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Sticta carolinensis T. McDonald

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Scientific name
Sticta carolinensis
Author
T. McDonald
Common names
 
IUCN Specialist Group
Lichens
Kingdom
Fungi
Phylum
Ascomycota
Class
Lecanoromycetes
Order
Peltigerales
Family
Lobariaceae
Assessment status
Published
Assessment date
2020-08-01
IUCN Red List Category
VU
IUCN Red List Criteria
B2ab(i,ii,iii,v)
Assessors
Lendemer, J.
Reviewers
McMullin, T.

Assessment Notes

The content on this page is fetched from The IUCN Red List of Threatened Species: https://www.iucnredlist.org/species/175710250/175710707

Justification

This species has an area of occupancy in the range of 432-532 km2, a severely fragmented population, and there are continuing declines in habitat quality observed and projected across its range. Tentatively, the higher estimate for the area of occupancy is used here, as this incorporates additional potential sites that have so far been unsampled. Thus, it is listed as Vulnerable under criterion B2ab(i,ii,iii,v). However, if further sites do not end up being found then the species could then warrant listing as Endangered.


Geographic range

Sticta carolinensis is endemic to south-eastern North America where it occurs from the southern Appalachian Mountains to the Coastal Plain (McDonald et al. 2003).

Population and Trends

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 690-1,380 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 (Yarnell 1998, Martinuzzi et al. 2015). 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 (Keyser et al. 2014, Klepzig et al. 2014, Cartwright and Wolfe 2016).

Population Trend: decreasing


Habitat and Ecology

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.

Threats

There are two primary pressures on 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 land, some of which is large in overall area and some of which is 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 urbanisation. All of these continue to be impacts to the species across its range, although threats vary depending on the individual site. Within the last 30-40 years, fragmentation has continued (Anderson et al. 2013, Klepzig et al. 2014) as the region has undergone rapid population growth. Available data indicate that the species is highly localised where it occurs. Furthermore, 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, while increasing fires are also impacting habitat quality.


Conservation Actions

Many areas where the species is known are within existing public lands, however locations outside of federally designated wilderness and National Parks could be subjected to resource extraction, habitat alteration or further fragmentation in the future. As such, additional protection of sites on both public and private lands is needed. Invasive species management is also needed to prevent or slow further large-scale alteration of forest stand structure and local environmental conditions. The species is not presently listed as threatened or endangered in any formal conservation framework, hence inclusion in existing policy and management frameworks is needed at both the national and regional levels. Additionally, increased education about the species and its threatened status is needed, as well as further research and conservation planning.

Source and Citation

Lendemer, J. 2020. Sticta carolinensis. The IUCN Red List of Threatened Species 2020: e.T175710250A175710707. https://dx.doi.org/10.2305/IUCN.UK.2020-3.RLTS.T175710250A175710707.en .Accessed on 31 January 2022

Country occurrence