Habitats of North Carolina
Habitat Group:
Habitat Type:
Members of Floodplain Forests:
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Floodplain Forests
General Wet Hardwood Forests
General Description This habitat includes river and stream bottomlands that support stands of hydrophilic species of hardwood trees. Upland depression swamps sharing the same species -- particularly Willow Oak -- are also included, as are non-riverine stands of wet hardwoods in the Coastal Plain. The soils of these habitats are frequently flooded and remain wet for prolonged periods following withdrawal of flood waters. However, they are not permanently inundated.

This is the most generalized of the forests associated with floodplains, occurring in at least two of the state's physiographic provinces and including species associated with both acidic, nutrient-poor soils and those that are high in pH and nutrient-rich. This habitat overlaps that of the Rich Wet Hardwood Forests but includes also encompasses hardwood forests growing in the blackwater floodplains of the Coastal Plain.

Abiotic Factors Geographic Regions: Low Mountains to Lower Coastal Plain. USDA Hardiness Zones: 6-8. Landform: restricted to floodplains and wet flats. Soil Moisture: wet but not hydric. Soil Texture: alluvial/loamy to silty -- soils are friable and permit burrowing but are prone to inundation. Soil pH: acidic to circumneutral -- includes blackwater as well as brownwater floodplain. Soil Nutrients: poor to rich. Microclimate: warm to cool, humid. Flood Frequency: annual to several times per year. Flood Duration: hours to days. Presence of Pools: common to abundant year-round. Fire Frequency: extremely rare. Drought Frequency: extremely rare. Ice Storm Damage: low to moderate. Wind Storm Damage: moderate (windthrows are common). Insolation: the canopy is well-insolated, lower strata are deeply shaded.

Biotic Structure Vegetation Type: Closed-canopy forests composed of hardwood trees (Loblolly Pines may be present but are not a key feature). Strata:Subcanopy, shrub, and herb-layers well-developed. Organic Shelter, Foraging, and Nesting Structures: woody debris and leaf litter are plentiful except in flood channels or other areas frequently scoured by floods.

Co-evolved Species Groups Phagic and Competitory Symbioses:
Betula nigra // Acronicta betulae-Bucculatrix coronatella-Peridea bordeloni
Carpinus caroliniana // Acrobasis carpinivorella-Oncopsis nigrinasi
Bottomland Oaks // Eratoneura comoides

Host // Commensal Symbioses:
(host-specific lichens and bryophytes)
(host specific decomposers)

Mutualist // Mutualist Symbioses:
(mycorrhizal assocations)
(Pollinator Associations)
(Host/Disperser Associations)

Competitor Guilds:
Light Competitors:
River Birch is considered shade intolerant and is often restricted to areas right along streambanks (Grelen, 1990). Willow Oak and Cherrybark Oak are also shade intolerant but persist into the subclimax stage of the forest (Krinard, 1990; Schlaegel, 1990). American Hornbeam is shade tolerant and persists or even becomes more abundant as bottomland forests reach their climax (Metzgar, 1990).

Determining Species
Lactuca floridanaWoodland LettuceG5S4S40.00041
Uvularia sessilifoliaSessile-leaf BellwortG5S4S40.00041
Viola affinisLecontes VioletG5S4S40.00041
Zephyranthes atamascoAtamasco LilyG4G5S4S5S4S50.00010
Dasineura pudibundaa gall-forming midge
Carex debilisWhite-edge SedgeG5S5S50.00000
Betula nigraRiver BirchG5S5S50.00000
Carpinus carolinianaAmerican Hornbeam, Musclewood, IronwoodG5S5S50.00000
Quercus pagodaCherry-bark OakG5S5S50.00000
Quercus phellosWillow OakG5S5S50.00000
Eratoneura comoidesSNR
Eratoneura nigriventerSNR
Oncopsis nigrinasiSNR
Haemopis septagona terrestrial leech
Acrobasis carpinivorellaGNRS3S4S3S40.00132
Cepphis decolorariaDark Scallop MothG4S3S4S3S40.00132
Heterogenea shurtleffiRed-eyed Button Slug MothGNRS3S4S3S40.00132
Hypomecis longipectinariaA geometrid mothG3G4S3S4S3S40.00132
Peridea bordeloniBordelon's PerideaGNRS3S4S3S40.00132
Xanthorhoe lacustrataToothed Brown CarpetG5S3S4S3S40.00132
Acronicta betulaeBirch DaggerGNRS4S5S4S50.00010
Chytolita petrealisStone-winged Owlet MothG5S4S5S4S50.00010
Vitis simpsoniiFlorida GrapeGNRS4S40.00041
Nr = Number of Ranked Species = 18
Ner = Number of Extant, Ranked Species = 18
Nv = Number of Historic and Extirpated Species = 0
Nar = Number of Species at Risk of Extirpation (State rank > S5) = 13
Nss = Number of Secure Species (State Rank = S5) = 5
Pss = Proportion of Secure Species (Nss/Ner) = 0.27778
ENE = Expected Number of Extirpations (Sum of PE) = 0.00986
Average PE (ENE/Ner) = 0.00055
Habitat Risk Index = (Nar+Nv) x Average PE = 13 x 0.00055 = 0.00715

Estimated Risk to the Determining Species Although some of the Determining Species have not yet been adequately surveyed, none have been identified as being of definite conservation concern, i.e., having state ranks of S3 or higher. The average probability of extirpation is 0.0.00086, which in our model is equivalent to a state rank of S4 and interpreted as Apparently Secure

Estimated Risk to the Co-evolved Species Groups
Estimated Security of the Habitat Five of the Determining Species are considered as Secure, having state ranks of S5. The Proportion of Secure Species is 0.2941. This is a relatively high score and reflects the presence of This is a moderately high value, indicating that the habitat overall is well-distributed across the state,with a large number of well-connected occurrences, particularly in the Piedmont and Coastal Plain.

