Effects of Wyoming Big Sagebrush Seeding Rate and Grass Competition on Long-Term Density and Canopy Volume of Big Sagebrush and Wildlife Habitat

Abstract

This research was initiated in 1997 to evaluate the effects of seeding rates of grass and Wyoming big sagebrush on the establishment of big sagebrush. The research was accomplished at the Belle Ayr West mine, south of Gillette, WY using a randomized complete block with three big sagebrush seeding rates (1, 2, and 4 kg PLS /ha) and seven grass seeding rates (0, 2, 4, 6, 8, 10, and 14 kg PLS /ha ) experimental design. Field data were collected from 1997-2004 and re- sampled in 2010 to evaluate the long-term effects of these seeding rate treatments on big sagebrush density and plant canopy volume. Wyoming big sagebrush average density decreased by 25-33 % from 2004 to 2010 but the density remained above the 1 plant/m 2 level required by regulatory standards. Wyoming big sagebrush average canopy volume in 2010 (per plant) was 15 times greater than observed in 2004. Shrub density, cover, and height met or exceeded the levels recommended for sage grouse and antelope habitat, two primary users of these lands that are a concern to wildlife management agencies and mine regulatory agencies in WY. General sage grouse requirements are 1.5 plants/m 2 , a shrub height of 18 to 26.6 cm, and shrub cover of 5.5 %. General antelope shrub height requirements are 22 to 46 cm, and cover requirements are 5 to 30 %. This emphasizes the importance of grass and sagebrush seeding rates necessary to achieve these desire goals.