Sticta fragilinata was described by McDonald et al. (2003) from eastern North America. Morphologically distinct individuals will smaller thalli outside of the core-range of S. fragilinata were subsequently shown to be distinct by Lendemer & Goffinet (2015) and S. fragilinata was confirmed as a southern Appalachian endemic with a restricted range. The species is easily recognized by its brown, foliose thallus, orange medulla visible through the cyphellae, and abundant marginal lobules.
The species is endemic to the southern Appalachian Mountains of eastern North America (Georgia, North Carolina, South Carolina Tennessee) (see McDonald et al. 2003, Lendemer & Goffinet 2015).
The total and presumed extant EOO is 19550 km2, and AOO is 348 km2.
The population of this species was likely naturally fragmented historically, occurring at sites in mature forest stands located in spatially restricted habitat types. At a site, the species is typically locally abundant, occurring as 1-5 clustered functional individuals. The current population size is estimated at 550-1110 individuals based on a conservative estimate of 5-10 functional individuals per site, and the known occurrence at 111 sites. We suspect that the population has declined historically (during the last 3 generations; 90 years, based on a 30 year generation time) due to the extensive history of logging throughout its range (1900-1970; Mastran & Lowerre 1983, Yarnell 1998), as well as substantial impacts air pollution and acid rain/fog. These activities have led the present extant population to become highly fragmented, as the species is restricted to mature forest stands in suitable habitat and these areas have become very limited in extent and are no longer contiguous (Ervin 2016). We suspect that the already fragmented and reduced population is currently decreasing due to numerous ongoing and projected trends in anthropogenic impacts that would directly affect this species (Keyser et al. 2013).
ASSESSMENT: Endangered B2a,b(iii)
This species is assessed as Endangered under criterion B2 based on the current AOO (348 km2), the severely fragmented population, and the continuing declines in quality of habitat observed and projected across its range.
Population Trend: Decreasing
The species is restricted to mature forest stands in high quality habitats with high humidity, especially riparian corridors and northern hardwood forests. It occurs primarily on the bark of hardwoods, especially mature sugar maple (Acer saccharum), buckeye (Aesculus flava) and oaks (Quercus montana, Q. rubra).
There are two primary threats to this species, habitat fragmentation and loss (historical and ongoing) and impacts from air pollution and climate change (historical, ongoing and projected). The species occurs primarily on existing public lands, some of which are large in overall area and some of which are available for multiple uses including resource extraction (Anderson et al. 2013). However the species naturally occurs in isolated sites where suitable habitat exists within large areas that are not suitable (i.e., mature forest stands with high humidity are spatially restricted within a matrix of younger forests, forests without appropriate tree hosts, and drier habitats). These naturally dispersed locations were degraded and fragmented historically due to extensive logging, building of roads alteration of riparian corridors by dams, and air pollution. Logging is ongoing at small scales within the range of the species. Fragmentation has continued as the region has undergone rapid population growth, suburbanization and development of non-primary residences/infrastructure for vacation and recreation. Hence available data indicates that the species is highly localized where it occurs, the habitat it has occurred in has become fragmented in the past and is increasingly fragmented in present (Anderson et al. 2013). Further the region is currently experiencing climate change impacts (increased fire frequency and severity, droughts, increased temperatures, decreased precipitation) and extensive alteration of forest communities due to invasive species (Keyser et al. 2014), all of which are likely to impact the species.
Many areas where the species is known are within existing public lands, however locations outside of National Parks and federally designated wilderness could be subjected to resource extraction or further fragmentation in the future. Increased education about the species and its threatened status is needed. Inclusion in local and national conservation policy is needed.
The distribution and ecology of the species are well known, however location level demographic data and population estimates are needed. Targeted efforts to locate additional populations in suitable habitat are needed. A monitoring and recovery plan needs to be developed.