Described from a collection made in Sierra County, California, USA (Petersen 1988).
Field identification can be tricky, as some collections are difficult to distinguish from the Ramaria rasilispora/magnipes complex without microscopic examination, and thus, many populations are probably overlooked in the field.
Coastal collections should be compared genetically with montane collections, as they may pertain to a distinct species.
Ramaria thiersii is an uncommon but widespread species in the California and the Pacific Northwest, currently known from ~25 locations, but likely under reported due to the difficultly distinguish it from the common Ramaria rasilispora/magnipes complex without microscopic examination.
Habitat requirements are largely unknown, but it appears to be restricted to mature or old growth forests, which are in decline in the Pacific Northwest due to stand replacing fires and logging.
Based on the taxonomic questions, lack of knowledge regarding habitat requirements, and population extent in the Sierra Nevada, I suggest listing as Data Deficient (DD).
In the mountains, it is known from the Sierra Nevada in California, the Cascade Range in California and Oregon, and the northern Rocky Mountains in Idaho. It is also reported from coastal collections in Mendocino County, California, USA and British Columbia, Canada; these collections should be regarded with some skepticism, and be compared genetically with montane collections.
Population occurs over a widespread area, with fairly continuous records in the Sierra Nevada range in California, and more disjunct populations in the Cascade Range, the Rocky Mountains in Idaho, and clusters of coastal northern California and British Columbia collections. Currently known from ~25 locations (Siegel et al. 2019, Mycoportal 2021), but likely under reported from the California mountains. Data to fully assess trends is lacking.
Population Trend: Uncertain
Ectomycorrhizal with conifers, likely with fir (Abies spp.). Most collections come from drier montane conifer forest in the Sierra Nevada and eastern slopes on the Cascade Range. Fruiting in spring or early summer. Many records do not include detailed habitat information. A few of the recent collections appear to be from areas with old growth or late seral stage Abies forests, but data tying this species to a specific habitat type is lacking.
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, via the logging of old-growth forests to which this species has a preference for. 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).
Climate change and droughts, along with forest management practices has made western forests highly susceptible to stand replacing forest fires. Fire is big threat to this species’ populations. A stand replacing fire could severely degrade and/or diminish its current range. Logging and machine clearing of understory vegetation should be limited in mature and old growth forest in areas where this species might occur.
This species is included on the United States Forest Service Northwest Forest Plan Survey and Manage list of rare/old growth forests dependent fungi, and has been actively surveyed for since the late 1990’s. (Castellano et al. 1999). Included on the Oregon Natural Heritage rare fungi list (Oregon Biodiversity Information Center 2019), as a S2 species.
Logging or machine clearing of understory should be limited in mature (or old growth forest) in areas this species in known to occur.
A better understanding of habitat requirements of this species, and if it is restricted to mature and old growth forests. Continued surveys for this species, especially in the central and southern Sierra Nevada in California. Genetic research and modern taxonomic work comparing coastal and montane collections.
Castellano, M.A., Smith, J.E., O’Dell, T., Cázares, E. and Nugent, S. 1999. Handbook to Strategy 1 Fungal Species in the Northwest Forest Plan. U. S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: Portland, OR. 195 p.
Exeter, R.L., Norvell, L. and Cázares, E. 2006. Ramaria of the Pacific Northwestern United States. United States Department of Interior, Bureau of Land Management: Salem, OR. 157 p.
Haynes, T.W. 1986. Inventory and value of old-growth in the Douglas-fir region. PNW-RN 437. U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, Portland, OR.
MyCoPortal. 2021. http://mycoportal.org/portal/index.php. Accessed on February 17.
Oregon Biodiversity Information Center. 2019. Rare, Threatened and Endangered Species of Oregon. Institute for Natural Resources, Portland State University, Portland, Oregon.
Petersen, R.H. 1988. Vernally fruiting taxa of Ramaria from the Pacific Northwest. Mycotaxon 33: 101–144.
Siegel, N., Vellinga, E.C., Schwarz, C., Castellano, M.A. and Ikeda, D. 2019. A Field Guide to the Rare Fungi of California’s National Forests. Bookmobile: Minneapolis, MN. 313 p.
Society of American Foresters. 1984. Scheduling the harvest of old growth : Old-growth forests in the Pacific Northwest : a position of the Society of American Foresters and Report of the SAF Task Force on Scheduling the Harvest of Old-Growth Timber. Bethesda, MD.