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s~ = variance among control area samples • <br />nA = number of affected area samples <br />nC = number of control area samples <br />The above calculated t valve is compared to a two-tailed t value at 95 percent confidence <br />(0.05 probability) with appropriate degrees of freedom, as presented in a standard t value <br />table. If the calculated value is less than or equal to the tabular t value, the <br />"comparability" of the reference and affected areas is deemed acceptable. <br />Woody plant density measurements in the sagebrush and mixed brush types taken by ERT in <br />1980 were measured in terms of number/4 m2. WROC measured woody plant density in terms of <br />number/50 m2 in 1983. For purposes of statistical comparisons, the ERT data as shann in <br />cable 10-3 was converted to stems/SO m2 by using a multiplier of 12.5. <br />Per agreement with CM LRD (Dan Matthews 1983, Appendix 10-1) for the 1983 field work, for <br />cases in which adequacy levels (N ) were not achieved, a maximum number of samples were <br /> min <br />taken, as follows: aspen mine area and reference areas - 30; sagebrush and mixed brush <br />production on the mine area - 50; sagebrush and mixed brush production on the original ~• <br />reference areas - 30. <br />Results and Discussion <br />The following results and discussion section covers baseline studies conducted on the <br />permit area and tie across haul road through 1983. Studies conducted in 1985 and 1990 are <br />presented in Appendix 10-B and 10-9, respectively. Table 10-4 lists sample <br />characteristics for the vegetation types in the mine area and along the haul road <br />corridor. Field data is presented in Appendices 10-2 through 10-7. <br />Mine Area. <br />Aspen. Appendix 10-2, 7abl es 2-5 and 2-6 lists the cover data collected Jurinq 19A3 in <br />the Aspen vegetation type for the mine site and original reference area. Tables 2-9 and <br />2-10 include shrub density data, Tables 2-11 and 2-12 include shrub height, and Tables <br />2-13 and 2-14 include tree height data. Tables 2-7 and 2-8 presenC herbaceous production <br />data for the Aspen type in the mine area and associated reference area. <br />• <br />Isolated yua king aspen eta nds occupy cool :.lope exposures near the top of ;he ridge <br />14 <br />