Executive Director Institute for Applied Ecology, United States
Abstract: Restoration islands are strategically-located, fine-scale applications of limited resources to advance habitat restoration goals that benefit species conservation. A restoration island strategy can complement a conservation strategy based on landscape-scale threats. For example, landscape-scale threats to populations of greater sage-grouse (Centrocercus urophasianus) include invasion of annual grasses, conifer encroachment, altered fire regimes, overgrazing, and development. Yet, without forbs and forb-associated arthropods in brood rearing habitat, sage-grouse have no chance of recovery. In this case, a restoration island strategy can focus on restoring forbs in brooding areas.
Despite substantial collaborative efforts to conserve greater sage-grouse and their habitat in the intermountain west of the United States, the dramatic decline in populations over the past 50 years has yet to be arrested. The breeding population of sage-grouse in Oregon was estimated to be 15,927 in 2021, the third lowest population estimate since 1980. Forbs, perennial grasses, and forb-associated arthropods in sagebrush understories are critical for chick-rearing and reproductive success. Studies have shown that annual recruitment is directly correlated to how sagebrush understories provide these dietary and cover resources. Therefore, restoration of these understory plant communities is a high priority, as they are scarce or missing in many sage-grouse priority habitat management areas. To identify best practices for restoring islands of forbs and perennial grasses, we tested how various treatments (seeding methods, mowing, micro-irrigation, and grazing exclusion) affect restoration success in core sage-grouse habitat in Oregon. Seeding methods included broadcast, seed pellets, and enhanced seed-soil contact with a Jang seeder. Mowing reduced sagebrush height to 20 cm. Results showed that the Jang seeding method more than doubles the germination success of seeded species, and that mowing and micro-irrigation increase the cover of perennial forbs. Results from our study can inform forb island restoration in core sage-grouse habitat and contribute to species recovery.
