Management Recommendations•Group 29

Noble Polypore: Bridgeoporus (=Oxyporus) nobilissimus (W.B. Cooke) Volk, Burdsall & Ammirati

by Claire Hibler & Thomas E. O’Dell
July 1997

TABLE OF CONTENTS

EXECUTIVE SUMMARY

Species: Bridgeoporus (=Oxyporus) nobilissimus (W.B. Cooke) Volk, Burdsall & Ammirati

Taxonomic Group: Fungi

ROD Components: 1, 2 & 3

Other Management Status: Bureau of Land Management Bureau Sensitive in Oregon, Oregon Natural Heritage Program List 1. Bridgeoporus nobilissimus is listed as a sensitive taxon in a preliminary report on endangered, threatened, and sensitive macrofungi of Washington State by Ammirati (1994).

Range: Bridgeoporus nobilissimus is endemic to Oregon and Washington Cascades, and in the Olympic Mountains of Washington. A population has been reported but not verified in the Coast Range of Oregon.

Specific Habitat: Bridgeoporus nobilissimus occurs in association with the collar or root crowns of large diameter (minimum 109 cm (43 inch)) old growth, Abies procera (noble fir) or Abies amabilis (Pacific silver fir) living trees, standing dead, snags, and stumps.

Threats: Threats to Bridgeoporus nobilissimus are those actions that disrupt stand conditions necessary for its survival. These include activities that cause removal of host trees or modification of microclimatic conditions required for fruiting, such as logging, road, trail, and campground construction.

Management Recommendations: Maintain habitat for this taxon at known sites on Federal land by retaining late-successional forest structure and soil conditions. Maintain and develop mature, large diameter, declining Abies trees, snags, and stumps at known sites.

Avoid disturbance at known sites on Federal land until additional data is collected on taxon viability.

Design and maintain Bridgeoporus nobilissimus Management Areas to protect the habitat of known populations. The design of the management areas should be based on results of species oriented inventories and the availablitly of potential habitat over the longterm.

Information Needs: Visit known sites to verify the status of populations and to characterize habitat and collect ecological data. Conduct inventories in stands containing Abies amabilis and A. procera in Oregon and Washington to locate additional populations of Bridgeoporus nobilissimus. Prioritize surveys in late-successional reserves, Research Natural Areas, and where management treatments or projects are scheduled or proposed. Monitor and determine the extent of populations to characterize population trends in the various seral stages at known sites. The major needs are to precisely locate populations and to determine their ecological tolerance and habitat preference.

Revisit suspected sites in the Oregon Coast Ranges to locate the population and verify identification.

I. NATURAL HISTORY

A. Taxonomic/Nomenclatural History

Bridgeoporus nobilissimus, W.B. Cooke was originally described (as Oxyporus) in 1949 from Mt. Rainier National Park in Washington State (W.B. Cooke 1949). It was later placed in Fomes as F. nobilissimus (W.B. Cooke) Lowe (1955). It was recombined into Bridgeoporus by Volk and others (1996). There are no other known synonyms. It is a perennial conk in the family Polyporaceae, order Aphyllophorales.

B. Species Description

1. Morphology

Bridgeoporus nobilissimus is a massive polypore. A large shaggy tan conk with the upper surface reminiscent of a shaggy, fibrous door mat. Frequently covered with algae, lichens, and debris. The combination of morphological features which differentiate B. nobilissimus from other polypores are the shaggy appearance of the pileal surface and the alternating white and brown tube layers in the fruiting body. The conspicuous and often extremely large size and fuzzy surface of the perennial conk makes B. nobilissimus easily noticed and identifiable in the field.

Conks have been found in three general shapes. Hoof-shaped and shelflike conks are found on the sides of the hosts. Centrally substipitate conks are found growing on the collars and root crowns of the hosts and on the top of host stumps. Maximum pileus measurements from the known sites are 750 mm (2.5 feet) long by 1010 mm (3 feet) wide by 510 mm (1.5 feet) high (Walker & Ammirati, 1995).

