A Sandhills agricultural landscape - not great, but at least usable
A true sandy Sandhills landscape - in this case used as a military training ground - Fort Bragg
BIOSPHERE DYNAMICS
As plants colonize a newly developing landscape - and help the soil to form - a 'vegetation sucession' takes place. over time the vegetation gets more complex and bigger. This is likely to be a result of a deeper soil allowing bigger plants to overshadow smaller ones, while providing a greater nutrient supply. In theory, this process will go on until there is an equilibrium - the vegetation growing in an area (a mix of types all working together within a particular habitat in an ecosystem) will be at the maximum allowed by the soil and the climate. In practice, this ideal stage is never reached.
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A Sandhills agricultural landscape - not great, but at least usable |
The Sandhills area is clearly very different from the result of the Piedmont and Coastal Plain. On the very longest time-scale, will the slow accumulation of humus on the soil slow down the drainage and move the area towards a more loamy soil, a different vegetation and a different landscape? Possibly, but not in our lifetime! |
A true sandy Sandhills landscape - in this case used as a military training ground - Fort Bragg |
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Much of the vegetation of the North Carolina mountains was established some 20,000 or more years ago, during the last great Ice Age. The area probably had a great deal of snow every winter, but was not glaciated. However, the vegetation that slowly became established - by the long process of vegetation succession - reflected those very cold conditions. Today we think of the current tree species as being appropriate in eastern Canada or the higher peaks of New England. Again, as the area warms - or perhaps if if warms sufficiently - these tees will succumb to competition from trees better adapted to warm conditions, and will vanish (The question of human activity and acid rain in this area really simply complicated the picture). Meanwhile, the southern Appalachians, because of the relatively recent climate change - has a tremendous diversity of tree species. |
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On a much shorter time-scale, a major characteristic of ecosystems is disturbance. Changes brought about by events such as ice storms, floods, droughts, or fire, will commonly kill the weaker members of a species. This often provides opportunities for new species to enter, or for the younger members of a species to grow vigorously.
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The charred lower portions of the trunks of these trees indicates that they escaped a recent fire in the area. The fallen trees were not so lucky and succumbed to low-level burning. However, opening up the tree canopy provides opportunity for other species to prosper - although there are already indications that the pines will eventually become re-established. |
This area was flooded a few days before the picture was taken (after Hurricane Dennis and before Hurricane Floyd in 1999). The parkland had been re-seeded late in the spring and the grass was not well established. In addition, rainfall was light in the summer, although some irrigation had been used. Thus the grass was already stressed when the flood came, and it covered the area long enough to kill the grass. The well established trees were largely unaffected. |
