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Mr. Tom Wainwright -2- February 10, 1983 Vegetation Information - Rule 2.04.10 1. The reference area-affected area comparability and sampling adequacy analyses for at least two of the vegetation types appear to be questionable. productivity data for the mixed brush reference area indicates a minimum sample size of 20U, rather than 14, as calculated by the applicant. The application indicates that all reference areas are equivalent, at the 95% confidence level, to their respective affected areas. However, Appendix 10-5, "Summary of Test Comparisons Between Reference and Proposed Disturbance Areas...", contains sample means for reference and affected areas which are intuitively not equivalent. For example, total productivity for the sagebrush type, affected area, is 196.9 y/m2 (176 lbs./acre) and total productivity for the reference area is 290.6 g/m (2592 lbs./acre). The reason that a t test would not indicate a significant difference between these means is related directly to inadequate sample size (i.e., the sampling intensity was not sufficient to detect a difference). , Similar results occurred when the Division calculated sampling adequacy for the sagebrush reference and study area production. Based upon the above discussion, it appears that re sampling may be required. The applicant should review the statistical analyses for other parameters and vegetation types, then meet with the Division to determine the appropriate course of action. Reclamation Plan - Rule 2.05.4 1. The applicant proposes to measure total basal cover in reclaimed and reference areas to establish a success standard for cover. Baseline cover estimates and reference area/study area comparisons were based on canopy cover. This is an apparent conflict with Rule 4.15.7, which requires consistency in sampling methods in comparisons between the reclaimed area and undisturbed areas. Please clarify. 2. Tlie application seems to indicate that production success for the reclaimed Wheatland will be based on clipped plot comparisons with a wheat reference area. For croplands, Rule 4.15.9 requires determination of revegetation success based on crop production (i.e., bushels of wheat per acre). 3. The applicant proposes the use of pre-mine livestock carrying capacity as a revegetation success standard, rather than herbaceous or total vegetation production. Carrying capacity determinations would utilize species composition and production data. Carrying capacity would be determined by use of methods outlined in the National Range Handbook (USDA Soil Conservation Service, 1976).