Spleenwort-leaved Goldthread (Coptis aspleniifolia Salisb.)
R. D. Lesher and J. A. Henderson
TABLE OF CONTENTS
Species: Coptis aspleniifolia Salisb. (Spleenwort-leaved Goldthread)
Taxonomic Group: Vascular Plants
ROD Components: 1, 2
Other Management Status: Region 6 Regional Foresters Sensitive Species List, Bureau of Land Management Assessment Species in Washington State, Washington Natural Heritage Program Sensitive Species
Range: Coptis aspleniifolia reaches the southern extent of its range in the Pacific Northwest, but is more common to the north in coastal British Columbia and Alaska. Coptis aspleniifolia is rare within the range of the northern spotted owl, and is currently known from 5 locations. Populations are known to occur in Snohomish, Clallam and Grays Harbor Counties, with 3 locations in the North Cascades and 2 sites on the Olympic Peninsula. Three historical sites are in question and need to be verified. Two of these populations occur on the Olympic Peninsula, and were searched for in 1994 but not relocated. The other reported population was in Tillamook County in the Oregon Coast Range, and is based on a herbarium record. This specimen was recently annotated by Dr. K. Chambers as Coptis laciniata. Coptis aspleniifolia has been documented on federal lands of the Mt. Baker-Snoqualmie National Forest and Olympic National Park. Most of the currently known populations on federal lands occur in land allocations that afford a considerable degree of protection, and where timber harvest is not an objective for management. The exception to this is the Lake Isabel population, where a portion of the population occurs in Matrix.
Specific Habitat: Habitat requirements appear to be moist, cool, mossy sites, in old-growth forests with a well-developed litter layer, below 850 m (2800 ft) elevation. Sites where this species occurs in the western North Cascades appear to be similar environmentally to sites farther north, i.e., in coastal British Columbia and southeast Alaska.
Threats: The major threats to this species are loss of populations due to activities that directly impact the habitat or the population. Actions that disrupt conditions necessary for its survival can include treatments that alter the moisture or temperature regime, trampling, or actions that cause disturbance to the soil litter layer. Climate change that alters conditions necessary for its survival may result in a decline in vigor of this species, or may be a factor in causing local extirpation.
- Maintain viable populations at each known site.
- Manage to protect the environmental conditions at known sites
- Monitor known populations in areas with trampling impacts
Viability and stability of known populations, especially in areas with known trampling impacts
Total number of populations in Washington and Oregon
Specific ecological requirements of Coptis aspleniifolia
Rates of reproduction and growth
I. NATURAL HISTORY
A. Taxonomic/Nomenclatural History
Coptis aspleniifolia Salisb. was originally described in 1807 from the northwest coast of North America (Hulten 1968, Hitchcock et al. 1964). Coptis aspleniifolia var. biternata Huth is the only synonym listed in Hitchcock et al. (1964).
B. Species Description (Hitchcock et al. 1964, Pojar and MacKinnon 1994, Hulten 1968)
Coptis aspleniifolia is an evergreen perennial herb with shiny, fern-like basal leaves. The bright yellow thread-like rhizomes led to the origin of the common name "goldthread" (Pojar and MacKinnon 1994). Its rhizomatous habit creates extensive spreading mats. It is a compact, low growing plant from 10-30 cm tall. Leaves are divided into 5 or more lobed and toothed leaflets that are 2-6 cm long (Figure 1).
This species is similar in morphology to Coptis laciniata, which is more common and widespread in the western Olympics and extends south into northwestern California. It differs primarily in the number of leaflets and height of the flowering stalk relative to the leaves. Coptis aspleniifolia has at least 5 leaflets and the flowering stalk is taller than the leaves at anthesis; Coptis laciniata has 3 leaflets, and the flowering stalk is shorter than the leaves. All goldthreads have a touch of yellow at the base of the leaf stalk.
Flowers are inconspicuous, greenish-white and regular, with 2-3 flowers nodding on a leafless stalk. The flowering stalk is usually taller than the leaves at anthesis, and has hyaline scales at the base. Sepals are somewhat linear and reflexed, 5-6 in number, 6-15 mm long. Petals are the same in number as the sepals, but shorter and strap-shaped with a broader, glandular base. Stamens are numerous. It flowers early in the season, from late April through May.
