Conservation Assessment for Elegant Fawn Lily

Дата канвертавання25.04.2016
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List of Tables and Figures


Table 1. Known Sites for E. elegans……………………………………... 13

Table 2. Associated Species for Mt. Hebo Forest Habitat……………….. 31

Table 3. Associated Species for Mt. Hebo Meadow Habitat…………….. 32

Table 4. Associated Species for Mt. Hebo Non-Forest Cliff Habitat……. 33

Figure 1. Erythronium elegans site distribution………………………….. 7

Figure 2. Key to Erythronium species from the Pacific Northwest………. 9

Figure 3. Photo of E. elegans from Mt. Hebo…………………………….. 10

Figure 4. Photo of forest habitat from Mt. Hebo………………………...... 15

Figure 5. Photo of meadow habitat from Mt. Hebo……………………..... 17

Figure 6. Photo of cliff habitat from Mt. Hebo………………………….... 17
I. Introduction
A. Goal
The goal of this CA is to summarize existing knowledge about Erythronium elegans, the Elegant Fawn Lily. Included will be summaries of current information on biology, ecology, threats, and management considerations, to facilitate Federal management for species conservation. Concern for E. elegans derives from its rarity and its limited distribution. It is apparently restricted to six population areas, all from the northern Coast Range of Oregon.
Federal management for this species follows US Forest Service Sensitive Species and OR / WA BLM Special Status Species policies. For OR / WA BLM administered lands, Special Status Species policies detail the need to manage for species conservation. The USFS Region 6, Sensitive Species policy requires the agency to maintain viable populations of all native and desired non-native wildlife, fish, and plant species in their geographic range on National Forest System lands and to develop and implement management actions to ensure that species do not become threatened or endangered.
B. Scope
The geographic scope of this assessment includes consideration of the entire known and suspected range of E. elegans, the Coast Range of northern Oregon (Figure 1). Species-specific information is included for federal lands, and for non-federal lands as it relates to the overall conservation of the species. Threats discussed represent known or suspected existing threats, any of which may change with time. Management considerations generally apply to specific localities, though some range-wide concerns such as habitat connectivity are addressed as well. Uncertainty is acknowledged where appropriate, and information updates will be necessary to keep this assessment current.

Figure1. Erythronium elegans locations
C. Management Status
Erythronium elegans has a Heritage Global (G) and State (S) rank of 1 in Oregon ("Critically imperiled because of extreme rarity (Oregon Natural Heritage Information Center 2007). This rank was last reviewed March 2003 (Natureserve 2009). It is a federal Species of Concern (SOC), an Oregon State Threatened species, and a US Forest Service Region 6 Sensitive and Bureau of Land Management Special Status species. Oregon Natural Heritage Information Center (ORNHIC) classifies this species as List 1 (Taxa that are threatened with extinction or presumed to be extinct throughout their entire range).
II. Classification and Description
A. Systematics
The taxonomic hierarchy for Erythronium elegans (USDA NRCS 2009b) includes:
Division: Magnoliophyta (Flowering Plants)

Class: Liliopsida (Monocotyledons)

Subclass: Liliidae

Order: Liliales

Family: Liliaceae (Lily Family)

Genus: Erythronium L. (Fawnlily)

Species: Erythronium elegans Hammond & Chambers

Paul Hammond and Kenton Chambers first described Erythronium elegans (Hammond and Chambers 1985) from a population on Mt. Hebo in the northern Coast Range of Oregon. Hammond and Chambers analyzed morphological traits to conclude that E. elegans may be intermediate between two genetically linked groups, the first represented by E. oregonum and E. revolutum and the second represented by E. montanum and E. klamathense. The authors hypothesized that E. elegans originated in an ancestral complex that included E. montanum and E. klamathense, possibly hybridizing with E. revolutum.

Investigations into the origins of the newly described E. quinaultense, from the Olympic Mountains of Washington, revealed that this species is tetraploid (2n=48) as is E. elegans (Allen 2001). All other species of Erythronium in western North America are diploid (2n=24) (Allen, Soltis and Soltis 2003). Based on morphological characteristics that are distinct from one another but intermediate between E. montanum and E. revolutum, and their shared tetraploidy, Allen proposed that E. elegans and E. quinaultense may have evolved from separate hybridization events of the same parent species (Allen 2001, 2007). Using chloroplast gene and nuclear ribosomal DNA internal transcribed spacer (ITS) sequences, Allen, Soltis and Soltis (2003) linked E. oregonum, E. revolutum, E. quinaultense, and E. elegans to one ‘clade’, separate from E. klamathense.
Results from a study comparing chloroplast DNA material inherited from the seed parent (Allen 2008, Allen pers. comm. 2009) suggests a hybrid origin of E. elegans that includes both E. revolutum and E. oregonum as seed parents from different hybridization events. The data does not support the involvement of E. montanum as a seed parent, however, based on morphological similarities with E. elegans, it is possible that it contributed as a pollen parent. The data also indicate that genetic differences between the six sites sampled (Fanno Meadows, Mt. Hebo, Lost Prairie, Saddle Bag Mountain, Rocky Point, Triangulation Point) are greater than previously thought and the species may have arisen from at least two separate hybridization events. Two possible scenarios include;

