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2.4 Determination of Woody Plant Density <br />Belt transects were co- located with the ground cover points to obtain a reasonable estimate of the <br />woody plant density of the mine site. At each of the sample sites in the larger revegetated areas ( >1.5 <br />acres), a 2 -meter wide by 50 meter or 4 meter by 25 meter long belt transect (depending on the distance <br />to the next sample point) was established in the direction of the next sampling point (typically in a <br />cardinal compass direction). Then within each belt, all woody plants (shrubs, trees, sub - shrubs, and <br />succulents) were enumerated by species. Determination of whether or not a plant could be counted was <br />dependent upon the location of its main stem or root collar where it exited the ground surface with <br />regard to belt limits. On sampling areas smaller than 1.5 acres, total counts of live shrubs were <br />conducted. This required systematically walking the entire unit and recording every live shrub within that <br />unit. <br />2.5 Sample Adeauacy Determination <br />Sampling within each unit was conducted with between 96 and 125 samples in revegetation and 15 <br />to 30 for reference areas for cover, production, and woody plant density (revegetation only) as described <br />in Section 1.1. For bond release applications, the typical procedure is that the sampling effort must <br />continue until an adequate sample, nmin, has been collected in accordance with the Cochran formula <br />(below) for determining sample adequacy, whereby the population is estimated to within 10% of the true <br />mean (N) with 90% confidence. <br />n,„in is determined as follows: <br />nmin = (t2s2) I (0.1x)2 <br />Where: n = the number of actual samples collected with a minimum of 15 in each unit; <br />t = the value from the t distribution for 90% confidence with n -1 degrees of freedom; <br />S 2 = the variance of the estimate as calculated from the initial samples; <br />z = the mean of the estimate as calculated from the initial samples. <br />When the inequality (n,,,in <_ n) is true, the sampling effort is deemed adequate. If the initial samples do <br />not provide a suitable estimate of the mean (i.e., the inequality is false), additional samples would be <br />collected until the inequality (nn,in <_ n) becomes true. <br />CEDAR CREEK ASSOCIATES, Inc. Page 14 Snowcap - Phase III Bond Release <br />Evaluation - 2012 <br />