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Revised March 18, 1992 <br />Since the initial sagebrush reference area had been shown to be <br />statistically comparable to the premine sagebrush community, <br />Colowyo located another sagebrush reference area which was <br />statistically comparable to the existing reference area. This new <br />reference area was intensively sampled for herbaceous cover and <br />production, using the same sampling methodologies and statistical <br />tests that were used to compare the present reference area to the <br />premine area. On August 21, 1981 Colowyo submitted revised <br />vegetative data summarizing the results of the selection of an <br />alternative sagebrush reference area. <br />Both the new sagebrush reference area and old sagebrush reference <br />area were intensively sampled for herbaceous cover and production <br />using the same methodologies and statistical tests as used on all <br />previous vegetative sampling programs with the following two <br />exceptions. For the purpose of sample adequacy, the 90% confidence <br />level has been attained for cover and production, whereas, in the <br />past the 80$ confidence level had been attained. For production <br />sampling, a larger 60cm. x 60 cm. frame was used rather than the <br />30cm. x 60 cm. frame used to gather baseline production data for <br />the original permit application. The use of a larger frame reduced <br />the sampling variance, thus reducing the numbers of samples needed <br />to achieve sample adequacy. <br />• The vegetative data is summarized on Table 5, Herbaceous Cover of <br />the Sagebrush Type, Old (1980) and New (1981) Reference Areas and <br />Table 6, Herbaceous Production of the Sagebrush Type, Old (1980) <br />and New (1981) Reference Areas. <br />For the location of the current sagebrush reference area, refer to <br />Map 3, Regional Vegetation. <br />Currently the mountain shrub reference area is located in an area <br />where grazing can be managed in accordance with the approved <br />postmining land use. <br />The reference areas will be fenced, as necessary, to insure that <br />the proper grazing management can be implemented. <br />Comparisons of weighted averages between reference areas and <br />revegetated areas under Subsection 4.15.7(4)(b) will be utilized to <br />determine revegetation success. The same methodologies and <br />statistical tests used to compare premine and reference areas will <br />be used to compare reference areas and revegetated areas. <br />4.15.8 ReveQetation Success Criteria <br />Colowyo will meet the requirements of this Subsection to insure <br />that the postmining vegetation will be adequate for final bond <br />• release. <br />4.15-12 <br />