Those who study how trees grow and how they can be encouraged to grow better to provide for the needs of people consider the oecological relationships of soils, climate, physiography, and biotic entities. Since forestry became a profession, oecology, now shortened to ecology, has been a forester's word. Silvics joined the vocabulary to accompany ecology. Silvics deals with the sciences basic to understanding how trees grow, and ecology with the relationships of living things to each other and to their environment. In this context, involving silvics and ecology we now consider the complex interactive nature of the South's woodlands. Biotic components—notably here the trees—of any particular site interact with physiographic, climatic, and edaphic factors to establish the kinds of vegetation at any one time and place.
Most of the commercial coniferous woods in the South come from trees with similar requirements for natural reproduction. For successfully establishing a new forest, seeds must, of course, be available. Then, to regenerate the principal species, mineral soil should be scarified to serve as the seedbed. Southern pine seeds seldom germinate and become seedlings if they fall on leaves, grass, and brush. Finally, full sunlight is desirable so that the young trees can be firmly established following seed germination. For instance, loblolly and shortleaf pines may survive with 50 to 60 percent of full sunlight on better sites, but often this shade-tolerance diminishes when seedlings reach heights of 6 to 10 feet.
In nature, fires and storms scarify the soil, exposing mineral matter as they remove leaves and grass lying on the ground. Fires and hurricanes, too, may obliterate vast areas so that full sunlight reaches the forthcoming seedlings that germinate from seeds in the soil. For successful forest renewal, seeds must be available at the time the soil is freshly disturbed and the canopy of overstory vegetation opened to the sun. Natural events often provide the scenario. Therefore, in making openings in the canopy, foresters attempt to imitate nature. Clearcutting is often unsightly for a season, but the method may be necessary to perpetuate pine forests.
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