Habitats of North Carolina
Habitat Group:
Habitat Type:
Members of Conifer Forests:
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Conifer Forests
Hemlock Forests
General Description This habitat consists of stands of both Eastern Hemlock (Tsuga canadensis) and Carolina Hemlock (Tsuga caroliniana). Consequently, it includes both the mesic forested sites preferred by T. canadensis as well as the dry, rocky, exposed sites occupied by T. caroliniana. Most occurrences are located in the mountains but they also extend into the foothills and the extreme western Piedmont; an isolated stand -- probably a Pleistocene relict -- occurs as far east as Wake County at the Hemlock Bluff Nature Preserve. Another uniting feature of this habitat is the common threat represented by the introduced Hemlock Wooly Adelgid, which has been detected on both species of Hemlocks and has been found in all areas occupied by these species.

Although the two species of Hemlocks do not individually occupy the entire range of this habitat, we include the as Determining Species based on the major threat they have in common in the Adelgid.

In addition to the two species of hemlocks, members of this habitat include a number of herbivorous insects that are strongly associated with hemlocks. In addition to Macaria fissinotata, which is narrowly limited to Tsuga, species are included in this group that feed to some extent on spruce or fir but that have the majority of their occurrences located below 4,000'. All of these species are highly threatened by the depredations of the Hemlock Wooly Adelgid although a few that also feed on spruce or fir may find some refuge in the small, remaining conifer forests located above 4,000', which face their own significant problems.

Abiotic Factors
Biotic Structure
Co-evolved Species Groups Phagic and Competitory Symbioses:
Tsuga-Picea-Abies // Caripeta divisata-Cladara limitaria-Eufidonia notataria-Eupithecia lariciata-Eupithecia mutata-Feralia comstocki-Feralia jocosa-Hydriomena divisaria-Macaria signaria-Nepytia canosaria-Syngrapha rectangula
Tsuga species // Gyponana striata-Macaria fissinotata

Determining Species
Tsuga carolinianaCarolina HemlockG2G3S2S20.03699
Tsuga canadensisEastern HemlockG5S4S5S4S50.00010
Gyponana striataSNR
Coleotechnites apicitripunctellaGreen Hemlock NeedleminerGNRS2S3S2S30.01230
Coleotechnites macleodiBrown Hemlock NeedleminerGNRS2S3S2S30.01230
Eufidonia notatariaPowder MothG5S3S4S3S40.00132
Macaria fissinotataHemlock Angle MothG5S4S40.00041
Nepytia canosariaFalse Hemlock LooperG5S4S40.00041
Eupithecia lariciataLarch Pug MothG5SUSU0.00202
Nr = Number of Ranked Species = 8
Ner = Number of Extant, Ranked Species = 8
Nv = Number of Historic and Extirpated Species = 0
Nar = Number of Species at Risk of Extirpation (State rank > S5) = 8
Nss = Number of Secure Species (State Rank = S5) = 0
Pss = Proportion of Secure Species (Nss/Ner) = 0.00000
ENE = Expected Number of Extirpations (Sum of PE) = 0.06585
Average PE (ENE/Ner) = 0.00823
Habitat Risk Index = (Nar+Nv) x Average PE = 8 x 0.00823 = 0.06584

Estimated Risk to the Determining Species
Estimated Risk to the Co-evolved Species Groups
Estimated Security of the Habitat
Index of Habitat Imperilment
Identified Risks
Observed Trends
Distribution Map
Major Conservation Reserves
Priority Areas for Surveys and Conservation Protection
Stewardship and Management Recommendations
References Adkins, J.K. and Rieske, L.K., 2013. Loss of a foundation forest species due to an exotic invader impacts terrestrial arthropod communities. Forest Ecology and Management, 295, pp.126-135.

Buck, S. L., P. Lambdin, D. Paulsen, J. Grant, and A. Saxton.2005. Checklist of insect species associated with eastern hemlock in the Great Smoky Mountains National Park and environs. Tenn. Acad. Sci. 80: 1-10.

Updated on 2022-09-26 03:35:22