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3. Species diversity - Reclaimed areas will achieve a standard of three grasses, one <br /> forb and one shrub with relative cover values greater than three percent. The <br /> combined relative importance will not exceed 85 percent and no one species will <br /> contribute greater than 40 percent relative importance. <br /> 4. Seasonal variety requirements will be waived since the proposed species will <br /> support the proposed post-mining land use. <br /> 5. Woody plant density -The live stem success standard will be 250 stems per acre <br /> on dry sites and 750 stems per acre on wet sites with at least one shrub having a <br /> minimum relative cover value of three percent. <br /> New Horizon Mine 2: <br /> 1. Cover-The success standard for irrigated pasture is 71.8% live vegetation cover, <br /> based on a 1987 vegetation baseline study conducted within the original New <br /> Horizon Mine 2 area. Cover sampling conducted in 1999 within representative <br /> irrigated pasture areas in the PR-05 revision area indicated only slightly higher <br /> cover levels (mean cover 76.8%), despite growing season precipitation which <br /> was 177% of normal during 1999,prior to sampling. The original cover standard <br /> will be sufficient to control erosion, and will remain in effect for the Mine 2 area, <br /> including the PR-05 revision area. Successful cover establishment will be <br /> demonstrated when live vegetation cover is not less than 90% of 71.8%, with 90 <br /> percent statistical confidence. <br /> The success standard for dryland pasture is based on a cover comparison with a <br /> new dryland pasture reference area established in 1999, which is described in <br /> Section 2.04.9, with location shown in Attachment 2.05.4(2)(e)-2. The new <br /> reference area more closely represents the proposed postmine vegetation than the <br /> sagebrush reference area previously utilized. The new reference area supports <br /> established introduced dryland pasture grasses on BLM managed land in the <br /> permit area vicinity. Successful cover establishment will be demonstrated when <br /> live vegetation cover on the reclaimed area is not less than 90% of the reference <br /> area cover, with 90% statistical confidence. <br /> A cover success standard for irrigated hayland is not applicable because <br /> revegetation success is only dependent on production. <br /> 2. Production - The production success standard for irrigated hayland in the New <br /> Horizon 2 area is a technical standard based on a combination of permit area <br /> landowner estimates, NRCS evaluation, and landowner production records for <br /> 1987 and 1999. for alfalfa hayland first cutting production. Yield estimates and <br /> records for the permit area landowners, and a June, 1998 letter from the NRCS <br /> supportive of a production standard of 1.84 tons/acre/year, for I"cutting irrigated <br /> 27 <br /> I <br />