Wayside Aster (Aster vialis [Bradshaw] Blake)
N. S. Wogen
TABLE OF CONTENTS
Species: Aster vialis (Bradshaw) Blake (wayside aster)
Taxonomic Group: Vascular Plants
ROD Components: 1, 2
Other Management Status: Aster vialis is considered endangered and threatened throughout its range (List 1) by the Oregon Natural Heritage Program (1995), and listed as a State Threatened species (OAR 603 - Division 73). In addition, Aster vialis is also classified as Bureau Sensitive in Oregon under a Draft Bureau of Land Management (BLM) Special Status Plant Policy. Aster vialis does not occur on the U.S. Forest Service R5 and R6 Regional Forester Sensitive Species List.
Range: Aster vialis occurs in Lane, Douglas, and Linn Counties, Oregon. The species is considered a Willamette Valley endemic (Gamon 1986) and is found primarily within the Willamette Valley Physiographic Province with a few sites found along valley margins of the eastern Coast Range Physiographic Province (Franklin and Dyrness 1973). There are approximately 24 sites on City of Eugene, Lane County, and private lands. Thirty extant sites occur on BLM Lands on the Eugene and Roseburg Districts, and 2 sites have been located on U.S. Army Corps lands. Potential habitat for Aster vialis may occur on the Willamette and Umpqua National Forests.
Specific Habitat: Aster vialis inhabits coniferous forests at elevations of approximately 152 m (500 ft.) to 960 m (3,150 ft.). The species typically occurs on dry upland sites dominated by Pseudotsuga menziesii (Douglas-fir), and is usually accompanied by hardwoods of drier forests such as Arbutus menziesii (Pacific madrone), Chrysolepsis chrysophylla (golden chinquapin), and Quercus garryana (Oregon white oak) (Alverson and Kuykendall 1989). The species also occurs on edges between forest and meadow.
While current populations of Aster vialis occur in sites representative of all stages of succession from recent clear-cuts to mature forest, the species preferred habitat is thought to have been historically sustained by frequent fire return intervals that create open forest conditions with widely spaced conifers. Particularly important to Aster vialis are gaps in the canopy where high light levels allow Aster vialis to flower (Alverson and Kuykendall 1989).
- Fire suppression leading to excessive understory brush competition, canopy closure, and reduction in suitable light levels
- Forest management activities including road construction and maintenance; plantation forestry where young stands reach canopy closure; and excessive ground disturbance where mineral soil is disturbed
- Noxious and exotic weeds in and around Aster vialis habitat, including Rubus discolor (Himalayan blackberry), Rubus laciniatus (evergreen blackberry), and Cytisus scoparius (Scot's broom)
- Habitat fragmentation and inbreeding depression
- Uncontrolled roadside maintenance such as brushing, ditching, and blading, and recreational activities that include Off Highway Vehicle (OHV) use, equestrian use, and hiking
- Browsing of flowering/nonflowering stems by black-tailed deer
- Seed predation on flowering stems
Management recommendations are to be applied to all known sites on BLM and National Forest lands and include:
- Avoid negative impacts to individual plants and adverse modification of habitat from road maintenance activities, exotic weed or competitive vegetation control, wildlife and recreation developments, and ungulate browsing.
- Create gaps and edge habitat through fine scale disturbances, open up forest canopy to 50-75 percent, and control understory competing vegetation.
- Periodically reduce duff layers in and around individuals to allow for seedling germination and establishment.
- Control noxious and exotic weeds using integrated noxious weed management techniques that do not negatively impact individual Aster vialis plants or that will not adversely modify habitat.
- Determine the genetic viability of populations and where inbreeding depression occurs, improve viability by utilizing techniques such as manual pollination.
- Conduct additional inventories for Aster vialis.
- Determine ecological and habitat requirements of Aster vialis, especially as they relate to promoting and maintaining seedling recruitment and flowering, and specifically whether 50-75 percent canopy cover is optimum.
