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are by definition the areas originally seeded to the sagebrush steppe plant community that <br />exhibit the characteristics of that community and meet either the core or ecotonal <br />requirement for full release. <br />Herbaceous Cover <br />For both Pre-2008 and Post-2008 revegetation targeting. (and achieving) the rangeland <br />land use subcomponent of rg_ azin lg and, herbaceous cover of the revegetated area will be <br />considered adequate for final bond release if it is not less than 90% of the herbaceous <br />cover as determined from the reference areas with a 90% statistical confidence utilizing a <br />standard students statistical t-test comparison of the means. As allowed under the rules <br />promulgated on 9/14/05, these comparisons may utilize one of three methods detailed <br />under Rule 4.15.11 (2) [(a), (b) or (c)]. Also as allowed by Rule 4.15.7 (4), either <br />weighted-average or individual protocols will be followed depending on the resulting <br />community that evolves (see Section 4.15.7 above). For grassland testing the weighted <br />average approach (Rule 4.15.7 (4) (b)) will be utilized where reference area data and <br />revegetated area data are "weighted" (each combined into single values for comparison) <br />based on the proportional acreage of pre-mine communities within the disturbance area <br />footprint. Testing will then follow procedures detailed under Rule 4.15.11 (2) with <br />preference being given first to subsection (a) [direct comparison], second to subsection <br />(c) [reverse-null testing], and third subsection (b) [classic t-test]. <br />For "targeted" Post-2008 sagebrush steppe revegetation (targeting the rangeland land use <br />subcomponent of wildlife habitat), herbaceous cover will be considered adequate for final <br />bond release if it is not less than 70%* of the sagebrush reference area's herbaceous cover <br />with a 90% statistical confidence utilizing a standard students statistical t-test comparison <br />of the means. If necessary, a reverse-null hypothesis testing procedure may be utilized in <br />accordance with procedures detailed in Rule 4.15.11 (2) (c). As allowed under Rule <br />4.15.8 (3) (ii), relaxation of the herbaceous cover standard for areas targeting wildlife <br />habitat post-mining land uses is designed to compensate for revegetation techniques <br />(prescribed ecological reclamation approach) that must discourage grasses to encourage <br />shrubs in the post-revegetated community. For "evolved" post-2008 sagebrush steppe <br />revegetation, the grazingland cover standard will be maintained. <br />A higher percentage of herbaceous cover is not practical or desirable for the following <br />reasons: <br />1. It is well documented that in mined-land reclamation the establishment of shrubs <br />to reach bond release levels has proven to be very difficult. Perhaps the most <br />detrimental condition affecting shrub establishment is the competition from <br />The value of 70% has been selected given the following rationale: 1) herbaceous competition must be <br />significantly restricted to facilitate emergence and growth of shrubs as indicated under Rule 4.15.11 (3) (ii); <br />2) the original value is 90%; 3) a value of 50% seems too low to adequately control erosion; 4) by regulation <br />(4.15.11 (3)(a)) a reduction to 70% is allowed for one of the demonstrations for revegetation success for <br />woody plant density; and 5) 70% of the herbaceous material in a native reference area should be adequate to <br />control erosion on slopes 10% or less. <br />4.15-16 Revision Date: 3/14/08 <br />Revision No.: TR-72