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2.2.1 Vegetation Cover Sampling <br />Vegetation cover was estimated using the same methods previously described for the <br />Test Plots. Vegetation cover transects on the Reference Area were randomly located <br />through gridding the entire Reference Area and then randomly selecting sample <br />locations. Vegetation cover data were collected until sample adequacy was achieved. <br />Sample adequacy calculation is discussed in Section 2.2.3. <br />2.2.2 Vegetation Herbaceous Production Sampling <br />Current year herbaceous production on the Reference Area was estimated using the <br />same methods discussed for the Test Plots. Herbaceous production data were collected <br />until sample adequacy was achieved. Sample adequacy calculation is discussed in <br />Section 2.2.3. <br />2.2.3 Determination of Sample Adequacy for Reference Area Sampling <br />Sample adequacy calculations were made for both vegetative cover and herbaceous <br />production sampling in the reference area in accordance with Colorado Division of <br />Minerals and Geology Guidelines (CDMG, 1988). The following formula was used for <br />these calculations: <br />(t)2 (s)2 <br />°min = -------------- <br />(d Xbar)2 <br />where: nmin =minimum sample size <br />t =the Student's t distribution value at the 90% confidence level <br />and sample size degrees of freedom <br />s =sample standard deviation (s)2= sample variance <br />d =percent acceptable deviation from the mean (]0%) <br />Xbar =sample mean <br />Sample adequacy was to be calculated for less than ten cover samples and less than 50 <br />production samples. If sample adequacy was indicated by less than the maximum <br />number of transects or quadrats, sampling was considered adequate for that parameter. <br />Parameters were tested at the 90`9 confidence level with atwo-tailed statistic. <br />10 <br />