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Bridgeoporus nobilissimus (W.B. Cooke) T.J. Volk, Burds. & Ammirati

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Scientific name
Bridgeoporus nobilissimus
(W.B. Cooke) T.J. Volk, Burds. & Ammirati
Common names
IUCN Specialist Group
Mushroom, Bracket and Puffball
Incertae sedis
Incertae sedis
Assessment status
Assessment date
IUCN Red List Category
IUCN Red List Criteria
A2c; C2a(i)
Vellinga, E.
Dahlberg, A.

Assessment Notes

The content on this page is fetched from The IUCN Red List of Threatened Species: https://www.iucnredlist.org/species/76195622/97167627


Bridgeoporus nobilissimus perennial fruitbodies only occur on very old and large, majestic veteran trees and stumps of Abies species in old-growth forests in the states of Washington, Oregon and northern California (USA); it is known from less than 30 localities. Logging of old-growth Abies forests, changes in forest composition, forest fires, and the disappearance of large enough trees to support the fruit bodies are the main threats. Fruitbodies are also prone to vandalism.

The habitat of this species, old-growth Abies forest, has declined more than 90% over the last century. The known sites of the species are protected, but the tree composition has been changed into Pseudotsuga dominated forest. The number of mature individuals per site is one or two, and the total number of sites does not exceed 50. The species has been extensively surveyed in all its known sites and possible habitats, and cannot have been overlooked as it forms huge conspicuous fruitbodies that are present the whole year through. The largest number of mature individuals in a single subpopulation is estimated to be less than 50, based on the extensive surveys that have taken place since 1998. This species qualifies for listing as Critically Endangered.

Taxonomic notes

See Burdsall et al. (1996) and Redberg et al. (2003) for taxonomic position.

Geographic range

Recorded from the Cascade Mountain Range in Washington and Oregon (USA), Coast Range on the Olympic Peninsula (Washington) and in Oregon, and one locality in north coastal California (USA).

Population and Trends

Less than 25 sites each with one perennial big fruiting body are currently known to exist and to sporulate, these are scattered over an area from northern California (USA) to central Washington (USA). Estimated number of sites does not exceed 35 (Cooke 1949, Castellano et al 1990, Trappe 1990).

Confined to old-growth Abies stands, a type of habitat that has been extensively logged. Only 9% of the old-growth forests in the area still exists. The species is not known to occur outside the western USA.

Decline is expected to continue, as the existent trunks are being decayed and no new big trees and trunks are available.

Population Trend: decreasing

Habitat and Ecology

Forming perennial conks at the base of very old very big living trunks, or dead snags and stumps of Abies procera, A. amabilis, and A. grandis in old-growth forests predominantly in the mountains, but also known from one coastal site in California. The fruit bodies are long-lived, and more than 100 tube layers per fruit body have been found. Fruit bodies are very rare, but the mycelium of fungus has been detected in living smaller trees of these and other species in the same areas where the fruit bodies are found (Gordon 2009 a, b; Gordon and Van Norman 2015). They have only been found fruiting on Abies.


Habitat destruction is the main threat. Old-growth forest, with the size of trees that will support the very large fruit bodies is rare and vulnerable. Logging for timber has decreased the extent of Abies. Forests are now managed for Douglas Fir (Pseudotsuga menziesii) as it grows faster than Abies. The main host, Abies procera, is restricted to mountain tops.

Forest fires are of major concern, as the fuel load of the present day forests is much higher than in the past, which will cause the fires to burn more severely, being crown fires and killing the trees, instead of only killing the undergrowth.

Deliberate destruction of the fruitbodies is also a major threat. For instance the one specimen recently discovered in northern California (Mushroomobserver.org/116383) was broken off the tree. The fruitbodies are perennial.

Conservation Actions

Habitat conservation, ensuring continuing growth of the host tree species (Abies) is most important.

This species is a so-called Strategy 1 species under the Northwest Forest Plan, and has been surveyed and managed within the range of the Northern Spotted Owl (Strix occidentalis caurina). All possibly suitable Abies stands have been surveyed and the presence of the species in only <50 sites has been confirmed.

Use and Trade

The species is not known to be used.

Source and Citation

Vellinga, E. 2015. Bridgeoporus nobilissimus. The IUCN Red List of Threatened Species 2015: e.T76195622A97167627. https://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T76195622A76195630.en .Downloaded on 30 January 2021

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