Evaluating winter/spring seeding of a native perennial bunchgrass in the sagebrush steppe

Authors: Boyd, Chad; Lemos, Jarod

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/13/2015
Publication Date: 11/1/2015
Publication URL: http://handle.nal.usda.gov/10113/62977
Citation: Boyd, C.S., Lemos, J.A. 2015. Evaluating winter/spring seeding of a native perennial bunchgrass in the sagebrush steppe. Rangeland Ecology and Management. 68(6):494-500. doi: 10.1016/j.rama.2015.07.009.

Interpretive Summary: Post-fire restoration of native perennial grasses is key to preventing invasion of exotic annual grasses in low to mid elevation sagebrush steppe plant communities, but traditional fall seeding has met with only limited success. We evaluated the feasibility of winter/spring seeding of bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Love) as an alternative to fall seeding over a three year period by planting seeds in fall, or weekly from late February through early May in 1m2 plots using a randomized block design with 5 replications. We found that seed germination and seedling emergence were correlated strongly with seasonal precipitation, regardless of timing of planting, and that winter/spring-planted seedlings had higher survival to the end of the first growing season relative to fall planting. Our results indicate that winter/spring seeding of bluebunch wheatgrass is practical in years approaching average precipitation, but additional research is needed to determine environmental factors driving within-year variation in demographics winter/spring planted seeds.

Technical Abstract: Sagebrush (Artemisia tridentata Nutt.) plant communities in the US Great Basin region are being severely impacted by increasingly frequent wildfires in association with the expansion of exotic annual grasses. Maintenance of native perennial bunchgrasses is key to controlling annual grass expansion, but post-fire restoration of these species has proven difficult with traditional fall drill-seeding. We investigated the potential for winter/spring seeding bluebunch wheatgrass (Pseudoroegneria spicata [Pursh] A. Love) in southeast Oregon. In 2011 – 2013 seeds were planted in fall, or weekly from March through early May in 1m2 plots using a randomized block design with 5 replications. Germination was estimated using a buried bag technique and emergent seedlings were counted and marked weekly from March – June. Germination and emergence varied strongly between years and by within-year timing of planting. With “average” precipitation percent germination was high (up to 100%) regardless of timing of planting and emergence density decreased (p < 0.05) with advancing winter/spring planting date in drier years. Emergence density was high (approaching 300 plants/m2) with adequate precipitation but varied strongly across planting weeks for winter/spring plantings. Percent survival of emergent seedlings to harvest (July) was approximately 25 – 50% lower (p < 0.05) for fall-planted seeds in all years; survival of winter/spring seedlings was 80 – 100% with no discernable pattern between weeks of planting. Our results indicate that winter/spring seeding of perennial bunchgrasses is practical in years approaching average precipitation. Additional research is needed to determine environmental factors driving within-year variation in demographics for winter/spring planted seeds.