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<br />SECTlONTWO <br /> <br />Environmental Sening <br /> <br />I <br />I <br />,I <br />,I <br />,J <br />1 <br />I <br />1 <br />I <br /> <br />The BOR is currently creating a new digital land cover/land use database for the Central Platte <br />Valley study area, using 1 :24,000 color IR aerial photography flown August 21, 1998. The study <br />area is somewhat larger than the WELUT database, and extends to Lexington. This study <br />tentatively includes about 39 mapping units, which are generally consistent with but more <br />detailed than the 24 mapping units used in the WELUT database. <br /> <br />The vegetation and land cover types used in the WELUT database are described below. <br /> <br />2.2.1 Croplands <br /> <br />Based on Currier et aI. (1985), croplands occupy about 62 percent of the study area, including <br />corn (45.7 percent), other crop (9.1 percent), and alfalfa (7.5 percent). The highest percentages of <br />com were found in the eastern part of the study area, between Kearney and Chapman. Other <br />crops include winter wheat, soybeans, sorghum, and fallow fields. The area of alfalfa was <br />highest in Segments 10 and 1 I. In these segments, alfalfa was grown to supply local dehydration <br />plants where it is fonned into pellets and sold for feed. There were about 20 dehydration plants <br />between Kearney and Lexington. Croplands were rarely found inside the floodplain boundary, <br />but riverine lands have been converted to cropland in a few areas through clearing and leveling. <br />A minimum mapping area of 10 acres was used for com, alfalfa, and other crops. <br /> <br />2.2.2 Grasslands <br /> <br />About 17 percent of the study area is in pasture and hayland including grassland (12.8 percent) ~ <br />and "wet meadow" (4.5 percent) (Currier et aI. 1985). Grasslands were mostly limited to the <br />highly dissected loess bluffs on the ancient river escarpment 1 to 2 miles from the floodplain. <br />Most of the wet meadows (bottomland grasslands) were found on large islands in the river <br />channel, including Mormon Island (Segments 2 and 3), Shoemaker Island (Segment 4), and Fort <br />Farm Island (Segment 7). Grasslands, including hayed, grazed, and fallow lands, were mapped <br />with a minimum size of 5 acres, and wet meadows were mapped with a minimum size of 10 <br />acres. <br /> <br />The principal native grass species of upland native prairie grasslands include the following <br />(names follow Great Plains Flora Association 1986): big bluestem (Andropogon gerardii), little <br />bluestem (Andropogon scoparius), sideoats grama (Bouteloua curtipendula), switchgrass <br />(Panicum virgatum), Indian grass (Sorghastrum nutans), blue grama (Bouteloua gracilis), <br />western wheatgrass (Agropyron smithii), junegrass (Koeleria pyramidata), and needle-and-thread <br />(Stipa comata) (Sidle and Faanes no date). Common forbs include scurfpea (Psoralea spp.), <br />dotted gayfeather (Liatris punctata), false boneset (Kuhnia eupatorioides), Missouri goldenrod <br />(Solidago missouriensis), purple prairie clover (Dalea purpurea), aster (Aster sp.), and scarlet <br />globemallow (Sphaeralcea coccinea). Typical shrubs include eastern pricklypear (Opuntia <br />macrorhiza), lead plant (Amorpha canescens), western snowberry (Symphoricarpos <br />occidentalis), white coralberry (Symphoricarpos albus), smooth sumac (Rhus glabra), and <br />soapweed yucca (Yucca glauca). <br /> <br />Nagel et aI. (] 995) evaluated 279 native prairie sites in the Central Platte Natural Resources <br />District (NRD) within Buffalo and Dawson Counties. Smooth brome (Bromus inermis) and <br /> <br />URS I1eiIJfIr MJn....1JJ* <br />2-2 ..F00972",""""."", 6I2I'~"S2AM)lURSGWCFS12 FedeRlSenIt:es <br />