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• 2.6 SPECIES DIVERSITY <br />Species/lifeform diversity was calculated for each study area by deter- <br />mining the number of species having a relative cover exceeding 3 percent and <br />grouping these by lifeform. <br />2.7 TIME OF SAMPLING <br />All quantitative data were collected from July 26-31, 1982. <br />2.8 AGENCY COORDINATION <br />Powderhorn Coal Company on 9 July 1982 submitted a plan detailing <br />sample procedures and methodology for conducting the vegetation inventory. <br />On 22 July 1982 Mr. Jim Herron, Reclamation Specialist, Colorado Mined <br />Land Reclamation, modified the vegetation plan. <br />This study has followed that modified plan except that 111 total vegetation <br />cover contrasted to herbaceous cover was determined; 12) shrub density <br />was determined by counting all individuals present, not just those greater <br />than 0.5 meters in height. These minor changes were approved by Mr. Dan <br />Matthews of Colorado Mined Land Reclamation during a telephone conversa- <br />tion with Mr. David L. Johnson of Western Resource Development on 27 July <br />• 1982. <br />Per Colorado Mined Land Reclamation direction, sample adequacy for <br />cover, production, and density was calculatetl per the following formula: <br />t' s° <br />M = (-Sc d~ <br />where M =the minimum number of observations needed <br />t =the two-tailed t distribution value at the 90X, confidence <br />level 11.64) or the BOb confidence level !1.281 <br />sZ = the variance estimate obtained from sampling <br />d =the level of accuracy desired for the estimate of the mean 10.1) <br />x =the sample mean <br /> <br />-4- <br />