Mycoporum biseptatum is endemic to high elevations in the southern Appalachian Mountains of eastern North America. It grows on shrubs in disjunct northern hardwood forests and globally unique, endangered spruce-fir forests. The narrow distribution, small area of occupancy (AOO; 24-192 km2), small number of locations (6-48), and threats to the ecosystems in which it lives, which include invasive species, climate change, resource extraction and recreation, all contribute to the vulnerable status of the species. A decline of at least 30% in population size is suspected to occur within the next 36 years (three generations). Therefore, it is assessed as Vulnerable under criterion A3c, and precautionarily under criterion B1ab(iii)+2ab(iii) too.
The population size of this species is suspected to be small, however, exact estimates of the number of individuals require additional targeted study. The population is presently suspected to be stable, based on the fact that the species occurs on the recent growth of understory shrubs that are abundant in the suitable high elevation habitat. However, based on projected reductions for other species with comparable ecology and distribution (e.g. Lecanora masana), we suspect a reduction of 30-40% in the population will occur in the next three generations (36 years). The highest elevation sites are found in spruce-fir forest, which have been, and continues to be, significantly negatively impacted by the invasive Balsam Woolly Adelgid. At the same time, the lowest elevation sites are likely to be negatively impacted by hotter drier climates (Allen and Lendemer 2016).
Population Trend: stable
The primary threats to this species involve ongoing and future impacts to its suitable habitat from climate change. These threats include increased frequency and intensity of fires, damage to intact vegetation from increased storm severity and intensity, and changes to available suitable habitat due to shifts and extreme temperatures. Although Mycoporum biseptatum does not grow on host plants directly targeted by resource extraction, logging is a threat to the species as a result of unintentional impacts from damage to non-target species. One of the subpopulations in North Carolina occur on public lands outside of protected wilderness areas where logging and other forms of resource extraction can occur. Ecosystem scale changes in climate due to the loss of keystone forest canopy species from introduced pathogens are also threats to this species, specifically loss of Frasier Fir (Abies fraseri) in spruce-fir forests due to the Balsam Wooly Adelgid, and American Beech (Fagus grandiflora) in northern hardwood forests due to Beech Scale Insect (Cryptococcus fagisuga) which vectors several fungal species (Neonectria faginata, Neonectria ditissima, and Bionectria ochroleuca). All known occurrences of this species are in highly visited recreation areas and damage to natural vegetation from recreation, and cutting of shrubs to maintain recreation infrastructure, likely threaten species. Clearing of vegetation to maintain road and utility right-of-ways likely also threatened this species in a similar ways.