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Arthopyrenia betulicola R.C. Harris, E. Tripp, & Lendemer

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Scientific name
Arthopyrenia betulicola
R.C. Harris, E. Tripp, & Lendemer
Common names
IUCN Specialist Group
Assessment status
Assessment date
IUCN Red List Category
IUCN Red List Criteria
Allen, J., Lendemer, J., McMullin, T. & Tripp, E.
Yahr, R.

Assessment Notes

The content on this page is fetched from The IUCN Red List of Threatened Species: https://www.iucnredlist.org/species/80702824/80702827


This southern Appalachian endemic species has a restricted range, split into 10 subpopulations. The overall population size is extremely small (c.100 mature individuals), with a maximum subpopulation size of 10 mature individuals. Ongoing declines are projected to occur as a result of the impacts of climate change, and invasive pests impacting the species’ habitat. Therefore, it is listed as Critically Endangered C2a(i).

Geographic range

Arthopyrenia betulicola is narrowly endemic to the southern Appalachians and grows only on the bases of large, mature individuals of Yellow Birch (Betula alleghaniensis). It is currently known only from two mountain ranges, the Great Smoky Mountains, where most documented subpopulations occur, and the Black Mountains, where only two subpopulations have been documented.

Population and Trends

There are currently 10 documented subpopulations of this species. Nine of the subpopulations are well protected in the Great Smoky Mountains National Park, and one subpopulation occurs in the Pisgah National Forest in the Black Mountains. All documented populations are small, consisting of 1-10 mature individuals. Widespread clear-cutting of forest in the Appalachian Mountains in the 19th and 20th century likely extirpated most populations of this species, leaving just the few that survive today. More recently, the drastic impacts of the invasive Balsam Woolly Adelgid (Adelges piceae) on Abies fraseri has substantially reduced the habitat quality.

Population Trend: unknown

Habitat and Ecology

The only known host for this species is Yellow Birch (Betula alleghaniensis), and it is ecologically restricted to the bases and sheltered faces of large, mature individuals (Harris et al. 2013). It has not been observed on young individuals of the tree, on trees in marginal habitats, or on other species of Betula.


The greatest current threats to this species are habitat degradation due to invasive pests (e.g. Balsam Woolly Adelgid, Adelges piceae) and climate change. Currently, all known populations are found on National Park, State Park and National Forest lands. As all known populations occur within management units protected from logging, road building, utility right-of-ways, development, and other changes in land use, the species is not considered to be threatened by these factors at this time, although logging may have impacted the species in the past. Pollution (acid rain) may also be having an impact on the species. Climate change impacts are based on projected species distribution models projected to 2050 and 2070 using two different climate change models (CCSM4 and HadGEM2-AO) at the lowest and highest carbon dioxide concentration (2.6 and 8.5 rcp) were recently built in Maxent for this species (Allen and Lendemer, in review). The results of the modelling predict an average suitable habitat loss of 99.7% with a minimum loss of 97.4% and a maximum loss of 100% (ibid.). This would represent a significant decrease in the Area of Occupancy and Extent of Occurrence for the species. 

Conservation Actions

Any changes in land use or alterations of currently documented populations are likely to result in the extirpation of this species, particularly if large individuals of Yellow Birch are removed from the forest. Thus, all areas where this species is known to occur should continue to be protected following existing, or more robust, regulations. Because climate change is the greatest threat to this species, global and regional reduction of greenhouse gasses is essential. Monitoring and planning for the conservation of the species would also be beneficial.

Source and Citation

Allen, J., Lendemer, J., McMullin, T. & Tripp, E. 2020. Arthopyrenia betulicola. The IUCN Red List of Threatened Species 2020: e.T80702824A80702827. https://dx.doi.org/10.2305/IUCN.UK.2020-3.RLTS.T80702824A80702827.en .Accessed on 3 February 2024

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