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Mean reference area species density (no. of species per 10D sq.mJ -1.15 s <br />The standard would be based on a weighted average as done with cover antl production. <br />In words, the selected standard is the midpoint (in terms of probability distribution) of the lower <br />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 D) below). <br />Noxious weeds are omitted. The point of addressing total species density, including <br />annual/biennial species and introduced species, is that the total species density is arguably a <br />strong indication of the existence of niche spaces that wuld eventually be occupied by the native <br />fort and woody plant species typipl of the pre-mining plant communities. <br />The final step for this assessment will be comparison of the mean total species density of the <br />BRB to the reference area-derived standard number (above). If the reclaimed area mean <br />exceeds the standard, the Test B is passed. If the BRB mean is less than the standard, a <br />hypothesis test will be undertaken. This would be accomplished using the expression set forth <br />above for aone-sample t-test comparing the reclaimed area species density mean. <br />Alternative Test C): Assessment of the Distribution of Species DensityAmong Lifeforms <br />in Comparison to the Reference Areas <br />This test relates to the distribution of the presence of species among the various lifefonns in <br />comparison to the reference areas. This standard will use the Motyka similarity index to assess <br />the resemblance of the distribution of species density by lifeforrn of the reGamation vegetation to <br />that of the reference areas. Because the average internal resemblance (i.e. between-sample <br />similarity) of applicable reference areas for species density data is often in the range of 70%, the <br />proposed standard is 63°,6 (0,9 x 70°k). (For this calculation, data from the extended reference <br />areas (Sagebrush, Mountain Brush, and Aspen) from the nearby Seneca II-W Mine were <br />examined. The Seneca II-W extended reference areas extend across sections of landscape <br />more comparable in dimension to the BRB areas than are the comparatively small Seneca II <br />reference areas. Thus, they are thought to be more indicative of pre-mining inter-stand <br />community diversity). <br />The Motyka similarity index will be used as follows: <br /> <br />• 10 <br />