i) E. oreganum (seed parent) X E. revolutum (pollen parent)

ii) E. revolutum, or an E. revolutum-E.oregonum hybrid (seed parent) X E. montanum (pollen parent).
Chloroplast DNA haplotype distributions place the Mt. Hebo, Lost Prairie, and Rocky Point sites in one haplotype, and the Saddlebag Mountain, Fanno Meadows, and Triangulation Point sites each with their own haplotypes (Allen 2008, Allen pers. comm. 2009). Saddlebag Mountain and Fanno Meadows were found to have two haplotypes at each site, indicating that they may have the most within-population genetic diversity. The implication of genetic studies completed to date is that E. elegans may not be a single uniform species, but may have distinct races or varieties. Further investigation of nuclear DNA sequences may reveal the origins of the pollen parent, the role of E. montanum, and more fully determine the genetic diversity of the species within and between sites.
We present a key to Erythronium species known from the Pacific Northwest (Figure 2) developed using Allen (2001), the Flora of North America (Allen and Robertson 2003), and Kozloff (2005).
Figure 2. Key to Erythronium species known from northwest Oregon, north to British Columbia

1a. Leaves distinctly mottled with white to brown transverse bands; leaf (lf) margin often planar, leaves (lvs) prostrate 2

1b. Leaves green, not mottled with white or brown transverse bands (or in E. elegans or E. quinaultense, sometimes with very faint bands); lf margin often sinuose and with leaf tips more upright 3

2a. Tepals uniformily pink at anthesis; anther filaments noticeably widened (lanceolate), 2.0 to 3.0 mm wide at mid-point; leaves mottled whitish; plants of immediate coast or within coastal influences, often riparian (British Columbia south to northern California) E. revolutum

2b. Tepals white to cream colored at anthesis, often aging with a blush of pink; anther filaments at least somewhat widened (narrowly lanceolate), 1.0 to 3.0 mm at midpoint; leaves mostly distinctly mottled with purple-brownish transverse bands; plants mostly east of the coastal mtns. in valley lowlands, well-drained habits, non-riparian. (British Columbia to southern Oregon) E. oregonum

3a. Tepals yellow; leaves glaucous, stomata often appearing in obvious rows (apparent at least in live plants); plants mostly at higher elevations in the Cascade Mountains and eastward, but occasionally found on Coast Range peaks and ridges. Plants of the Coast Ranges have pale, instead of yellow or reddish anthers, and have been referred to as var. pallidum (British Columbia to California) E. grandiflorum

3b. Tepals white to cream with a yellow zone at base, often blushed with pink; leaves not glaucous, stomata more random; distribution various 4

4a. Tepals white at anthesis; filaments linear, ≤ 0.8 mm wide; plants of the Cascade and Olympic Mtns., not likely to be found below 3,500 feet in the Cascades and 3,000 feet in the Olympic Mts.. (British Columbia to central Oregon Cascades) E. montanum

4b. Tepals tinged with pink at anthesis; filaments narrow lanceolate, ≥ 0.8 mm wide; endemic plants of the coastal mountains in northwest Oregon and western Washington 5

5a. Tepals ± white to pinkish, the outer ones generally more strongly colored, especially on the outer surface; anther filaments 0.8–1.4 mm wide, white; known only from the Coast Range in northwestern Oregon E. elegans

5b. Tepals ± white near base, shading to pink at margins and tips; anther filaments 1.0–1.8 mm wide, often pink-tinged; known only from the Olympic Mountains in western Washington E. quinaultense

B. Species Description
The genus Erythronium is a spring-blooming, bulb-producing perennial of about 28 species. It is morphologically homogeneous and easily recognizable. All species of Erythronium emerge from a bulb, producing basal leaves and a flowering stalk with one or more flowers (Allen and Robertson 2003; Allen, Soltis and Soltis 2003). Descriptions provided in Flora of North America (Allen and Robertson 2003), Eastman (1990), Hammond and Chambers (1985), and Kozloff (2005), as well as field observations suggest that populations of E. elegans show variation in flower color, leaf shape, and leaf mottling.
The tepals of E. elegans are lance-shaped with slightly recurved tips. They may be up to 2" long, and vary in color from white to cream to pink. A single stem may contain as many as 3 flowers. The leaves of E. elegans are mostly deep green or sometimes very faintly mottled with a few brown or white lines. Leaf margins are often sinuate (J. Knurowski Pers. Comm. 2006).
A taxonomic description from the Flora of North America (Allen and Robertson 2003) follows:

Bulbs slender, 30–50 mm. Leaves 7–20 cm; blade green or faintly mottled with brown or white, narrowly ovate, margins often wavy. Scape 10–30 cm. Inflorescences 1–2(–4)-flowered. Flowers: tepals: inner ± white, outer ± white and tinged (often strongly) with pink, especially abaxially and along midline, becoming more generally pinkish with age, both inner and outer with yellow band at base, lanceolate to narrowly elliptic, 20–40 mm, abaxial surfaces and outer tepals often darker, inner auriculate at base; stamens 13–22 mm; filaments white, flattened, slightly widened, linear to lanceolate, 0.8–2 mm wide; anthers yellow; style white, 10–20 mm; stigma with slender, usually recurved lobes 2–4 mm. Capsules obovoid to oblong, 2–5 cm.