- Determine the optimum connectivity for genetic exchange and whether inbreeding depression is occurring within populations. Determine if reductions in pollination are causing adverse impacts on the species.
- Determine how seed predation and ungulate browsing are impacting the reproductive capacity of the species.
I. NATURAL HISTORY
A. Taxonomic/Nomenclatural History
Bradshaw described the taxon in 1921 as Eucephalus vialis from his Eugene, Oregon, collection. In 1928 Blake referred to the taxon as Aster vialis. L.F. Henderson described the plant in 1933 as a new species of Sericocarpus sipei, not knowing it had previously been described. The plant was not reported between 1934 and 1980 (Gammon 1986).
The only recent alternative taxonomic treatment of the taxon was by Thompson (1977), who treated it as a variety of Aster engelmannii (A. engelmannii var. vialis) (Gammon 1986). However, since this has not been formally published, it is not a valid name and Aster vialis (Bradshaw) Blake remains the valid treatment.
It has been suggested that the entire Eucephalus species-complex in the Pacific Northwest is in need of taxonomic review. Species distinctions in the group, including Aster vialis, tend to be weak (Kaye et al. 1991).
B. Species Description (Eucephalus vialis, Bradshaw, Torreya 20: 122. 1921; Aster vialis Blake, Rhodora 30: 228. 1928; Sericocarpus sipei Henderson, Madrono 2: 105.1933; Additional descriptions of the species can be found in Hitchcock et al. 1955; Abrams 1960; and Peck 1961).
A perennial, mostly 61-122 cm (2-4 feet tall), from a stout base. The lowest leaves are small and somewhat scale-like. The leaves are largest near the middle; they get gradually smaller near and in the inflorescence. The leaves, which are attached directly to the stem without petioles, are dull green and may or may not have irregular teeth. There are several leafy flower heads, which are about 1.27 cm (.5 in.) wide (Gammon 1986).
Recent observations suggest that scattered plants may have flower heads with an occasional vestigial ray(s).
Perennial (many-stemmed) from a stout caudex (or creeping rhizomes and stems scattered) mostly 6-2 dm (23.62-47.24 in.) 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 sharp teeth, 5-9 cm (1.97-3.54 in.) long, 1.5-3 cm (.59-1.18 in.) wide, glabrous or nearly so above, glandular beneath; heads several or many in a leafy-bracteate inflorescence, turbinate, the disk 1-1.5 cm (.39-.59 in.) wide; involucre 8-10 mm (.31- .39 in.) high, the bracts well imbricate, sharp-pointed, with a strong midvein and tending to be somewhat keeled, greenish above; ray flowers wanting; (disc flowers yellow); pappus commonly with a few short outer setae (Gammon 1986).
Figure 1. Aster vialis (line drawing from Hitchcock et al. 1955)
Reprinted by Permission of the University of Washington Press
2. Reproductive Biology
Flowering usually occurs from mid-July to September. Although seed production is evident, seeds often appear sterile. Seedling recruitment appears limited to nonexistent within certain populations. Seeds are primarily wind dispersed, but many remain near the parent plant (Gammon 1986). Vegetative reproduction is common within populations making it often difficult to differentiate between individuals.
Aster vialis pollinators include Bombus vosnesenskii (bumblebees), Lasioglossum sp. (smaller bees), Epicanta puncticollis (blister beetle), and Ochlodes sylvanoides (skipper) (Alverson and Kuydendall 1989). Data from controlled pollination experiments demonstrate that Aster vialis is an obligate outcrosser and almost completely self-sterile (Kaye et al.1991). Habitat fragmentation for the species may be restricting pollen flow between populations as is evidenced by plants with apparently sterile seed. Because inbreeding depression can occur when pollen flow is restricted to a single site, maintaining as many of the known sites as possible is extremely important to the long-term viability of Aster vialis (Kuykendall 1991).
Although all germination treatments tested for Aster vialis resulted in low germination rates, studies indicate that mild heat treatments (50C/122F) enhance germination (Guerrant 1991). Additional studies are needed to determine the role of heat in breaking dormancy and whether fire or other factors influence germination and the ability to colonize new areas. Seedling germination has been reported from very few sites and, where this has occurred, individuals often do not reach maturity.
