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C1989074: 29=004 Vegetation Sampling Report <br />Sample adequacy was achieved for vegetation cover but not for vegetative productivity. Minimum <br />sample size is reported on Tables 2 and 3. <br />Statistical Analysis <br />Evaluation of revegetation establishment and success was accomplished through a comparison of the <br />reclaimed azea mean and the approved permit revegetation success standazds, permit page 2.05.4(2)(e)- <br />4. A "student's t-test" was used for the statistical comparison. This analysis is consistent with the <br />recommendations of the Colorado Division of Minerals and Geology in the April 18, 1995 Guideline <br />reQazding selected Coal Mine Bond Release Issues. The reverse null hypothesis was used for evaluation <br />of the productivity data. Plant species relative cover derived from quantitative total cover information <br />provided the basis for assessment of species composition. <br />Revegetation Success Standards: <br />Cover: 41 <br />Production: 514 ]bs/acre (air dry weight) <br />Shrub Density: 0 <br />Species Diversity: At least three perennial grass species, each contributing at least 3%, but not <br />greater than 60% relative cover. At least one of these species will be a warm <br />season grass and at least one shall be a cool season grass. <br />Results <br />Cover <br />Live vegetative cover measured during the July 2004 vegetation sampling event measured 37.73%. This <br />value is less than the revegetation standard of 41 %. The minimum number of cover samples required to <br />achieve statistical sample adequacy was 8.63. Fifteen cover transects were collected, vegetative cover <br />data achieved sample adequacy. Ninety percent of the cover standard is 36.9%. Evaluation of the cover <br />data using the student's t-test found that the cover data was greater than ninety percent of the standard <br />with a ninety percent statistical confidence. The reclamation achieved the vegetation cover success <br />standazd. <br />Production <br />Live herbaceous biomass measured 25.81 g/ one-fourth of a squaze meter quadrat. This value equals <br />103.2 g/ Mz or 931.91bs./acre. The herbaceous productivity measured on the mine site exceeded the <br />reclamation standard. Vegetative productivity data did not achieve sample adequacy. The reverse null <br />hypothesis is an acceptable tool for evaluating data that does not achieve statistical sample adequacy and <br />contains a minimum sample size of thirty samples. Evaluation of the data using the reverse null <br />hypothesis assumes that the sample mean is less than or equal to ninety percent of the standard, stated <br />as: H°: µ < Q. If evaluation of the data using the reverse null hypothesis results in rejection of the <br />hypothesis, then the reclamation is considered successful for production. <br />The sample mean (x) of the reclamation production was evaluated using the following reverse null <br />formula: <br />