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2.2.3 Herbaceous Production <br />Herbaceous production was estimated by the harvest method. One herbaceous production <br />plot was located and randomly oriented at the origin of each cover transect. Additional <br />production plots were randomly located. Herbaceous production plots were 0.50 square <br />meters in area. All current year above ground live herbaceous plant biomass was clipped <br />within the 0.50 square meter quadrat. Production material was air dried until weights varied <br />by no more than 0.1 g. <br />2.2.4 Species Composition <br />Species composition information was derived from quantitative vegetation cover data. <br />Relative cover information provided a basis for evaluation of the importance of each <br />encountered plant species and lifeform and for comparison to the final revegetation success <br />criterion. The tables presenting data summaries for total vegetation cover for each area <br />sampled also contain the relative cover by species, and a column depicting the numerical <br />ranking of each species by relative cover within the area. <br />2.3 SAMPLE NUMBERS/SAMPLE ADEQUACY <br />For the purposes of this study, total vegetation cover and total herbaceous production <br />sampling were undertaken to sample adequacy for each sampling unit with a minimum of <br />fifteen (15) samples. Parameter testing occurred at the one-sided 90% confidence level. <br />Comparisons between sample mean parameter values and the revegetation success standard <br />assume that the sample mean value accurately represents the population mean in all cases. <br />The following formula was used for sample adequacy calculations: <br />(t)2 (s)2 <br />min - ---------------- <br />(d Xbar)2 <br />where: nmin = minimum sample size <br />s = sample standard deviation <br />t = the Student's t distribution value at the 90% level (one-sided) <br />d = percent acceptable deviation from the mean (10%) <br />Xbar = sample mean <br />2.4 STATISTICAL ANALYSIS <br />Statistical analysis for the revegetation success criterion of total vegetation cover is required <br />if the value of the sample mean from the reclaimed area is less than 90 percent of the value of <br />the final revegetation success criteria for total vegetation cover or total herbaceous <br />production. <br />Sampling revealed that the mean total vegetation cover for the 1998, 1999, and 2000 <br />reclamation area sampling units was greater than that of the final revegetation cover success <br />standard value, therefore no statistical analysis was required. Similarly, total herbaceous <br />Coors Energy Company Keenesburg Mine Page 7 <br />Areas 2,5,6,7,9,10,15, 16, and 19 Vegetation Study (2009)