2008-05-13_REVISION - C1981008 (5)

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New Horizon Mine: 2007 Vegetation Sampling for Phase 2 Bond Release • t~s= n~ ~ (~}° where: n, =minimum sample size s= =Sample variance (n-1 degrees of freedom) d =.Precision (0.10`for. cover and production; 0.15 for woody plant density) x = Sample arithmetic mean t = 'fhe (u=.10) t-table value fora 1 tail t-test, n-1 degrces of freedom (infinite degrees of freedom may be used if n> 30) n =Sample size Mean values for cover and production were calculated for each study area. Mean values for each post mine land use type were compared to the standard (respective reference area means) according to the general procedures described above in section 1. Because different statistical tests were used for different comparisons, statistical tests are described below in section 3, Results. 3.0 RESULTS: IRRIGATED PASTURE 3.1 Irrigated Pasture Reference Area • On field inspection of the reference area with Dan Mathews of CDRMS, it was agreed that a portion of the pasture in the southwest corner had been disturbed by livestock winter feeding, and should be excluded from the reference area. We avoided sampling in that area, and figure 3 shows the approximate location of the excluded area. Cover measurements for each transect and summary statistics are shown in Table Al (Appendix A). Fifteen cover transects were completed, and sample adequacy was not demonstrated because of the relatively high variance of the sample mean caused by the somewhat uneven distribution of desirable vegetation in the pasture. For the statistical procedures that ultimately were selected based on the nature of the collected data, a minimum of 30 samples was required. However, this was not apparent at the time of sampling, and only 15 cover samples were obtained. Production data and summary statistics are sown in Table A7. Forty-four plots were sampled without reaching sample adequacy, again due to the somewhat uneven production in the pasture. 3.2 Irrigated Pasture Phase 2 Bond Release Area Cover measurements for each transect and summary statistics are shown in Table A2. Fifteen samples were taken, and sample adequacy was demonstrated. Although not necessary to demonstrate adequacy for Phase 2 bond release, we measured production in the Phase 2 bond release area, and compared cover and production in the reclaimed area to values in the irrigated pasture reference area, to determine the likelihood that • current Phase 2-elegible reclaimed lands would meet Phase 3 revegetation requirements in the BIO-Logic Environmental 8 November 12, 2007