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

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A research study aimed at assessing the role of fourwing saltbush (Atriplex canescens ssp. aptera) as a "pioneer" plant to enhance the later establishment of big sagebrush and to evaluate the role of this plant in excluding big sagebrush when seeded at rates in excess of 2.2 kg PLS ha' was reported by Schuman and Booth (1998). Grass competition was not evaluated in this study; hence, the only herbaceous plant competition that existed was from plants that became established naturally through the topsoil seedbank or other means of recruitment. The entire study area had a stubble mulch. They found that fourwing saltbush neither improved nor restricted sagebrush establishment; however, they did report greater total shrub densities where fourwing saltbush was over - seeded a year later with big sagebrush. Big sagebrush represented 42% of the shrub density and the seeding strategy produced about 10,000 more total shrub seedlings per hectare than other seeding strategies. Gores (1995), Booth et al. (1999), and Olson et al. (2000) also reported that shrub densities were greater when more than one shrub species is included in the reclamation seed mixture. Schuman et al. (1998) and Schuman and Booth (1998) showed that big sagebrush seed maintains its viability for much longer than thought (Young and Evans 1989) because new seedlings were noted 3 -5 years after the initial seeding of big sagebrush in the research they reported. Wyoming big sagebrush has been shown to have some seed dormancy (McDonough and Harniss 1974, Booth et al. 1997); therefore, Schuman et al. (1998) and Schuman and Booth (1998) believe that continued germination and establishment of big sagebrush for several years was related to seed dormancy, the continual development of "safe sites" for seed germination and establishment (Harper 1977) and improved climatic conditions (precipitation and temperature) in subsequent years. Research has also shown that seeding a mixture of shrub species also results in greater overall density, species diversity, and structural diversity than is achieved by a single shrub species (Gores 1995, Booth et al. 1999 and Olson et al. 2000). Gores (1995) and Olson et al. (2000) also reported that sites seeded to several shrub species resulted in higher diversity indices of reclaimed sites compared to those where only fourwing saltbush was seeded (Figure 3). Greater species and structural diversity greatly enhance wildlife habitat quality. Conclusions /Summary Research reviewed in this paper has answered many questions related to establishment of Wyoming big sagebrush on mined lands; however, not all of the issues /concerns have been fully addressed. Current research is assessing the effects of sagebrush seeding rates and multiple levels of grass competition on sagebrush establishment should further aid in defining and developing a big sagebrush establishment technology. The fact that big sagebrush has exhibited some seed dormancy and has been shown to retain seed viability for several years after being seeded greatly increases the probability of a good "precipitation and temperature year" occurring while the seed is still viable. This fact alone may make it desirable to seed big sagebrush at a higher rate than previously recommended to ensure an adequate seed bank for germination and establishment over several years. Even though big sagebrush seed is relatively expensive, this cost would be much lower than having to mobilize equipment and a contractor a second year to ensure adequate and desired sagebrush densities are achieved.