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Large amounts of seed and regenerative root materials are present in the upper layers of topsoil, particularly in productive plant communities and fertile soils such as those found at the Seneca II Mine. Big sagebrush, a common species at the Seneca II Mine, propa- gates by seed only, but this is partially offset by the large quantities of seed produced and the relative ease with which seedlings may become established (McArthur et. al., 1979, Tisdale and Hironaka 1981). Mueggler (1956) found Thar large quantities of big sagebrush seed are residual in soils after disturbance. On the other hand, the remaining dominant shrubs (Gambel oak, mountain snowberry, Saskatoon serviceberry, and common chokecherry) reproduce both by seed and root sprouting; the latter usually being more important (Tisdale and Hironaka 1981, USDA Forest Service 1974, Vines 1976). 7taeya~~>,asewv~•is iwiper~ent-iiwnrAnr~M•regsnereiian o€ native shrubbX: species.. The time of season that topsoil is stripped and replaced will determine to some extent how much regeneration occurs. Because of the short field season at the Seneca II Mine, topsoil stripping and replacement must be maximized during late spring, summer, and early fall. During those early periods in the season when soil moisture levels are high and warming temperatures occur, root development and seed germination are stimu- lated. During The drier summer and early fall months, soil moisture levels may not be adequate and equipment handling of topsoil may actually contribute to desicating condi- tions. Several transacts in fall topsoiled areas showed lower densities and may have been partially affected by dry soil conditions. In addition to time of topsoil replacement, maximizing direct haul, and upper lift replacement of topsoil that rnntains the highest number of reproductive materials and soil microbial populations will aid in regenero- lion. Those areas that showed evidence of being upper lift topsoil also had generally higher densities of shrubs. Because of seed viability and root sprouting abilities of the various shrubs (Tisdale and Hironaka 1981), topsoil in stockpiles less than one year may retain quantities of viable reproductive materials. Shrub regeneration in the reclaimed spoil areas that were not topsoiled is quite limited and localized to those areas closest to undisturbed stands of native vegetation. Wind blown seed from stands of rubber rabbitbrush and big sagebrush is the most likely method of establishment for these two species in the graded spoils area. Even though grading and seeding of this area occurred eight to Ten years ago, very limited regeneration has occurred. Avery heavy stand of alfalfa and grass has become established which has effectively slowed the establishment of invading species. Bartolome and Heady (1978) found that sagebrush reinvasion was slowed or halted in areas that were cleared of sage- -8-