by Theresa Sprague ’08
The following article was originally published in the September 2017 newsletter of our partner organization, the Ecological Landscape Alliance.
Over the past seven years, the team at BlueFlax Design LLC has managed a multitude of landscapes degraded by invasive plant species. We have managed sites for species including shrub and vine honeysuckle, porcelainberry, Asiatic bittersweet, border privet, autumn olive, black swallowwort, Japanese knotweed, and others. Four years ago we were introduced to a coastal site on Cape Cod that was comprised, almost exclusively, of each and every one of these invasive plants, covering just over a one-acre area. While this was one of the worst infestations we had experienced to that point, we were ready for the restoration challenge.
Success Begins with a Plan
Whenever we approach an invasive species management and restoration project we start with a plan, but in the case of this particular project we knew that a well thought out, feasible, multi-year management plan would be essential to the successful outcome of the project. After working with stake holders including property owners, the local Conservation Commission, abutters, and others, we developed a five year plan that has seen us through four years of transformation from an overwhelmingly degraded coastal wetland resource area, to restored ecological integrity.
Once the management plan is in place, it is time to begin implementation.
The Project – Existing Conditions
As described earlier, this project site comprised approximately 46,000 square feet of heavily invaded coastal bank and buffer zone wetland resource areas. Invasive plants present on site included Japanese knotweed, black swallowwort, Asiatic bittersweet, porcelainberry, shrub honeysuckle, vine honeysuckle, autumn olive, and border privet.
Site History and Challenges
The project site was formerly host to a popular hotel, renowned for its sunset views. Some invasive plant species, such as border privet, autumn olive, and porcelainberry, had been purposefully planted as part of the hotel’s extensive landscaped grounds. The hotel was demolished and redeveloped in the 1980s, a project that consisted of intensive regrading of the site. In 2004, a restoration attempt was made; however, due to lack of oversight, internal conflicts, regulatory issues, and lack of a clear long-term plan, this restoration attempt failed, and all areas of the property within conservation jurisdiction (wetland resource areas) remained relatively untouched until our project implementation began in 2014.
Project Goals and Objectives
Working with project stakeholders through the planning process we identified five major goals for the project:
- Improve stability and function of the Coastal Bank and Adjacent Upland Resource Area
- Improve Wildlife Habitat Value
- Maintain Historical Water Views
- Improve Aesthetics for Property Owners
- Develop a realistic and feasible long-term management and maintenance plan
From the existing conditions and identified goals and objectives, we developed a five year management plan consisting of invasive species management methodologies (selective herbicide treatments, mechanical removal, and mowing), along with protocols for seeding and stabilizing soils, phased restoration planting, and long-term maintenance.
After obtaining all proper permits from the local Conservation Commission and Department of Environmental Protection, implementation was underway in early summer 2014.
Immediately post clearing, soils are raked out, seeded, rolled, and covered with chopped straw on flatter area. On steep slopes, we spread 100% biodegradable erosion control blanket.
Three months post initial intensive management phase seed mix has germinated and covered most bare soils. Selective follow up herbicide treatments to Japanese knotweed, black swallowwort, and other invasive species continued. We observed excellent to patchy germination of seed mix throughout project area, so commenced plugging of native grasses in areas where germination was spotty.
Following the first year intensive management phase, follow-up management and maintenance was underway, beginning with the year one mowing protocol. At this point cool season European pasture grass and annual/biennial non-invasive weeds were the most significant management issue. As predicted, black swallowwort remained a serious management challenge, while bittersweet and porcelainberry resprouts were as expected. Woody native vegetation, flush cut for protection during the intensive management phase, had already begun to regenerate. Over seeding and plugging of bare soils the previous fall resulted in significantly improved germination and coverage.
Eighty percent control or better was achieved, and the first phase of restoration planting was undertaken. Follow-up management of Japanese knotweed continued, while native plants including bayberry, beachplum, and staghorn sumac, flush cut during the initial management phase, continued to vigorously resprout.
Fast Forward – October 2016, Maintenance Year 3
Management and maintenance continued per the management plan throughout spring and summer of 2016 with some minor plan changes made based on weather conditions. Temporary irrigation was installed to support restored woody vegetation throughout the drought period of 2016. Selective treatment of black swallowwort was ongoing and required more monitoring and maintenance than initially planned. Japanese knotweed control was successful, and replanting of that management area began.
Management and maintenance continues per the Management Plan established back in 2013. The structure of the meadow, being a dynamic system, has changed as some species, such as black-eyed Susans, have diminished, and others, such as more aggressive goldenrods, have proliferated. However, native warm season grasses including Indian grass, switch grass, big bluestem and little bluestem have established as the backbone of the meadow. Black swallowwort management is ongoing, and will continue to be an important part of the long-term maintenance plan for this project. Annual mowing will continue in early spring as part of the long-term maintenance of the project area, allowing us to properly monitor the site and respond rapidly to signs of re-infestation. With the careful planning for long-term maintenance built into the management plan before the first vine was removed and the dedication of the property owners and other stakeholders involved in this project, we are confident that this restoration project will continue to be a success.
About the Author
Theresa Sprague ’08 is the owner of BlueFlax Design in Harwich, MA, where she focuses on merging science with the fine art of landscape design to create beautiful, ecologically sound, and sustainable landscapes, restoring ecological function and integrity to the built environment. She seeks to create habitats that support the needs of both people and wildlife. Theresa holds a master’s degree from the Conway School of Landscape Design, where she is also a board member, and has over 15 years of planning, design, ecological restoration, gardening, and land management experience. She may be reached at theresa @ blueflaxdesign.com.