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<br /> <br />STATE OF COLORADO RICHARD D, LAMM, Gov c~~a~ 999 <br />DEPARTMENT OF NATURAL RESOURCES <br />D. Monte Pascoe, Executive Director <br />MINED LAND RECLAMATION <br />423 Centennial Building,1313 Sherman Street <br />Denver, Colorado 80203 Tel. (303) 866-3567 <br />David C. Shelton <br />July 2, 1982 Director <br />TO: Rich Domingue ~~ /~ <br />FROM: Sandy Emri chl~/ 1 %~~ <br />RE: ARCO, Stipulation No. 3I <br />The Use of the Similarity Index in Evaluating Reclamation <br />Success at the Mt. Gunnison No. 1 Mine <br />ARCO has presented the above-referenced paper and is proposing to use a <br />similarity index as a success standard for evaluating species diversity. <br />The approach is acceptable and reasonable. However, a few questions remain. <br />The similarity index measures the degree of similarity between two vegetation <br />communities or, in this case, between a reference area and the reclaimed area. <br />A subjective decision must be made to determine the acceptable limits of <br />similarity. ARCO has not proposed what the limits will be to determine success, <br />Therefore, a minimum limit of similarity must be established. The Division <br />feels an acceptable minimum limit of similarity is 80~. <br />ARCO is proposing to base the similarity index on the growth-forms identified <br />in Table 1 of the report. A breakdown in the categories of perennial native <br />grasses (PNG) and perennial introduced grasses (PIG) to include warm season <br />and cool season PNGs and PIGS is important to identify the seasonality. <br />Annual and perennial weeds should be included as growth-forms in Table 1 also. <br />This table should be revised so the analysis will reflect the "seasonal <br />variety", and weeds in the reclaimed areas. <br />ARCO should identify whether cover, production or a combination of the two <br />parameters in an importance value will serve as the basis for the index <br />values. They have used cover in their examples. <br />The similarity index is a good alternative to the Shannon-Weiner index and <br />should provide a good measure of the species diversity. OSM has been contacted, <br />and they also feel the similarity index is a valid, acceptable diversity <br />success standard. <br />/mt <br />