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The 1989 average vegetation cover reflected a reduction of 24 percentage points from the vegetation cover measured in 1987. The change in cover from 1987 to 1989 for the Sagebrush Reference Area was nearly the same as the reclaimed areas (approximately 25 percentage points). In 1990, the overall reclaimed area average rebounded by about 12 percent, while the Sagebrush Reference Area recovered by 9 percent. In 1991, the Sagebrush Reference Area cover increased by over 6 percent, while the reclaimed area average went up by about 5 percent. In 1992, the Sagebrush Reference Area declined by about 11 percent while the overall average dropped by about 8 percent. In 1993, the increase in cover in the reclaimed areas was accompanied by a slight increase in the Sagebrush Reference Area and a rather large jump in the Mountain Brush Reference Area. Over the period of record, there has been a clear pattern in which cover in the reclaimed areas has varied in the same direction of cover variations in the Sagebrush Reference Area. This, along with the prevalence of sagebrush and snowberry, suggests successional development of reclaimed areas toward the Sagebrush vegetation type. On the other hand, the heavy woody cover of the Mountain Brush Reference Area has shown a tendency to react with delay; reduction in cover percent during drought has been delayed, as has recovery following cessation of drought. The Mountain Brush Reference Area dropped only 9.7 • percentage points from 1987 to 1989 (during the worst of the drought), but continued to drop another 2 percentage points in 1990 (as the drought abated). In 1991, the Mountain Brush Reference Area cover increased by nearly 8 percent, and in 1992 the total cover decreased by 13 percent. The 1992 decline relates partly to the fact that the boundaries of the reference area as sampled for 1992 had been adjusted to reflect the originally identified reference area limits more correctly, and included less of the very heavy oak and serviceberry stands on the steep east-facing slopes; this is responsible for at least some of the decline in cover since experience has shown the dense overhead canopy of these species generally corresponds to higher total plant cover than any other type of vegetation in the area. In 1993, with the same sample area boundaries used in 1992, the total cover increased by 7.3 percent. As has been the case for the previous years' monitoring at the Seneca II Mine, the 1993 cover data reflect a parallel variation in the herbaceous component of vegetation cover between reclaimed and reference areas. Considering the herbaceous cover only, as would be possible under Colorado Division of Minerals and Geology (DMG) regulations, all of the reclaimed areas have cover values above an herbaceous cover standard set by either of the reference areas. i 24