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<br />relative cover. The three predominant understory species <br />may be considered indicative of the severity of previous <br />disturbance, The yellow sweetclover was probably seeded at <br />one time, and although not necessarily an undersirable <br />plant, it is noted for its weedy growth habit and preference <br />for disturbed sites. <br />The mean Cx>, standard deviation <s), and sample size (n) <br />for total vegetation cover are shown in Table 15: Mean and <br />Standard Deviation of Percent Vegetation cover. The <br />Table I5 <br />• <br />Mean and Standard Deviation <br />of Percent Vegetation Cover, <br />and Mean Percent of RocK, Litter, and Bare Ground <br />Mean <br />Vegetation Standard Number of Mean Mean Mean <br />Cover Oeviatian Samples Rock Litter Bare Ground <br />69.9 8.96 20 3.8 15.5 11.1 <br />Division of Mined Land Reclamation requires that for shrub <br />dominated vegetation types, vegetation sampling muat detect <br />a ten percent variation in the mean with eighty percent <br />confidence. Two methods of demonstrating sample adequacy <br />are presented here. The first is a calculation of percent <br />"reliability", which is the percentage of increase or <br />reduction in the mean which can be detected at a given <br />confidence level at a given intensity of sampling. This is <br />a function of the relationship between the mean and the <br />standard deviation, given as: <br />1/2 <br />x1-x2 <br />C100) _ % reliability = C100) <br />x1 <br />81 <br />2s2 <br />t.20 n <br />xl <br />Revised 5/87 <br />