Tuesday, December 18, 2007

Drought Good?

Is a drought a good thing? There are plenty of people in the Southeast and around the world that might argue that there is nothing good about a drought. However, drought-like conditions are required for a Bald Cypress (Taxodium distichum) swamp to regenerate itself.

An article on the subject appeared in Sunday's The Post and Courier written by SC Department of Natural Resources' Walt Rhodes. Entitled "Drought is a necessary evil," it described the conditions necessary for Bald Cypress trees to regenerate. He wrote:

"The extirpated Carolina parakeet used to help disperse the hard seeds of cypress, but today wildlife plays a minor role for cypress and tupelo seed dispersal. Water is the main transport mechanism, however, the seeds must eventually come to rest on saturated but not flooded soil to germinate.

Once sprouted, seedlings of both species grow quickly so that once the water returns their needles or leaves will be above the water. If a seedling remains underwater for more than a month it will die."

Therefore, the edge of the swamp is where young Bald Cypress trees are often found. The edge of the swamp is the first area to dry when the water in the swamp recedes and the last to get wet again once the water level rises. An extended drought, often a once-in-a-100-year event, along with adequate sunlight are required to allow Bald Cypress trees to germinate deep in the swamp. Obviously, such conditions have occurred, because there are giant Bald Cypress trees throughout the swamp, including the mature tree standing behind a youngster.

Although water levels have been low enough this year, as they often are when cypress seeds fall, it is the water level in the spring that is critical. Bald Cypress trees are deciduous, so being underwater in the winter when they are already dormant is not an issue. However, when spring arrives and the trees put out their needles, they must be above the water to survive. Many thousands will germinate each year, but will drown when spring water levels rise.

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