Habitats of North Carolina
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General Shrublands
Montane Rhododendron Thickets and Balds
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General Description Dense and extensive thickets composed of Rhododendrons are conspicuous features of acidic coves in the mountains, where they are commonly referred to as "Rhododendron Hells". Rhododendrons also grow out in the open on high elevation heath balds.

This habitat is associated with montane climates. A few species, such as Rhododendron maximum and R. catawbiense, that occur in the Piedmont are included in the Cool Mesic Forests habitat although they are also major components of Rhododendron thickets in the Mountains. Animal species belonging to this habitat include herbivores that specialize on Rhododendrons and two species that rely on Rhododendron thickets for cover.

Abiotic Factors Geographic Regions: Low to High Mountains. USDA Hardiness Zones: 6a-6b. Landform: slopes, ridges, ravines, and bottomlands. Slope Aspect: all aspects, particularly above 4,000'. Soil Moisture: Mesic. Soil texture: rocky to loamy. Soil pH: acidic. Soil Nutrient Content: nutrient poor. Microclimate: Cool and humid. Hydrological Features: springs and seeps are common, particularly at the interface between slopes and bottomlands. Fire Frequency: very rare. Drought Frequency: uncommon to rare. Ice Storm Damage: moderate to severe. Wind Storm Damage: moderate. Insolation: heath balds are well insolated but acidic cove forests are deeply shaded

Biotic Structure Vegetation Type: open shrublands to closed canopy forests Strata: forest canopy is present or absent; the herb layer is typically sparse. Woody debris and leaf litter: logs and fallen branches are common; leaf litter can be plentiful

Co-evolved Species Groups Phagic and Competitory Symbioses
Rhododendron species // Lyonetia latistrigella-Synanthedon rhododendri

Determining Species
sciNamecomNameg_ranks_rankmod_s_rankprob_of_extirpation
BIRDS
Cardellina canadensisCanada WarblerG5S4S40.00041
MAMMALS
Sylvilagus obscurusAppalachian CottontailG4S3S30.00407
MOTHS
Synanthedon rhododendriRhododendron Borer MothGNRSUS1S30.03699
Lyonetia latistrigellaRhododendron Leaf MinerGNRSUS2S30.01230
Caloptilia porphyreticaSH
SHRUBS
Rhododendron cumberlandenseCumberland AzaleaG4S1S10.33330
Rhododendron carolinianumCarolina AzaleaG4S3S30.00407
Rhododendron vaseyi Pink-shell AzaleaG3S3S30.00407
Rhododendron pilosumMinniebushG4G5S4S40.00041
Nr = Number of Ranked Species = 9
Ner = Number of Extant, Ranked Species = 8
Nv = Number of Historic and Extirpated Species = 1
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) = 0.39562
Average PE (ENE/Ner) = 0.04945
Habitat Risk Index = (Nar+Nv) x Average PE = 9 x 0.04945 = 0.44505

Estimated Risk to the Determining Species Two species are ranked as S2 or higher and the Average PE is equivalent to a state rank of S2
Estimated Risk to the Co-evolved Species Groups
Estimated Security of the Habitat No species in this group are considered secure
Index of Habitat Imperilment The combination of a relatively high Average PE and one historic species produces a relatively high value of HRI for an otherwise fairly small number of species. It falls within our Tier 3 of Conservation Concern (0.5 ≥ HRI > 0.05), indicating a moderate priority for conservation actions.

Identified Risks
Observed Trends
Distribution Map
Distribution
Major Conservation Reserves
Priority Areas for Surveys and Conservation Protection
Stewardship and Management Recommendations
References
Updated on 2023-01-24 21:52:43