Stiff hyphal fibers form a mat on the top of the conk which provide habitat for algae and epiphytic bryophytes. Needles and leaves from the canopy and shrub layers become embedded in the rough texture of the hyphal mat. The combination of the diverse plant and debris community on the conks contrasting with the velvety ivory margin reminds some observers of a green pizza.

Basidiospores 5.5-6.5 x 3.5-4.5 µ, broadly ovoid, hyaline, smooth, thin-walled, inamyloid.

2. Reproductive Biology

This taxon is a terrestrial polypore and thus it presumably depends upon wind for spore dispersal. Animal (especially arthropod) dispersal is also possible. No specific information on reproductive biology is available at this time.

New Bridgeoporus nobilissimus conks have been observed at Goat Marsh, Larch Mountain, and Snow Peak. Death of conks have been observed at Goat Marsh, East Fork Humptulips, Larch Mountain, and Snow Peak. The death of conks appear to be related to advanced decay of the substrate.

A Bridgeoporus nobilissimus conk collected in 1988 at the Snow Peak site was aged by counting the tube layers and was determined to be approximately four years younger than the plantation (Ammirati, 1995). Therefore, it is possible that the B. nobilissimus did not fruit until the host was dead for 4 or more years. The fungus may occupy the heartwood of the host tree and live inassociation with the tree for many years before it fruits (Burdsall, 1996).

3. Ecology

Little is known about the autecology of Bridgeoporus nobilissimus but it is apparently a parasite (butt rot) or saprobe on Abies spp. (Volk et al., 1996). Conks grow up to 122 centimeters (four feet) off the ground on live trees, standing dead, snags, and stumps. They are also found on the ground, growing off of the collars and root crowns within 2 meters (approximately six feet) of the base of the host (W.B. Cooke, 1949).

C. Range, Known Sites

Bridgeoporus nobilissimus is endemic to Oregon and Washington, where it is known from 9 sites from Linn Co., Oregon to King Co., Washington and the Olympic Penninsula. Washington: Pierce Co., Mt. Rainier National Park, lower Tahoma Creek; Cowlitz Co., Mt. St. Helen’s National Monument, Goat Marsh Research Natural Area; King Co., Mt. Baker-Snoqualmie National Forest, Asahel Curtis Nature Trail; Grays Harbor Co., Olympic National Forest, East Fork of Humptulips river. Oregon: Clackamas Co., Mt. Hood National Forest, Wildcat Mountain; Clackamas Co., Barlow Butte; Multnomah Co., Mt. Hood National Forest, Larch Mountian; Multnomah Co., Salem District BLM, North Mountain; Linn Co., Salem District BLM, Snow Peak. Another potential site with vague locality data extends the range to Benton Co. in the Oregon Coast Range. No sites are known from California.

D. Habitat Characteristics and Species Abundance

Potential suitable habitat is defined as mesic to wet microsites in forests of all seral stages in the Pacific Silver fir zone in Oregon and Washington. All known Bridgeoporus nobilissimus sites are in the Pacific Silver Fir Zone and have old, large diameter dead Abies procera material as the substrate with the exception of the East Fork Humptulips population which is on dead Abies amabilis. All sites are in mesic to wet micro-environments. Known sites are in a wide range of seral stages from a plantation (on old-growth stumps) to old-growth forests with large diameter (109 - 208 cm; 43 - 82 inch) Abies procera or A. amabilis. The conks are found on Abies snags, stumps, or dead portions of declining large, live trees.

The Washington Cascade populations are located low on the north side of slopes in protected areas. In contrast, the Oregon Cascade populations are located in the vicinity of mountain tops and are on gentle ridges with west to north aspects. Portions of the populations at Snow Peak and Goat Marsh are associated with avalanche chutes.

