Influence of Seed Conglomeration Technology and Planting Season on Wyoming Big Sagebrush Restoration

Abstract

Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis [Beetle & A. Young] S. L. Welsh) is a species of great concern due to its massive reduction in the past century. This species is challenging to incorporate into restoration projects due to its small seed and accompanying nonseed parts, which impedes flow and broadcast distance. In addition, seeding efforts commonly fail to produce plant densities that are sufficient to meet management objectives. Seed conglomeration is a novel technique that improves seed delivery and may also enhance plant establishment. We evaluated how seed conglomeration influences Wyoming big sagebrush plant emergence and establishment, for seed sown in the fall and winter, at five sites throughout Utah and Nevada. We found that seed conglomeration improved emergence by 60% and plant establishment by 26% in comparison with untreated seed. We estimate that this improvement in seeding success reduces the cost to produce established plants by 6%, which comes on top of a 55% savings provided by the technology through decreased time and labor required to sow the seed. We also found that the influence of planting season varied by site, with a fall planting outperforming a winter planting at two sites, a winter planting outperforming a fall planting at one site, and at the other two sites planting season had no effect. This finding is somewhat contrary to traditional seeding recommendations for Wyoming big sagebrush, which suggest seeding success will be higher with a winter planting. On the basis of these research results, further evaluations are merited to continue the development and assessment of seed conglomeration technology. Research should also continue to explore how planting date influences seeding success. Overall, this research does not provide strong justification for land managers to delay planting until winter and suggests they could be planting in the fall.