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4.13 Sample Adequacy 1987 and 1999 The following formula was used to determine the <br />adequacy of the quantitative cover, production, and woody density samples in the New Horizon <br />2 studies: <br />Nmin = (st)z/(dx)2 <br />where, <br />Nmin = minimum sample size <br />s = sample standard deviation <br />t = two -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 were <br />exceeded, or the prescribed maximum number of observations were collected. Maximum <br />sample sizes were developed during the consultation process with OMLR staff and CDMG staff <br />prior to and during the field studies (letter correspondence from Mr. Peter O'Connor to J. Lunan <br />of Peabody dated August 7 and September 3, 1987), (1999 site visits with Dan Matthews and <br />Harry Ranney, and phone conversations with Janet Binns all of the CDMG). <br />4.14 Livestock Carrying Capacity Stocking rates were calculated for the irrigated pasture <br />vegetation type only using the results of production samples collected in the type. The rates <br />were based upon the standard 27 pounds/day dry weight intake per animal unit. The rates <br />were expressed as available forage in animal unit months (AUMs). <br />4.15 Species Diversity Qualitative assessments of species diversity (species richness, <br />numbers, and equity) were made on the basis of the cover and frequency data collected in the <br />irrigated pasture, swale/drainage, and sagebrush vegetation types. Quantitative methods, <br />including diversity indices and rank correlation tests, were not applied because of the inherent <br />shortcomings associated with these techniques (Chambers 1983). Similarity coefficients were <br />not applied because of the inherent dissimilarity of the plant communities found on the study <br />site, and the fact that a reference area approach for determining revegetation success at the <br />New Horizon 2 area is not being proposed. <br />February 2015 JR -66) 2.04.10-25 <br />