Sites range in elevation from 305 meters (1000 feet) at East Fork of Humptulips river to 1219 meters (4000 feet) at Snow Peak. Site elevations in the Cascades range between 640 and 1219 meters (2100 - 4000 feet).

This species occurs at sites with a range of disturbance conditions. All of the locations at the Snow Peak site were harvested in the middle 1960s and are now in the open sapling seral stage. All of the Bridgeoporus conks at this site are on the stumps that were created during a timber salvage operation over 30 years ago. The Wildcat Mountain site was railroad harvested in the 1930s; it now supports a 60-year-old stand of timber and is in the closed sapling seral stage. Though Larch Mountain is classified as old growth, it too has had some selective timber harvest. After a fire swept through andkilled portions of the stand there was a salvage harvest of the dead timber which left pockets of old growth on the site. A similar situation occurs at Barlow Butte where a salvage operation occurred after a blowdown. The remnant old-growth stand at Barlow Butte is relatively intact and surrounded by clearcut and partial cut units. The Goat Marsh, Asahel Curtis, and East Fork of Humptulips River populations are all in old-growth stands.

Associated tree species are those typically found in the Pacific Silver fir zone and include Abies amabilis, Abies procera, Pseudotsuga menziesii (Douglas-fir), Thuja plicata (western red cedar), and Tsuga heterophylla (western hemlock). Dominant shrubs found at the sites include Gaultheria shallon (salal), Menziesia ferruginea (fools huckleberry), Rhododendron macrophyllum (rhododendron), and Vaccinium alaskense (Alaska huckleberry).

Sporocarp abundance varies between the sites, ranging from 1 to 20 conks per site. Snow Peak is the largest known population (possibly due to the higher survey intensity there) with 20 conks and an area occupancy of at least 30 acres at one of its locations. Goat Marsh has 13 conks between 2 locations. Seven conks have been found at Larch Mountain. North Mountain had only 1 conk which was collected prior to timber harvest in the late 1980s. Despite systematic searches no other Bridgeoporus nobilissimus conks are known from this population. Barlow Butte had only 1 conk. A revisit to the site yielded the same conk but in extremely poor condition. Two conks have been identified at East Fork of Humptulips river, 1 at Asahel Curtis, and 2 at Mount Rainier National Park.

II. CURRENT SPECIES SITUATION

A. Why Species is Listed under Survey and Manage Standards and Guidelines

Bridgeoporus nobilissimus is a rare, regional endemic known from only 9 sites within the range of the northern spotted owl. It reaches the southern limit of its range in Linn Co.,Oregon. Under Option 9, it was considered to have a 10 percent likelihood of being well distributed throughout its range, 25 percent likelihood of being locally restricted, 43 percent likelihood of restriction to refugia, and 22 percent likelihood of extirpation on Federal lands.

B. Major Habitat and Viability Considerations

The major viability consideration for this taxon is loss of known populations on Federal land within the range of the northern spotted owl. Considerations include all management or recreational activities that remove or damage the host, its roots, snags, or stumps. The presence of extant sites in high recreational use areas exposes it to adverse impact due to management or recreational activities, particularly those that remove or damage the host or its roots.

The autecology of this taxon is not well known. It is a presumed saprophyte or pathogen associated with Abies amabilis and A. procera. Therefore, disturbance that affects the substrate will potentially strongly affect this taxon. Recreational activities are a significant threat to this taxon because a number of known populations are from high recreational use sites.

Climate change may result in decline in vigor of this taxon and may result in the extirpation of the taxon from the range of the northern spotted owl. Climate change could potentially impact all populations of this taxon. An increase in temperature or a decrease in precipitation could affect disjunct populations.

C. Threats to the Species

Threats to Bridgeoporus nobilissimus are those actions that disrupt stand conditions necessary for its survival. These include activities that cause removal of host trees or modification of microclimatic conditions required for fruiting, such as logging, road, trail, and campground construction.

This taxon is not routinely harvested for use as food.

Other identified threats include the trampling and collecting of Bridgeoporus conks.

