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Yoast Mine SL-3 February 2011 <br />Phase 11 Bond Release Request <br />• n = Sample size <br />t, = Calculated t value <br />tt =Tablet value (alpha= 0.1) see Rohlf and Sokal (1969) <br />The (traditional) null hypothesis being tested is that the Phase II bond release block allowable <br />all hit herbaceous cover mean (µ) is greater than or equal to 90% of the standard, stated as Ho: <br />µ >_ Q. If t, is less than or equal to the 1-tailed t table value for alpha error probability of 0. 10, <br />at (n-1) degrees of freedom, then Ho is not rejected, and revegetation success for cover is <br />deemed successful. The results of the statistical testing is as follows. <br />The calculated t statistic is: tc = (45.17 - 42.97)/(15.87/35) = 0.820 <br />The critical t value (table t value) = 1.306 (one-tailed, alpha = 0. 1, 34 d.f.). <br />Since the calculated t value is less than the critical t value (0.820 < 1.306), revegetation <br />success for cover is deemed successful. <br />Species Composition and Diversity <br />The species composition and diversity evaluation below is based on the species diversity <br />revegetation success evaluations in Tab 22 of the approved Yoast Mine permit. <br />• Test A requires that no single plant species may exceed 60% relative cover. A determination <br />of PASS was made because the species with the greatest relative cover (Medicago sativa) had <br />27.6 percent relative cover which is far less than the 60 percent limit. <br />Test B requires the total mean species density in the reclaimed area equals or exceeds the <br />central 75% of the distribution of the area weighted overall species density determined from <br />the cover sampling in the 100 sq.m. sample plots of the reference area. Species density <br />numbers were subjected to sample adequacy assessment. For purpose of setting the range of <br />species density within the Reference Area, the 75% range of variation would be established <br />as: <br />z x s <br />Where: <br />z = the number of standard deviations (both ways from the mean) encompassing 75% of the <br />normal distribution (= 1.15; see Rohlf and Sokal 1969, Table P) <br />s = area weighted species density standard deviation for the reference area (n-1) <br />The standard is the point at which the central 75% of the distribution of overall species <br />density in the reference areas begins (the midpoint (probability distribution) of the lower half <br />of the range of variation for the reference area). Mathematically this is: <br />n <br />U <br />7