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until sample adequacy for cover was achieved. Figures 1 and 2 show the sample points <br />for 2007 and 2008. <br />Cover <br />Vegetation cover was estimated by the use of the point-intercept method. A laser (ten) <br />point frame was used to minimize instrument error and maximize precision and observer <br />accuracy. Cover transects were 50 meters in length, with ten sample data points collected <br />at 5.0 meter intervals along the transect on the right side of the transect centerline, for a <br />total of 100 points per transect. Transect orientation was determined by navigating with a <br />hand held GPS unit to the next transect point. In no event were transects allowed to <br />extend within ten feet of revegetated area boundaries, to minimize impacts from "edge <br />effect." <br />For statistical purposes, each cover transect served as a sample unit. Data points recorded <br />the first vertical "hit" on vegetation (as determined by the laser point frame), soil (bare <br />ground), rock, or litter. The data were summarized by computing mean cover, relative <br />cover (percent of total vegetation cover attributed to each species), and species <br />composition. Species composition information was computed from vegetation cover data <br />using a ratio of individual species cover to total vegetation cover. <br />Production <br />Biomass production data were obtained using a harvest method. All of the current year's <br />growth included within a one-half square meter quadrat was clipped at each transect. <br />Succulents, noxious weeds, and cushion plants were not clipped. Clipped biomass was <br />placed in paper bags, and dried in Colorado State University's Rangeland Ecosystem <br />Science Laboratory forced air ovens for 24 hours at 105°C. Samples were weighed on an <br />appropriate scale to the nearest tenth of a gram and reported in g/m2 and lbs/acre. <br />Clipped samples less than 0.10 grams were reported as trace samples. Average paper bag <br />weight was subtracted from weighted samples. <br />Sample Adequacy <br />Sample adequacy calculations were made for vegetative cover and production of the <br />sampled reclaimed area. The following formula, accepted by the Division, was used for <br />these calculations: <br />nmin = t 2 S 2 <br />(d Xbar)2 <br />where : <br />nmin = 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 />Xbar = sample mean