This species was described by McDonald et al. (2003) from collections made throughout southeastern North America. Since that time no occurrences have been published from outside of this region despite extensive studies of Sticta worldwide. The species is easily recognized in the field by its brown foliose thallus, white medulla visible through the cyphellae, and abundant lobules.
This species is endemic to southeastern North America where it occurs from the southern Appalachian Mountains to the Coastal Plain (see McDonald et al. 2003).
The total and presumed extant EOO is 917961 km2, and AOO is 432 km2.
The population was likely naturally fragmented historically, occurring at sites in mature forest stands and spatially restricted habitat types. Where it occurs, the species is often locally abundant, occurring as 1-5 clustered functional individuals. The current population size is estimated at 690-1380 individuals based on a conservative estimate of 5-10 functional individuals per site, and the known occurrence at 138 sites. We suspect that the population declined historically (during the last 3 generations; 90 years, based on a 30 year generation time) due to extensive of logging, habitat loss, and land use change throughout its range (Martinuzzi et al. 2015, Yarnell 1998). 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 (e.g., Ervin 2016). We suspect that the already fragmented and reduced population is currently decreasing due to numerous ongoing and projected trends in anthropogenic and climate change impacts that would directly affect this species (Cartwright & Wolfe 2016; Keyser et al. 2013, Klepzig et al. 2014).
ASSESSMENT: Endangered B2a,b(iii)
This species is assessed as Endangered under criterion B2 based on the current AOO (432 km2), the severely fragmented population, and the continuing declines in quality of habitat observed and projected across its range.
Population Trend: Decreasing
Sticta carolinensis primarily occurs on the bark of mature hardwood trees, although it also occasionally is found on shaded non-calcareous rock outcrops. It is restricted to high quality, mature forest stands and is typically associated with humid habitats such as riparian corridors and swamps.
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 in existing public lands, some of which are large in overall area and some of which are protected from resource extraction and other impacts. However the species naturally occurs in isolated locations 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, drier habitats as well as more generally within a highly fragmented matrix anthropogenic land uses). These naturally dispersed locations were degraded and fragmented historically (last 90 years) due to extensive logging, building of roads, alteration of riparian corridors by dams, ditching/draining of swamps, air pollution, agriculture and urbanization. All of the above are still impacts to the species across its range, although threats vary depending on the individual site. Within the last 30-40 years, fragmentation has continued as the region has undergone rapid population growth. Available data indicate that the species is highly localized where it occurs, the habitat it occurrs in has become fragmented in the past and is increasingly fragmented in present (Anderson et al. 2013, Klepzig et al. 2014). Further the region is currently experiencing climate change impacts (increased fire frequency and severity, droughts, sea level rise) and extensive alteration of forest communities due to invasive species.
Many areas where the species is known are within existing public lands, however locations outside of National Parks and federally designated wilderness can 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.