Populations of Aster vialis occur in sites representative of all stages of succession from recent clear-cuts to mature forest. Plant vigor and flower production seem to be inversely proportional to canopy coverage, i.e., the more light that reaches the plants, the greater the species vigor and flowering. It is not clear whether plants are moving into younger stands or whether they are being "released" after disturbance events. Aster vialis appears to decline as succession proceeds. This is probably due to decreased light, but may also involve competition for other requirements such as nutrients and water (Gammon 1986). Several sites for Aster vialis occur in stands where canopy closure is occurring, characterized by plants that do not produce flowers.
An important factor affecting the long-term survival of this species is the rate at which new individuals are recruited into previously unoccupied habitat. Observations suggest that because new habitats are not being created in the same way as historical habitat conditions, recruitment into new habitat is probably low. In addition, the reduction in reproductive potential through small effective population size may also contribute to limitations in colonization.
The structure, function, and composition of forests that support Aster vialis today are probably distinctly different from conditions that supported this species historically. Rather than being characterized by old-growth Pseudotsuga menziesii (Douglas-fir) forests found in the Cascade or Coast Ranges (where fire return intervals were quite long), the presettlement forest of central Lane County (where several sites of Aster vialis occur) exhibited a much more open structure due to frequent fire return intervals. Increases in tree density, due to the absence of fire over the last 140 years, suggests that there are no existing stands that resemble those that supported Aster vialis prior to settlement around 1850.
Patterns of succession in short rotation forestry do not duplicate the presettlement successional patterns that characterized the habitat of Aster vialis before the arrival of European settlers. While removal of the canopy through clear-cutting or regeneration harvest may appear to be similar to the disturbance created by fire, there are some important distinctions. First, fires often did not result in the death of all trees in the stand. Larger individuals of fire tolerant species, such as Pseudotsuga menziesii (Douglas-fir) and Pinus ponderosa (ponderosa pine), often survived fires, and thus provided some structural diversity and shade to the resulting stand. This is evident from the presence in existing stands of old trees with fire scars. Regeneration of trees was probably more patchy, or distributed over a longer time frame, and included a greater diversity of tree species compared to the results of dense planting of Pseudotsuga menziesii (Douglas-fir) in managed stands. As a result, presettlement stands were probably more diverse, in terms of species and structure, than a typical Pseudotsuga menziesii (Douglas-fir) stand. Particularly important to Aster vialis, both currently and historically, are gaps in the canopy where high light levels would allow Aster vialis to continue to flower. As fully stocked Pseudotsuga menziesii (Douglas-fir) stands mature, the canopy closes, allowing very little light to reach the forest floor, thus greatly reducing diversity and biomass of the understory vegetation. Under a frequent fire interval of every 5-25 years, the presettlement forest would not reach the stage of complete canopy closure (Alverson and Kuykendall 1989). This information is important in helping to design effective management treatments for maintaining Aster vialis habitat at known sites.
Limited observations suggest that Aster vialis seedling establishment may depend on the removal of duff layers. Historically, fire may have contributed to this function. At one site, plants were found on uprooted trees where mineral soil had been exposed. The few sites where seedling recruitment has been observed were also found on mineral soil surfaces where some duff was removed. Very few seedlings at these locations have survived to mature plants.
Evidence of seed predation has been observed in many populations. A study completed in 1989 suggested that, while many populations exhibited seed damage, plants were still able to produce viable seed. Aster vialis appears to compensate for some fruit loss by maturing additional ovules, and thus may minimize some damage from predispersal seed predators (Kaye et al. 1991). Browsing by black-tailed deer has also been observed at many populations and is thought to negatively impact the reproductive output of plants. At some sites, browsing appears variable depending on the year. Because of this fluctuating nature, it is not clear if these impacts are having long-term impacts on viability (Alverson and Kuydendall 1989).