Fruits are follicles, up to 12 in a head, 7-9 mm long, membranous with a very short beak, and with 5-10 seeds. Fruits are upright and spreading when mature. The fruits split open along the upper side, which is believed to be an adaptation for splash-cup dispersal (Pojar and MacKinnon 1994). Fruits are visible beginning in May or June.
Figure 1. Coptis aspleniifolia (line drawing from Hitchcock et al. 1964).
Reprinted by permission of University of Washington Press.
2. Reproductive Biology
Coptis aspleniifolia reproduces both vegetatively and sexually (Tappeiner and Alaback 1989). There is limited information on its reproductive biology and early growth. One study in Alaska (Tappeiner and Alaback 1989) provides the following information. However, it is unknown how populations or clones of Coptis aspleniifolia at the southern edge of its range compare to those in Alaska.
The germination rate was high for Coptis aspleniifolia, with significantly higher percent emergence in old stands (250+ year) compared with young (40 year) stands. Germination and seedling emergence was completed by September following a winter on the forest floor. They reported that litterfall killed 10-15 percent of the seedlings of Coptis aspleniifolia in a young stand. There was considerable mortality of 3-year old seedlings, and only a small percentage survived. It was also apparent that seedlings had become established in the understory of the young stand, rather than persisting from the previous stand. Height growth is slow in young stands, reaching only 10 mm at 3 years. Average annual rhizome growth measured in young stands ranged from 0-3 cm compared with 1-15 cm in the old stand. Establishment of Coptis aspleniifolia may be limited by the low light levels in moss mats, as the seedlings are only 10-12 mm tall compared with the moss height of 15-20 mm. No predation of the Coptis aspleniifolia seed capsules was observed. Tappeiner and Alaback concluded that this species maintains itself in old stands by both seedling establishment and vegetative development of clones. However, the compact clones of this species may limit its ability to migrate by vegetative growth compared to other species in the study.
Little is known about the ecology of Coptis aspleniifolia within the range of the northern spotted owl.
C. Range, Known Sites
Coptis aspleniifolia occurs from south-central Alaska, south through coastal British Columbia to Washington, and perhaps Oregon (Hitchcock et al. 1964; Hitchcock and Cronquist 1973; Pojar and MacKinnon 1994; Hulten 1968; Buckingham and Tisch 1979; USDA and USDI 1994 Appendix J2; Mt. Baker-Snoqualmie National Forest Botany Program Files; Washington Natural Heritage Program Sighting Reports; Oregon State University Herbarium). In the Washington Cascades, this species is known from 3 populations in Snohomish County: the Skykomish River basin at Lake Isabel and the Wallace River, and Lake Twenty-two Research Natural Area in the South Fork of the Stillaguamish River basin (Figure 2).
Figure 2. Distribution of Coptis aspleniifolia in Washington and Oregon.
Four populations of Coptis aspleniifolia have been reported from the westside of the Olympic Peninsula, although currently only 2 populations are known to exist (Figure 2). Two Olympic Peninsula populations were verified in 1994 in Clallam and Grays Harbor Counties (Figure 2). The known population on federal land occurs in Olympic National Park on the Bogachiel River. The other population reported in 1994 occurs on Washington State Department of Natural Resources land in the Harlow Creek area of the southwestern Olympic Peninsula. The other 2 populations previously documented in Jefferson County were searched for in 1994 but not relocated. These populations occurred on the Quinault Indian Reservation and Washington State Department of Transportation land. It has been reported from the Oregon Coast Range (USDA and USDI 1994 Appendix J2), but a search of the Oregon State University Herbarium revealed only one specimen identified as Coptis aspleniifolia from Tillamook County, on Rogers Peak within the Tillamook Burn area (C. Mayrsohn 1995, pers. comm.). This specimen was recently annotated by Dr. K. Chambers as Coptis laciniata. Therefore, there are no known records of Coptis aspleniifolia for Oregon.
