Abronia umbellata var. breviflora on the Oregon coast: Reintroduction and population monitoring
Pink sand-verbena (Abronia umbellata var. breviflora) is listed by the Oregon Department of Agriculture as endangered, and a Species of Concern by the U.S. Fish and Wildlife Service. Since the
Pink sand-verbena (Abronia umbellata var. breviflora) is listed by the Oregon Department of Agriculture as endangered, and a Species of Concern by the U.S. Fish and Wildlife Service. Since the late 1970’s, the number of natural populations in Oregon has dwindled from around ten down to about five. The primary threats to the species include competition from European beachgrass (Ammophila arenaria) and habitat disturbance by off road vehicles. This report summarizes pink sand-verbena research along the Oregon coast since 1997, including seeding and transplantation experiments and population monitoring at several beach and dune habitats. In 2012 plant measurements were taken on randomly selected plants at all Forest Service and BLM sites. Substrate samples were collected at each site monitored in 2012.
In 2012, our actions and observations included:
- USDA Forest Service, Siuslaw National Forest sites
- Tahkenitch: 100,00 seeds were distributed at Tahkenitch in 2012, resulting in 381 plants (135 reproductive). This was the second seeding at the site since 2005.
- Siltcoos Creek: 50,000 seeds were distributed, resulting in 605 plants (135 reproductive), the second highest number of plants ever recorded at the site. Plants at this site were among the most robust observed in 2011 surveys, this was not so in 2012.
- Overlook: This population is now one of the largest in Oregon and we strongly recommend continued beachgrass removal and seed addition. North Overlook had double the number of reproductive and vegetative plants recorded in 2011and South Overlook remained stable.i. North: 60,000 seeds were distributed, resulting in 4,860 plants (1,627 reproductive)ii. South: 60,000 seeds were distributed resulting in 2,247 plants (628 reproductive).
- USDI Bureau of Land Management, Coos Bay District sites
- New River: In 2012, 120,000 seeds were distributed, resulting in 66 plants (26 reproductive). This represents a significant decrease from previous years. Most plants were found in areas where breaks in the foredune had allowed overwash to occur highlighting the affinity of pink sand-verbena to continued disturbance (and possibly nutrient input). Continued seeding at the site should augment the existing seed bank.
- Coos Bay North Spit: 100,000 seeds were distributed. Monitoring of the area was divided into three sub-sections and the entire population was subsampled. Only reproductive plants were counted and the estimated population size is 346,658 reproductive plants, a nearly twofold increase from 2011.
3. Elk River (private land managed by the USFWS)
1. Elk River: 100,000 seeds were distributed resulting in 556 plants (384 reproductive).
- Additional sites
- Bandon Beach (restoration area approximately 2 miles south of China Creek): In2012, 100,000 seeds were distributed, resulting in 161 plants (84 reproductive). Six additional plants were found area near China Creek. This area has not been seeded since 2008.
- Port Orford: This is a natural population that was augmented with seeding and transplants in 1996. In 2012 240 plants were found at the site.
- Floras Lake: This site was last seeded in 2000 and had not been monitored since 2009. In 2012 we found 67 plants (8 reproductive) indicating that a long-term seed bank is likely present at the site.