Cetradonia linearis
(Evans) Wei & Ahti
Rock Gnome Lichen
G3VulnerableGlobal Rank
VulnerableIUCN
HighThreat Impact
Bonnie Isaac, CC0 1.0
Curtis Hansen, CC BY 4.0
Curtis Hansen, CC BY 4.0
Bonnie Isaac, CC0 1.0
Hill Craddock, CC BY 4.0
Identity
Unique IDELEMENT_GLOBAL.2.124874
Element CodeNLLEC75010
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryFungus
IUCNVulnerable
Endemicendemic to a single nation
KingdomFungi
PhylumAscomycota
ClassLecanoromycetes
OrderLecanorales
FamilyCladoniaceae
GenusCetradonia
Synonyms
Gymnoderma lineare(A. Evans) Yoshim. & Sharp
Other Common Names
rock gnome lichen (EN)
Concept Reference
Esslinger, T.L. and R.S. Egan. 1995. A sixth checklist of the lichen-forming, lichenicolous, and allied fungi of the continental United States and Canada. The Bryologist 98(4): 467-549.
Taxonomic Comments
Esslinger (2018) transfers Gymnoderma lineare to Cetradonia linearis; these represent the same concept for the element.
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2023-12-28
Change Date2013-05-13
Edition Date2023-12-28
Edition AuthorsWeakley, Alan; rev. G. Davis (2000), B. MacBryde (2000), rev. Eberly (2023)
Threat ImpactHigh
Range Extent5000-20,000 square km (about 2000-8000 square miles)
Number of Occurrences81 - 300
Rank Reasons
Cetradonia linearis is a fruticose lichen endemic to the high mountains of the southern Appalachians in the eastern United States. There are over 85 occurrences spread across Georgia, North Carolina, South Carolina, Tennessee, and Virginia. It is threatened by habitat change especially due to the loss of Fraser-fir and Hemlock forests and by heavy recreational use of its habitat. Reduced cloud immersion as a result of climate change is also a concern for this species which is sensitive to desiccation. Continuous monitoring is necessary to understand trends, populations sizes, and the impact of threats to this species.
Range Extent Comments
Cetradonia linearis occurs in the eastern United States where it is restricted to the southern Appalachian Mountains in Virginia, North Carolina,Tennessee, South Carolina, and Georgia.
Occurrences Comments
According to the United States Fish and Wildlife Service (2020), there are 85 occurrences (populations).
Threat Impact Comments
The greatest concern for this species is a warming and drying of its humid and shady microclimate that is largely created by conifer forest and cloud immersion (high elevation sites). The death of Fraser-fir forests due to wooly adelgid infestation adjacent to the habitat where Cetradonia linearis occurs has caused changes in the local microclimate, including desiccation and increased temperatures (USFWS 1995, 2020; Abella 2014). At lower elevations, hemlock have declined due to multiple pests including Hemlock Wooly Adelgid (Kantola et al. 2014). In addition, frequent cloud immersion at high elevations is predicted to decrease with climate change (Culatta and Horton 2014).
Recreational development and activities, like rock climbing and hiking, can damage lichens through trampling or scrape them from rocks causing mortality (USFWS 1995, 2020). Logging is a threat, as it may reduce humidity and expose lichens to direct sunlight, but species protections have led to restrictions of this activity (USFWS 2020). Development may impact a few populations on private land (NatureServe 2023).
Air pollution may be a threat to population health and viability and fog is known to concentrate air pollutants (Isil et al. 2022).
Recreational development and activities, like rock climbing and hiking, can damage lichens through trampling or scrape them from rocks causing mortality (USFWS 1995, 2020). Logging is a threat, as it may reduce humidity and expose lichens to direct sunlight, but species protections have led to restrictions of this activity (USFWS 2020). Development may impact a few populations on private land (NatureServe 2023).
Air pollution may be a threat to population health and viability and fog is known to concentrate air pollutants (Isil et al. 2022).
Ecology & Habitat
Habitat
This species grows in two different habitats with low light and high humidity: boulders and cliffs at high elevations and at lower elevation, rock outcrops associated with seeps and high humidity. It is further described as "found in areas of high humidity, either on high-elevation cliffs, where it is frequently bathed in fog, or in deep river gorges at lower elevations. It is primarily limited to vertical rock faces, where seepage water from forest soils above flows at (and only at) very wet times, and large stream side boulders, where it receives a moderate amount of light but not high-intensity solar radiation" (USFWS 2000, 2020).
