Habitats of North Carolina
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Lentic Habitats
General Beaver Ponds and Semi-natural Impoundments
General Description This habitat consists of open, shallow ponds located along stream and river channels; unlike depression ponds -- the other major type of natural pond habitats in North Carolina -- they do not occur in isolation from stream flow. Instead, they occur as the result of dams, originally made by beavers but now frequently man-made as farm ponds. A major difference between these two types of ponds is that beaver dams are relatively permeable -- the loose construction and frequent breaches allow aquatic species to more through them, whereas man-made dams constituted nearly impenetrable barriers to movements. For the same reason, silt and pollutants can pass through the dams made by beavers but cannot do so in artificial ponds. During times of drought, beaver ponds also continue to allow some degree of water flow downstream, helping to preserve water availability in entire watersheds. Artificial impoundments, on the other hand, preserve water only in their small, isolated localities. As a result of these differences, beaver ponds are highly important in maintaining native species not only within their own limits but across entire river and stream basins.

Artificial ponds are included in this habitat only where they have not been subject to heavy agricultural runoff, intensive use by livestock, or overstocking of game or farm fish. Where allowed to exist under semi-natural and unpolluted conditions, these ponds often support species that were originally associated with beaver ponds. In fact, the proliferation of farm ponds that followed the massive extirpation of beavers may have been an important factor allowing these species to survive within our region.

The Determining Species of this habitat include only aquatic or amphibious species associated with open, shallow ponds. Species associated with "beaver meadows", marshes, shoreline shrub-thickets and other habitats often found as part of the larger complex of habitats created by beaver activities are treated separately. The same is true for species that make use of deep water lakes and reservoirs, coastal marshes, forested wetlands or ephemeral pools.

Currently, this group is mainly composed of Odonates that are associated with small, shallow, open ponds. The nymphs of these species dwell within the ponds themselves and the adults forage over the ponds or along their shorelines, where mating also takes place. Since dispersal is done mainly by flying adults, the barrier effect of artificial dams is not a major factor for this group of species, many of which are common sights along the edges of semi-natural farm ponds. While frogs, toads, and pond-dwelling salamanders also have adults capable of overland dispersal, most also make use of other types of wetlands, especially those that are intolerant of the presence of fish species.

Abiotic Factors Geographic Regions: Low Mountains to Lower Coastal Plain. USDA Hardiness Zones: 6-8. Landform: restricted to the floodplains of perennial streams and rivers. Soil Moisture: hydric. Soil Texture: alluvial/loamy/silty/mucky. Soil pH: acidic to circumneutral -- includes blackwater as well as brownwater floodplains. Soil Nutrients: poor to rich. Microclimate: warm to cool, humid. Flood Frequency: permanently flooded. Flood Duration: year-round. Presence of Pools: a key factor for this habitat. Fire Frequency: generally not a factor except around the margins of a pond. Drought Frequency: extremely rare. Insolation: full sun; in addition to the limiting effects on tree species of permanent inundation, woody species located along the margins of the ponds are felled by beaver for food.

Biotic Structure Vegetation Type: open ponds that may or may not have significant floating vegetation. Woody Debris: standing snags and fallen logs are a common feature of beaver ponds, especially in their earlier successional stages; beavers also actively harvest trees and shrubs in the vicinity of the ponds and haul them into the ponds themselves for storage

Co-evolved Species Groups Competitor Guilds:
Dragonfly nymphs and adults show interspecific aggression related to competition and/or interspecific predation (see Moore, 1964; Pezalla, 1979; Wissinger, 1989). Species that are similar in size, phenology, and range and that use similar habitats and foraging techniques fall into the classic structure of competitory guilds as described by Root (1967). Pond-dwelling Odonates can be placed in the following guilds:
Pond Edge Percher/Salliers: Dythemis velox-Libellula auripennis-Libellula cyanea-Libellula luctuosa-Libellula pulchella-Lestes australis-Lestes inaequalis
Pond Edge Hoverer/Gleaners: Enallagma doubledayi-Enallagma geminatum-Enallagma traviatum
Pond Littoral Libellula Nymphs: Libellula auripennis-Libellula cyanea-Libellula luctuosa-Libellula pulchella

Determining Species
Taxa Global RankState RankProbability of Extirpation (PE)
Anax longipes - Comet Darner G5S40.0007
Celithemis elisa - Calico Pennant G5S50.00
Celithemis fasciata - Banded Pennant G5S50.00
Celithemis ornata - Ornate Pennant G5S50.00
Celithemis verna - Double-ringed Pennant G5S3S40.0020
Dythemis velox - Swift Setwing G5S4S50.0002
Enallagma doubledayi - Atlantic Bluet G5S50.00
Enallagma geminatum - Skimming Bluet G5S50.00
Enallagma traviatum - Slender Bluet G5S50.00
Enallagma vesperum - Vesper Bluet G5S3S40.0020
Epitheca costalis - Slender Baskettail G5S40.0007
Epitheca cynosura - Common Baskettail G5S50.00
Ladona deplanata - Blue Corporal G5S50.00
Lestes australis - Southern Spreadwing G5S50.00
Lestes inaequalis - Elegant Spreadwing G5S40.0007
Libellula auripennis - Golden-winged Skimmer G5S50.00
Libellula cyanea - Spangled Skimmer G5S50.00
Libellula luctuosa - Widow Skimmer G5S50.00
Libellula pulchella - Twelve-spotted Skimmer G5S40.0007
Nehalennia integricollis - Southern Sprite G5S40.0007
Perithemis tenera - Eastern Amberwing G5S50.00
Sagittaria platyphylla - Delta Arrowhead G5SH0.00
Expected Number of Extirpations with a PE value (Sum of PE) = 0.0077
N = Number of Extant Species with a PE value = 8
Average PE = ENE/N = 0.0010
Number of S5 species = 13
Proportion of Secure Species = Number of S5 Species/N = 1.6250
Habitat Risk Index = ENE x (1 – PSS) = -0.0048

Estimated Risk to the Determining Species
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 Moore, N.W., 1964. Intra-and interspecific competition among dragonflies (Odonata). The Journal of Animal Ecology, pp.49-71.

Pezalla, V.M., 1979. Behavioral ecology of the dragonfly Libellula pulchella Drury (Odonata: Anisoptera). American Midland Naturalist, pp.1-22.

Wissinger, S.A., 1989. Seasonal variation in the intensity of competition and predation among dragonfly larvae. Ecology, 70(4), pp.1017-1027. Available online at: http://links.jstor.org/sici?sici=0012-9658%28198908%2970%3A4%3C1017%3ASVITIO%3E2.0.CO%3B2-9

Updated on 2021-12-30 14:03:49