using volunteers to control yellow iris populations. Over the course of three seasons, volunteers dug out 335 clumps and 710 single yellow iris plants (using 125 volunteer hours). Larger clumps that were too big to dig (126) were treated chemically using a wetland-safe herbicide, and were treated in the fall to minimize impacts on amphibians and other plants.
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, which can help distinguish it from other plants. 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 plant 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 HRS/Riverscape Ecology, we set up test plots in Town Farm Bay in 2020 to determine if pulling flowering rush would allow for adequate control, and to see if cutting the plants back multiple times over the course of a season would allow minimize re-growth the following year. The results of this study are available here, and a press release summarizing the study is also available. An additional detailed document on flowering rush is available here from the Ontario Invasive Plant Council.