×

Mesic Mixed hardwood forest

Acidic
David Blevins Photography
Swift Creek Bluffs, Wake County

The Mesic Mixed Hardwood Forest is a common Orange County natural community found on acidic, north-facing moderate to steep lower slopes or other sheltered sites, above the bottomland communities that adjoin streams. The soil is above the floodplain, but is generally moist and rich from colluvium and moisture input from the slopes above.

Dominated by a canopy of mesic hardwoods, beech, tulip poplar, and red oak are common trees. The understory and herb layers are often moderately dense and diverse. Eastern red maple, flowering dogwood, American holly, and American strawberry-bush are prominent understory plants.

Local Sites
Basic
Carolina Vegetation Survey
Natural vegetation of the Carolinas: Mafic Dry-Mesic Forests

The rare Basic Mesic Forest is found on moderate to steep lower slopes, similar to the Mesic Mixed Hardwood Forest, with deep, well drained soils and a dominance of mesic hardwoods. The soil pH, base saturation, and levels of ‘base’ cations like calcium are all higher than for Mesic Mixed Hardwood Forest soils, although the soil pH is not necessarily basic, or even circumneutral. The Basic Mesic Forest differs from Mixed Hardwood in its its denser herb layer and its greater floristic diversity. Basic Mesic forests often mount delightful displays of spring ephemeral wildflowers in February and March.

The indicators of base-rich soils are typically herbs and include black cohosh, wild ginger, northern maidenhair, bloodroot, green-violet, and doll’s-eyes.

×

Heath bluff

unknown photographer

In positions where steep, nutrient poor slopes are facing north and are thus relatively cool and moist, the uncommon Heath Bluff community can occur. This community is distinguished by a variable, usually open, tree canopy and a closed, often dense, shrub layer. Catawba rhododendron, mostly found only in the higher parts of the mountains, occurs at several sites around Chapel Hill and Durham.

The shrub layer is dominated by mountain laurel or Catawba rhododendron. The species diversity is generally very low.

Local Sites
×

Dry-mesic oak-hickory forest

Acidic
David Blevins Photography
Nature Trails, North Carolina Botanical Garden

The most common Orange County natural community, the Dry-Mesic Oak-Hickory Forest occupies upland slopes and somewhat sheltered ridges. While dominated by a mix of oaks and hickories, at many sites fire exclusion has led to poor oak recruitment and understory invasion by fire-intolerant mesic species such as red maple, American beech, and sweet gum. The herb layer is typically fairly sparse and less diverse than in the moister, richer Mesic Mixed Hardwood Forest.

Dominant oaks include white oak (generally the prevalent oak species), red oak, and black oak. Flowering dogwoods, and hickories are characteristic, often abundant understory trees. Flora are limited to species tolerant of acidic soils such as flowering dogwood, black gum, sourwood, blueberry, pipsissewa, downy rattlesnake-orchid, and little brown jug.

Local Sites
Basic
Carolina Vegetation Survey
Natural vegetation of the Carolinas: Basic Oak-Hickory Forests

The rare Dry-Mesic Basic Oak-Hickory Forest community is found on upland sites similar to its acidic counterpart but with less acid, more fertile soils. Though soil data show that many examples do not have basic or even circumneutral pH, these soils have higher pH, higher base saturation, and higher levels of ‘base’ cations like calcium than the more acidic Dry-Mesic Oak-Hickory Forest. The basic version has a greater diversity of plant species, more hickories, and more herbaceous species typical of mesic sites.

The canopy is dominated by white oak, along with other oaks and hickories. Occurrence of more base-loving flora includes species such as white ash, eastern redbud, Carolina buckthorn, and coralberry.

Local Sites
×

Dry oak-hickory forest

Acidic
Mecklenburg County Park and Recreation, Natural Resources Section
Dry Oak-Hickory Forests

On drier upland sites, typically south-facing slopes and ridge tops, the fairly common Dry Oak-Hickory Forest can be found. Dry-site oaks, mainly white oak, post oak, and Southern red oak, dominate the canopy. The shrub layer ranges from sparse to dense with a generally sparse herb layer.

Acid-tolerant flora such as black gum, sourwood, hillside blueberry, deerberry, and farkleberry predominate.

Local Sites
Basic
Carolina Vegetation Survey
Natural vegetation of the Carolinas: Basic Oak-Hickory Forests

The rare Dry Basic Oak-Hickory Forest contains less acidic, more fertile soil than its acidic counterpart. White oak is a major canopy tree, post oak or southern red oak is significant, while red oak is a minor presence. Because many species that are confined to relatively mesic areas on acidic substrates inhabit apparently drier sites on higher pH soil, they occur here although to a lesser extent than in Dry-Mesic Basic sites.

The understory usually features abundant white ash, eastern redbud, chalk maple, and various viburnums. Species that are even less tolerant of acidic conditions, such as Carolina buckthorn, coralberry or fragrant sumac, often are present.

Local Sites
×

Monadnock forest

unknown photographerOcconeechee Mountain State Natural Area

On sites where the soil is rocky and nutrient poor, the Monadnock Forest occurs. This rather rare natural community is found in several upland sites in Orange County, typically on isolated erosional remnant hills, but occasionally occurs on bluffs. Not all isolated hills support this community type. Abundance of rock and soil chemistry may be factors in determining occurrence. Extreme soil acidity, accompanied by aluminum toxicity, has been suggested as important.

