Arthonia kermesina grows only on the bark of large, mature individuals of red spruce (Picea rubens) in high-elevation forests of the southern Appalachians where it is restricted to small areas of two mountain ranges: the Great Smoky Mountains and Black Mountains (Allen & Lendemer 2016, Lendemer et al. 2013). This species is most threatened by climate change and habitat loss. Ensuring the continued existence of high-quality, old-growth spruce forests in the high-elevations of the southern Appalachians is essential for the continued existence of this species. This species warrants Endangered status under the A2c criterion due to an estimated historical decline of 52% in the species Area of Occupancy, and thus a loss of >50% of previously extant populations. This estimated decline is based on species distribution models. First, the suitable habitat was modelled throughout the region and used as the estimated historical distribution and AOO, resulting in an area of 1069.8 km². Then, areas that were predicted to be climatically suitable for the species, but where it does not currently occur, most likely due to logging history, were removed resulting in an estimated current AOO of 518.5 km². The resulting figures were used to estimate a 52% decline within the past three generations (~100 years). This estimated decline is further supported by the documented land use history of the spruce-fir forest on which this species relies, since it was subject to over extensive clear cut logging over the same time period after which as much as 53% of this forest type was replaced by hardwoods (Noss et al. 1995, White et al. 2012). Additionally, most of the remaining old-growth spruce-fir forest occurs in Great Smoky Mountains National Park, where this species is most abundant (Rose & Nicholas 2008).
It also qualifies as Endangered under criterion B1 due to its small extent of occurrence (1210 km²) in combination with severe fragmentation of the population and continuing decline in area of occupancy, extent of occurrence, extent and quality of habitat, number of subpopulations, and number of mature individuals.
Additionally, it qualifies as Endangered under criterion D as its population size is estimated as 160-220 mature individuals.
Assessor/s: Allen, J., Tripp, E. & Lendemer, J.; Reviewer/s: Scheidegger, C.; Contributor(s): Weerakoon, G. & Læssøe, T.
Allen, J.L. & Lendemer, J.C. (2016) Loss of endemic, high-elevation lichens predicted in a biodiversity hotspot. Biodiversity and Conservation22: 555-568.
IUCN (2019) The IUCN Red List of Threatened Species. Version 2019-3. Available at: www.iucnredlist.org. (Accessed: 10 December 2019).
IUCN (2020) The IUCN Red List of Threatened Species. Version 2020-2. Available at: www.iucnredlist.org. (Accessed: 13 June 2020).
Lendemer, J.C., R.C. Harris, & E.A. Tripp (2013) The Lichens and Allied Fungi of Great Smoky Mountains National Park: : an annotated checklist with comprehensive keys. Memoirs of The New York Botanical Garden104(i-viii): 1-152.
Natural Heritage Program (2014) List of Rare Plant Species of North Carolina. In: L.G. Robinson & J.T.Finnegan (eds), List of Rare Plant Species of North Carolina, North Carolina Natural Heritage Program, Raleigh.
Noss, Reed F., Edward Terhune LaRoe, & J. Michael Scott (1995) Endangered ecosystems of the United States: a preliminary assessment of loss and degradation. US Department of the Interior, National Biological Service, Washington, DC-USA.
Rose, A. & Nicholas, N. S. (2008) Coarse woody debris in a Southern Appalachian spruce-fir forest of the Great Smoky Mountains National Park. Natural Areas Journal28: 342-355.
White, P.B., S.L. van de Gevel, & P. T. Soulé (2012) Succession and disturbance in an endangered redspruce-Fraser fir forest in the southern Appalachian Mountains, North Carolina, USA. Endangered Species Research18: 17-25.
Find out more about the IUCN Red List Categories and Criteriahere.