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Sample Adequacy <br />The following formula was used to determine the sampling adequacy of the <br />quantitative cover (perennial non-restricted and non-noxious species) and production <br />in the Apex Mine studies: <br />Nmin (st)2/(dx)2 <br />where, <br />Nmin =minimum sample size <br />s =sample standard deviation <br />t =single tailed t-value at the 90 percent confidence interval <br />(alpha = 0.10) with infinite degrees of freedom (t = 1.645) <br />d =desired level of reduction about the sample mean (0.10) <br />x =sample mean <br />In all cases, sampling was continued until the minimum sample adequacy requirements <br />were met or exceeded. <br />Standards <br />The standard for live non-restricted and non-noxious perennial cover is 42 percent. The <br />standard for live non-restricted and non-noxious perennial production is 900 Ibs/acre. <br />For diversity, the reclaimed areas will have at least 3 perennial species with relative <br />importance equal to or greater than 3 percent but with all 3 perennial species combined <br />not to exceed 80 percent in relative importance. Any one of the 3 species cannot <br />exceed 55 percent in relative importance. This standard was revised for the drought <br />year 2002 see attachment 5. Relative importance means the percent cover of the <br />perennial species will be compared to the percent cover of all perennial species except <br />noxious weeds. <br />Results <br />Tables 1 and 2 represent cover and species diversity for the Apex Mine. <br />2001 -Apex Mine reclaimed land had 16.4 percent bare ground, 27.3 percent litter, 5.7 <br />percent rock fragments, 3 percent annual grasses, 2.6 percent annual forbs, 45.7 <br />percent perennial grasses, and 1.6 percent perennial forbs for a total of 47.3 percent <br />perennial live vegetation. Apex Mine reclaimed land also had 0.7 percent noxious <br />and/or restricted weeds. Detailed results listed by species occur in Table 1 and <br />Attachment 3. <br />2002 -Apex Mine reclaimed land had 8.3 percent bare ground, 36.1 percent litter, 4.8 <br />percent rock fragments, 1.1 percent annual forbs, 47.5 percent perennial grasses, 1.6 <br />percent perennial forbs, for a total of 49.1 percent perennial live vegetation. Detailed <br />results listed by species occur in Table 2 and Attachment 4. <br />Page 5 of 26 <br />August 23, 2002 <br />