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These acreages represent the minimum acreages to be used; however, whenever possible, comparisons • <br />will consider the maximum undisturbed area available at anp given time as the sampling universe. <br />Quantitative cover and production data Erom these types will serve as the basis for developing <br />weighted averages for cover and production comparisons in the II-W azea (including the South <br />Extension azea). For purposes of creating these weighted averages, the following percentages of <br />vegetation types that were present in the disturbed azea prior to mining (as deternrined during baseline <br />studies) will be used: <br />Aspen - 11.0%, Mountain Brush - 34.5%, Steep Mountain Brush - 12.8°/q Sagebrush/Snowberry <br />31.3%, and Western Wheatgrass/Alkali Sagebrush - 10.4%. <br />As a block of reclaimed land is delineated for bond release, then pre-mining vegetation types will be <br />evaluated to determine if these percentages need to be adjusted fox that particulaz block. <br />Statistical Testing_to Demonstrate Revegetation Success <br />Statistical testing will be used when the parameter sample mean for the reclaimed bond release azea is • <br />less than 90 percent of the standazd. Aone-sample t-test will be used in testing the hypothesis that <br />the tme mean of the bond release pazcel (or monitoring pazcel) is indistinguishable from the number <br />representing 90 percent of the standazd. One-sample hypothesis testing, as well as the sample <br />adequary formulas to be used when hypothesis testing is required and when parameter estimation <br />alone is suffident, will be consistent with the Division's Guideline Regatdutg Selected Coal Mine <br />Bond Release Issues (April, 1995). The parameters to be tested for revegetation success are cover, <br />production, woody plant density, and speaes diversity. <br />Cover. For all reclaimed II-W areas (including the A-W South Extension azea), successful <br />revegetation for the parameter of cover will be evaluated as follows. Cover data will be collected from <br />the above Eve described vegetation types within the designated extended reference area. Included in <br />the average will be data from the Aspen Woodland, Mountain Brush, Steep Mountain Bmsh, <br />Sagebrush/Snowberry and Western Wheatgrass/Alkali Sagebrush vegetation types. The eaten[ of <br />herbaceous cover in each of the five vegetation types will be represented by the "all-hit" measure of <br />cover in which the full extent of a species cover, whether or not it is overlapped by the canopy of <br />another species is independently assessed. Although the development of trunks, branches, twigs, and • <br />leaves of shrubs and trees overarches fairly extensive azeas in several of the vegetation types, the <br />herbaceous component Is still quite extensive in most, though often in the shade of the woody <br />TR-50 <br />46 <br />