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<br />1008 E. Elizabeth <br />Fort Collins, Colo. 80524 <br />June 14, 1982 <br />t•1r. W. S. Robie <br />Adolph Coors Company <br />Department 807 <br />Golden, Colo. 801+01 <br />Dear Bill: <br />This responds to your letter of 6~10~82, in which you submitted copies of MLR <br />standards for species diversity. <br />As proposed by MLR, Coors must: "Establish a minimum of seven (7) perennial <br />species, of which four (4) are warm season grasses, two (2) are cool season grasses, <br />and one (1) is a forb, to be measured using relative frequency (taken by species). <br />No one component (species) of the above should comprise greater than 40/ relative <br />importance, nor less than 3jo relative importance. Sandsage is to be reestablished <br />as the woody plant species to the woody plant density standard." <br />As explained in a recent meeting, State and Federal reclamation people have agreed <br />on the general approach to species diversity. The number of species to be <br />regr.ired, and the grouping by life form and seasonal diversity, will be determined <br />fron. data presented to describe pre-mining vegetation. Furthermore, supporting <br />date. may be by either herbaceous cover or frequency of occurrence. Within the <br />scope of these terms, we may consider Coors prospects i'or success and the need for <br />a new draft of Section 2.04.10(4)e Species Diversity for your reclamation plan. <br />To Evaluate Coors chances for success in meeting the requirements proposed by h1LR, <br />sae t~egin with Table 2.01F.10(4), which needs to he revised as proposed on the <br />next. page. This table shows that four warm-season grass species, two cool-season <br />grass species and one forb species had a relative importance (RI) of 2`0 or more, <br />and that none exceeded 390. Thus, it could be concluded that Coors should establish <br />a minimum of seven species consisting of at least four warm-season grass species, <br />two cool-season grass species and one forb species at individual RI not greater <br />t.har. 40% or less than Zo as measured by frequency of occurrence in 12-inch quadrats. <br />llowever, Coors faces two problems in meeting that requirement: the first has to <br />do ~~ith cool-season grass species and the second with the forb species. We must <br />consider these two problems and propose small revisions in the requirements. <br />PagE three presents a table that could be included in the new draft of Section <br />2.0%.10(4)e. The data are identified as Table 2.04.10(5), which shows that, on <br />test. plots, we established five warm-season grasses, one cool-season grass, and <br />zerc forb species at RI between 2 and 40"1. Since seeding the test plots, we <br />I]a VE revised the seed mixture to improve species diversity. <br />The revised (and approved) seed mixture includes, as cool-season grass components, <br />western and thickspike wheatgrasses, Indian ricegrass and (as a substitute for <br />rieed.leandthread) small amounts of the introduced grasses smoothbrome, pubescent <br />wheatgrass, crested wheatgrass and Russian wildrye. 4lestern~Thickspike wheatgrasses <br />1 <br />