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• herbaceous production on the Disturbed Predisturbance Area. Sample adequacy, at the 90 <br />percent confidence interval, was achieved for plant cover on the Disturbed Reference Area. <br />Sample adequacy, was not achieved for shrub density at the 90 percent confidence interval, on <br />either the Disturbed Predisturbance Area and corresponding Disturbed Grassland Reference <br />Area. Neither was sample adequacy achieved for herbaceous production on the Disturbed <br />Reference Area. However, according to the directions given us in the field and the policies of <br />the Division, a maximum of 50 tlansects was sampled on each of these two areas so an adequate <br />sampling of all areas was achieved. <br />With respect to the similarity of the corresponding predisturbance areas and reference areas, the <br />"pre-mining comparison" as found on page 16 of the Division's Guidelines for Compliance with <br />Land Use and Vegetation Requirements for Coal Mining was evaluated for all areas sampled. <br />Upon comparing the Juniper-Grassland Predisturbance Area with the corresponding Juniper- <br />Grassland Reference Area, ~ values were calculated for each of the three parameters evaluated. <br />The calculated ~ value for plant cover was determined to equal 1.0718; for production the <br />calculated ~ value was determined to equal 1.3779; and for woody plant density the calculated <br />tc value was determined to equal 0.6375. The corresponding tabular tt value for plant cover was <br />2.048 and 2.000 for production and shrub density. Since in all instances for the Juniper- <br />Grassland areas sampled the calculated ~ values were less than the corresponding tabular t< <br />values, it can be concluded that all of the Juniper-Grassland Predisturbance Areas are <br />statistically similar to the corresponding Juniper-Grassland Reference Areas with respect to the <br />required parameters of total plant cover, herbaceous production and woody plant density. <br />• Upon comparing the Disturbed Predisturbance Area with the corresponding Disturbed <br />Reference Area, ~ values were calculated for each of the three parameters evaluated. The <br />calculated tc value for plant cover was determined to equal 0.3280; for production the calculated <br />~ value was determined to equal 0.0767; and for woody plant density the calculated ~ value was <br />determined to equal 1.0660. The corresponding tabular t< value for plant cover was 2.048 and <br />2.000 for production and shrub density. Since in all instances for the Disturbed areas sampled <br />the calculated ~ values were less than the corresponding tabular tt values, it can be concluded <br />that all of the Disturbed Predisturbance Areas are statistically similar to the corresponding <br />Disturbed Reference Areas, with respect to the required parameters of total plant cover, <br />herbaceous production and woody plant density. <br />'This summary suggests that sufficient sampling was conducted on all areas needing to be <br />evaluated and that the predisturbance areas are statistically similar to the proposed reference <br />areas to satisfy the Division's regulations and guidelines and that the proposed reference areas <br />are suitable for use as a measure of final revegetation success. <br />• 11 <br />