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• At least 2 cool season perennial grasses with between 3% and 50% relative cover, <br />and; <br />• Either all fortis or all shrubs combined with between 1% and 50% relative cover. <br />Under the proposed standard, adequate diversity could be demonstrated by as few as two <br />grasses providing a combined 99% relative cover and one or more fortis providing a <br />combined 1% relative cover. Please provide the rationale for the proposed change to the <br />previously approved diversity standard (or retain the original standard). Please also <br />provide a rationale for the differing standards proposed for the three reclamation <br />categories (pre-2008 grazingland, post-2008 grazingland, and post-2008 wildlife <br />habitat). <br />29. Proposed diversity standards for the two post-2008 reclaimed categories appear to be <br />generally appropriate, given the respective land use emphases (grazingland and sagebrush <br />steppe/wildlife habitat). The Division has a couple requests for modification, to ensure that <br />the standards will reflect reclamation plan objectives, and practicable targets based on the <br />seedmixes and practices employed. <br />a) For the grazingland emphasis, please specify that each principle cool season grass to <br />be counted will be a native cool season grass, and that, if five or more native perennial <br />grass taxa contribute between 3% and 50%, the minimum combined relative cover of <br />perennial fortis and shrubs shall be no less than 1 %. <br />b) For the wildlife habitat emphasis, please specify that a minimum of two principal <br />native cool season grasses will be established (each between 3% and 50% relative <br />cover). The sentence regarding negatement of the forb/shrub requirement should be <br />deleted, to reflect the importance of life form diversity in the wildlife habitat area. <br />c) For the forb component of the wildlife habitat diversity standard, please consider <br />specification of "at least 4 perennial fortis, each with at least 0.5% relative cover, <br />minimum 3 of which are native; or a total perennial forb component of at least 10% <br />relative cover, at least 5% relative cover of native perennial fortis", to better reflect the <br />emphasis on establishing a diverse, native dominated community. The woody plant <br />requirement will be addressed within the density standard, and does not need to be included <br />in the diversity standard. <br />30. Under Success Evaluation in Section 4.15.11, on amended page 4.15-31, there is a <br />discussion of the reverse null hypothesis test. Some further elaboration of the reverse null <br />may be warranted, as there are certain particulars that are not fully described in the rule. <br />Specifically, sample adequacy must be achieved in the reference area in order for the one <br />sample test to be used. If sample adequacy is not achieved in the reference area (for cover <br />or production sampling), a two sample reverse null t-test, with Satterthwaite approximated <br />degrees of freedom and standard error can be employed. A minimum sample size of 30 is <br />required in the reference area, as well as the reclaimed area, in this instance. <br />The Division recommends that this clarification be included in the text. <br />Colowyo Coal Company, C-1981-019 TR-72 <br />April 29, 2008 Page 14 <br />