02/27/2008 Env Bd Packet - Laserfiche WebLink

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Degraded Hardwood Forest A 1.5 acre degraded hardwood forest occurs within the far northwest corner of the site. This forest remnant canopy is comprised of American Elm (Ulmus americana), Box Elder (Acer negundo), Black Cherry (Prunus serotina), Green Ash (Fraxinus americana), and Hackberry (Celtis occidentalis), with occasional large Northern Pin Oak (Quercus ellipsoidalis) and Red Oak (Quercus rubra) trees intermixed. Common Buckthorn (Rhamnus cathartica), an invasive exotic understory species, is dominant throughout the understory and shrub layer of this forest remnant, as understory trees (up to 12" in diameter), large shrubs, saplings, and seedlings. Due to the presence of the dense buckthorn stand and past soil disturbance and compaction, the herbaceous layer is highly degraded (and absent in places). Forest soil development is poor, and forest leaf little is sparse to absent. Buckthorn removal and management is an immediate need within this forest remnant, and will require several years of follow -up restoration and management to begin re- establishing a native shrub and herbaceous layer. Upland Old Fields and Pastures Portions of the proposed conservation areas are currently non -native dominated old field and pastures dominated by Smooth Brome and Kentucky Bluegrass, and other introduced pasture grasses. The old fields typically occur on sandy, well- drained soils on pronounced knolls, but also transition into more poorly drained areas at toe slopes and along wetland edges. Within lower -lying areas, the old fields are dominated by Reed Canary Grass and Sensitive Fern, with occasional Aspen, Willow, and Raspberry. Old fields should be restored to dry prairie in the driest of areas, and transition to mesic and wet prairie at the base of slopes and along wetland edges. Furthermore, restored prairies of Foxborough's conservation areas will likely grade into restored oak savannas and oak woodlands, as well as managed aspen woodlands. Compensatory Wetland Mitigation Area (SE Corner of Site): The compensatory wetland mitigation area 1.99 -acre (87,097 square feet) in size is planned for construction within a degraded upland old -field over sandy, well - drained soils. Vegetation of the old field in May 2005 was predominantly invasive non- native grasses, such as Smooth Brome (Bromus inermis) and Kentucky Bluegrass (Poa pratensis), with Pennsylvania Sedge (Carex pensylvanica), Sun - Loving Sedge (Carex heliophila), and Canada Goldenrod (Solidago canadensis). In accordance with the site plan and wetland mitigation plan, this old field will be excavated to a depth below the normal water table elevation to facilitate the establishment of an on site compensatory wetland mitigation area. Although the original wetland mitigation plan calls for establishment of wetland vegetation within a saturated (to inundated) sterile sandy subsoil condition, CCES recommends excavating the mitigation wetland 2 to 4 inches deeper, and back filling to designed elevations with a weed -free native organic wetland soil that would be donated from wetland areas to be filled elsewhere on the site. A native organic wetland soil medium will better facilitate the establishment of high quality native wetland seed mixes (and plant material) to be prescribed for and installed within this wetland mitigation area. To achieve 2 inches of organic material across 2 acres of wetland mitigation area will require 14,520 cubic feet (or 537 cubic yards) of native wetland soils donated from impacted wetland areas elsewhere on the site. Foxborough Conservation Development Restoration and Management Plan 11