Is pile seeding Wyoming big sagebrush(Artemisia tridentata subsp. wyomingensis) an effective alternative to broadcast seeding?

Authors: Boyd, Chad; OBRADOVICH, MATTHEW - Bureau Of Land Management

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/11/2014
Publication Date: 5/1/2014
Publication URL: http://handle.nal.usda.gov/10113/59318
Citation: Boyd, C.S., Obradovich, M. 2014. Is pile seeding Wyoming big sagebrush(Artemisia tridentata subsp. wyomingensis) an effective alternative to broadcast seeding?. Rangeland Ecology and Management. 67(3):292-297. DOI: 10.2111/REM-D-13-00107.1.

Interpretive Summary: Sagebrush plays an important role in maintenance of ecological function for sagebrush plant communities and provides critical habitat to a number of sagebrush obligate wildlife species, but restoring sagebrush on depleted areas has proven difficult with conventional techniques. Our objective was to evaluate “pile seeding” (placing mature seed heads on the ground) of Wyoming big sagebrush as an alternative to traditional broadcast seeding. Our results indicate that in the year following seeding, seedling density was up to 60-fold higher in pile-seeded plots compared to non-seeded and broadcast plots, however, extremely high seedling mortality over a 2 – 3 year period largely negated treatment differences. This research suggests that pile seeding is limited by high mortality following seedling emergence, however, the initially high seedling density relative to broadcast treatment suggests that pile seeding may offer advantages to other direct seedling methods such as broadcast seeding.

Technical Abstract: Sagebrush plays an important role in the ecological functions of sagebrush steppe plant communities and is a necessary component of habitat for a variety of wildlife including sage-grouse. At lower elevations, increased fire frequency associated with exotic annual grass invasion has heightened the need for effective sagebrush restoration strategies, but existing techniques have been largely ineffective. Our objective was to evaluate “pile seeding” (placing mature seed heads on the ground) of Wyoming big sagebrush as an alternative to broadcast seeding. We used a randomized block design (n = 5) replicated in two years and at two contrasting ecological sites in southeast Oregon. Treatments applied to 100 x 1.5 m plots included: 1) pile seeding (four mature seed heads•pile-1 x 10 piles•plot-1), 2) broadcast seeding (0.5 kg PLS•ha-1), and 3) non-seeded control. Planting occurred in fall 2008 and 2009, and plots were monitored for seedling establishment for three or two growing seasons post-planting. Seedling density was estimated at the plot scale, and within a 50 cm radius of each seed head pile (“pile scale”). In the year following planting, sagebrush seedling density at the plot scale was up to 60-fold higher (P < 0.05) in pile-seeded plots compared to control and broadcast plots. Seedling mortality was high (up to 98% reduction in density) for pile-seeded plots between the first and second growing seasons post-planting and differences between broadcast and pile-seeded plots had dissipated by 2– 3 years post-planting. While pile-seeding had higher initial density than broadcast seeding, neither technique had sufficient multi-year survival to suggest restoration efficacy at the plot scale. Seedling density at the pile scale suggests that pile-seeding may be useful for establishing sagebrush islands, depending on year conditions.