Several populations of Aster vialis are competing with noxious and exotic weed species including Rubus discolor (Himalayan blackberry), Rubus laciniatus (evergreen blackberry), and Cytisus scoparius (Scot's broom). Known sites will be out competed by these species if not treated.
C. Range, Known Sites
Aster vialis occurs in Lane, Douglas, and Linn Counties, Oregon. It is considered a Willamette Valley endemic (Gammon 1986) and is found primarily in the Willamette Valley Physiographic Province (Franklin and Dyrness 1973) with a few sites along valley margins of the eastern Coast Range. Approximately 24 sites have been found on City of Eugene, Lane County, and private lands. On federal lands, Aster vialis is located on BLM lands on the Eugene and Roseburg Districts and 2 sites are located on U.S. Army Corps lands. As of March 1998 no sites have been located on U.S. Forest Service lands. Potential habitat for this species exists on adjacent Umpqua National Forest land. On BLM lands there are 30 extant sites. Four sites occur on Roseburg District BLM and 26 sites occur on the Eugene District BLM lands. In some cases several "sites" may constitute one, interbreeding population.
D. Habitat Characteristics and Species Abundance
Aster vialis is primarily a species of coniferous forest at elevations of 152-457 m (500-1,500 ft.). Typically the species occurs on dry, upland sites dominated by Pseudotsuga menziesii (Douglas-fir), where it is usually accompanied by hardwoods typical of drier forests, such as Arbutus menziesii (Pacific madrone), Chrysolepsis chrysophylla (golden chinquapin), and Quercus garryana (Oregon white oak). On the xeric end of the spectrum, one population occurs adjacent to grassland under a woodland of Quercus garryana (Oregon white oak) and Pseudotsuga menziesii (Douglas-fir). Anomalous habitats include a few mesic occurrences and a high elevation site at 960 m (3150 ft.) on thin soils associated with rock outcrops (Kuykendall 1989).
Many sites show evidence of fire history. Unmanaged forest stands adjacent to or within Aster vialis sites show large, old Pseudotsuga menziesii (Douglas-fir) trees with large lower limbs, indicating that trees were once open-grown. Around such trees are often younger cohorts that gradually established into stands. In some areas around and within Aster vialis sites, remnant stands of Pinus ponderosa (ponderosa pine) are still found, suggesting an environment that was probably fire-dependent. While fire is thought to be critical in maintaining Aster vialis habitat, other sites suggest that fine scale disturbances themselves or in combination with fire may also have contributed to species maintenance. Fine scale habitat features recorded for the species include gap formation from single trees falling or openings found amid rocky outcrops.
Approximately 2,300 plants occur on BLM lands. Sites range from having one plant to several hundred but, due to the plants rhizomatous nature and the difficulty in differentiating individuals, population counts are most likely inflated.
II. CURRENT SPECIES SITUATION
A. Why Species is Listed under Survey and Manage Standards and Guidelines
The viability ratings estimated a 48 percent chance that Aster vialis would stabilize with significant gaps and a 52 percent chance of being restricted to refugia with strong limitations on interactions between populations. These ratings reflect concern that a threshold may have passed due to highly fragmented populations, fire suppression, and plantation forestry beyond which long-term population viability is uncertain. The range and habitat is so fragmented that population interactions on a wide scale probably will not occur. This species requires natural, "delicate" disturbance, with the role of fire probably important to maintaining viability. Restrictive guidelines that limit use of fire and tools, which mimic natural disturbance, may be detrimental (USDA, Forest Service, and USDI, Bureau of Land Management 1994).
B. Major Habitat and Viability Considerations
The major viability considerations for Aster vialis are loss or alteration of populations due to activities that directly impact suitable habitat and individual plants. Direct impacts including recreational activities such as hiking, equestrian traffic, and trail bikes; road maintenance activities such as grading, ditching, and blading; urban and rural development; and forest management activities, including regeneration harvest and road-building, are known to have negatively impacted or extirpated individual populations. Loss of populations and fragmentation of habitat is limiting the ability of this species to outcross with other populations and is thought to be compromising the long-term viability of Aster vialis.
