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. APPENDI% 22-1 <br />The following evaluations were completed to demonstrate the Comparability of the affected <br />area end the extended reference area. The projected mine disturbance boundary shown on <br />Exhibit 22.1 (Sheet 2 of 2), Postmining Vegetation Mep, was transferred to a work map of <br />Exhibit 10-1 (Sheet 2 of 2), Vegetation Map. The extended reference area samples are <br />those which occur between the projected life of mine disturbance boundary and the current <br />permit boundary. Affected area samples are those which occur within the projected <br />life-of-mine disturbance area. The above segregation of reference area and affected area <br />samples was completed for the three types (aspen, mountain brush, and sagebrush) to be <br />used for the shrub grassland success criteria and the two types (mesic drainage and <br />improved pasture-subirrigated) to be used for the mesic drainage success criteria. Means <br />and standard deviations were calculated from cover data sets (A samples, 1990 data; B <br />samples, 1992 data) and the Students t-test used to test comparability. Production and <br />density were not used in comparisons because of the extreme variation encountered for <br />these two parameters (see data summaries in Tab 70, Vegetation). Herbaceous production <br />only was collected during baseline studies. The amount of herbaceous production is <br />• strongly influenced by the density and composition of woody plants resulting in this <br />variation. An additional measure of comparahi lity was made using a similarity index based <br />on Motyka and others' version of Sorensen's Similarity Index. Species cover (all hit <br />cover) by morphological class was used to determine the similarity index. Affected end <br />reference area cover data sets, as previously described, were used in the comparison. <br />Students t=test formula: <br />tc = I%. - xil <br />1 <br />2 2 <br />+ s~ <br />n, n. <br />1 ~ <br />where: <br />x, = Reference area cover sample mean <br />1 <br />n, = Affected vegetation type cover sample mean <br />i <br />n, = Number of reference area samples <br />1 <br />n = Number of effected vegetation type samples <br />i <br />. t ~ = Calculated t value <br />c <br />sp = Pooled sample variance <br />22-1-1 Revised 06/19/95 <br />