II. Aster vialis Bradshaw (wayside aster)
Area of Application: Throughout the area covered by the Northwest Forest Plan.
A. Introduction
Aster vialis is classified as a Survey and Manage Strategy 1 and 2 species under the FSEIS/ROD (USDA Forest Service and USDI Bureau of Land Management 1994). A. vialis is also considered to be endangered and threatened throughout its range (List 1) by the Oregon Natural Heritage Program (1998), and is listed as a State Threatened species, as per OAR 603-Division 73. Additionally, A. vialis is considered Bureau Sensitive under a Draft BLM Special Status Plant Policy. These designations for A. vialis reflect concern that a threshold to maintain viable populations may have been passed because of highly fragmented populations, fire suppression, and plantation forestry.
B. Unique Characteristics, Biology, and Ecology
The following is a technical description of Aster vialis:
Perennial (many-stemmed) from a stout caudex (or creeping rhizomes and stems scattered), mostly 6-12 dm tall; lowermost leaves reduced and scale-like, the others numerous and nearly alike, gradually reduced toward the inflorescence, elliptic or broadly lanceolate, sessile, entire or with a few irregular teeth, 5-9 cm long, 1.5-3 cm wide, glabrous or nearly so above, glandular beneath; heads several or many in a leafy-bracteate inflorescence, turbinate, the disk 1-1.5 cm wide; involucre 8-10 mm high, the bracts well imbricate, sharp-pointed, with a strong mid-vein and tending to be somewhat keeled, greenish above; ray flowers wanting (disk flowers yellow); pappus commonly with a few short outer setae.
Flowering usually occurs from mid-July to September. Seed production is evident on plants, although seedling recruitment appears to be limited within populations. Studies by Kaye et al. (1991) have indicated that A. vialis is an obligate outcrosser and almost completely self-sterile. Seed often appears sterile. Seed dispersal is accomplished by wind transport. Studies by Guerrant (1991) have indicated that mild heat treatment of the seed enhances germination. Vegetative reproduction is evident within some populations.
Frequent fire intervals (approximately 5-25 years) are thought to be critical in maintaining habitat for Aster vialis, in that it creates patch openings and maintains an open forest canopy structure. Disease and small scale disturbances (e.g., windthrow) may also play a vital role in maintaining this type of habitat.
C. Specific Habitat Associations
Aster vialis is found in coniferous forests at elevations ranging from 152 m (500 ft.) to 960 m (3150 ft.). Typically the species occurs on relatively dry upland sites dominated by Pseudotsuga menziesii (Douglas-fir). Associated hardwoods include Arbutus menziesii (Pacific madrone), Chrysolepsis chrysophylla (golden chinquapin), and Quercus garryana (Oregon white oak). Aster vialis is most commonly found in canopy gaps and in forest edge environments. Current populations of A. vialis occur in sites representative of all stages of secondary succession, ranging from clearcuts to mature or second growth forest. In descending order of occurrence, these sites are found within road corridors, in mature or second growth Douglas-fir/Grand fir forests with canopy gaps, on edges where forest and meadow meet, and in clearcuts.
D. Range of Aster vialis
1. Known Range
Aster vialis occurs within the State of Oregon in Linn, Lane, and Douglas Counties. In these counties, the species is found primarily in the Willamette Valley Physiographic Province as described by Franklin and Dryness (1973). A few sites occur on the eastern perimeter of the Coast Range Physiographic Province along valley margins. Because of the species' narrow distribution it is generally considered a Willamette Valley endemic (Gammon 1986). It is found on lands managed or owned by the City of Eugene, Lane County, private, and federal agencies. On federal lands it is located on Bureau of Land Management (BLM) lands in the Eugene and Roseburg Districts, and one site is located on Army Corps of Engineers land at the Cottage Grove Reservoir. On BLM land there are 30 known sites. In some cases, several "sites" may constitute one population. Approximately 24 other sites have been located on city, county, and private lands.
2. Suspected Range
Potential habitat for Aster vialis may occur on the Willamette and Umpqua National Forests.
E. Timing of Surveys
Surveys should be conducted during the flowering or fruiting period (mid-July through September) when plants are most easily seen and identifiable.
F. Threats
Management Recommendations (Wogen 1998) identified the major threats to A. vialis as follows:
- Fire Suppression and Forest Succession
- Forest Management Activities
- Exotic Weed Invasion
- Habitat Fragmentation/Inbreeding Depression
- Roadside Maintenance, Road Use, and Recreation
- Wildlife Forage
- Predispersal Seed Predation
REFERENCES
Franklin, J. F. and C. T. Dryness. 1973. Natural Vegetation of Oregon and Washington. Pacific Northwest Forest and Range Experiment Station, U.S. Department of Agriculture Forest Service, General Technical Report PNW-8, Portland, OR
Gammon, J. 1986. Unpublished Draft Status Report. Oregon Natural Heritage Database, Portland, Oregon.
Guerrant, E. O. 1991. Effects of Heat on Germination of Aster vialis Seeds. Final Report Submitted to the BLM by the Berry Botanic Garden. Portland, Oregon.
Kaye, T., K. Kuykendall, W. Messinger. 1991. Aster vialis Inventory, Monitoring, and Pollination Biology. Final Report Submitted to the BLM by the Oregon Department of Agriculture. October 1990.
Oregon Natural Heritage Program. 1998. Rare, Threatened and Endangered Species of Oregon. Oregon Natural Heritage Program, Portland, Oregon. 92 pp.
USDA Forest Service and USDI Bureau of Land Management. 1994a. Final supplemental environmental impact statement on managing of habitat for late successional and old-growth species within the range of the northern spotted owl. Portland, Oregon.
Wogen, N. S. 1998. Management Recommendations for wayside aster (Aster vialis Bradshaw). Unpublished manuscript
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