Index of Habitat Imperilment
Identified Risks Conversion of habitats to agriculture and silviculture/ Filling in of floodplains for human habitation and other uses/ Creation of impoundments, which permanently destroy bottomland forests, cut off the flow of nutrient rich sediments, and alter the natural flood cycle/ Loss and fragmentation by clear-cutting and road construction/ Invasion by exotic species/ Increased risk of drought and fire due to climate warming/ Increased risk of severe flooding due to climate change/ Impacts to insect populations due to mosquito-spraying and use of insecticides on adjoining lands/ Impacts due to artificial lighting/ Loss of bottomland habitats in the Lower Roanoke and other brownwater rivers due to sea level rise and saltwater intrusion

Observed Trends Floodplains in the Mountains offer some of only flat lands in that area. Despite the threat of flood damage, these are the sites that have been most extensively developed for agriculture and human settlement in that region. The wide floodplains in the western Piedmont have also been extensively converted to agriculture, dating back to colonial times.

Large tracts of brownwater bottomlands have been destroyed on several of the state’s largest rivers due to reservoir construction: Randleman and Jordan Lakes in the Cape Fear drainage; Kerr, Gaston, and Roanoke Rapids on the Roanoke; Falls Lake on the Neuse; Lake Norman and Mountain Island Lake on the Catawba; and High Rock, Badin, Tillery, and Blewitt Falls on the Yadkin-Pee Dee River. Additionally, some losses are now occurring at the mouth of the Cape Fear River due to sea level rise and salt water intrusion, which is converting floodplain forests to open marshes.

In addition to conventional timber harvests, which continue to affect thousands of acres of natural forest lands, the development of the wood-chipping industry has created additional pressures.

Invasive species, particularly Privet and Stilt Grass, are significant problems in many bottomland habitats, overgrowing native herbaceous species and tree seedlings. These impacts may actually now be increasing due to the destruction of groves of Green Ash, which are creating large light gaps that favor the growth of the invasive plants (see Ash Forests for a discussion of the direct impacts of the Emerald Ash Borer).

In areas of bottomland hardwoods along the northern border of the state, where Gypsy Moths have become established, Bacillus thuringiensis (Bt) is frequently applied to suppress outbreaks. Widespread spraying of this agent, however, has impacts far beyond the Gypsy Moth and affects a large number of non-target species of moths and butterflies (see Hall et al., 1999). Within the group included in the Rich Wet Hardwood Forests, the five leaf-mining species are probably at low risk of exposure to Bt, but the rest are likely to be at risk since they feed on the external surfaces of the leaves where Bt is deposited.

Distribution Map
Distribution Tracts of this habitat occur across the state except for the high mountains and barrier islands, both of which lack floodplains in general.
Major Conservation Reserves In addition to the preserves associated with brownwater rivers listed in the Rich Wet Hardwood Forests account, preserves representing this habitat include the following on blackwater rivers:
Drowning Creek in the Sandhills Game Land/ Little River and its tributaries in Fort Bragg/ Lumber River State Park/ Juniper Creek Game Land/ Waccamaw River in the Lake Waccamaw State Park and NC Coastal Land Trust Preserve/ Northeast Cape Fear River and Trumpeter Swamp in the Holly Shelter Game Land/ Black River TNC Preserve/ Great Coharrie Creek DEQ Mitigation Site/ Dismal Swamp State Park

Priority Areas for Surveys and Conservation Protection
Stewardship and Management Recommendations Promote floodplain forests as important carbon sequestration reserves, flood control areas, and water-quality enhancing systems/ Limit clear-cutting and prohibit filling in of floodplains for development/ Create buffers along adjoining slopes to limit impacts due to human encroachment/ Combat spread of exotic invasives, particularly Privet/ Use Gypsy Moth-specific control agents to combat outbreaks of this exotic species in bottomland forest habitats generally

References Grelen, H.E.. 1990. Betula nigra. River Birch. In: R. Burns and B. Honkala (Technical coordinators). Silvics of North America, 2. Available online at: https://www.srs.fs.usda.gov/pubs/misc/ag_654/volume_2/silvics_v2.pdf

Krinard, R.M. 1990. Quercus falcata var. pagodifolia Ell. Cherrybark Oak. In: R. Burns and B. Honkala (Technical coordinators). Silvics of North America, 2. Available online at: https://www.srs.fs.usda.gov/pubs/misc/ag_654/volume_2/silvics_v2.pdf

Metzger, F.T. 1990. Carpinus caroliniana Walt. American Hornbeam. In: R. Burns and B. Honkala (Technical coordinators). Silvics of North America, 2. Available online at: https://www.srs.fs.usda.gov/pubs/misc/ag_654/volume_2/silvics_v2.pdf

Schlaegel, B.E. 1990. Quercus phellos L. Willow Oak. In: R. Burns and B. Honkala (Technical coordinators). Silvics of North America, 2. Available online at: https://www.srs.fs.usda.gov/pubs/misc/ag_654/volume_2/silvics_v2.pdf

Updated on 2022-02-04 16:34:01