The greatest reduction of genetic variation in small populations results from the random fixation or loss of genes, which is called random genetic drift. Subsequent generations of mating among low numbers of related breeding individuals can result in inbreeding depression. Immigration from a large source population can retard, halt, or even reverse the loss of genetic variation, even with only one or a few migrants per generation (Wright 1931).
Natural ecological processes at Aster vialis sites, including fire and gap forming agents, have been reduced on the landscape, limiting population viability at several locations.
Deer browsing, seed predation, and possible pollinator disruption have all been documented as impacting the reproductive capacity of this species.
The introduction of noxious and exotic species into several populations is threatening populations with extirpation by competition if not actively controlled.
C. Threats to the Species
- Succession and Fire Suppression - Aster vialis occurs in areas with a historically high fire frequency due to hot, dry summers, and lightning. It is also possible that native people, prior to Euro-American settlement, used fire to maintain open land and control wildlife and vegetation. Fire suppression, since pioneer settlement, has altered much of the habitat of Aster vialis. Many of the sites for this species occur on south-facing slopes in coniferous woodlands that have become closed-canopy forests over the past 100 years. Prior to fire suppression efforts, this habitat was most likely open woodland with many forest gaps and higher light levels available on the forest floor. At this time, however, fire suppression has resulted in increased tree density and reduced light within the habitat of Aster vialis.
Studies indicate that the size and reproductive capacity of Aster vialis are negatively correlated with canopy closure (Kaye 1993), and thus fire suppression can be detrimental to the viability of Aster vialis populations. Some populations occur in closed-canopy forest stands and contain no flowering individuals and/or very low levels of new plant establishment, presumably because of limited light availability. Reintroduction of natural or prescribed fires into the habitat of Aster vialis is one tool for managing the species, although burning is likely to be difficult at populations adjacent to residential areas and private forest land. Without some reintroduction of fire, the largest populations of this species on public lands may continue to decline or may disappear over time.
Gap formation and small forest openings, not related to fire processes, are also important habitat for Aster vialis. Other gap forming agents include wind-throw from storms and tree root pathogens. These types of openings are also undergoing forest succession, resulting in canopy closure (Kaye 1995).
- Forest Management Activities - Logging activities that destroy plants or result in extensive soil disturbance are a serious threat for this species, as is logging followed by the development of dense tree plantations that rapidly lead to a closed canopy forest. Logging in the form of selective thinning and targeted tree removal can be used as a management tool if these detrimental practices are avoided. Practices such as density management techniques designed to create a pre-fire suppression forest structure would be good management actions. Some populations of Aster vialis have responded positively to logging in the first 30 years after harvest, but may show signs of decline shortly thereafter due to competition from fast-growing and aggressive weedy species, such as Rubus discolor (Himalayan blackberry) and Cytisus scoparius (Scot's broom) (Kaye 1995).
- Exotic Weed Invasion - Several of the populations of Aster vialis have a notable presence of invasive weeds either adjacent to or within them. Populations along roadsides and disturbed areas, such as skid roads and clear-cuts, are especially prone to invasion by weedy species, including Rubus discolor (Himalayan blackberry) and Rubus laciniatus (evergreen blackberry), Cytisus scoparius (Scot's broom), and smaller amounts of Dactylus glomerata (orchard grass) and Hypericum perforatum (Klamath weed). These weeds and others have the potential to dominate the vegetation of nearly all populations of Aster vialis, and they may impede efforts to successfully restore habitat of the species. Control of weedy species can substantially improve the viability of Aster vialis (Kaye 1995).