Dominated by chestnut oak, species diversity is usually low, with an understory strongly dominated by sourwood, and red maple and having a patchy shrub and sparse herb layer.

Local Sites
×

Xeric hardpan forest

VA Dept of Conservation & Recreation
Piedmont Hardpan Forests

Where circumneutral clay soils develop an impermeable hardpan, the Xeric Hardpan Forest may occur. Quite rare and restricted to the Piedmont, Xeric Hardpan Forest communities have a stunted, open tree canopy. This community is found on broad upland flats in environments that are xeric because of restricted rooting depth caused by dense or shrink-swell clay, sometimes in combination with rock. Canopy density is less than in dry forests and depends more on fire and disturbance history.

The canopy is xerophytic, dominated by post oak, with or without blackjack oak, Carolina shagbark hickory or pines. Base-loving flora such as white ash, winged elm, eastern redbud, viburnums, fragrant sumac, coralberry, and curlyheads are usually common.

×

Upland depression swamp forest

VA Dept of Conservation & Recreation
Upland Depression Swamps

The uncommon Upland Depression Swamp Forest is an isolated forested wetland found in poorly drained depressions on upland ridges and flats. It occurs on unusually flat areas with hardpan soils derived from mafic rocks or slates. Habitats include shallow, seasonally rain-flooded upland basins where water stands for part of the year but is not great enough to prevent a closed tree canopy from forming. Sites which hold enough standing water can be important breeding sites for amphibians.

Upland depressions vary in size and are usually dominated by willow oak, or sometimes overcup oak, swamp white oak, basket oak or sweet gum. The shrub and herb layers are sparse but typically include greenbrier and sedges.

Local Sites
×

Alluvial forest

David Blevins Photography
Morgan Creek, Mason Farm Biological Reserve

The Alluvial Forest occurs in the narrow floodplains of small streams or on large rivers where the floodplain is narrowed by bedrock. These floodplains are too small to differentiate communities by depositional landform. Flooding occurs for shorter periods and is more variable than on the larger floodplains of bottomland forests. The canopy is mixed, including floodplain species, widespread species, and upland species but with widespread species dominating.

Most of the canopy is widespread species such as sweet gum and tulip-tree but characteristic alluvial species such as sycamore, river birch or Southern hackberry are common.

Local Sites
×

Bottomland forest

NC Geological Survey
Eno River Geology Destinations: Floodplain deposits

Bottomland Forests that are located on the higher parts of large floodplains are flooded for brief to moderate periods during the growing season. These sites occur on terraces, on the higher parts of depositional ridge and swale systems, and on some wide flat floodplains. Natural vegetation is a mix of bottomland oaks, tulip-tree, sweet gum, and sometimes American beech mixed with upland oaks and hickories. Bottomland Forests that are located on lower terraces, ridges, and flat floodplains lack an appreciable number of upland species.

Bottomland Forests vary in composition depending on whether they are close to the river or higher up the floodplain. Oaks are usually a prominent feature and may include willow oak, basket oak, cherrybark oak, overcup oak, water oak, and sometimes white oak.

Local Sites
×

Low elevation seep

VA Dept of Conservation & Recreation
Coastal Plain/Piedmont Acidic Seepage Swamps

The Low Elevation Seep community occurs in seepages and springs at the base of slopes or the edges of bottomlands. Well-developed seeps contrast sharply with adjacent communities in their abundant wetland vegetation and permanently saturated, mucky soils. Seeps are fairly common and tend to be small, often shaded by the canopy of trees rooted in adjacent communities. Despite a lack of much standing water, seeps are important breeding and foraging sites for amphibians.

Low elevation seeps are distinguished by wetland vegetation including Southern wild raisin, Northern wild raisin, orange jewelweed, cinnamon fern, royal fern, netted chain fern, and sedge.

Local Sites
×

What is a natural community?

A natural community is comprised of groups of different species living together in a particular physical environment. The groups that thrive in the same kinds of environments tend to appear across the landscape in predictable patterns.

Easy Science for Kids Ecosystems

What determines a natural community?

The North Carolina Natural Heritage Program has developed a classification system for natural communities. Communities are defined by a wide range of ecological characteristics, with the greatest emphasis upon vegetation and readily observable aspects of the physical environment such as topography, elevation, and wetness. While there is some overlap between the species and physical environments in different communities, each represents a distinct combination of species plus physical characteristics.

Why are natural communities significant?

For the home gardener, familiarity with natural communities provides a framework in which to recognize patterns in the landscape. They help shape a meaningful picture of the natural world.

  • Natural communities can inform garden design.
    Gardens with plants that share a site’s natural community better adapt to existing conditions and, once established, are more likely to thrive with little care.
  • Natural communities are important components of biodiversity.
    Gardens that are designed to mimic natural communities can approximate the richness of our local natural areas and help to support a large number of locally native animal and plant species.

Estimate your natural community

Although many factors influence natural community type, you can estimate your natural community by determining your landscape position — landform (e.g. ridge, hillside, valley), orientation (e.g. north-facing vs. south-facing slope), slope steepness and, for stream communities, the width of the floodplain.

  • To view the area a community occupies, mouse over or tap once
  • To see details (description, photo of a typical plant association, list of plants found in the community, map links for local examples), click or tap twice
mesic
mixed hdwd.
heath
bluff
dry-mesic oak-hickory
dry-mesic oak-hickory
dry oak-hickory
dry oak-hickory
monadnock
alluvial
bottomland

Sources

×