Effects of Wyoming big sagebrush seeding rate and grass competition on the long-term density and canopy volume of the big sagebrush and wildlife habitat

Authors: VICKLUNAD, LAUREL - Belle Ayr Mine; SCHUMAN, GERALD - Retired ARS Employee; Mortenson, Matthew

Submitted to: American Society for Surface Mining & Reclamation Annual Meeting Proceeding
Publication Type: Proceedings
Publication Acceptance Date: 2/15/2011
Publication Date: N/A
Citation: N/A

Interpretive Summary: Coal mining in the Northern Great Plains drastically disturbs the natural plant community used for grazing and wildlife habitat. Re-establishment of the plant community, especially the shrub component, can be very challenging. Seeding rate of big sagebrush and grass seeding rates were evaluated to determine the best combinations that provide good grass production and also shrub density and cover for important wildlife habitat. The study was initiated at the Belle Ayr West mine near Gillette, WY in 1997 and big sagebrush density, canopy volume, height and cover were assessed 13 years later in 2010. Grass seeding rates of 6-8 kg ha-1 and big sagebrush seeding rates of 2or 4 kg ha-1 provided big sagebrush densities, cover, and height necessary to meet reclamation standards and wildlife habitat requirements for the dominant wildlife of the region. This research provides information that can be adopted by the regulatory agencies and mining industry in the Northern Great Plains.

Technical 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 experimental design with three big sagebrush seeding rates (1, 2, 4 kg PLS ha-1) and seven grass seeding rates (0, 2, 4, 6, 8, 10 14 kg PLS ha-1 ). Field data were collected from 1997-2004 and resampled in 2010 to evaluate the long-term effects of these seeding rate treatments on big sagebrush density and plant canopy volume. Wyoming big sagebrush density decreased by 25-33% from 2004 to 2010 but the density remained above the 1 plant/m2 level required by the Wyoming Department of Environmental Quality shrub density standard. Wyoming big sagebrush canopy volume (per plant) was as much as 50 times greater than observed in 2004. When expressed on an area basis (cm3 m-2), 2010 canopy volume was about 15 times greater than measured in 2004. Grass competition did not have a significant effect on both an area basis and canopy volume in 2010, even though it continues to influence sagebrush density. This observed trend may be the result of the sagebrush developing deeper root systems and becoming less dependent on competing for shallow soil moisture compared to earlier years when the sagebrush were smaller. However, we believe it remains important to consider the effects of grass competition and shrub seeding rates to ensure desired shrub densities on reclaimed mined lands in the Western U.S. Shrub density and cover meet the guidelines for the dominant wildlife species in the region after 13 years.