- Habitat Fragmentation/Inbreeding Depression - The Pseudotsuga menziesii (Douglas-fir) forest habitat of Aster vialis has been subject to timber harvest activities on public and private lands for several decades, which has resulted in large-scale habitat fragmentation. Urban and rural development have most likely impacted populations along valley margins. The noncontiguous pattern of existing Aster vialis habitat isolates populations from one another, thus limiting the frequency of genetic exchange between them. Aster vialis requires insects (mainly bumblebees) for pollination, so populations must be within the flight-range of a pollinator for genetic exchange to occur. This gene-flow is important for Aster vialis conservation because isolated populations are vulnerable to inbreeding depression, resulting in reduced production of viable seeds. Protection or acquisition of populations on private lands and establishment of new colonies on public lands that link protected sites may be necessary for maintaining genetically viable populations (Kaye 1995).
- Uncontrolled roadside maintenance, road use, and recreation - Potential and historical impacts from various roadside maintenance activities include mowing, spraying, brushing, ditching, blading, and snow plowing. Frequent dusting of roadside populations from traffic traveling unsurfaced roads adjacent to plant populations during critical pollination times may impact reproductive capability. Recreational activities in Aster vialis habitat that have been observed include trail bikes traveling in and adjacent to populations; equestrian use in and adjacent to populations; and trail use through Aster vialis populations to fishing areas (Kaye 1995).
- Browsing - Native wildlife, primarily black-tailed deer, browse populations of Aster vialis regularly. Browsing intensity differs from site to site and year to year, but is frequently intense, often affecting the majority of reproductive plants. Deer browsing normally results in the removal of the flowering heads, thus reducing or eliminating the reproductive potential of browsed stems. Minimizing browsing pressure could increase successful flowering and seed production. The role of ungulates in maintaining the long-term viability of this species is unknown (Kaye 1995).
- Predispersal seed predation - Seed predation has been observed on Aster vialis. While some studies have been implemented on seed predation, additional studies are needed to more clearly understand how predation affects the reproductive capacity and viability of this species (Kaye 1995).
D. Distribution Relative to Land Allocations
Of the 30 populations located on BLM lands, 28 populations occur in Matrix lands. One site on the BLM Roseburg District is located within an Adaptive Management Area (AMA) and one site on the BLM Eugene District occurs within an Area of Critical Environmental Concern (ACEC). Sites within Roseburg and Eugene BLM Districts occur within Botanical Reserve Areas, which are designed to be managed for the long-term viability of Aster vialis (USDI, Roseburg and Eugene BLM Districts, ROD/RMP 1995).
III. MANAGEMENT GOALS AND OBJECTIVES
A. Management Goals for the Taxon
The management goal for Aster vialis is to assist in maintaining species viability within the range of the northern spotted owl.
B. Specific Objectives
Reduce habitat and population fragmentation by managing Aster vialis at all known sites. Provide habitat conditions suitable for flowering and seedling recruitment, eliminate noxious and exotic weed competition, control recreation and road maintenance activities that adversely impact Aster vialis populations, reduce browsing in populations that are not reaching reproductive potential, and reduce the potential for inbreeding depression.
IV. HABITAT MANAGEMENT
A. Lessons from History
Observations of extant sites have provided some insight into effects of various past management actions on this species. Some of these observations are as follows:
- Roadside brushing at the appropriate time of year (when Aster vialis is dormant) has probably reduced competing vegetation and helped to maintain open habitat conditions, allowing some populations to persist over time. Road maintenance activities, however, have probably contributed to the spread of noxious weeds into several of these areas and may have directly impacted populations when brushed at the wrong time of year.
- Stands approximately 20-30 years old appear to exclude plants and reduce population viability.
- Stands where some thinning has occurred will support flowering individuals, but recruitment still appears to be limited.
- Stands that have been clear-cut provide additional light and induce plants to flower but, within several years, support high levels of competing vegetation, which is thought to reduce population viability.
- Reproduction has been noted where mineral soil has been exposed and duff layers removed.
- Prescribed fire can be effective in reducing competing vegetation and may be an effective tool in maintaining Aster vialis habitats as is evidenced by past fire history events at Aster vialis sites.
B. Identification of Habitat Areas for Management
Management recommendations are to be applied to all known sites occurring on Forest Service and BLM land throughout the range of the northern spotted owl.
