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1) That within the sample all species in the parent population are represented. <br /> 2) That the parent population exists as a homogeneous entity. <br /> 3) That the parent population or collection consists of no more than two species. <br /> Pielou (1966) altered the Shannon-Weiner (Weaver) formula to mitigate assumption number 3. His <br /> modification is described as follows: <br /> H' (s) _ -Z i pilogspi;where s =the number of species. <br /> However, as such, H'(s) no longer measures diversity as typically defined. Instead, it provides a measure <br /> of evenness, or how individuals are portioned among the species in the entire community. <br /> Finally, and most importantly, one must be aware that to compare a portion of an undisturbed, natural and <br /> relatively stable community (permanent reference site) against what will be a changing community (at <br /> least for most of the liability period) by a standard which is subjective in design and intent, is extremely <br /> statistically and legally questionable. As it now exists, the diversity index obtained is simply a number that <br /> is largely meaningless since it cannot be compared to any known standard for management purposes. <br /> It is important at this point to state what we feel is common ground on the issue of diversity between <br /> Trapper Mine and the regulatory agencies. <br /> 1. Diversity is ill defined mathematically and controversial. <br /> 2. The importance of species or life forms should be considered in terms of the end land use. <br /> 3. A meaningful, acceptable, reproducible standard should be used. <br /> 4. The standard must be based upon easily obtainable data such as cover, production or density. <br /> In light of the described problems, a technique based on more traditional range analysis methods will be <br /> used to determine if a diverse plant community is reestablished. Tables 2.3-3 and 2.3-5 list the <br /> percentage that each species contributed to the herbaceous aerial cover on range sites A and B in 1980. <br /> On range site A, 6 species (4 grasses and 2 forbs) each comprised greater than 3.0% of that cover (see <br /> Table 2.3-3). On range site B, 5 species (4 grasses and 1 forb) each comprised greater than 3.0% of that <br /> cover (see Table 2.3-5). <br /> A diversity standard for evaluating success would appropriately include 4 grass species exhibiting greater <br /> than 3.0% relative plant cover. In addition, given the desire to include a diverse mixture of forb species <br /> that would individually contribute less than 3.0% relative plant cover, setting an overall forb life form <br /> standard of 5.0% relative cover would be appropriate. <br /> 4-121 <br /> Revision: TR-126 <br /> Approved: <br />