08/28/2006 Council Packet - Laserfiche WebLink

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• • (Geranium maculatum), Virginia creeper (Parthenocissus inserta), wild sarsaparilla (Aralia nudicaulis), and hog - peanut (Amphicarpaea bracteata). Commonly, at least some of the oak trees in the dry stands have multiple stems and thick, spreading lower branches, indicating that these trees grew up in a disturbed and more open setting. Minnesota public land survey records indicate, in fact, that many of these dry stands were oak savanna or oak woodland before European settlement and with fire suppression have succeeded to forest. Oak regeneration is rare in these stands now, as the oak species reproduce poorly under forest canopies. In the absence of fire, relatively mesic or fire- sensitive species such as bitternut hickory, basswood, and red maple, are increasing in abundance in the community. Northern red oaks, white oaks, or bur oaks dominate the more mesic stands of Oak Forest. These stands occur on sites that had fewer severe fires before European settlement than the sites on which dry Mixed Oak Forest occurs. These mesic stands most likely were always forest, rather than woodland or savanna. They have tall (> 20 meters), straight, single - stemmed trees that lack spreading lower branches. Commonly, mesic fire- sensitive tree species are present with the oaks in these stands, especially in the understory. These species include basswood, green ash, bitternut hickory, big- toothed aspen, and butternut. The shrub layer in mesic stands is sparser than in dry stands and, correspondingly, the forb layer is denser and more diverse and there are more graminoid species. Like the drier stands, however, there is little oak regeneration, and most mesic Oak Forests appear to be succeeding to Maple - Basswood forest. Heavy selective logging of the oaks in mesic stands may accelerate this trend, producing young stands of Maple- Basswood Forest. The mesic stands often grade into drier stands of Maple- Basswood Forest, but differ from them by having a somewhat denser shrub layer and the herbs woodrush (Luzula acuminata) and pointed - leaved tick - trefoil (Desmodium glutinosum) in their understory. In general, most existing stands of Oak Forest have been disturbed by grazing or selective cutting, or have been fragmented by development. Natural stands of mesic Mixed Oak Forest are rare. Drier stands are more common, in part because relative to the mesic forests they occur on sites with soils less suitable for cultivation. Additionally, dry Oak Forests may have increased in extent somewhat following fire suppression, succeeding from oak savanna and woodland. Disturbed stands of oak forest commonly have dense subcanopies of prickly ash, or of the exotic species common buckthorn and Tartarian honeysuckle, which have also now invaded many undisturbed stands. Disturbance through grazing may also be partly responsible for the lack of regeneration in Oak Forests, especially in stands with heavy soils that compact readily with trampling. Compensatory Wetland Mitigation Area The compensatory wetland mitigation area planned for construction is within a degraded upland old -field over sandy, well - drained soils. 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. Native emergent marsh, wet meadow, and wet prairie seed mixes appropriate to the region will be used to revegetated the mitigation area. The wetland mitigation will be monitored and managed in accordance with the Minnesota Wetland Conservation Act rules for wetland replacement areas. The Preserve Conservation Development - Restoration and Management Plan 19