Piedmont Forest Types

• History of development and land alteration

• Much of the land area cleared for agriculture

• all of our major urban areas are in the Piedmont

• Major factors that influence Piedmont forests: disturbance and age (succession), soils, and moisture. Topography can also play an important role.

• Distinctions among community types can be subtle—lots of variation

• 

• Pine-Oak or Mixed Hardwood Forest (grades into the Coastal Plain)

• Oak-Hickory Forest (grades into the foothills)

• Other types: we have Bottomland Hardwood Forests and Cypress-Gum Forests that are similar to the coastal plain versions. Check out Swift Creek Bluffs (bottomland) and Robertson Millpond (Cypress-Gum) in Wake County.

• Major factors that separate Piedmont forest types: Disturbance and age (succession), soils, and moisture. Topography can also play an important role.

Piedmont Forest History

• NC was only about 1/3 forested 150 years ago

• Nearly all of the Piedmont was timbered and/or cleared for agriculture

• Land use practices were destructive; soil eroded and lost fertility

• End of the Civil War shifted the economy. Land was sold cheaply as farms were abandoned and regenerated forest

• The second wave of land abandonment in the NC Piedmont was in the 1930s, during the Depression. The first section of Umstead State Park was purchased by the state and developed by the CCC in the mid-1930s. It's also crazy to think about the fact that Umstead was segregated (with two separate entrances, that still exist today) until 1966.

• 

Piedmont Forest Development

• Following agricultural abandonment (widespread in the Piedmont post-Civil War)

• 0-3 years: Broomsedge and baby pines

• 3-10 years: Pine, sweetgum, weedy shrubs

• 10-25 years: Canopy closure, pine-oak forest

• 25-75 years: Pine-Oak Forest (pine canopy, oak understory)

• 75-150 years: Oak-Hickory Forest (pines drop out; understory grows up)

• Much of this research on succession was done by Catherine Keever and Elsie Quartermain in the Duke Forest

Pine-Oak Forest transitions to Oak-Hickory Forest

• Forest structure

  • develops over time

    • before canopy closure

    • after canopy closure

    • as forest continues to age

  • soil dependent

  • disturbance dependent

  • canopy species dependent

• Species composition

  • environmental factors determine species composition

  • Mesic— “moderate,” higher moisture, less acidic, more nutrients, protected sites

    • sweetgum, red maple, yellow-poplar, white oak, northern red oak, American beech, white ash, shagbark hickory

    • Mesic forests that had less historical disturbance, higher pH, and higher nutrients have a significant component of spring ephemerals

      • spring ephemerals: small wildflowers that complete their life cycles before canopy leaf-out

  • Xeric— “dry,” less moisture, often more acidic, nutrient poor, exposed to sites

    • Virginia pine, chestnut oak, black oak, scarlet oak, red maple, sourwood, sassafras, winged elm

    • more exposed ground and rock

  • Canopy

    • Loblolly pine, shortleaf pine, Virginia pine

  • Understory (becomes canopy)

    • white oak, black oak, northern red oak, mockernut hickory, pignut hickory

• Environmental factors

• Disturbance regime

  • Fire suppression means that Piedmont forests have more thin-barked species (red maple, American beech, yellow-popular); fewer oaks

  • Windthrow from storms creates gaps and microhabitats (Hurricane Fran)

  • Disturbance in these Piedmont forests creates gaps in the canopy, which allows light to reach the forest floor, so the diversity of the stand increases because early successional species can capture those gaps. Without disturbances like fire, these stands can become very, very dense.

• Threats

  • Development: rapid urbanization

  • Climate change: drought is more frequent