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• 2.0 METHODS <br />This addendum employed the same methods of evaluating revegetation success that the <br />2002 investigation employed (Savage and Savage, 2002a). This evaluation of the 2002- <br />2004 sampling data accepted the conclusion reached in the 2002 investigation that for the <br />purposes of developing predictive models, total vegetation cover and total herbaceous <br />production of both the Osgood Sand Reference Area and reclamation azeas were best <br />predicted by a precipitation regime (summation of total precipitation accruing during that <br />timeframe) that extended from September of one year to the following July. Based on the <br />precipitation record, the month of August did not significantly contribute to growth in <br />either cool season or warm season plant species in the area. <br />In supplementing the data set of the 2002 investigation the cumulative precipitation <br />amount from the September-July precipitation regime was regressed against total <br />vegetation cover and total herbaceous production in the azeas sampled. For developing <br />the best-fit curves for the reclamation azeas, the average of the means from the three years <br />was used to generate the curve (or curves) with the highest level of correlation. <br />While a continuous sampling record of the Osgood Sand Reference Area has occurred <br />since 1994, sampling of the reclamation azeas has changed over time with subsequent <br />Phase I and II liabihty release of some areas and the addition of other revegetated pazcels. <br />For the purposes of this addendum, the Osgood Sand Reference Area data from 2002 to <br />• 2004 were evaluated as was data from the same time period for the 1995, 1997, and 1998 <br />reclamation areas. <br />For a complete discussion of the methods employed to develop predictive mathematical <br />regression equations, the 2002 investigation is referenced. <br />3.0 RESULTS <br />3.1 2002 RESULTS <br />In the case of total vegetation cover at both the Osgood Sand Reference Area and the <br />1985, 1486, and 1987 Reclamation Areas (from 1994-1998) as depicted in Figure A35 <br />(2002) and Table Al a quadratic equation (either second or third order) yielded high levels <br />of correlation (Rz values) between 0.8446 (for the reclamation azeas) and 0.9462 for the <br />Osgood Sand Reference Area. The form of the predictive equations for both vegetation <br />communities was that of a convex quadratic equation originating with a rapid rate of <br />growth, progressing to a decreasing rate of overall increase in cover, and ending <br />asymptotically (or relatively so) at the highest levels of precipitation encountered in the <br />data set. <br />With total herbaceous production (Table Al and Figure A37 (2002)), again second and <br />is third order quadratic equations provided the greatest levels of correlation (RZ values from <br />Coors Energy Company Keenesburg Mine Page 4 <br />2005 AdAendum to Revisbn of Revegetation Success Criteria <br />