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4.4.1.4 Species Diversity Standard <br />• <br />As discussed in Section 3.6.1.3 species diversity is commonly defined as the number of species which <br />occur in a community (richness) in combination with the physical distribution of individuals among those <br />species (evenness). This is about as far as ecologists have progressed in the establishment of an <br />accepted diversity concept. A review of available literature provides one with a host of techniques and <br />formulas all claimed to be the method for calculating diversity (refer to Section 3.6.1.3). This point is <br />also confirmed by Hill (1973) who stated: <br />"Unfortunately, when we look for a suitable numerical definition, we <br />find that no particular formula has a pre-eminent advantage, and that <br />different authors have plausibly proposed different indicies." <br />The problems associated with diversity indicies do not stop here. Hill continues in the same publication <br />by saying "...whereas it is easy enough to define measures of diversity which apply to a particular <br />sample, very often they will have no meaning when applied to in the whole community." According to <br />Hill (1973), the reason for this is that as the size of the sample (n) is increased, the calculated diversity of <br />the community will likewise increase. As sampling intensities fluctuate yearly due to differences in <br />population variances, so will the diversity index. <br />Just as other authors on diversity, Hill (1973) presents his own technique for defining the elusive parame- <br />ter. Hill proposes that one should attempt to estimate the "effective number of species" in a sample. <br />According to the Office of Surface Mining, the ideal formula for defining diversity is yet another formula <br />that is a modification of the Shannon and Weiner (Weaver) formula (Bonham, et.al., 1980). This formula <br />is described as follows: <br />H' _ - E pi log pi <br />where: H'= diversity measure <br />pi = Ni/N <br />Ni = dominance measure for ith species <br />N = Sum of all species dominance measures <br />The Office of Surface Mining (OSM) states that the Shannon-Weiner (Weaver) formula is recommended <br />by Pielou (1975) as the appropriate index for diversity (Bonham, et.al, 1980). However, based on past <br />publications by Pielou (1966, 1966b), he concluded the Shannon and Weaver formula for diversity is <br />inappropriate. According to Pielou (1966), H' should only be used to calculate diversity under the <br />following assumptions: <br />C? <br />4-120 <br />Revision: <br />Approved: y?i8 8.