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• The lower 1989 average vegetation cover reflected a change of 24 percentage points from <br />the vegetation cover measured in 1987. The change in cover from 1987 to 1989 for the <br />Sagebrush Reference Ares' was nearly the same as the reclaimed areas at approximately <br />25 percentage points. In 1990, the overall average recovered by about 12 percent, while <br />the Sagebrush Reference Area recovered by 9 percent. On the other hand, the Mountain <br />Brush Reference Area only dropped 9.7 percentage points from 1987 to 1989, but <br />continued to drop another 2 percentage points in 1990. Closer examination of the cover <br />data from the Mountain Brush Reference area show that this net drop of 2 percent in 1990 <br />was comprised of a decrease of nearly 11 percent in woody cover along with an increase <br />of nearly 9 percent in herbaceous cover. <br />The reclaimed areas are dominated by herbaceous species and the Sagebrush Reference <br />Area also has a heavy herbaceous component. It is speculated that the herbaceous <br />species are more quickly responsive to changes in climatic conditions than are shrubs, <br />especially the tall shrubs that dominate cover in the mountain brush community, perhaps <br />because these woody species generally root more deeply and may have greater <br />carbohydrate reserves. In addition, the atypically mesic conditions of the Mountain Brush <br />Reference Area may further buffer cover values in this area from the effects of drought. <br />Nonetheless, the effects of drought may finally have shown themselves in the decrease of <br />woody cover of the Mountain Brush Reference Area coincident with an increase of <br />herbaceous cover during a year of apparent slight amelioration of drought conditions. <br />The lag effect apparent in the woody cover of the Mountain Brush Reference Area may <br />lead to a lack of proportional response to climatic conditions of a given year, thus <br />compromising one of the basic assumptions regarding reference areas, and certainly <br />questioning the use of areas dominated by woody vegetation to set annual standards for <br />primarily herbaceous reclaimed areas. <br />Production <br />Only the herbaceous component was sampled for annual production in both the reclaimed <br />and reference areas. Because the reference areas are both dominated by woody plants, <br />the herbaceous component of production is small and is greatly exceeded by the <br />production of the reclaimed areas where woody plants comprise only a small amount of <br />total vegetation composition (Figure 21. Whether or not the large annual production of the <br />reclaimed areas equals or exceeds the total (woody plus herbaceous 1 annual production of <br />• the reference areas is unknown. <br />13 <br />