D. Habitat Characteristics and Species Abundance
Coptis aspleniifolia occurs in moist forests and bogs (Hitchcock et al. 1964), at low to middle elevations, in areas with a strong maritime influence (Klinka et al. 1989). It is common and widespread in Alaska and British Columbia (Pojar and MacKinnon 1994), but becomes restricted to localized populations in the western North Cascades and western Olympics. At the southern limit of its range, it occurs in cool, moist, old-growth forest habitats.
In coastal British Columbia, Coptis aspleniifolia indicates very moist, acidic, nitrogen poor soils with high organic matter content and generally occurs on forest floors matted by fungal mycelia (Klinka et al. 1989). It is commonly associated with Sphagnum girgensohnii (sphagnum moss) and Blechnum spicant (deerfern).
Habitat information is limited for Coptis aspleniifolia in northwestern Washington or the Oregon Coast Range. On the Mt. Baker-Snoqualmie National Forest, it occupies cool, moist sites that are similar climatically to environments farther north in British Columbia and Alaska. It occurs adjacent to wetlands, rivers, streams or lakes, or on higher ground in areas with high precipitation, and generally in sites with low evaporative stress. Sites are generally on gentle lower slopes, and often northerly aspects. It is thought that these sites have low incident solar radiation because of their location on the landscape. Sites have a mean annual temperature less than 9 C (48 F), and average annual precipitation greater than 250 cm (100 in) (Henderson 1995).
Known populations from the Mt. Baker-Snoqualmie National Forest occur in old-growth to near climax forests, with canopy structure ranging from closed to open and patchy. Coptis aspleniifolia occurs in moist plant associations in the Western Hemlock Zone or lower Silver Fir Zone. Overstory tree species are commonly western hemlock, western redcedar and occasionally Pacific silver fir. Common associated understory species include Sphagnum spp. (sphagnum moss), Blechnum spicant (deerfern), Rubus pedatus (five-leaved bramble), Lysichitum americanum (skunkcabbage), Maianthemum dilatatum (false lily-of-the-valley), Cornus canadensis (bunchberry), Tiarella unifoliata (single-leaved foamflower), Athyrium filix-femina (ladyfern), Oplopanax horridum (devil's club), Vaccinium alaskaense (Alaska huckleberry), Rubus spectabilis (salmonberry), Gymnocarpium dryopteris (oakfern), Galium kamtschaticum (boreal bedstraw), Ribes bracteosum (stink currant), Listera cordata (heartleaf twayblade), Menziesia ferruginea (fool's huckleberry), and Cladothamnus pyrolaeformis (copperbush). Sites where Coptis aspleniifolia occur often have a well-developed moss or duff layer, or wet organic soil.
On the Olympic Peninsula, both populations occur in areas with high precipitation, >250 cm (100 in) and high humidity (Henderson 1995). The Bogachiel population occurs at 670 m (2200 ft) elevation, in a boggy site along the trail. This site was originally reported in 1967 and was revisited in 1994. The Harlow Creek site occurs on DNR land in a designated Forest Health Plot. This stand was harvested about 15 years ago but not burned, and currently has about 20 percent cover of western hemlock. Understory species on this wet site include abundant Sphagnum (sphagnum moss), Gaultheria shallon (salal), Vaccinium ovalifolium (oval-leaf huckleberry), Carex obnupta (slough sedge), Menziesia ferruginea (fool's huckleberry) and Blechnum spicant (deerfern). This population of Coptis aspleniifolia was reported as very large.
Coptis aspleniifolia tends to occur in extensive mats. Due to its rhizomatous growth habit, it is difficult to determine how many individuals occur at each location. However, the number of aerial stems reported from the known sites in Washington varies from a few hundred to over 10,000.
Two other sites of Coptis aspleniifolia previously reported on the west side of the Olympic Peninsula were searched for in 1994, but not relocated. These sites are in close proximity. The original 1982 sighting report for the Quinault Indian Reservation population noted that brush and succession may be possible threats (WNHP 1993). When this site was revisited in 1994, the population was not relocated; the forest canopy had closed and there was a sparse understory of swordfern and oxalis. The 1994 sighting report suggested Coptis aspleniifolia may have been suppressed by forest development. The other site reported in 1988 from the Washington State Department of Transportation land was revisited in 1994, but not relocated. It was reported that Coptis aspleniifolia may have been misidentified at this site.
