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Mass: Alewife wetlands model in the making
by Ellen Mass
Friday, December 10, 2004
An amazing wetland model for New England by the city of Cambridge and Massachusetts Water Resources Authority (MWRA) correlates with the state Department of Conservation and Recreation's Master Plan for Alewife. Several firms, with the lead group, Bioengineering, will additionally restore parts of Fresh Pond and the DCR Greenway downstream through Arlington and Somerville.
At Alewife, over 68,000 plants have been chosen as appropriate to existing ecosystems: emergent marsh, low and high marsh, broad-leafed floodplain, riparian woodland (two types), and shrub-shrub. The entire storm water project complies with the recent national pollution discharge elimination standards (NPDES) of EPA. The low flow river and lack of successful hydrology on stagnant marsh lands create invasive conditions. The storm water plan will change all this with moving water and newly constructed marsh ecosystems with fresh soil which will keep the marshes healthy and free from invasive species.
Riparian woodland plantings around the basin and the unusual Alewife spawning oxbow as well as the central nesting island contain white pine, red oak, gray birch, northern bayberry and black huckleberry. Other woodland tree plantings include green ash, swamp white oak, red oak, American elm (disease resistant), tupelo, hazel alder and red maple. Tree height at planting ranges from 6 to 10 feet.
Clusters of trees surround the large ascending teaching area with around 40 flattened natural boulders and engraved wildlife granite. Five hundred low blueberry bushes are planted throughout. Other woodland and popular wildlife plantings are common winterberry, cranberry viburnum, and arrowwood.
Emergent marsh plants of sedges and rushes including over 5,000 green and soft stem bulrushes which attract green-wing teal, black ducks, potential rails, sandpipers, song birds, sparrows, and pheasant completing a swamp-shrub ecosystem. Mixed among the marsh is rye, marsh hibiscus, wool and rice grasses. The 5,000 spike rushes will produce seed clusters eaten by meadow voles and white-footed mice and shrews. One acre of grassland which is planned may hold up to 200 of these living "lawn mowers" which are sometimes 85 percent of the diet for small hawks and owls.
Sedge meadows are tall enough to remain above the water even when flooded. Voles and animals burrow under the rhizomes. Rails, sparrows and redpolls are attracted to the rank growth which produce insects and worms, bringing wrens, swallows and snipes such as woodcock.
In the newly constructed broad-leafed floodplain, large berry arrow arum attracts wood ducks, rails and other shorebirds. White water lilies bring beaver, muskrat, ducks and shorebirds.
Blueberries there may also attract scarlet tanagers, bluebirds, thrushes, various songbirds, foxes (both gray and red), chipmunks, deer, rabbit, and birds such as phoebes, titmice and towhee. Other floodplain plants include cinnamon and royal fern, boneset, 124 swamp and 240 New England aster plantings. The restored marsh area is also surrounded with geese netting to protect the new plants.
Fertile silts on the emerging marshes will sprout grasses, herbs and even mushrooms. In the shrub swamp where the pussy willows and alder will be planted, yellow warblers dine on the fluffy seeds from the willow which are water tolerant.
The deep marsh of the storm water wetland basin may give mallards, northern shovellers, pintails, and blue-winged teals a place to rest and feed especially on the central oxbow island where nesting habitat is anticipated.
Alder trees of nitrogen-rich soil bring worms which will help woodcock if the area is large enough. Gray catbirds use the alders and chickadees and redpolls. Deer (one dead one sighted last year) eat twigs and buds of these tress which are plentiful on the reservation.
Under the basin's mud, turtles and frogs will burrow. Ducks and young will tip-end for insects and seed food in plant-filled shallows.
Turtles will lay eggs in safer places.
Friends of Alewife Reservation has published "Biodiversity of the Alewife Reservation Area," with its study of ecosystems. FAR is now studying the plantings with its Riverways Stream Team to concur, or suggest plant alternatives to plans now on the design drawing boards.
Ellen Mass, a Cambridge resident, is president of Friends of Alewife Reservation. For suggestions or questions, call 617-547-1944 or 617-876-0223.