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Jan.15,1981 <br /> <br />JcACtation Inventory and Evaluation <br />Tne sit^ oi' the proposed gypsum mine is on the north side of a NY.-SE oriented hog- <br />back. The sypsum deposits begin in the Bullied foot~opes of the hogback and er.- <br />t .d to the sou h under the steeper sideslopes. The ,plant community on the Site Ss~ <br />a~i~liyon-juni:p 'troodYancl xith a loN~glte index: Tree size varies from 3 to 15 feet <br />xith the majority of the trees being older and mature. The under story is composed <br />;~of midgrasses and various shrub species. The pez'Cent 'mound Cover `(ground covered <br />y line plant croxns) is extremely variable because oT the chopped p nature of the <br />topography and concentration cf pinyon-juniper over story. Under and near mature <br />trees, ground cover is near zero. Irr open areas xhere the grass understory is <br />.dominant, ground cover averages 10 to 12 percent. <br />Current annual production of air dry forage xas based upon ocular estimates of the <br />affected area and the general slopes of the hogback. Production from the pinyon- <br />juniper overstory xas not considered. Production estimates are given as ranges <br />because of production variation Sn the diverse slope aspects and soil depths. Shallox <br />west or south facing slopes aze alsays less productive than north or east facing slopes. <br />~ 'a~+~ ~ierl~+i~ ~a3~'e`°'~fY''~vcMe-ewers cgs on <br />e m~iiiilg~ $4~J Production of annual forage during a favorable yeaz would vary from <br />50 to 400 pounds of air dry herbage per acre. An estimated average production is <br />around 150 pounds per acre. <br />~14i~ww+ts • ~qa ~ t~ ~~e xad~+y+' s2epes acrd open 11at0Ae6. 3~sn <br />yen~3rniptr.~ B2tss.~raaa a e~wn grasp grow in association with the si~e- <br />Fouruing salt~fust~"''dfiii Cambel oak are sparsely scattered on the lower rocky <br />s opes. Scribners needlegrass. and pinion ricegrass occur near and under the pinion <br />trees or on occasional grassy knobs, that once supported trees. In such areas of <br />deeper soil the Scrigners needlegrass is the dominant forage producer and grows in <br />association xith needleandthread grass, Indian ricegrass and xestern wheatgrass. <br />Indian ricegrass is generally scattered throughout but does occur almost exclusively <br />xith Bigelox sage on bare gypsum outcrops and slopes. Yucca also grows abundantly <br />~n soils influenced by the gypsum. <br />Vegetation on the gully bottoms and sides is dominated by xestern xheatgrass and <br />~eedleandthread. Bigelox sagebrush, fringed sage, rabbitbrush, skunkbush sumac, <br />and mountainmahogany are scattered throughout the gullies, mostly on the gully side- <br />slopes, mountainmahogany is mere common on the higher, cooler slopes. <br />Vegetation Percentages and Heights <br /> l <br />t <br />Type of Plant Common Name Scientific Name Commun <br />ity Height <br />GYassese Sideoats grams Bouteloua curtipendula 20 12-18 inches <br />Indian ricegrass Oryzopsis hymemoides 15 12-15 inches <br />Western xheatgrass Agropyron smithii 10 18-20 inches <br />Scribners needlegrass Stl~a scribneri 10 18-20 inches <br />pinyon ricegrass Piptochaetlum fimbriatum Trace 12-15 inches <br />sand dropseed Sproobolus cryptandras Trace 15-20 inches <br />threeaxn Aristida longiseta Trace 6-8 inches <br />A'EEDLEAIiDTHREAD Sti a comata 10 24-36 inches <br />blue gsama Boutcloua gracilis 5 4-6 inches <br />ATTACHI~;II~T E <br />• <br /> <br />