SOILS and VEGETATION of NORTH CAROLINA
An Introduction
All diagrams are taken from:
Daniels, R.B., S.W. Buol, H.J. Kleiss and C.A. Ditzler, 1999: Soil Systems in North Carolina, North Carolina State University, Soil Science Department, Raleigh, NC. |
Mountain Soils
|
Topography and altitude plays a major role in the soil and vegetation development in the Mountains. | |
 |
 |
The valleys are often areas of easily eroded weak rock, with
the results of mass wasting filling much of the flat valley floor.
As a result they are frequently now used for agriculture - often intensive
agriculture - while the slopes remain forested.
The intensive agriculture demands that the plants have water at the exact times - and in the exact quantities - that they need it. Although water in the soil is commonly adequate in this valley-bottom area, and the soil is thick enough to provide an adequate supply the irrigation ensures a high-quality crop. |
|
|
The road on the valley edge picks out the flood plain - a clear indication that this area has floods with some frequency. |
 |
This diagram summarizes much about the relationship between the forces creating the mountain environment (even if the quality needs much improving) |
|
|
One of the major unexplained features of North
Carolina's natural vegetation is the presence of 'balds' on mountain
tops. The one at right has dense rhododendron vegetation - others
have mainly grasses.
Trees are more normal for mountain vegetation, in this case poplars which are 'relics' from much colder climatic conditions associated with the last ice age. They only survive in sheltered, shady spots, which are often frost hollows (and were sufficiently isolated to avoid removal by forestry in the 19th century |
|
0 |
The pattern of agriculture in the valleys, forestry on the higher land (with exceptions such as that at the right!), continues throughout the mountains, with various tree species present. Soil tends to be rather thin, and gray-black in color. |  |
The Piedmont
 |
Although the soils of much of the Piedmont have been derived from similar parent material to those of the mountains, they have been exposed to higher temperatures and more severe chemical weathering. |  |
|
Almost all the Piedmont soils are Ultisols, with light upper layers and a reddish sub-soil The most common local soil (and the "State Soil") is the Cecil soil, seen here in profile, uprooted, and with a distribution map
|
 |
|
The red soil shows slightly through this grass field. Many ultisols can be very productive although they need frequent attention to ensure that the clays do not become dominant.
|
Not all Piedmont soil is red. This forest is on a clay soil which developed in the Triassic basin near Durham. This grayish, very compact clay soil is extremely difficult to work, and has been little used for agriculture
|
|
|
The Upper Piedmont has rolling terrains, and the distribution of soil types is frequently akin to that in the mountains. The soils, however, are warmer and, generally, redder. The vegetation also characteristically shows the 3 layers typical of the southern forests. |
|
The Sandhills
A long-leaf pine woodland near Southern Pines |
The Sandhills sit astride the Piedmont-Coastal Plain border, with a landscape dominated by the sandy soils derived from sediments produced by an ancient river delta. | 
A real 'sandy' soil - this one in the middle of the Fort Bragg Military Reservation - with a pine vegetation dominating. |
The Coastal Plain
|
|
The map indicates that the
Coastal Plain extends from the Piedmont edge right to the coast.
There are a series of terraces - steps down - created by old shorelines,
which give changing landscape patterns as we move coastward. So we
have divided this section into 2: - Tidewater |
|
The Coastal Plain itself is commonly regarded as an exceptionally rich agriculture land. The soils can vary tremendously, particularly in texture, which depends on exactly how the parent material was deposited when this region was ocean at the edge of the continent.
 |
The illustration at right shows the gently rolling Coastal Plain not too far east of Raleigh, with a rather sandy soil. At left, somewhat farther east, is a flatter region and a lighter soil (the road through the cotton is too light, but gives a good indication of the light gray topsoil). |  |
 |
Throughout the coastal plain, but particularly as the lower, poorer drained tidewater is reached, there is a distinct land-use difference which reflects soil difference. Often agriculture on the well-drained level 'uplands', with the swampier river channels left in forest |  |
|
|
The rivers of the southern portion of the Coastal Plain - from the Neuse southwards - have carved asymmetric valleys in response to the general dip of the rocks towards the south. The southern walls are often well marked and several feet - or even tens of feet high, while the northern ones may be only a few feet in height, and often very gradual. |
|
A view from the top of one of the southern 'valley walls' In this case the feature (the 'Cliffs of the Neuse') is very well developed and has been designated a State Park
|
A 'reverse' view - looking from the river towards the valley wall. Although this is not far from the illustration at left - being about 5 miles upstream- the cliffs are by no means as spectacular.
|
|
|
Another feature - combining soil, vegetation and landform - which is unique to the coastal plain of North and South Carolina (with a slight extension into Georgia), is the Carolina Bay. The origin of these oval shaped depressions is obscure. None of the obvious explanations - meteor shower, glaciation, out gassing from the earth's crust - fits. They remain a mystery. The key feature is the bay trees which fill the interior once the lakes have been infilled as a result of ecological succession. |
|
Tidewater
| Much of tidewater is very close to sea level and rather
poorly drained. The land is generally flat. The various old
cliff-line 'scarps' are the major physiographic features, and they
influence the soils and vegetation. Often, below the scarp, is a
pocosin - often a swampy feature, sometimes one with marshy
grassland. The soil, if drained, is fertile. Much of the area
is now used for extensive agriculture.
|
 |
|
|
On the horizon is the Surry scarp, seen here west of Elizabeth City. The feature is less than 10 feet high, but is made more impressive (and visible) in this area because trees have been left on the slope. All the flat land in front has been cleared for cultivation. |
 |
Prior to drainage, much of the area was in pocosin - 'swamp on a hill' - vegetation. The swamp interior was commonly composed of organic soils, which gave rather little strucutral support for large plants. The result was rather low-growing scrubland (as seen to the right, where the force of the gale suggests some of the stresses likely on tall vegetation in this area). The edge of the region may have had larger trees on the more 'normal' soils with a high inorganic matter content. |
|
 |
Where land is not drained the true swamp survives - as suggested by the conditions at left. Where drainage has taken place, the rich agricultural land has tended to compact. Thus the field at right is below the level of the road and the (managed) forest seen in the left of the picture. |  |
The Coast
|
Finally - the coast itself.
In some places the swamp seems to grade imperceptibly from freshwater to salt water. |
 |
rt |
In other areas there is clearly a dune system, which itself supports a highly distinct vegetation, adapted to salty and alternate wet and dry conditions. |  |
