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= Sample standard deviation s , =Standard error of the mean When tc was less than or equal to the 1-tailed t table value for aloha error probability of n 10 at the appropriate degrees of freedom, then Ho was not rejected and the revegetation was deemed successful for that parameter. Reclamation Area Success Standards An acreage weighted reference area comparison based on the relative acreage of each predisturbance plant community was used to calculate cover and product on success standards for each bond release unit. The following disturbance acreages were us~to calculate these weighted means: Absolute Disturbance Areages by Vegetation Type Alkali Sagebrush Sagebrush-grass Pre-1986 Reclamation 92.0 16.3 ~ 1995 Reclamation 171.7 4.8 1996 Reclamation 48.4 11.6 Therefore, the following weighting factors were used to calculate cover and production success standards: Relative Disturbance Areages by Vegetation Type Alkali Sagebrush Sagebrush-grass Pre-1986 Reclamation 0.849 0.151 ~ 1995 Reclamation 0.973 0.027 1996 Reclamation 0.808 0.192 oIC Shrub density at the Kerr Mine is evaluated using a technical standard of 1500 shrubs per acre. RESULTS Data from the 1999 revegetation monitoring studies at the Kerr Mine are presented in Tables 1 through 15 contained in Appendix 1. The list of plant species observed during these studies (reclaimed and reference areas) is included in Appendix 2, Table 20. Seed mixes applied on Pre- 1986, 1995, and 1996 Reclamation Areas are included for reference in Appendix 3, Tables 21 and 22. In the cover descriptions below, species listed as "also present" were not "hit" during point- intercept sampling but were present within one meter on either side of the 50 m sample transect line. Cover percentages referred to in the following results as "percent of total vegetation cover" are relative vegetation values. Pre-1988 Reclamation (Photographs 1 through 4) Cover (Table 1) Native perennial cool season grasses were the dominant lifeform in this area and contributed 45.8 percent of total vegetation cover. Sheep fescue (Festuca brachyphylla ssp. coloradensis), western wheatgrass (Pascopyrum smithiQ and thickspike wheatgrass (Elymus lanceolatus fm.