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1 <br />I SEC'IIONTWO <br />Environmental Setting <br />Kentucky bluegrass (Poa pratensis) were invading species prevalent on 40 percent of the sites. <br />In comparison with reference areas, most of the upland sites rated poor to fair condition. In <br />addition, most of the upland sites had lost their tallgrass species and much of their native forb <br />component, especially legumes. <br />Wet meadows were defined by Currier et al. (198 5) as areas of grassland within the floodplain <br />which had interspersed emergents or open water. Detailed information about bottomland <br />grasslands is provided in Section 2.7. The grasslands typically consist of grazed pastures with <br />ribbons of palustrine emergent vegetation in depressions that follow the natural drainage <br />patterns. This mapping unit includes three of the meadow vegetation types described by Currier <br />(1982) in his phytosociological analysis of the floodplain vegetation of the Platte River. Wetland <br />meadows are present along intermittently flooded river channels and other lowland areas within <br />open grasslands and woodland. Dominant species include American bulrush (Scirpus <br />americanus), sedges (Carex spp.), spikerush (Eleocharis palustris), fog fruit (Phyla lanceolata), <br />switchgrass, and lady's thumb (Polygonum persicaria). Lowland grazed meadows occur in areas <br />which are too wet to plow or cut for hay. Dominant species include common ragweed (Ambrosia <br />artemisiifolia), Kentucky bluegrass, redtop (Agrostis stolonifera), sedges, and red clover <br />(Trifolium pratense). Lowland prairie/hayfield is dominated by native non - wetland grass <br />species, especially big bluestem and little bluestem, but also including needle and thread, Indian <br />grass, hairy grama (Bouteloua hirsuta), and sideoats grama. <br />2.2.3 Riverine Cover Types <br />Riverine cover types include channel, exposed sandbar ( beach/bar), herbaceous, shrub, and <br />woody (Currier et al. 1985). Wet meadows were considered to be both a riverine and an <br />agricultural type. Riverine types (excluding wet meadow) occupied about 10 percent of the <br />study area, with the largest types being woody (5.6 percent) and channel (1.6 percent). <br />Channel was defined as the bank to bank inundated channel. The area of channel was greatest in <br />the segments with the least woody vegetation (Segments 1 to 8). The percentage of open water <br />channel ranged between 0.8 percent in Segments 9 and 10 to 2.5 percent in Segment 1. <br />Beach/bar is an ephemeral habitat type that decreases in area with high flows and increases with <br />low flows. Beach/bar was greatest in Segments 9 to 11 (1.1 to 1.5 percent) and was somewhat <br />less in Segments 1 to 8 (0.2 to 0.8 percent). Areas identified as beach/bar consisted of <br />unvegetated sandbars. These are areas adjacent or within the river channel which are exposed <br />during the summer as river levels decline. Higher river levels during spring cause scouring of <br />the sandbars and removal of short-lived plant species. <br />Herbaceous included herbs and woody seedlings under 3.3 feet tall inside the floodplain. The <br />vegetation includes annuals and biennials that can become established quickly following high <br />water, such as lovegrass (Eragrostis pectinacea), nutsedges (Cyperus spp.), cocklebur (Xanthium <br />strumarium), barnyard grass (Echinochloa crusgalli), and sand dropseed (Sporobolus <br />cryptandrus) (Currier 1982). Slightly more elevated areas which are exposed earlier and for a <br />longer period of time develop a modest cover of perennial vegetation, including willow (Salix <br />spp.) and cottonwood (Populus deltoides) saplings, spikerush, purple loosestrife (Lythrum <br />salicaria), prairie cordgrass (Spartina pectinata), and American bulrush. <br />IBS Dvhw Wbdward t <br />68FOD97286OO /r1.doc 62N999(9:52AM)/URSGWCFS2 2-3 <br />