Terrestrial Habitats
Forest/WoodlandForest - ConiferBare rock/talus/screeCliff
Palustrine Habitats
Riparian
Other Nations (1)
United StatesN3
| Province | Rank | Native |
|---|---|---|
| Georgia | S1 | Yes |
| South Carolina | S1 | Yes |
| Virginia | S1 | Yes |
| North Carolina | S3 | Yes |
| Tennessee | S1 | Yes |
Threat Assessments
| Threat | Scope | Severity | Timing |
|---|---|---|---|
| 1 - Residential & commercial development | Small (1-10%) | Serious - moderate | High (continuing) |
| 5 - Biological resource use | Unknown | Serious - moderate | Insignificant/negligible or past |
| 5.3 - Logging & wood harvesting | Unknown | Serious - moderate | Insignificant/negligible or past |
| 6 - Human intrusions & disturbance | Pervasive (71-100%) | Moderate or 11-30% pop. decline | High (continuing) |
| 6.1 - Recreational activities | Pervasive (71-100%) | Moderate or 11-30% pop. decline | High (continuing) |
| 8 - Invasive & other problematic species, genes & diseases | Pervasive (71-100%) | Moderate or 11-30% pop. decline | High (continuing) |
| 8.1 - Invasive non-native/alien species/diseases | Pervasive (71-100%) | Moderate or 11-30% pop. decline | High (continuing) |
| 8.1.2 - Named species | Pervasive (71-100%) | Moderate or 11-30% pop. decline | High (continuing) |
| 11 - Climate change & severe weather | Large (31-70%) | Moderate or 11-30% pop. decline | High (continuing) |
| 11.1 - Habitat shifting & alteration | Large (31-70%) | Moderate or 11-30% pop. decline | High (continuing) |
Plant Characteristics
Economic Value (Genus)No
Roadless Areas (4)
North Carolina (4)
| Area | Forest | Acres |
|---|---|---|
| Bearwallow | Pisgah National Forest | 4,113 |
| Graveyard Ridge (addition) | Pisgah National Forest | 1,958 |
| Sam Knob (addition) | Pisgah National Forest | 2,576 |
| Wilson Creek | Pisgah National Forest | 4,863 |
References (10)
- Abella, S.R. 2014. Impacts and Management of Hemlock Woolly Adelgid in National Parks of the Eastern United States. Southeastern Naturalist 13(6):16-45.
- Culatta, K.E. and J.L. Horton. 2014. Physiological Response of Southern Appalachian High-Elevation Rock Outcrop Herbs to Reduced Cloud Immersion. Castanea 79:182-194.
- Dey, J.P. 1978. Fruticose and foliose lichens of the high-mountain areas of the Southern Appalachians. The Bryologist 81(1): 1-93.
- Esslinger, T. L. 2018. A cumulative checklist for the lichen-forming, lichenicolous and allied fungi of the continental United States and Canada, Version 22. Opuscula Philolichenum 17:6-268. [http://sweetgum.nybg.org/philolichenum/]
- Esslinger, T.L. and R.S. Egan. 1995. A sixth checklist of the lichen-forming, lichenicolous, and allied fungi of the continental United States and Canada. The Bryologist 98(4): 467-549.
- Kantola, T., P. Lyytikäinen-Saarenmaa, R. Coulson, S. Strauch, M. Tchakerian, M. Holopainen, H. Saarenmaa, and D. Streett. 2014. Spatial Distribution of Hemlock Woolly Adelgid Induced Hemlock Mortality in the Southern Appalachians. Open Journal of Forestry 4:492-506.
- Southern Appalachian Species Viability Project. 2002. A partnership between the U.S. Forest Service-Region 8, Natural Heritage Programs in the Southeast, NatureServe, and independent scientists to develop and review data on 1300+ regionally and locally rare species in the Southern Appalachian and Alabama region. Database (Access 97) provided to the U.S. Forest Service by NatureServe, Durham, North Carolina.
- U.S. Fish and Wildlife Service (USFWS). 1995. Endangered and threatened wildlife and plants; <i>Gymnoderma lineare</i> (rock gnome lichen) determined to be endangered. Federal Register 60(11): 3557-3562.
- U.S. Fish and Wildlife Service (USFWS). 2000. Endangered and Threatened Wildlife and Plants; Determination of Whether Designation of Critical Habitat is Prudent for the Rock Gnome Lichen. Federal Register 66: 18062-18068.
- U.S. Fish and Wildlife Service (USFWS). 2020. Rock gnome lichen (<i>Gymnoderma lineare</i>) 5-Year Review: Summary and Evaluation, 2020 Addendum. U.S. Fish and Wildlife Service Southeast Region Asheville Ecological Services Field Office Asheville, North Carolina.