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Alternative Test B.• Total Species Density Test <br />i <br />This overall reclamation diversity standard will be judged based on the species density values observed <br />along with cover sampling in the 100 sq.m. sample plots that accompany the standard cover /species <br />presence samples. Species density numbers will be subjected to sample adequacy assessment in the <br />usual CDMG manner. Experience has shown that species density almost always is adequately <br />sampled at the point that cover sampling is adequate and that is usually with the minimum sample <br />number. <br />For purpose of establishing the range of species density within the Reference Area, the 75% range of <br />variation would be established as: <br />zxs <br />Where: <br />z = the number of standard deviations (both ways from the mean) encompassing <br />75% of the normal distribution (= 1.15; see Rohlf and Sokal 1969, Table P) <br />• s = standard deviation (n -1) <br />The standard is the point at which the central 75% of the distribution of overall species density in the <br />Reference Areas begins. Mathematically this would be: <br />Mean Reference Areas species density (no. of species per 100 sq.m.) - 1.15 s <br />In words, we are selecting as the standard the midpoint (in terms of probability distribution) of the <br />lower half of the range of variation of the Reference Areas. <br />Note that this test addresses total species density, not just native species density (see Alternative Test <br />D below). (Noxious weeds will be omitted in conformance with other existing requirements). The <br />point of addressing total species density, including annual /biennial species and introduced species, is <br />that the total species density is arguably a strong indication of the existence of niche spaces that could <br />eventually be occupied by the native forb and woody plant species that exist in the Reference Areas. <br />The "best" (in the agricultural sense) stands of grass might not qualify because they would have <br />• crowded out the "weeds" (which, in the agricultural sense, means most of the species that we are <br />interested in here). At the other end of the spectrum, protection from accepting an actual `weed <br />TR -65 51 Revised 9/09 <br />