Sewall Woods Invasive Species Management Project
Project Overview
The Lakes Region Conservation Trust (LRCT) is conducting a long-planned natural resource improvement project in the Sewall Woods Conservation Area (SWCA) in Wolfeboro. This project was selected for funding through the Natural Resources Conservation Service (NRCS) Environmental Quality Incentives Program (EQIP) for a contract to implement several recommended practices, starting with Forest Stand Improvement Thinning for Wildlife and Forest Health removal.
The project aims to address the thriving stands of invasive species that have colonized the property in accordance with the NRCS Forest Management Plan done by TSP Forester, Tim Nolan. The primary species include Oriental Bittersweet, Multiflora Rose, Japanese Barberry, and to a lesser extent, Glossy Buckthorn, Burning Bush, Autumn Olive, Honeysuckle, Japanese Knotweed, and Garlic Mustard. In many areas, this invasion is outcompeting and choking out native plants, limiting biodiversity, establishing a deep seed bank to further spreading, prohibiting other management practices, including timber management and trail maintenance, and forming dense thickets that impact native wildlife habitat. Under the contract, 30 acres will be managed for heavy brush management (where invasive species comprise 75-100% land coverage), with another 30 acres managed for light to moderate brush management (where the coverage is 20-70%).
The Issue of Invasive Species
Non-native invasive species have become an overwhelming problem resulting in impacts to the natural environment and managed landscapes. Invasive species typically possess traits that give them an advantage over most native species. The most common characteristics include the production of many offspring, early and rapid development, adaptability, and high tolerance to various environmental conditions. These traits allow invasive species to be highly competitive and typically suppress native species. Studies show that invasive species can reduce natural diversity, impact endangered or threatened species, reduce wildlife habitat, create water quality impacts and stress, reduce forest and agricultural crop production, damage personal property, and cause health problems (Cygan, D., 2023, NH Guide to Upland Invasive Species).
In SWCA, areas of heavy infestation of invasive are outcompeting and choking out native plants, killing trees, limiting biodiversity, establishing a deep seed bank to further spreading, and forming dense thickets that impact native wildlife habitat. Due to the severity of the infestation of Oriental Bittersweet, Multiflora Rose, and Japanese Barberry, timber management (for long-term forest health) cannot occur without first addressing the invasive species. Attempting to conduct active timber management would only serve to make the invasive problem worse, as these species thrive on ground disturbance and the increased light that harvesting would provide.
Invasive species such as the ones in question do not discriminate against conservation lands from backyards. Retaining the invasive species on this site only allows these plants to spread out beyond the conservation area land. The density of the invasive plants in SWCA produces a lot of seeds, which are easily carried off the property and can establish in adjacent backyards and can cause further spread far beyond this managed land. By helping to eliminate the seed bed, we are preventing the spread to other areas and breaking the cycle of the invasion. Letting these species thrive will only lead to establishment in other areas where they will eventually need to be managed in the same way.
Certain invasive species, such as Japanese Barberry have been shown to provide habitat for unfavorable insects such as disease-carrying deer ticks. The density of the invasive thickets and brush provides increased areas for high humidity which ticks need to survive and thrive in warmer weather. These also provide protective cover for their mammal hosts, particularly mice. By removing these thickets, the pest population is anticipated to decline.
We understand the concern of altering the visual aesthetic by removing this brush, but it is at the point where the larger trees have become trellises for these species to spread and broadcast seeds. The brush also limits the movement and habitat for certain species of animals. While it may be considered an eyesore in its immediate aftermath, the practice will ensure the long-term viability of the conservation area. It will ensure a restored, healthier natural area that future generations will be able to enjoy.
Many considerations were taken prior to adopting the prescribed control methods. Volunteers have dedicated time over the past decade to manually remove some of the invasive plants. While somewhat successful, the scale of this project vastly exceeds what volunteer resources can accomplish. Unfortunately, in cases this dense and widespread, brush mowing, and the use of herbicide after, is required. The only other alternative would be complete mechanical removal of the root system of these invasive plants. That level of disturbance will cause significant soil disruption and increase the erosion vulnerability of the soil. This could lead to catastrophic soil loss that could end up in the lake impacting the water quality and aquatic organism ecosystems.
More Information and Best Management Practices: NH Guide to Upland Invasive Species
Background
LRCT acquired 4 separate, adjoining parcels of land between 1998 and 2007 that comprise the SWCA in its present state. The property consists of the A. Denny McLean and Mary McLean McBride Forest, purchased in 1999; the Raymond Tuttle property, received as an extraordinary gift in 2000; the Munro property, purchased in 2003; and the Horn property, purchased in 2007. The most recent properties were formerly agricultural land, hay land, and orchard, that slowly converted to woodland prior to acquisition.