Figure 3 Erythronium elegans, Mt Hebo

Photo by M.Stein

III. Biology and Ecology

  1. Life History and Reproductive Biology

Erythronium elegans is known from six population areas in the northern Oregon Coast Range. Existing information on life history and reproductive biology has been collected from the Lost Prairie, Saddlebag Mountain, Rocky Point (all Bureau of Land Management jurisdiction); Mt Hebo (US Forest Service jurisdiction), Fanno Meadows (private ownership,Willamette Industries) and the Triangulation Point (Oregon Department of Forestry) sites. Investigations into pollination biology, herbivory and vegetative competition from these populations have provided insight into life history and reproductive biology.
The pollination biology of most species of Erythronium is not well known. Pollinators are presumed to include bees and other insects. Bumblebees have been observed pollinating Erythronium grandiflorum, which occurs in close proximity to E. elegans on Mt Hebo. A pollination study at Lost Prairie (Raven 1995) found that E. elegans was self-compatible, and produced viable seed from self-pollinated flowers, as well as those which were out-cross pollinated. During one year of the study the number of seeds produced per fruit was significantly greater for the out-crossed individuals compared to self-pollinated fruits.
Herbivory of flowers appears to be an important factor for determining how many mature fruits will be produced (Raven 1995). Nets and cages used in Raven’s study excluded herbivores as well as pollinators. Over a two-year period, plants protected from herbivory were compared with unprotected controls: In the protected group, 6 percent and 13 percent of plants were missing flowers in each of the two years compared to 36 percent and 27 percent of plants in the control (unprotected) group. Deer and elk were the presumed grazers and browsers of the control group of plants. Among other things, the study demonstrated that exclusionary devices like cages could be effective in reducing herbivory, thus increasing fruit set.
Vegetative competition does not appear to be a major factor in initial seedling growth and survival of E. elegans seedlings. An experiment at the Lost Prairie site assessed the competitive effects of salal (Gaultheria shallon), a woody shrub, on E. elegans germination, seedling growth and condition (Raven 1995). A comparison of areas with salal competition versus those without suggested that there was no statistical difference between the two for either germination rate or seedling condition. Greater than 80 percent of the seed germinated with 90 percent of the seedlings in good health in both cases.
Vegetative competition may be a factor in herbivory of E. elegans. Raven (1996) investigated whether salal is a factor in the herbivory of E. elegans where both species occur concurrently. In treated plots, all salal was clipped to the ground. Salal was left unclipped in the untreated plots. One year out of three, more E. elegans plants had their flowers and leaves browsed where salal had been clipped. In the other two years, the number of browsed flowers and leaves was similar for both clipped and unclipped plots. Although study results were mixed, it appears that E. elegans gains some protection from leaf, flower, and fruit herbivory when growing amidst salal. Herbivores may find it easier to browse on E. elegans if interfering vegetation is absent. Study results suggest that plants growing amongst salal are taller, with more leaf area. Perhaps salal provides some shading which reduces temperature or evaporation rates, or somehow contributes to other unknown microsite requirements (Raven 1996).
Some genetic and morphological information suggests that E. elegans is able to reproduce vegetatively (Guerrant et al. 1996). Genotype sampling of individuals within the same clump revealed their identical genetic heritage, distinct from all others in the area. Field observations of a bulb exposed at ground surface revealed that the mechanism for vegetative reproduction is the production of small offset bulbs. Vegetative reproduction by means of stolons is known from eastern North American species of Erythronium, and from a single western species. E. multiscapoideum. For species lacking stolons, including E. elegans, Allen, Soltis and Soltis (2003) also concluded that vegetative spread may result from small offset bulbs.
Vegetative dormancy, where plants don’t consistently emerge in consecutive years, was demonstrated for E. elegans in Guerrant’s work (Guerrant 1999). While conducting demographic studies that followed individual plants over a period of time, Guerrant found emerging plants that were clearly not seedlings, but which also had not been present the previous year. Data from several years convinced him that these were dormant plants that had remained beneath the surface for one or more growing seasons. Data also suggested that up to 14 percent of individuals could be dormant in a given year and that dormancy could last as long as three years. With the conclusion that vegetative dormancy occurs also came the acknowledgement that this greatly complicates monitoring work on E. elegans.
The overall phenology of E. elegans is variable, probably depending on microhabitat conditions (Raven 1995). Emergence from the bulb begins early- to mid-April. Raven observed that flowering plants generally emerge before vegetative plants, with fully mature flowers developing in late April. The flowering period lasts approximately one month until late-May to early-June, at which time fruits begin to develop. Fruits reach full size in July, and begin to dehisce from mid-July through August, when plants wither and die back to the soil surface.

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