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where: nmin - mrmmum sample size <br />t =the Student's t distribution value at the 90% confidence level <br />• s =sample standard deviation (s)2= sample variance <br />d =percent acceptable deviation from the mean (10%) <br />Xb~. =sample mean <br />2.4 SPECIES IDENTIFICATION ANA VERIFICATION <br />Species identification was accomplished in the field through the use of plant identification <br />keys (Harrington, 1954, Weber, 1987; Whitson, 1987; Zimdahl, 1990, Stubbendieck, et al, <br />1995). In cases where plant identification was inconclusive in the field, voucher specimens <br />were pressed for lab identification. <br />3.0 RESULTS <br />3:1 QUANTITATIVE EVALUATION <br />3.1.1 Rabbitbrush/Big Sage Mixed Shrubland <br />The rabbitbrush/big sage mixed Shrubland represents approximately 50 acres of the native <br />and introduced vegetation within the area proposed for surface disturbance. This vegetation <br />community is located on the relatively flat colluvial bottom that is present between the <br />• drainage basin side slopes. Two ephemeral and discontinuous arroyo features extend up the <br />arms of the colluvial bottom. The majority of the area within this vegetation community <br />exhibits sheet flow drainage to the southwest. Soils are generally silty in texture, with little <br />incorporated organic matter. <br />The vegetation community was visually dominated by the woody shrubs Chrysothamnus <br />nauseosus (rubber rabbitbrush) and Artemisia tridentata (big sage) with occasional individual <br />incursions of pinyon (Pinus edulis) and Utah juniper (Juniperus osteosperma). The <br />herbaceous understory is a mix of introduced and native species reflecting active ranching <br />use. The dominant species in this community is Bromus tectorum (cheatgrass), Bromus <br />inermis (smooth brome), Agropyron trachycaulum (slender wheatgrass), and Agropyron <br />smithii (western wheatgrass) contributing significantly to the herbaceous component. <br />A total of twenty-seven species were encountered in the community; seven graminoids, <br />fourteen forbs, one sub-shrub, three true shrubs, and two trees. Specific sampling <br />information for the reference area is contained in Tables 2 - 4. <br />3.1.1.1 Vegetation Cover <br />Total vegetation cover of the rabbitbrush/big sage mixed Shrubland was 77.33 percent. <br />Graminoids provided 48.13 percent mean cover (63.44% relative cover), forbs contributed <br />4.00 percent mean cover (9.29% relative cover), sub-shrubs accounted for 0.53 percent total <br />-- --------------- <br />National King Coal LLC Page 4 <br />King If Mine 2005 Baseline Vegetation Report <br />