Effects of Seeding Rates and Competition on Sagebrush Establishment on Mined Lands

Shrub establishment on reclaimed coal mines of the Powder River Basin in Wyoming is a vital component of reclamation. Efforts to revegetate using xerophytic shrubs have been unsuccessful due to competition for moisture, poor seedling vigor, and altered edaphic conditions. As a result, methods to re-establish Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) are needed to meet shrub density standards. This study examines effects of grass competition and sagebrush seeding rate upon establishment of big sagebrush seedlings at the Belle Ayr Coal Mine near Gillette Wyoming. Experimental plots seeded with three sagebrush rates (1, 2, and 4 PLS kg/ha) and seven rates of a grass mixture (0, 2, 4, 6, 8, 10, and 14 PLS kg/ha) were used to assess effects of sagebrush seeding rate and grass competition on seedling density and survival. Data from four sagebrush seedling counts (June 30, August 3, August 31, and October 25, 1999) show fewer sagebrush seedlings at higher grass seeding rates, although not statistically significant. Sagebrush seedling density differed among sagebrush seeding rates. On all four sampling dates, sagebrush seedling density was greater for the 4 kg/ha sagebrush seeding rate than the 2 and 1 kg/ha rates. Mean seedling counts on June 30 differed among all three sagebrush rates whereas on August 3, 31, and October 25 the 2 and 1 kg/ha rates had similar seedling densities. Sagebrush seedling density and grass and forb production determined in 2000 will provide us with further information about treatment effects on sagebrush seedling establishment and survival. We anticipate that this study and other recent research on the effects of other cultural practices on sagebrush establishment will enable proposal of a seeding strategy for Wyoming big sagebrush