C. Management Within Habitat Areas
1. Avoid negative impacts to individual plants and adverse modification of habitat. Specifically:
a. Avoid roadside mowing or brushing during the growing season.
b. Restrict herbicide use to target application on individual noxious weed plants.
c. Ensure control methods for competitive vegetation do not negatively impact Aster vialis.
d. Avoid ditching, trenching, blading, or plowing along roadsides where impacts to individual plants or habitat could occur.
e. Minimize browsing damage where viability is a concern through the use of exclosures.
f. Control recreation (Off Highway Vehicle use, hiking, equestrian trail use) using techniques such as gates, signs, fences, and closures.
g. Avoid wildlife and recreation developments within known sites where these actions would negatively impact individual plants or adversely modify habitat.
2. Create gap and edge habitat with a 50-75 percent canopy cover using techniques such as prescribed fire, tree girdling (or other types of snag creation), tree falling, and selective tree harvest in populations that are in poor condition or have a decreasing trend. Consider factors such as aspect, slope, and adjacent stand structure to determine the size of the treatment area (Chen et al. 1995). Where increased light from the above prescriptions has led to high levels of competing understory vegetation, implement control measures such as prescribed fire, which produce conditions that allow for recruitment. Emphasis should be on fine scale disturbances. Avoid direct impact to plants during implementation of management activities. Monitor to evaluate effects of treatments (see Section IV, Research, Inventory, and Monitoring Needs).
Avoid timber management activities such as regeneration harvests and salvage logging in any known site that would result in the creation of habitat conditions outside of this prescription.
3. To facilitate germination periodically reduce duff layers through the use of such tools as prescribed burning. Monitor to evaluate effects of treatments (see Section IV, Research, Inventory, and Monitoring Needs).
4. Control noxious and exotic weeds using integrated noxious weed management techniques that do not negatively impact individual Aster vialis plants or that will not adversely modify habitat.
5. Determine the genetic viability of populations and where inbreeding depression occurs, improve viability by utilizing techniques such as manual pollination.
D. Other Management Issues and Considerations
Where possible from willing landowners, pursue acquisitions through land exchange or purchase populations of Aster vialis that occur on private lands. Where acquisition is not possible, conservation easements may be suggested to provide for population viability. Priority should be given to populations that are split between federal and private lands and to other populations that may serve as critical genetic links.
V. RESEARCH, INVENTORY, AND MONITORING NEEDS
The objective of this section is to identify opportunities for additional information which could contribute to more effective species management. The content of this section has not been prioritized or reviewed as to how important the particular items are for species management. While the inventory, research, and monitoring identified below are not required, these recommendations should be addressed by a regional coordinating body at the Northwest Forest Plan level.
A. Data Gaps and Information Needs
Conduct surveys to locate populations of Aster vialis in areas identified as potential suitable habitat. Prioritize surveys in areas where management treatments or projects are scheduled or proposed. Potential suitable habitat is identified as all seral stages from clear-cuts and meadows to old-growth forests along valley margins from 152-953 m (500-3,150 ft.) within the Willamette Valley Physiographic Province and the eastern edges of the Coast Range Physiographic Province (Franklin and Dyrness 1973) in Lane, Douglas, and Linn counties. Drier forest types should be given priority.
B. Research Questions
The following are suggested research topics needed to better understand how to manage this species:
- How do you achieve long-term viability for Aster vialis, and will it occur under these Management Recommendations?
- What are optimum habitat conditions for this species, and how can they best be maintained; what management prescriptions are appropriate for this species; what are the specific light requirements for this species and is 50-75 percent canopy cover optimum?
- What constitutes a "safe site" for seedling establishment for Aster vialis and why is germination low for this species? Is duff removal necessary (if so how often and to what depths), and does removal have deleterious effects on nutrient cycling?
- Can estimation of the level and pattern of genetic variation using isozyme analysis of Aster vialis be used to evaluate whether inbreeding depression due to random fixation or loss of genes is occurring?
- Are forest stands managed to exhibit prefire suppression forest structure and composition able to maintain and recover Aster vialis; what was the historic fire history for this species?