D. Distribution Relative to Land Use Allocations

Bridgeoporus nobilissimus is known from 2 sites that are in Late-Successional Reserves, Olympic National Forest and Wildcat Mtn., Mt Hood National Forest. The site at Mt. Rainier National Park is Congressionally withdrawn. The sites at Asahel Curtis, Goat Marsh, and Larch Mountain are administratively withdrawn. The sites at Snow Peak and North Mt. are on matrix lands, within temporary 600 acre management reserve areas.

III. MANAGEMENT GOALS AND OBJECTIVES

A. Management Goals for the Taxon

Management goals for this taxon are to assist in maintaining viable populations on Federal land within the assessment area. Known sites on Federal land of this rare taxon should be protected until sufficient information is generated to suggest management can sustain taxon viability, particularly on Federal land.

B. Specific Objectives

Maintain and develop mature, large diameter, declining Abies trees, snags, and stumps at known sites. Maintain and design Bridgeoporus nobilissimus management areas to protect the habitat of known populations. The design of the management areas should be based on results of species oriented inventories and the availability of potential habitat over the long term.

IV. HABITAT MANAGEMENT

A. Lessons from History

There has not been any specific management of sites for Bridgeoporus nobilissimus. Since it is a presumptive saprobe or parasite, an abundance of potential host trees should be protected where fungal populations exist. Although not documented for this taxon, many fungi are harmed by air pollution, acid deposition, N deposition, and SOx (Gulden et al., 1992).

B. Identification of Habitat Areas for Management

There are 8 known sites of Bridgeoporus nobilissimus that have good potential to be managed to maintain population viability. The sites on the Gifford Pinchot National Forest, Mt. Baker-Snoqualmie National Forest, Mt. Hood National Forest, Olympic National Forest, and SalemDistrict, Bureau of Land Management should be managed to maintain population viability. One population occurs in a National Park.

C. Management Within Habitat Areas

Status of specific management activities is unknown for extant sites. However, at and around known sites, it is recommended that current habitat conditions and micro-climatic conditions be maintained, impacts from recreational activities minimized, and disruption to snags and stumps avoided.

• Maintain dominance of specific overstory tree associates as outlined in section 1D.
• Minimize loss or disruption of host tree snags and stumps, particularly from management, road, trail and campground construction or recreational activities.
• Manage tree diseases in the area to minimize loss of overstory trees.

This protection could include conservative silvicultural treatments to develop mature, large diameter, declining Abies trees, snags, and stumps. The guiding objective of any such treatment could be to encourage the development of mature, large diameter, declining Abies amabilis and A. procera trees, snags, and stumps over the long term. All known sites should be evaluated for the presence and health of Abies amabilis and A. procera in the habitat area.

Sites not in land use allocations that protect the populations from timber management should have a 600 acre temporary reserve area around them until: (1) all of the potential habitat within the reserve is inventoried for additional Bridgeoporus nobilissimus conks and potential hosts and (2) a site specific Bridgeoporus nobilissimus management plan is prepared. The Barlow Butte site and a portion of the Goat Marsh are in matrix land and should have temporary 600 acre management reserves designated.

Silvicultural treatments within the Pacific Silver fir zone, in all land use allocations could promote the development of mature, large diameter Abies procera. For example, when designing a timber harvest unit in the matrix, the largest and oldest Abies procera could be selected as a major component of the required leave trees.

Potential trampling and collection impacts may be mitigated by not developing trails and recreation sites in the vicinity of known Bridgeoporus nobilissimus sites.

D. Other Management Issues and Considerations

No other management issues and considerations have been identified.

V. RESEARCH, INVENTORY AND MONITORING NEEDSV. RESEARCH, INVENTORY AND MONITORING NEEDS

A. Data Gaps and Information Needs

Revisit known sites and collect ecological data to more completely characterize habitat. Conduct surveys to locate additional populations of this taxon in Research Natural Areas and when appropriate where management treatments or projects are scheduled or proposed. Conductinventories to locate additional populations of Bridgeoporus nobilissimus in areas identified as potential habitat. Prioritize inventories where management treatments or projects are proposed in potential habitat and around known sites.

