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2.5.1 Sample Numbers/Sample Adequacy <br />Sample adequacy calculations were made for vegetative cover of the sampled reclaimed <br />area. The following formula, accepted by the CDMG, was used for these calculations: <br />nm;°= t z s z <br />(d ~)2 <br />where <br />n,ri° =minimum sample size <br />t =the "T" distribution value at the 90% confidence level <br />s =sample standard deviation <br />s2 =sample variance <br />d =percent acceptable deviation from the mean (10%) <br />X~ =sample mean <br />Sample adequacy was achieved for total vegetation cover sampling. Thirty cover <br />transects were initially sampled. Minimum sample size was 15, as reported in Table 1. <br />3.0 Results and Discussion <br />3.1 Reclaimed Area Description <br />The seven acre permit area's vegetation consists mainly of three types: Mountain Shrub, <br />cropland, and Pinon-Juniper. These vegetation types occur within the mine azea at <br />elevations ranging from 7,360 feet to 7,680 feet. The reclaimed area north of La Plata <br />County Road 120 is primarily located in the Pinon-Juniper vegetation type, which has a <br />reduced understory of herbaceous vegetation, and lower general species diversity. The <br />average annual precipitation in this area is approximately 20 inches. However, during the <br />last several growing seasons there has been a statewide drought. This drastic reduction in <br />precipitation has limited the growth potential of many areas of the state, including all <br />reclaimed areas. Therefore, declines in production, species diversity, woody plant stem <br />density, and cover are to be expected. Additionally, the type and amount of vegetation <br />varies with differences in slope, exposure, and soil depth. <br />3.2 Cover <br />Eleven individual species representing three lifeforms were encountered during the <br />sampling of the reclaimed area. They included graminoids, forts, and shrubs. The plant <br />species observed and their characteristics are presented in Table 1. Total mean <br />vegetation cover of the reclaimed area was 33.9 percent. Based on cover sampling, <br />graminoids represented 13.6 percent mean cover (40.1 percent relative cover), forts <br />accounted for 1.00 percent mean cover (2.9 percent relative cover), and shrubs 19.3 <br />percent mean cover (57.0 percent relative cover). <br />La Plata # 1 Mine Page 5 <br />2003 Vegetation Sampling <br />