Phaeocollybia oregonensis is a rare endemic fungus to the Pacific Northwest of North America. It is characteristic for old-growth mature forests where it forms ectomycorrhiza with Abies amabilis, Pseudotsuga menziesii, and Tsuga heterophylla. Despite extensive survey efforts under the Northwest Forest Plan since 1998, it is only know from 12 sites. The old growth mature forest habitat has become very rare due to timber logging during the last century, and the habitat is assessed as still declining (>60% population reduction in the past 100 years; i.e. two generations, based on >90% loss of old growth forest). All the sites where this species occurs contain considerably less than 250 mature individuals, and though the present sites are protected, the future of the habitat is insecure. It is assessed as Endangered (EN) under criteria A2c; C2a(i).
An ectomycorrhizal species characteristic for old-growth mature forests in the Pacific Northwest of North America, known only from 12 sites. Exemplary for the Phaeocollybia diversity that exists in western North America.
Phaeocollybia oregonensis is endemic to northwestern North America and is only known from 12 sites; two in western British Columbia, Canada (Vancouver Island and near Vancouver), one in Washington (USA) and nine in Oregon (USA).
It is known from 12 sites (Norvell and Exeter 2008). Fruiting is irregular. The species was re-discovered at the type locality more than 40 years after the first find. The herbarium database Mycoportal (mycoportal.org) contains records from only three sites. No recent observations by amateur mycologists species are known (mushroomobserver.org).
This species has been extensively searched for under the Northwest Forest Plan since 1998 (Castellano et al. 1999); despite these intensive survey efforts, the number of known sites has not increased.
Population Trend: Decreasing
Mycorrhizal and terrestrial in old-growth forests with a high amount of coarse woody debris, dominated by Abies, Tsuga heterophylla and Pseudotsuga menziesii (Norvell and Exeter 2008). It often fruits together with other Phaeocollybia species.
This is a ectomycorrhizal fungus species dependent on living host trees for viability. The major threat to this species and its co-occurring co-generic brethren is habitat destruction, viz. the logging of old-growth forests to which it is confined. The extent of old growth forest in the Pacific Northwest of North America has declined 90% in the last century (Society of American Foresters 1984, Haynes 1986).
Habitat protection: the known sites, especially the Mount Hood and the Larch Mountain sites in Oregon, have to be protected from logging and other disturbances.
This species is a so-called Strategy 1 species under the Northwest Forest Plan (Castellano et al. 1999), and has been surveyed and managed within the range of the northern spotted owl (Strix occidentalis caurina).
Castellano, M.A., Smith, J.E., O’Dell, T., Cazáres, E., and Nugent, S.. 1999. Handbook to strategy 1 fungal species in the Northwest Forest Plan. Gen. Tech. Rep. PNW-GTR-476. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 204 p.
Norvell LL, Exeter RL. 2008. Phaeocollybia of Pacific Northwest North America. USDI BLM/OR/WA/GI-08/100-1792. 228 p.
Smith AH, Trappe JM. 1972. The higher fungi of Oregon’s Cascade Head Experimental Forest and vicinity: I. The Genus Phaeocollybia (Agaricales) and notes and descriptions of other species in the Agaricales. Mycologia 64: 1138-1153.