II. CURRENT SPECIES SITUATION
A. Why Species is Listed under Survey and Manage Standards and Guidelines
Coptis aspleniifolia is at the southern limit of its range in Washington. Here this species is rare and known from only a few isolated populations in the western North Cascades and Olympic Peninsula. Given the conspicuous and distinctive vegetative condition of this species, it is believed that surveys have been extensive enough to locate populations of this species and that few new populations will be found with additional surveys. This taxon was believed to be at medium risk under the Northwest Forest Plan because of its rarity. Potentially this species is at risk from land management or recreational activities.
B. Major Habitat and Viability Considerations
The major viability considerations for Coptis aspleniifolia are loss of populations due to management activities that directly impact the habitat or the population, or trampling from recreational use. Climate change could result in a decline in vigor of this species, and may result in an even more restricted distribution, or may be a factor in causing local extirpation.
Relatively little is known about the autecology of this species within the range of the northern spotted owl. It is a species of cool, moist, old-growth forest habitats, and it is believed that its survival and viability depends on maintaining these conditions. It is thought to be a shallowly "rooted" species that may be very sensitive to disturbance of the soil litter layer, e.g., from trampling. Therefore, disturbance that changes the microclimatic regime or soil litter layer may have significant impacts on local populations.
Fire history analysis shows little evidence of any historical fires in the sites where Coptis aspleniifolia is known. Fire is not a significant threat to Coptis aspleniifolia because the habitats where this species occurs are cool and wet. However, if fire were to occur, it could have a devastating affect on this species from disturbance to its rooting habitat of soil litter and duff, or by altering the environmental conditions.
Climate change could be a potential impact to the populations of Coptis aspleniifolia. An increase in temperature or decrease in precipitation could affect populations of this species, as it tends to be restricted to localized areas that are cool and moist, and similar to environments that occur farther north. As climate has warmed during the last century, stress on the populations of Coptis aspleniifolia at the southern edge of its range may have increased.
C. Threats to the Species
Threats to Coptis aspleniifolia are those actions that disrupt stand conditions that are necessary for its survival. This includes treatments that alter the moisture or temperature regime, or actions that cause disturbance to the soil litter layer.
Trampling from recreational use is currently believed to be the main threat to this species for the majority of the populations in western Washington. Trampling impacts on Coptis aspleniifolia have been documented at the Lake Isabel site on the Mt. Baker-Snoqualmie National Forest (Potash 1995, pers. comm.). There is potential impact from trampling of the Lake Twenty-two population along a trail that gets heavy recreational use. The Wallace River site is fairly remote and does not have trail access, so there is little threat of trampling in this area. The Olympic National Park population occurs along the trail on the Bogachiel River. There is a boardwalk through part of this area, but trampling may potentially impact this population.
This species is important deer forage in the northern part of its range (Pojar and MacKinnon 1994). Browsing is a potential threat to this species in Washington.
D. Distribution Relative to Land Allocations
Most of the known populations occur in land allocations that currently afford a considerable degree of protection and where timber harvest is not the objective for management. This species may potentially be impacted by changes in land allocations that would afford less protection to its habitat. The Lake Twenty-two population occurs in a Late-Successional Reserve, the merged land allocation for the Wallace River population is 1B/LSOG, which is Semi-Primitive Non-motorized/Late- Successional Old-growth within Marbled Murrelet Zone 1. The Lake Isabel population is within the Matrix, but parts of the sub-populations fall within Riparian Reserve boundaries. Of the 2 currently known Olympic Peninsula populations, the Bogachiel site is in the Olympic National Park and, therefore, has no threat from timber harvest activities; the Harlow Creek population occurs on Washington State Department of Natural Resources land, in a young stand that has already been harvested.
III. MANAGEMENT GOALS AND OBJECTIVES
A. Management Goals for the Taxon
The management goal for Coptis aspleniifolia is to assist in maintaining species viability within the range of the northern spotted owl.
