Simple methods for calculating minimum diameter and sustainable yield in mixed tropical forest
Methods are described for calculating optimum felling diameter for timber production and the sustainable yield wich non-equilibrium diameter distributions on the basis of tree growth and mortality data from permanent sample plots. Optimum diameter is calculated by calculating the cumulative age and volume of the survivors from a regenerating cohort, to derive a mean annual increment per 100 seedlings (MAI percent). The maximum MAI percent represents an optimum felling diameter for timber production. For three species in Ghana (Guarea cedrata, Khaya ivorensis, Triplochiton scleroxylon) this optimum appears to be about 60 cm diameter. Sustained yield is calculated by an iterative method using a spreadsheet package. Inventory data are organized by classes whose width is the time of passage through one felling cycle. The survival to maturity is calculated for each class. A fraction of each class may be retained and accrued to later cycles. The iterative calculation from trial values of sustainable yield derives suitable retention values for each class. The method is simple to operate in practice and requires only basic or assumed growth data.
| Main Authors: | , , , |
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| Format: | biblioteca |
| Published: |
Oxford (RU)
1992
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| Subjects: | CORTA, DIAMETRO, RENDIMIENTO, CRECIMIENTO, MORTALIDAD, GHANA, |
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