Left unmanaged, such conversion generally results in unfavorable or invasive plants establishing and spreading. That was the case in this instance and those are the areas requiring the most intensive management of the invasive species that have been established.
Since SWCA was conserved, it has been managed primarily for recreation with its network of walking, cross-country skiing, and biking trails. LRCT’s long-term management goal has been to restore the ecological integrity of the conservation area and enhance the health of its forests and habitats.
Project Development and Planning
- The invasive plant infestation was present at the time SWCA was conserved. LRCT has worked over the past ten years to remove invasive species in the sparse areas with an “early detection, rapid response” approach to keep the sparse areas from developing into heavy infestations. This ongoing work is accomplished by hand cutting and pulling by volunteers, staff, and AmeriCorps members, and still occurs annually.
- In 2015, LRCT sought the advice of the NH State Invasive Species Coordinator, Doug Cygan, on the best management practices to remove the densely infested areas and restore health to the forest. Doug conducted a site inspection and determined that the only course of action would be to mechanically mow these areas and follow up with targeted herbicide applications on re-growth, and subsequent annual mowing to maintain field areas.
- In 2019, LRCT applied to NRCS for contracts to have Forest Management Plans (FMP) written for eighteen of its Conservation Areas and Preserves, including SWCA.
- In 2021, Forest Management Plan funding was granted, and TSP foresters contracted. LRCT contracted TSP Forester, Tin Nolin, to write the NRCS Forest Management Plan for SWCA.
- In 2022, the SWCA FMP was completed. The plan provided recommendations to achieve two primary goals; the management of invasive species on the property, and timber stand management for future forest health. The recommendations provided for invasive species management matched those from the State Invasive Species Coordinator. Additionally, it was noted that due to the severity of the infestation of Oriental Bittersweet, Multiflora Rose, and Japanese Barberry, timber management could not occur without first addressing the invasive species infestation. Attempting to conduct active timber management would only serve to make the invasive problem worse, as these species thrive on ground disturbance and the increased light that harvesting would provide. LRCT shared the FMP with its partners who help manage SWCA for feedback, all of which was favorable.
- In 2023, LRCT applied for NRCS EQIP funding to implement the FMP recommended practices, including Brush Management for invasive species control, Early Successional Habitat Management for old fields, and Tree and Shrub Establishment for forest regeneration.
- In 2024, NRCS approved funding for the above recommended Practices. LRCT has contracted Granite State Land Management who specializes in invasive removal to conduct the Brush Management this fall (Map of project Area below). LRCT held an onsite SWCA stakeholder meeting in the spring to review the project with our partner organizations who manage the recreational uses of the property and help manage and protect the conservation values of SWCA. These partners are the Wolfeboro Cross Country Ski Association, the Greater Wolfeboro New England Mountain Bike Association (GWNEMBA), and the Town of Wolfeboro Conservation Commission. All three partners fully support this project and will work cooperatively to manage trail use during the project implementation.
Project Timeline
Two public information walks occurred onsite before the project began. These sessions provided the opportunity to the public to see the infested areas and learn more about their damaging effects, the best management practices that will be conducted throughout the project, the expected outcomes of the work, and the future management of the property.
Phase 1: The first phase of the project began in September of 2024. This consisted of moderate-to-heavy brush management in the prescribed area, as shown in the map above. Heavy machinery equipped with a forestry mulching head was used to pulverize the unwanted invasive species thickets, focusing on the northeastern corner of the property. Operations resumed in 2025 to focus on the northwestern portion of the property.
Phase 2: The second phase began in 2025, with targeted herbicide application occurring in the northeastern portion of the property as a follow-up to the brush management conducted the previous year. The targeted herbicide treatment is used to remove plants that could not be removed by machinery or that re-emerge due to the presence of the existing root systems that generate new plants. This practice is done by a contracted licensed herbicide applicator and will reoccur in 2026 to help eliminate the return and re-establishment of the unwanted species.
Two additional practices will occur (date is TBD): Early Successional Habitat Management for Old Fields, and Tree and Shrub Establishment for Forest Regeneration. The Old Field Management constitutes delayed brush-hogging of a 2-acre area annually to maintain the old field for early successional species and pollinators. Tree and Shrub Establishment for Forest Regeneration will be accomplished by planting a minimum of two hundred trees per acre within portions of the brush management area.
What to Expect During Project
- Best Management Practices – BMPs will be followed in all aspects of the project.
- Trail Closures – Portions of the property and trails may be closed to the public for safety. The closures will be limited to the live operating zone and will shift as progress is made. The equipment and operation can be dangerous to passersby who could be showered by chips and debris. These machines are large and loud enough to draw attention from a distance away.
If you have any questions about this project, please contact Land and Recreation Manager Phil Croteau at pcroteau@lrct.org.