PERMFILE67186

• Permit No: C1981028
• IBM Index Class Name: Permit File
• Doc Date: 6/15/2006
• Doc Name: Revegetation Success Criteria
• Section_Exhibit Name: Appendix TR-37
• Media Type: D
• Archive: No

• curves. The polynomial inflection point was more pronounced at the highest levels of
precipitation (particulazly in 2003), revealing a decrease in projected total vegetation
cover at the highest levels of precipitation. Though a shght decrease in correlation
coefficients occurred between 2002 and 2004 over the data set, the variance explained by
the best-fit equations was very high. With the exception of the apparent inflection point at
the highest levels of precipitation, the best-fit predictive equations remain competent
estimators of the observed vegetation cover at the reference area.
4.1.2 Total Herbaceous Production
As was the case with total vegetation cover, no significant change in the overall shape of
the best-fit curves took place with the addition of the 2002 through 2004 data. With the
addition of the data, the inflection area observable in the mid ranges of precipitation was
smoothed from the best-fit curve obtained from the data set in the 2002 investigation.
Correlation coefficients decreased between 2002 and 2004, though the lowest correlation
coefficient explained neazly 80 percent of the variation in the data. With the inflection
point in the center of the x data range smoothed with the addition of the 2002-2004 data,
best-fit curves for estimating total herbaceous production at the reference area better
reflect observed conditions in the field. The overall decrease in the correlation coefficients
in this investigation from those in the 2002 investigation renders the newer best-fit
equations slightly less useful than that from the 2002 investigation. The level of
correlation for the entire data set remains significantly high for biologic data.
• 4.1.3 Species Composition
There was no change in the number of important species (those comprising three or more
percent relative cover) in the Osgood Sand Reference Area with the addition of the 2002-
2004 data. Important species included one woody shrub, three warm season grasses, and
one cool season grass. The annual introduced weedy cheatgrass continues to increase in
importance, and for the first time since 1994, sand bluestem was not encountered in the
cover sampling in 2004.
4.1.4 Conclusions: Osgood Sand Reference Area (2002-2004 data)
Overall, the addition of 2002-2004 total vegetation cover data did not increase the
correlation or improve the predictive ability of the best-fit curves or equations developed
in the 2002 investigation. The addition of 2002-2004 data in the case of total herbaceous
production had the same overall effect as that of total vegetation cover; there was no
significant change in best-fit curve shape, but an overall decrease in the amount of
variance predicted by the best-fit curves and equations. It was concluded that the addition
of the 2002-2004 data did not improve the predictive ability of the equations developed in
the 2002 investigation.
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Cooro Energy Company Keenesburg Mine Page 8
2005 Addendum to Revision of Revegetatbn 5uccese Criteria