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3.2.5 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 <br />success criterion. The tables presenting data summaries for total vegetation cover for <br />each area sampled also contain the relative cover by species, and a column depicting the <br />numerical ranking of each species by relative cover within the area. <br />3.3 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 <br />standard assume that the sample mean value accurately represents the population mean in <br />all cases. <br />The following formula was used for sample adequacy calculations: <br />Nmin <br />(d Xbar)2 <br />(t)2 (S)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 />3.4 SPECIES IDENTIFICATION AND VERIFICATION <br />Species identification was accomplished in the field through the use of plant <br />identification keys (Harrington, 1954, Weber, 1987; Whitson, 1987; Zimdahl, 1990, <br />Stubbendieck, et al, 1995). In cases where plant identification was inconclusive in the <br />field, voucher specimens were pressed for lab identification. <br />4.0 RESULTS <br />The historic record vegetation community is comprised of an old field or pasture <br />vegetation community. Several expressions of this type of community are present within <br />the West Elk Mine permit area, notably, east of the study area and on primary terraces <br />above the drainage of Sylvester Gulch. These agricultural and range communities are <br />well defined, though intermixing occurs at the edges with the adjacent vegetation <br />Mountain Coal Company, LLC Page 5 <br />Historic Record Study Area Vegetation Sampling Report: 2010