Smith Habitat Management
Habitat Restoration and Invasive Plant Control
The Smith Conservation Land has outstanding conservation values: It hosts multiple habitat types, provides habitat for a rare turtle, contains three high-quality vernal pools, is part of a regionally significant habitat corridor, and is considered a high priority area for protection by the state’s BioMap2 ranking system designed to guide land managers in strategic biodiversity conservation in Massachusetts. The property has become a popular destination for area residents and visitors.
Unfortunately, the property also hosts a great diversity of aggressive invasive plants. Most notably, Oriental bittersweet has spread across 26 acres of this 54-acre conservation land. The invasive plants here severely compromise the habitat values of the site. Oriental bittersweet in particular strangles trees and overwhelms and displaces all other vegetation in its path.
SVT’s goal at the property is to restore quality, diverse habitat in the areas that have been degraded by Oriental bittersweet. These restored areas will once again be home to a diverse collection of native plants, which, in turn, support a myriad of wildlife.
The restored habitat will support native pollination systems and birds. Native pollinators are increasingly at risk due to the direct loss of habitat, conversion of habitat to other uses, and invasion of non-native plants. Many of our native pollinators are "specialists"--that is, they rely on a specific species of plant for their habitat and simply cannot utilize invasive plants. In turn, the majority of our birds need an abundance of caterpillars to feed their young during nesting season. Studies have shown that invasive plants do not support the abundance of insect food needed by our birds.
At Smith Conservation Land, there is an additional issue of a red pine stand that is dying out and has become both a safety hazard as well as a breeding ground for aggressive growth of Oriental bittersweet. Smith hosts another monoculture of European tamarack that is equally invaded by bittersweet. This tamarack is not native and – as with all monocultures – it is at greater risk of disease and insect pests especially in a changing climate.
The Management Proposal
Oriental bittersweet is well-documented to be difficult to control due to its extensive, networking root system and aggressive resprouting capabilities. While small infestations can be effectively controlled with repeated hand-pulling and mechanical removal over multiple years, it is impossible to control Oriental bittersweet with mechanical methods over large areas. Compounding the problem, mechanical removal will increase root growth and sprouting unless the entire plant and root system is removed or the cutting is frequently repeated during the growing season.
At Smith Conservation Land, SVT has concluded that the limited and targeted use of state-approved herbicides is the most effective solution to controlling Oriental bittersweet while also limiting the risk to human or environmental health.
In response to neighbors’ concerns, SVT is reducing the area across which synthetic chemicals will be used and will phase the treatments. SVT will maintain 100-foot buffers around residential water wells (as recommended by the Littleton Health Department) and will maintain 50-foot buffers around residential activity areas for those neighbors who wish to have this additional safeguard. In those buffer areas, SVT will only use mechanical controls to prevent the bittersweet from going to seed and to attempt to keep the vines from spreading onto the treated habitats.
While organic herbicides are beginning to be used and tested for their effectiveness; these chemicals and substances are not regulated, which means that they are not tested for their toxicity and environmental and health impacts. Therefore, SVT chooses not to use them in any large-scale control effort.
In the first phase, SVT is limiting herbicide treatment to the red pine stand, European tamarack plantation, and a few small areas with large bittersweet vines – Units 1 and 2 and small portions of Unit 5 on the accompanying map (in total, approximately 12 acres). In these areas, SVT will conduct a cut stump treatment with a triclopyr-based herbicide in late November – December 2020.
In the following summer, a spot spray treatment will be conducted to control low-growing dense bittersweet (whose stems were too small to cut and dab) and any resprouts from bittersweet roots. The spray treatments will utilize battery-operated back pack sprayers that allow the operators to very specifically target the invasive plant and minimize non-target impacts. Follow-up summer treatments will be conducted as needed to control any resprouting bittersweet. Hand-pulling seedlings will be conducted in between treatments. Typically, these follow-up treatments are much smaller in area and volume of chemical needing to be used. All treatments will be conducted by licensed applicators experienced in treating natural areas.
When the abundance and cover of the Oriental bittersweet has been effectively reduced in Units 1 and 2, we will then initiate herbicide treatment in the remaining areas, Units 3, 4, and 5 (excluding mechanical only treatment areas).
SVT is dedicated to preventing invasion of the healthy forest habitat to the west by using hand pulling of bittersweet and other invasive plants along the woodland edge. In the mechanical-only areas, SVT will use hand removal technique as much as is possible, utilizing staff and volunteers. Goats may be used to keep some areas open.
SVT will mow in open areas. The mowing will increase bittersweet root growth, but will keep it from going to seed and climbing trees. We may use large machinery to mulch bittersweet and trees consumed by bittersweet on the southeast field edges and then keep those additional areas mowed.
We will continue to adapt our approach as we see what works (and what doesn’)t as we strive to restore the ecological treasure that is the Smith Conservation Land. Throughout, we will continue to keep interested parties informed.