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described above, but woody plant density samples were not collected in any of the reference <br />areas. Sampling proceeded using a single stage statistical design. <br />Sample locations in reclaimed areas were randomly plotted by use of an internal script routine <br />within ArcGIS 9.2 software. Minimum spacing between sample points was 170 feet (one 50 m <br />transect length). <br />In the extended reference areas, each reference unit was gridded and numbered. Grid cell size <br />was 200 feet X 200 feet. These grid cells were placed contiguously by hand on maps of 1:4,800 <br />scale. Sample locations were selected as the center points of grid cells selected using random <br />numbers generated by computer. <br />Sample points were located in the field using Garmin III handheld GPS units and topographic <br />maps. Cover and woody plant density transects were located and oriented using, at a glance, the <br />seconds reading on a wristwatch x 6 as an azimuth or a blind throw of a meter stick . The final <br />location of each herbaceous production plot was chosen with a blind throw of the sampling hoop <br />made from the origin of the associated cover/woody plant density transect. At each cover/woody <br />plant density sampling location, the slope (percent) and aspect of the site were determined and <br />recorded, as was the orientation of the transect (in degrees not corrected for magnetic <br />declination). <br />STATISTICAL METHODS <br />Sample adequacy calculations for parameter estimation were carried out using the formula as <br />prescribed by the Colorado Mined Land Reclamation Board for parameter estimation without <br />hypothesis testing (DMG 1995): <br />tat S2 <br />Nmin= <br />(d x )z <br />where: <br />t« =one-tailed t-value with (n-1) degrees of freedom, a=0.10 <br />s2 =sample variance <br />d = 0.1 (0.15 for woody plant) (level of precision or desired detectable reduction) <br />x = sample mean <br />• <br />4 <br />