Monday, November 14, 2011

Floodplain

This narrow strip of level floodplain area was the last field not near the house that was used for the production of annual crops. This was the largest area of deep soil to be found on the property and would have been a prime area for Burley Tobacco production. Its progression to a more natural ecosystem is progressing along an interesting course and I’m not sure where it will ultimately end. Despite a large number of deciduous trees scattered through the site, the area remains relatively open.

Green and White Ash are the dominant trees here. They are quite tall, but the trunks have a rather narrow diameter. This is typical of trees that begin life in a highly fertile soil. A typical tobacco field abandoned in the late 1970’s would have been left with an inflated level of fertility. Trees growing from these fields would have shown excessive growth through the pole stage and would have produced a stand of tall, thin trees.

Sycamores, growing along the bank of the creek, are much older and were in place and growing at the time the field was being cropped. These trees managed to avoid the die-backs that affected many Sycamores about 20 years ago.

Across the floodplain from the Sycamores are Honey Locusts that thrive where the base of the hill meets the level ground. Black Walnuts are the second most prominent tree on the floodplain. I don’t know whether or not the walnuts were naturally seeded or were planted as seedlings. The surrounding woods contain no walnuts that could have served as a seed source.

The Ash trees have been dieing at a rapid rate over the last ten years. This is also typical of trees that begin life in high fertility soils. It takes less root mass to support a tree under high fertility conditions, so the top outgrows the roots. When fertility levels begin to decrease, the roots have trouble expanding rapidly enough to keep the top growth from being stressed. The stress may kill the trees outright or it may allow the trees to fall victim to insect and disease invasions.

Another indicator of earlier high fertility conditions is the absence of cedars from the tree mix. Cedars quickly invade low fertility sites, but have trouble competing against vegetation that is boosted by high fertility. This section is completely free of cedars despite the fact that surrounding hillside areas show a heavy cedar growth.

The ground cover is primarily composed of species that have a broad range of light tolerance. I haven’t yet decided how this should be managed. As one tree grows to produce more shade, another dies to bring in more sunlight. As far as I can tell, this pattern will continue for quite some time. I guess I still have some time to study the area and decide on some management options before the site naturally evolves into something else.

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