Duke Forest Field Trip
Week of Sept 4, 2005
Ongoing threads and themes to think about: Disturbance, soil chemistry, succession, new
things going on- exotics, deer
PLEASE don’t forget to watch out for poison ivy during the trip and do a thorough tick
check when you get home today!!!
Stop 1: Orientation at the bridge
Background: Duke Forest ~8000 acres total, today we are in the Korstian Division.
Durham Spoke & Axle Co. cut oaks for crossties in 1900s; 1920s Duke acquired the land,
and in the 1930s it was the base for the forestry school. From the 1930s until present the
land was mostly untouched (salvage logging, Juniper theft for fenceposts, some logging
of pine stands by Duke Forest). Korstian is the second largest division; much of the land
is abandoned agricultural land
Geomorphology: the area is geologically complex and landforms reflect that complexity.
The land first formed as an island arc off the coast of Africa. Volcanic ash was
compressed to form Carolina Slate. When the continents collided, intrusions of other
rock were created (more black means more Mg and Ca, extreme is diabase), causing
different rocks to mixed and become exposed. Continental rifting (separating) created
stripes of rock like stretch marks in the landscape. The Triassic Basin, which runs north
south from here to RDU airport, is a half graben (drops in on one side) which formed as
continents pulled apart. Uplands have been weathering for ~200mya, and as a result are
very infertile. Chapel Hill is on a ridge along the basin.
Different soil chemistries result in different communities. More fertile soils occur where
1) parent material is darker- more Ca and Mg, 2) river basins where sediments are
deposited, and 3) on hills where erosion exposes less weathered rock. Rivers here are
some of the less polluted and are very episodic in flow, with frequent floods. This river
flows to New Hope Creek and then Jordan Reservoir.
Geomorphology: the area is geologically complex and landforms and vegetation reflect
that complexity
Soil Chemistry – What factors drive soil chemistry? How does soil chemistry affect
vegetation?
How does land use history affect the vegetation we see today?
Species indicating nutrient rich soils:
Cercis canadensis- redbud
Juglans- walnut
Morus- mulberry
Stop 2: New cutting of the pine forest on the left
Old field succession in the NC piedmont
Erechtites – fireweed
Liquidambar – sweetgum
Liriodendron tulipifera- tulip poplar
Eupatorium – dog fennel
ON THE RIDE TO THE NEXT STOP!!!
Before the next stop, watch out the windows. Look at the understory of the forest. How
far can you see? Is there much growing there? Why or why not?
Stop 3: [Big white oak] Relatively rich area (Ca Mg tending towards shrink swell clay)
What is the soil like? Why?
Stop 4: Extreme Shrink Swell
Effects of lack of fire
Stop 6: Graveyard plot
Background- has not been cut since ~1916
How has the plot changed since 1950s?
Microstegium- Japanese stilt grass; invasive
Vinca- periwinkle
Lycopodium- club moss
Juniperus virginiana –(cedar) ancient ~1850
Elaeagnus- Russian olives
Old barn:
Is herb diversity high or low? Why?
What is interesting about the power line right of way?
Stop 7: Stream, Old Mill, and Diabase Dike
River- floods, frequencies, erratic flow, erosion
Tree species:
Platanus occidentalis – Sycamore
Acer barbatum – Southern sugar maple
Betula nigra – River birch
Alluvium soils
What is the effect of soil fertility on diversity here?
Look for small beaver items/ evidence.
Species:
Lindera benzoin- spicebush
Uniola latifolia- River oats
Aesculus- buckeye- found in rich soils, diabase dikes
Stop 8: Permanent Plots 35, 36, and 37
1930s Established by Korstian
Classic Piedmont oak-hickory (white oak- Quercus, hickory- Carya tomentosa and C.
glabra)
Some species:
Quercus alba- white oak
Carya tomentosa- mockernut hickory
Carya glabra- pignut hickory
Acer rubrum- red maple
Oxydendron arboretum- sourwood
Soil pit- what is Carolina slate like?
Plot 36:
Are the plants mostly woody or herbaceous? Why?
Plot 37:
How is this plot different from 36? Why might it be different?
Plot 35: Shrink swell pit, diabase, very weathered
What is the shrink swell soil like?
Species:
Quercus stellata- Post oak
Quercus phellos?- willow oak
Three species of pine (!!!) naturally reproducing:
Pinus taeda- loblolly pine
Pinus virginiana- Virginia pine
Pinus echinata- Shortleaf pine
Carya ovata- shagbark hickory- dominant hickory on shrink swell soil here
Acer rubrum- red maple
Sedges- because 9 months out of the year water is here. Why?
How is this plot different from the 2 across the road?
Look out the window at the regeneration of pine after cutting!
Stop 9: Rhododendron Bluffs
Rhododendron catawbiense
Pleistocene relics- Remnant populations
What makes it possible for these populations to persist here?
DUKE FOREST ASSIGNMENT
In a BRIEF paragraph address one of the following:
Describe how an invasive species can alter a community.
How does disturbance impact the Duke Forest?
How does land use affect the pattern of succession in the piedmont?
Why is it important for ecologists to understand soil chemistry?