Data are lacking regarding the specific response of this taxon to management practices such as logging, road, trail, and campground construction, prescribed fire and collection of secondary forest products. Information is also needed on the area required to support viable populations, population age structure, dispersal requirements and maximum distance over which populations interact.

The Interagency Oxyporus Team suggested the following format for a GIS plot to identify potential habitat areas for Bridgeoporus nobilissimus: range of Pacific Silver fir zone from Stevens Pass and North Bend Ranger Districts south to Eugene District BLM and Willamette National Forest, west to the Olympic Mountains in Washington and the Coast Ranges in Oregon, and east to the extent of the range of the northern spotted owl and known sites. Verify the Bridgeoporus nobilissimus site in the Oregon Coast Range.

B. Research Questions

• What ecological factors characterize the habitat of Bridgeoporus nobilissimus?
• What is the range of suitable microclimate conditions, particularly humidity, soil moisture, and soil temperature necessary for population viability?
• What is the relationship of stand age to population viability for this taxon?
• What is the density of tree hosts needed to sustain population viability?
• At what decay stages does Bridgeoporus nobilissimus colonize Abies snags, stumps and large diameter trees?
• What are the spore dispersal mechanisms/agents of this species?
• What are the specific habitat requirements of this species? In what age and diameter range of Abies can Bridgeoporus nobilissimus become established? Could an assay be developed from wood cores?
• How does this taxon respond to manipulation of stand structure and composition, particularly as it relates to the development of mature, large diameter Abies snags, stumps, and declining old-growth trees?

C. Monitoring Needs and Recommendations

Known sites should be monitored to assess compliance with managment guidelines and evaluate impacts.

Monitor recreation impacts to known sites at Asahel Curtis Nature Trail and Larch Mountain.

It is recommended that populations within federally managed areas be monitored to gather basic ecological information and to ensure that the populations at the known sites remain viable andmonitor possible site impacts.

VI. REFERENCES

Ammirati, J. 1994. Endangered, threatened and sensitive macrofungi of Washington State. Official Letter to C. Turley, Science team leader, Washington State Dept. of Natural resources. Dated March 26, 1994.

Ammirati, J. 1995. University of Washington. Personal communication.

Burdsall, H., 1996. USDA Forest Products Laboratory; Madison, Wisconsin. Personal communication.

Cooke, W.B. 1949. Oxyporus nobilissimus and the genus Oxyporus in North America. Mycologia 41:442-455.

Gulden, G., K. Hoiland, K. Bendiksen, T.E. Brandrud, B.S. Foss, H.B. Jenssen, and D. Laber. 1992. Macromycetes and Air Pollution: Mycocoenological studies in three oligotrophic spruce forests in Europe. Bibliotheca Mycologica 144: 1-81.

Norvell, L.L. unpublished report on file, Corvallis Forestry Sciences Lab.

Interagency Oxyporus Team Meeting minutes. March, 1995.

Roger, J. 1996. Oregon Mycological Society. Personal communication.

Stein, M. 1996. Mt. Hood National Forest. Personal communication.

Sullivan, Molly. 1996. Mt. Hood National Forest. Personal communication

Thomas, J.W. et al. 1993. Forest Ecosystem Management: An Ecological, Economic, and Social Assessment. Report of the Forest Ecosystem Management Assessment Team to the Departments of Agriculture, Commerce and the Interior, and the Environmental Protection Agency. Portland, OR.

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.

USDA Forest Service and USDI Bureau of Land Management. 1994. Record of Decision for Amendments to Forest Service and Bureau of Land Management Planning Documents with the Range of the Northern Spotted Owl, and Attachments. Washington D.C.

Walker, G. & J. Ammirati. 1995. University of Washington. Personal communicaton.