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evaluation is: ~~`~ • <br />xREV ~ •90~Da)(xM0) + (IPSa)<xIPS) <br />Te <br />with 90 percent statistical confidence <br />where: xREV = average vege ration cover, reclaimed area <br />MDa = mesie drainage acreage, premine area <br />IPSa = improved pasture-subirri gated, premine area <br />xM0 average reference area herbaceous cover-mesic drainage <br />xIPS = average reference area herbaceous cover-improved <br />pasture-subirrigated <br />Ta = total .of relotive community types used in comparison, premine area <br />Average vegetation cover will be used for reclaimed areas because successional development <br />will have established a predominantly herbaceous community even with shrubs present. <br />The cover success standard for all permanently reclaimed areas in the haul road corridor <br />will be 35 percent. This value represents the uei ghted mean herbaceous vegetation cover • <br />for the sagebrush, western wheatgrass/alkali sagebrush, alkali sagebrush/greaseuood, and <br />alkali meadow types. The latter two types encompass only 3.2 and 7.4 acres, respectively. <br />In addition, the alkali meadow type has been variously disturbed. Neither type is <br />extensive or unique enough to warrant a separate success standard. The weighted mean <br />cover value was determined from cover data for the four types as determined during 1992 <br />supplemental baseline vegetation studies (see Appendix B to Attachment 10-1, Tab 70, <br />Vegetation). For vegetative cover, the revegetated area shall be considered acceptable if <br />it is not less than 90 percent of the standard (35) with 90 percent statistical <br />confidence. <br />The value of 35 percent herbaceous vegetation cover is a reasonable value when combined <br />with the anticipated litter values of 75 percent (see previous discussion) and the more <br />xeric site Conditions along the corridor. Also, the value of 35 percent herbaceous cover <br />for the standard is nearly identical to the herbaceous cover for the upland improved <br />pasture type sampled during the 7992 supplemental baseline studies. This premine type <br />represents reseeded lands previously occupied by the sagebrush and western wheatgrass/ <br />alkali sagebrush types prior to disturbance. The sagebrush and western wheatgrass/alkali • <br />sagebrush types represent the dominant native vegetation types along the corridor which <br />40 Revised 06/19/95 <br />