B. Specific Objectives
Maintain current cool, moist habitat conditions of known populations
Minimize impacts from trampling where it is a current or potential threat
Prevent disruption to the soil litter layer
IV. HABITAT MANAGEMENT
A. Lessons from History
There has been little management of sites where Coptis aspleniifolia occurs within the range of the northern spotted owl. This species has been studied in Alaska in response to timber harvest, but it is not expected to respond to treatments in Washington and Oregon the same as it does farther north. The following examples relate to timber harvest activities on the Olympic Peninsula.
In Washington, there are 2 known sites of Coptis aspleniifolia that occur in young stands, both in the Western Olympics. The Quinault Indian Reservation site was reported by N. and H. Buckingham in 1982. The sighting report noted this population may be potentially threatened by brush and succession, implying that it may be outcompeted by the developing vegetation (WNHP 1993). When this site was revisited in 1994, the population of Coptis aspleniifolia was not relocated (Salstrom 1994, pers. comm.). Salstrom reported the canopy had closed, the diameter of trees in the stand ranged from 10-35 cm (4-14 in) dbh and the understory was sparse. Salstrom concluded that Coptis aspleniifolia may have been suppressed by forest development (Salstrom 1994, pers. comm.). It appears that in this case this species was not able to survive and compete with vegetation in the young stand, and could not survive the period of canopy closure in the stand development process.
The other Olympic population in Harlow Creek area, occurs in a young stand on Washington State land in a DNR Forest Health plot. As of 1994, it was the only known population surviving in a young forest in Washington. Monitoring this population would supply information on how this species responds to early stages of stand development. Information on site history, stand treatment, and response of Coptis aspleniifolia to harvest may be available from the Department of Natural Resources. This stand has not reached canopy closure yet. It is important to follow the population through this stage of stand development to determine how Coptis aspleniifolia responds.
In southeast Alaska (Tappeiner and Alaback 1989), Coptis aspleniifolia was able to survive clear-cutting and persisted into young forests. Very little is known about the response of Coptis aspleniifolia to disturbance at the southern limit of its range. No research or monitoring studies have been conducted to document response to disturbance and, therefore, no conclusions can be made. The response of this species may be quite different throughout its range.
B. Identification of Habitat Areas for Management
The 3 known sites of Coptis aspleniifolia on the Mt. Baker-Snoqualmie National Forest are identified as areas where management should be implemented to maintain the viability of known populations.
C. Management Within Habitat Areas
Most known sites occur in areas that are not allocated for timber management activities. However, within these habitat areas, it is recommended that current habitat conditions and microclimatic conditions (i.e., cool, moist) be maintained, impacts from trampling are minimized, and disruption to the soil layer is prevented.
Highest priority should be given to those populations where trampling impacts are currently occurring, i.e., Lake Isabel and Lake Twenty-two Research Natural Area. Actions to minimize recreational impacts from trampling may include barriers, signing, educational material, and trail re-route. The site in the Olympic National Park along the Bogachiel trail should be evaluated for trampling impacts and managed to prevent trampling impacts.
Sites with known populations should be managed to include an area that is large enough to maintain the habitat and associated microclimate of the population (Chen et al. 1995). This includes undisturbed forest structure, cool, moist, shaded conditions, and undisturbed soil litter layer. The size of the area should be determined by a field visit.
D. Other Management Issues and Considerations
No other management issues and considerations are identified at this time.
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 Coptis aspleniifolia 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 low to middle elevation old-growth forests with low incident radiation, a cool temperature regime, and high precipitation (Henderson 1995).
B. Research Questions
How does Coptis aspleniifolia respond to forest clearing activities (i.e., thinning or harvesting) at the southern edge of its range, especially related to changes in microclimate or changes to the soil surface layer?
What is the reproductive strategy for this species? Does the species reproduce sexually or does it rely on vegetative reproduction? What is its pollination mechanism?
What is the reproductive status of known populations? Are seeds viable?
How sensitive is Coptis aspleniifolia to different degrees of soil disturbance?
What are the dispersal mechanisms for this species?
C. Monitoring Needs and Recommendations
Monitoring is needed at the Lake Isabel and Lake Twenty-two RNA populations to evaluate and document trampling impacts and recovery after trampling is eliminated.
Monitoring of the population of Coptis aspleniifolia in the Forest Health plot on Washington Department of Natural Resources land would help determine the response of this species to canopy cover and competition during the early stages of stand development.
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