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• 21, sample adequacy was achieved or nearly achieved for all cover sampling (except for 1992 <br />and PECOCO Pasture reclaimed areas), was close to being achieved for herbaceous production <br />sampling only in the Wadge Pasture, and was achieved for shrub density nowhere using one- <br />stage random sampling; high variability in shrub presence in the reclaimed areas left <br />calculated sample adequacy levels mostly astronomical. Note however that the two-stage <br />sampling of shrub density in the Wadge Pasture did achieve sample adequacy (see discussion of <br />this sampling above). <br />Noxious Weeds <br />Of plant species observed during 1996 sampling, only Canada thistle (Cirsium arvense, aka <br />Breea arvensis) is listed state-wide as a noxious weed (Thornton et al., 1974). Pennycress <br />(Thlaspi arvense) is a restricted noxious weed in Colorado (Thornton et al., 1974). <br />Pennycress is a common species in the youngest reclaimed areas, and disappears within a few <br />years. <br />Climatic Conditions <br />• Precipitation data by month from the Seneca II Mine for 1991, 1992, 1993, 1994, 1995, and <br />1996, as well as the 10-year average for the mine are shown in Figures 6a and 6b. As can be <br />seen in chase graphs, 1993 had been a relatively favorable precipitation year, but beginning in <br />November 1993 and continuing through 1994, only two months (April and November) even <br />reached average precipitation. In 1995, however, January, February, and March were close to <br />average, and April and May were far above normal (with a total of over eight inches in those two <br />months). For 1996, precipitation returned closer to normal with below average amounts in <br />March and August of 1996. <br />When examined from the standpoint of what climatic indices seemed to have correlated most <br />closely with the extremely favorable growing conditions of 1995, it would appear that the Total <br />Precipitation for the Previous 6 months (Figure 8) or the Total Precipitation for the Previous <br />4 Months (Figure 9) were better predictors than the Total Precipitation for the Previous 12 <br />Months (Figure 7). Both Figures 8 and 9 showed that 1995 was greatly superior to other years <br />and this corresponds to the extremely high levels of vegetation growth that were observed in <br />1995. 1996 shows up as somewhat less favorable (previous 6 months, Figure 8) or <br />considerably less favorable (previous 4 months, Figure 9). Based on the drop in productivity <br />• <br />31 <br />