- Is fire the best tool for managing populations and, if so, what should the frequency, duration, and intensity of fire be in managed stands; are there other techniques that can be utilized to maintain this species?
- What are the factors leading to high seed predation, and how can these be mitigated for?
- Are there other limiting factors for this species such as soils, nutrients, etc.?
- What is the role of ungulates in this system, and how is it impacting plant populations?
- What are the patterns of pollination, and are pollinators secure?
- What is the dispersal capability of this species?
- What is the taxonomic status of this species?
C. Monitoring Needs and Recommendations
- Are populations maintaining and/or recovering in response to management treatments that prescribed modification of the canopy to 50-75 percent, removal of duff layers, and control of competing vegetation? Specifically, is recruitment occurring within populations and are plants colonizing new areas within the managed forest? Are fine scale disturbances providing for effective habitat?
- Are recreational, road maintenance, and construction/development activities that are currently or potentially impacting species being mitigated for?
- How are management actions affecting herbivore and seed predation; where these problems are negatively impacting the viability of the species, are these problems being controlled?
- Are forest processes, such as prescribed fire, enhancing populations and maintaining conditions necessary to support this species when introduced into the stand?
- Is the genetic "fitness" being evaluated within the populations? Has manual pollination been implemented and is it effective in mitigating inbreeding depression/genetic drift?
- Are noxious and exotic weed problems being effectively controlled without harm to Aster vialis?
Alverson, E. R., and K. Kuykendall. (1989). 1989 Field Studies on Aster vialis. Final Report Submitted to the BLM by the Oregon Department of Agriculture. February 1990. 36 pp.
Chen, J., J. F. Franklin, T. A. Spies. 1995. Growing-Season Microclimatic Gradients From Clear-cut Edges Into Old-Growth Douglas-Fir Forests. Ecological Applications, 5(1). 1995. pp. 74-86.
Department of Interior. Bureau of Land Management. 1995. Eugene District, Record of Decision and Resource Management Plan. 263 pp.
Department of Interior. Bureau of Land Management. 1995. Roseburg District, Record of Decision and Resource Management Plan.
Franklin, F. F., and C. T. Dyrness. 1973. Natural Vegetation of Oregon and Washington. USDA Forest Service Technical Report PNW-8. U.S. Forest Service, Portland, Oregon 417 pp.
Gammon, J. 1986. Unpublished Draft Status Report, Aster vialis. Oregon Natural Heritage Data Base. Portland, Oregon. 49 pp.
Guerrant, E. O. 1991. Effects of Heat On Germination of Aster vialis seeds. Final Report Submitted to the BLM by The Berry Botanic Garden. 7 pp.
Hitchcock, C. L., A. Cronquist, M. Ownbey, and J. W. Thompson. 1997. Vascular Plants of the Pacific Northwest. Part 5: Compositae. University of Washington Press, Seattle.
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. 22 pp.
Kaye, T. 1993. Population Monitoring for Aster vialis on the BLM Roseburg District. Final Report Submitted to the BLM by the Oregon Department of Agriculture. September 1993. 19pp.
Kaye, T. 1995. Draft Conservation Strategy for Aster vialis. Draft Report Submitted to the BLM by the Oregon Department of Agriculture. October 1995. 11 pp.
Kuykendall, K. 1991. Pollination Study of Aster vialis. Senior Thesis, Portland State University Honor's Program. 10 pp.
Thompson, D. D. 1977. Taxonomic studies of the Eucephalus complex of Aster in the Pacific Northwest. Unpubl. M.S. Thesis, Oregon State University, Corvallis.
USDA, Forest Service and Department of The Interior, Bureau of Land Management. 1994. Final Supplemental Environmental Impact Statement on Management of Habitat for Late-Successional and Old-Growth Forest Related Species Within the Range of the Northern Spotted Owl. Appendix J2, Results of Additional Species Analysis, Portland OR.
Wright, S. 1931. Evolution in Nendelian Populations. Genetics 16. 159 pp.