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s1 = the variance of cover or production for the affected area <br /> s2 = the variance of cover or production for the reference area <br /> n, = sample size in the affected area <br /> n2 = sample size in the reference area <br /> When I xl — x2 1 is less than or equal to the other calculated value, <br /> the affected area and reference area are considered comparable for the <br /> purpose of evaluating reclamation success. <br /> 2.3.1 Coordination with State <br /> A Mid—Continent Resources representative and a plant ecologist <br /> from Western Resource Development met with OSM and CMLR personnel in a joint <br /> meeting in September 1979 to develop plans for the establishment of reference <br /> areas for the Coal Basin mines. It was agreed at this meeting that reference <br /> areas should be selected for the major vegetation types disturbed. Reference <br /> areas were to be similar to affected areas with respect to vegetation struc— <br /> ture, species dominance, species composition, estimated cover, estimated <br /> production, slope, and aspect . It was further agreed that reference areas <br /> could be located by the Western Resource Development ecologist based upon <br /> his experience. <br /> During the 1979 growing season the entire permit area was mapped <br /> and each vegetation type was qualitatively described from field observations. <br /> Reference areas were located and quantitatively sampled for vegetation cover . <br /> Plans were developed to complete the production study during the 1980 growing <br /> season. An interim report summarizing results was prepared and sent to CMLR <br /> and OSM. <br /> A second meeting was held on 7 July 1980 with OSM and CMLR. <br /> Agency personnel stated Mid—Continent Resources must now meet the require— <br /> ments of the Colorado Surface Coal ,'Mining Reclamation Act by obtaining a new <br /> permit. ;or vegetation, reference areas must be located by a different <br /> process. The emerging methodology was to sample adjacent to existing dis— <br /> turbances and to use that data to locate statistically valid reference areas <br /> per developed standards. <br /> This report now encompasses all agency requests from the 7 July <br /> 1980 meeting. <br /> 2.3.2 Collection and Analysis of Reference Area Data <br /> Techniques for obtaining quantitative information on cover , <br /> production, shrub height , and shrub density were the same as described <br /> in Section 2.2 above. Sample locations were selected randomly in eacn <br /> reference area. <br />