Non-native invasive plant species pose a major threat to critical habitats that are essential for the health of native plants and wildlife. The control and elimination of these plants from the FLCA and surrounding areas is one of the BBC’s most important objectives. Our efforts in this sphere include workdays targeted to the hand removal of certain species, attendance at workshops on control methods and, more recently, the use of herbicides to combat specific invasive plant infestations. To better understand the type and distribution of invasive plant species, several BBC members compiled an “invasives map” of the FLCA in the summer of 2007 that identified the locations of major stands of multiflora rose, Phragmites, asiatic bittersweet, spotted knapweed and Japanese knotweed, as well as isolated incidences of purple loosestrife, black locust, exotic honeysuckles, common and glossy buckthorn, Japanese barberry, Norway maple, autumn olive and several other non-native plant species. In addition, it had been noted that a heavy infestation of water chestnut had become established at the eastern end of Fitzgerald Lake. Our efforts to combat several of these unwelcome visitors are described in the following.
An intensive effort to remove water chestnut from Fitzgerald Lake was initiated in the summer of 2006 using one of the most effective techniques available: hand-pulling from canoes and kayaks on the water. Each summer thereafter, a small flotilla has set out on 2-3 summer days to find, pull and dispose of as much water chestnut as possible. In 2007, for instance, 20 people in 12 boats spent over 100 person-hours on the lake. A significant drop in the water chestnut population was observed that year although it was evident that the infestation had spread more widely than originally thought. Nonetheless, the water chestnut population was noticeably diminished in 2008 and 2009. Complacency is not in order, however, as water chestnut seeds persist for many years. We envision that the lake will have to be carefully scanned in the future to make sure that the infestation does not become re-established.
The common reed, Phragmites austrailis, forms dense, 8- to 10-feet tall stands that choke out native plant species and diminish the usefulness of the marshland habitat for wildlife. Work on the control of Phragmites, which covers about 0.6 acres in the wetlands downstream from the wildlife blind, was initiated in the winter of 2009 by Polatin Ecological Services (PES), who cut the dormant stalks to a height of 2-3 feet. This was followed in late September and early October by a carefully targeted application of Rodeo®, a glyphosate-based herbicide approved for use in wetlands, to suppress new growth. Rodeo will be applied to surviving plants again in 2010 and, possibly, 2011 to attain the highest feasible level of control. According to PES, we can expect 85% control after the first year and up to 100% control subsequently, although continued surveillance will be needed to guard against recurrence in the future. This project is being carried out with grants from the Massachusetts Land Trust Coalition, the Natural Resource Conservation Service of the USDA and the Northampton Community Preservation Committee.
Several years ago, a small but significant patch of Black Swallow-Wort was found on private land adjacent to the FLCA on which the City holds a conservation easement. If left unchecked, the abundant dispersal of Swallow-Wort seeds could lead to the invasion of open land within the FLCA and surrounding areas where it has the potential to form extensive, monotypic mats that crowd out and replace grasses, goldenrod, milkweed and other native plants. In the summer of 2009, the plants were individually sprayed with herbicides on two occasions in a highly targeted manner. Most died as a result but, here again, further herbicide treatment will be carried out for at least one more season and continual monitoring will be needed thereafter to ensure that the Swallow-wort does not become re-established.
Glossy Buckthorn and Spotted Knapweed
Early in 2009, the Stewardship Committee met to prioritize our efforts to combat other problematic plant invasions in the FLCA. In view of the surprisingly rapid increase of Glossy Buckthorn and Spotted Knapweed in Cooke’s Pasture and on the dam, we decided that these species should be next ones targeted for control. Both plants are very aggressive and threaten to infest the entire pasture if left unchecked. We have solicited advice from invasive plant control experts as well as environmental service firms as to the best methods for achieving control of these plants while minimizing “collateral damage” to native shrubs and grasses. We plan to begin our Glossy Buckthorn and Spotted Knapweed control programs in the spring and summer of2010.
In 2008 and 2009, the BBC was successful in obtaining tree grants totaling $23,000 to support the control of invasive plant species as well as pastureland mowing, in the FLCA. We are indebted to the Wildlife Habitat Incentives Program (WHIP) of the Natural Resources Conservation Service (USDA), the Massachusetts Land Trust Coalition’s “Empowering Local Land Trusts in Western Massachusetts Western Massachusetts” Program and the Northampton’s Community Preservation Committee for their generosity and support
One non-plant invasive came to our attention in the summer of 2009. In response to the report of zebra mussel infestations in several lakes in the Berkshires during July, we evaluated the possibility of their spread to Fitzgerald Lake. The best way to prevent the spread of zebra mussels–as well as the introduction of other invasive aquatic plants and animals–is to ensure that boaters thoroughly clean the hulls and the interiors of their boats before launching. A sign reminding boaters to do this was placed next to the kiosk at the NFR entrance. However, we also learned that zebra mussels require high calcium concentrations for development and shell growth. While many lakes in the Berkshires are supplied with calcium due to the abundance of calcareous rock in the region, the geology of the Connecticut River valley is quite different. Subsequent analysis of a water sample from Fitzgerald Lake revealed that the calcium concentration is less than 10 ppm (mg/L), a value that is generally believed to be below the threshold for zebra mussel proliferation.