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• assessing revegetation success should be discounted. Further, the older reclamation azeas <br />realistically present a representation of the herbaceous graminoid dominated prairie <br />community that will develop over time in the reclaimed azeas. <br />For these reasons, it is proposed that the equation y = (-)0.4478xT + I4.llx - 63.217, <br />where x is the value of the cumulative September-July precipitation at the mine and y is <br />the value of the total vegetation cover be used as a predictive equation to determine <br />revegetation success at the Keenesburg l~fine site. As with any revegetation success <br />criteria, revegetation success for this pazameter would be deemed demonstrated if the total <br />vegetation cover of the azea to be tested is greater than 90 percent of the predicted value <br />with 90 percent statistical confidence. <br />4.2 Total Herbaceous Production <br />Figures 36 and 37 provide a comparison of total herbaceous production and both <br />precipitation regimes for the Osgood sand reference area and the 1985, 1986, and 1987 <br />reclamation azeas. Both figures reflect the best-fit curve for the reference azea and the <br />second order polynomial for the reclamation azeas (second order curves for the reference <br />azea revealed inflection points in the middle of the data range, defying empirical <br />observations). All curves reflect the expected overall increase in total herbaceous <br />production with increasing precipitation, though the curves for the reference azea reflect <br />the inflection points described before. Total herbaceous production for the reference azea <br />• is generally significantly less than that for the reclamation azeas since the annual <br />production of the woody species (Artemisia filifolia) that dominates the reference azea is <br />not accounted for in sampling for this pazameter. <br />There is no significant difference between the correlation coefficients of the two equations <br />for the older reclamation azeas. There is evidence of an inflection point in the January-July <br />plot at the lower end of the data range, whereas the September-July plot remains <br />asymptotic to the x-axis in this range. <br />For these reasons, it is proposed that the equation y = S.1676x~ - 87.19x + 464.85, where <br />xis the value of the cumulative September-July precipitation at the mine and y is the value <br />of total herbaceous production be used as a predictive equation to determine revegetation <br />success for this parameter at the Keenesburg Ivfine. As with any revegetation success <br />criteria, revegetation success for this parameter would be deemed demonstrated if the total <br />herbaceous production of the azea to be tested is greater than 90 percent of the predicted <br />value with 90 percent statistical confidence. <br />4.3 Species Composition <br />As detailed above, the current species composition success criteria is not realistic when the <br />Osgood sand reference area, from which this criterion was developed, cannot meet the <br />• criterion. Based on statistically adequate vegetation cover data taken between 1994 and <br />2001, a new species composition success criterion should be implemented. Any criterion <br />-15- <br />