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• Vegetation Information -Rule 2.04.10 <br />I. The reference areo-affected area comparability and sampling adequacy analyses for <br />at least two of the vegetation types appear To be questionable. Productivity data <br />for the mixed brush reference area indicates a minimum sample size of 200, rather <br />than 14, as calculated by the applicant. <br />The application indicates That all reference areas are equivalent, at the 95% <br />confidence level, to Their respective affected areas. However, Appendix 10-5, <br />"Summary of Test Comparisons Between Reference and Proposed Disturbance <br />Areas ...:', contais sample means for reference and affected areas which are <br />intuitively not equivalent. ~or example, total productivity for the sagebrush type, <br />affected area, is 16.9 g/m (1776 Ibs/acre) and total productivity for the reference <br />area is 290.6 g/m (2592 Ibs./acre). The reason that a t test would not indicate a <br />significant difference between these means is related directly to inadequate sample <br />size (i.e., the sampling intensity was not sufficient to detect a difference). <br />Similar results occurred when the Division calculated sampling adequacy for the <br />sagebrushreference and study areo production. <br />Based upon The above discussion, it appears that resampling may be required. The <br />applicant should review The statistical analyses for other parameters and vegetation <br />types, then meet with the Division to determine the appropriate course of action. <br />• RESPONSE: After coordination with CMLRD (D. Matthews, April 6, 1983) resampling <br />was conducted during the 1983 field season. The detailed results of this resampling <br />effort are included in the totally revised vegetation report. Table 10-3 (Tab 10) shows <br />comparability between reference areas and mine site sampling. Comparability was cal- <br />culated using a two-tailed t-test at 95 percent (0.05 probability) confidence as described <br />in the Methodology Section. <br />Resampling was conducted in the aspen Type for total cover, woody plont density, and <br />herbaceous production. The sagebrush and mixed brush types were also resampled for <br />herbaceous productivity. Per agreement with CMLRD, a maximum number of samples <br />were collected on the aspen mine site for woody plant density and in both the mine site <br />and reference urea for herbaceous production on the sagebrush and mixed brush type. <br /> <br />