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Big Island Nature Park Management Plan November 2011 <br />____________________________________________________________________________ <br />13 <br /> <br />generally low level of exotic species. The two recreational areas are not classified as native <br />plant communities. These consist of altered/non-native grassland and some impervious <br />surface. There are steep bluffs on the eastern shoreline of the site. <br /> <br />Climate observations for the region are made at the Minneapolis-St. Paul International Airport, <br />roughly 20 miles east of the site. The 30-year mean (1971-2000) precipitation is 29.41 inches <br />per year. The 30-year normal temperature range is 4.3 - 21.9 ºF in January and 63.0 - 83.3 ºF in <br />July. Upland soils were mapped by the Hennepin County Soil Survey as mostly Lester loam <br />morainic, 6-12 and 12-18 % slopes, eroded. Wetland soils were classified as Glencoe loam <br />depressional (hydric). Most maple-basswood forest in the region grows on till plains and <br />stagnation moraines from the Des Moines Lobe of the Wisconsinan glaciations. <br />Wetlands <br />Five wetlands on the site were field assessed as part of the District‘s Functional Assessment of <br />Wetlands (FAW). Two were given the manage class ―Preserve.‖ The ―preserve‖ designation <br />was assigned based on wetland functions. The FAW lists the following management goals for <br />a preserve wetland: ―avoid and preserve wetland if at all possible. No change in wetland <br />hydrology. No increase in nutrient load.‖ According to the MLCCS, the easternmost basin is a <br />palustrine open water wetland, about 1.1 acres in size. On the western isthmus there is a 4.9 <br />acre wetland classified as a semi-permanently flooded cattail marsh. The marsh received an <br />MLCCS quality grade of ―C,‖ indicating a moderate quality natural community with obvious <br />human impacts, but still recognizable as native plant community. The FAW also recognizes a <br />lacustrine fringe wetland on the north side of the isthmus, and two small (1/4 to 1/3 acre) <br />forested ephemeral wetlands. <br />Vegetation <br />A limited natural resources inventory was performed by MCWD staff on May 26, 2010. The <br />recreation areas were dominated by leafy spurge (Euphorbia esula) and non-native grasses. <br />The maple-basswood forest had a somewhat disturbed ground layer, dominated by upland <br />sedges and other species tolerant of earthworms and deer browse. The shrub layer and <br />subcanopy had good diversity and showed evidence of forest regeneration, with young sugar <br />maple (Acer saccharum), ironwood (Ostrya virginiana), basswood (Tilia americana), <br />hackberry (Celtis occidentalis), and green ash (Fraxinus pennsylvanica). There were common <br />buckthorn (Rhamnus cathartica) shrubs and seedlings scattered throughout. The plant <br />community in the isthmus wetland was cattail marsh, with lake sedge (Carex lacustris) in <br />shallower areas. There were scattered native forbs, and very little reed canary grass (Phalaris <br />arundinacea). The open water wetland has a fringe of sedge species with a few patches of <br />cattails and reed canary grass. <br />Wildlife and fisheries <br />State listed special concern species exist on the island. A bald eagle (Haliaeetus <br />leucocephalus) nest is located in the woodland on the south side of the isthmus. There are also <br />records of two special concern fish species, pugnose shiners (Notropis anogenus) and least <br />darters (Etheostoma microperca), near Big Island. There is a record of one special concern <br />vascular plant species on the island.