Lepra andersoniae has a limited Extent of Occurrence (4,027 km2) and Area of Occupancy (16 km2), a limited number of locations (3), and there are ongoing declines in habitat quality inferred from the large-scale changes to southern Appalachian spruce-fir ecosystems as a result of changing climate and environmental conditions. The species occurs in highly visited areas and may be threatened by recreation either directly through trampling/damage to rock habitats, or indirectly through expansion or improvement of recreation infrastructure. Therefore, it is listed as Endangered under criteria B1ab(iii)+2ab(iii).
The total population is distributed across fewer than 10 sites comprising three geographically restricted subpopulations. The Virginia subpopulation was located in 1936 and confirmed extant in 2016 (estimate, 20 functional individuals). The Roan Mountain (North Carolina) subpopulation was located in 1993, relocated in 1994, and confirmed extant in 2019 (estimate, 20-50 functional individuals). The Grandfather Mountain (North Carolina) subpopulation was located in 1935, relocated in 2020, and is estimated to comprise 300-500 individuals (the large range is due to inaccessibility of shear vertical rock faces). We estimate a maximum total of 570 extant individuals comprise the population, and 87% of these are located in a single subpopulation at one location.
Population Trend: stable
Damage to colonies of this species from recreational use of the habitat poses a threat to all subpopulations, each of which is located in fragile natural communities in highly visited areas. Across its range, the species is threatened by changing climate and environmental conditions (Keyser et al. 2014), including from changes in cloud cover and humidity in high-elevation rock outcrops (Cullata and Horton 2014), and loss of shade from mature, healthy spruce-fir forest due to the Balsam Wooly Adelgid (Rose and Nicholas 2008, Rollins et al. 2010, White et al. 2012). Logging or other land use change would also result in major declines to the population of this species.
The species is not currently included on lists of threatened taxa, but it occurs in the Great Smoky Mountains, and on National Forest and State Park land. Monitoring of all extant subpopulations is required to confirm that the species has stabilised. Detailed surveys and increased protection for suitable habitat is also needed. A species-based management plan needs to be developed, and the species needs to be incorporated into existing management plans for suitable habitat and extant sites. Increased education about the species, its ecology, and how it could be conserved would also be highly beneficial.