2002-07-08_GENERAL DOCUMENTS - M2002004 (3)

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INTRODUCTION Xerophytic shrubs are a significant component of rangelands throughout much of the arid/semiarid West and provide many benefits to the function and utility of rangeland ecosystems (McKell and Goodin 1973). Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) is one of the most widely distributed and adapted shrub species in Wyoming and the region (Beetle and Johnson 1982). However, its re- establishment on mined lands has generally proven difficult because of low seedling vigor, an inability to compete with herbaceous species, and altered edaphic conditions (Harniss and McDonough 1976, Young and Evans 1989, Schuman et al. 1998). Reduced levels of arbuscular mycorrhizae (AM) in the disturbed soils have also been postulated as a factor limiting the success of re- establishment of big sagebrush on disturbed lands (Call and McKell 1982, Stahl et al. 1988). Arbuscular mycorrhizae can improve the host plant's ability to extract nutrients and water from soil (Stahl et al. 1988). Indirect evidence has indicated that water availability is one of the key factors involved in big sagebrush seedling establishment success (Jones 1991). Allen (1984) reported that sagebrush is particularly dependent upon mycorrhizal symbiosis to reach full growth potential. Use of "pioneer" plants to improve soil conditions, including mycorrhizal levels, of disturbed lands for later seral species has also been postulated as a means to enhance re- establishment of big sagebrush (Booth 1985, Meyer 1990). It is evident from this brief review of the literature that much additional information was needed to enhance our understanding of big sagebrush seedbed ecology and to develop a seeding technology that would result in successful re- establishment of this species. Recent Findings Schuman and Booth (1998), Stahl et al. (1998), Schuman et al. (1998), and Booth et al. (1999) reported on recent research evaluating the effects of historic reclamation practices, soil management, mulching, competition, and arbuscular mycorrhizal on big sagebrush establishment. Schuman and Booth (1998) and Schuman et al. (1998) in a study to evaluate the effect of topsoil management (stockpiling vs direct placement), mulching (stubble, surface, stubble + surface, and no mulch), and competition ( three grass seeding rates) found that all three variables affected big sagebrush seedling establishment in an interactive manner. Sagebrush seedling densities responded differently to the treatments during the first year (1992) after seeding and the following spring than they did in the fall of 1993 and 1994 (Table 1 -3). The largest increase in sagebrush seedlings were observed between the spring 1993 and fall 1993 due to the wet and cool conditions during that period. Big sagebrush seedling densities observed in 1992 on the direct placed topsoil -no competition - mulched treatments (Table 1) exceeded the shrub density standard ( 1 shrub m adopted in Wyoming (Federal Register 1996). If we use Kriger et al. (1987) findings that 32% of the big sagebrush established the first year will survive after 11 years we still have adequate seedling densities for the stubble and surface mulch treatments to achieve this standard. This emphasizes the importance of good cultural practices in establishing big sagebrush since 1992 was a below