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A Comparison of Variety and Standing Crop of Vegetation on a One-Year and a Twelve-Year Abandoned Field

1965; Wiley; Volume: 15; Issue: 2 Linguagem: Inglês

10.2307/3565118

1600-0706

Frank B. Golley, John B. Gentry,

Animal Ecology and Behavior Studies

Studies of the development of old-field vegetation over 12 years on the AEC Savannah River Plant (SRP), Aiken, South Carolina, USA, showed that an inverse relationship existed between the variety of species and the net production of dry matter of the plant community (ODUM 1960; GOLLEY 1965). After farming was abandoned on the SRP, the annual net production of the natural vegetation during the first year of the old-field sere was about 500 g dry matter/m2/year. In three years production declined to about 300 g/m2/year and stabilized at this level through the seventh year. During these first seven years the community was composed of a collection of plant species dominated by the composites Leptilon canadensis, Haplopappus divaricatus, Gnaphalium purpureum, Heterotheca subaxillaris, and the grass Digitaria sanguinalis. During the forb stage the number of species contributing more than one g/m2/year to net production increased from about 5 to 15. In the eighth year the dominance of the community changed from forbs to grasses. The grass Andropogon virginicus became the most important plant in the community and net production increased to 650 g/m2/year, while the variety of dominant species fell to 8. During the succeeding four years the net production declined to 550 g/m2/year and species variety increased to 14. Since the rate of change within or between seral stages of a community may be influenced by the size of the unvegetated area and the invasion ability of the species growing adjacent to the abandoned field (GOLLEY 1965), the observed inverse oscillation between species variety and net production may not always occur. For instance, in small fields succession may be very rapid, with the