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At each sample point he sighting device was directed vertically <br /> upward if overstory vegetation was present and then downward into the <br /> understory stratum. The first hit along a vertical line was recorded <br /> as vegetation (by species) , rock, litter, or soil . When vegetation <br /> was intercepted on the first hit additional hits were taken until <br /> soil , litter, or rock was intercepted. First hits were used in cal- <br /> culating the absolute percent cover. <br /> 2.3.2 Collection and Analysis of Shrub and Tree Data <br /> Data on shrub density were recorded at the randomly located <br /> vegetation cover sample sites. Shrub densities were tallied from a <br /> 50 meter by 1 meter quadrat constructed along the axis of the cover <br /> transect . The number of shrubs rooted within the quadrat was deter- <br /> mined by species. <br /> Per Colorado Mined Land Reclamation (CMLR) specialist <br /> request, trees within the affected area were counted from aerial <br /> photographs, because of low density, erratic occurrence, and the poten- <br /> tial problem of achieving sample adequacy. <br /> 2.3.3 Collectior and Analysis of Production Data <br /> Rectangular plots 1 meter by 2 meters were used for produc- <br /> tion estimates. The �rrent year's growth of all herbaceous plants <br /> was clipped. All gra es were cut and sorted by individual species <br /> while forbs were comb ned into a single category. Each production <br /> plot yielded one samp e. <br /> In the I at oratory, clippings were oven-dried at 1050C for <br /> 24 hours and weighed to the nearest tenth of a gram. Data were recorded <br /> as grams per 2 square meters (g/2 m2) . Production estimates were also <br /> converted to pounds per acre ( lbs/ac) . <br /> 2.3.4 Sample Adequacy Calculation <br /> Sample adequacy requirements for cover, shrub density, and <br /> production were calculated using the formula <br /> 2s2t2 <br /> nmin (d5) 2 <br /> where nmin = the minimum adequate number of samples (cover transects, <br /> production or density quadrats) <br /> s2 = sample variance (n-1) <br /> ���• <br /> 110 <br /> t = a one-ta ed t-statistic with 80% confidence and infinite <br /> degrees M freedom (t = 0.84) �I <br /> d = desired limits of detection (d = 0.1) <br /> x = sample Mean <br /> -3- <br />