Influencia de diferentes niveis de exploracao florestal em uma floresta tropical na regiao de Marabá-PA
Several intensities of sustained yield management regimes were tested in an area of tropical forest at a Forest Reserve belonging to Cia Vale do Rio Doce-CVRD, located in the municipality of Maraba, Para State, Brazil. The statistical design for this test was Complete Randon Blocks with four replications, and the treatmens were: 1) No thinning; 2) Clear cutting; 3) Thinning trees with DBH over 45 cm, and 4) Thinning trees with DBH lower than 20 cm and DBH above 60 cm. This test was installed in 1984 and data collected before and after thinning (August, 1984 and October, 1984), and in 1986 and 1988. In each experimental plot, trees with circunference at over breast height (CBH) bark over 15,7 cm were measured. Seedlings from natural regeneration were counted in each plot. The species of each trees were identified by its botanical and popular names. With these data, the JENTSCH mixture quocient and Importance Value Index (IVI) for each experimental plot were calculated, as well as the growth increment expressed as number of trees recruited and annual and periodic growth in basal area. The main conclusions were: a) Treatment 2 showed the best wood volume after thinning (fuel wood and saw-wood) and after four years of growth, 74 percent of the initial basal area were reached, but species diversity is lower than the other treatments. At this time there is numerical superiority of pioneer and early secondary species, b) Species composition observed in 1988, at the treatments 1,3 and 4 is similar to that one observed in 1986. Treatment 2 showed an irregular unsteady pattern in the period under consideration, c) The number of plots to study natural regeneration was lower than the necessary (10 percent sampling error with 95 percent probability level), but it was possible to get statistical significance among treatments, d) The growth increment expressed as number of trees and basal area, was greater in diameter class form 5 to 20 cm, for all treatments, e) It was not possible to recommend anyone treatment, because the period of observation (four years) is not enough to reach stability, f) It is suggested a development of a sampling scheme to monitor natural regeneration under several thinning intensities, and a demostration program for forest management in the Amazon.
| Main Authors: | , |
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| Format: | biblioteca |
| Language: | spa |
| Published: |
Piracicaba, SP (Brasil)
1990
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| Subjects: | MANEJO FORESTAL, CARACTERISTICAS DEL SITIO, COMPOSICION BOTANICA, ESTRUCTURA DEL BOSQUE, INVENTARIOS FORESTALES, CRECIMIENTO, VOLUMEN, SISTEMAS SILVICULTURALES, DENSIDAD DE LA POBLACION, BOSQUE TROPICAL HUMEDO, AMAZONIA, BRASIL, |
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| Summary: | Several intensities of sustained yield management regimes were tested in an area of tropical forest at a Forest Reserve belonging to Cia Vale do Rio Doce-CVRD, located in the municipality of Maraba, Para State, Brazil. The statistical design for this test was Complete Randon Blocks with four replications, and the treatmens were: 1) No thinning; 2) Clear cutting; 3) Thinning trees with DBH over 45 cm, and 4) Thinning trees with DBH lower than 20 cm and DBH above 60 cm. This test was installed in 1984 and data collected before and after thinning (August, 1984 and October, 1984), and in 1986 and 1988. In each experimental plot, trees with circunference at over breast height (CBH) bark over 15,7 cm were measured. Seedlings from natural regeneration were counted in each plot. The species of each trees were identified by its botanical and popular names. With these data, the JENTSCH mixture quocient and Importance Value Index (IVI) for each experimental plot were calculated, as well as the growth increment expressed as number of trees recruited and annual and periodic growth in basal area. The main conclusions were: a) Treatment 2 showed the best wood volume after thinning (fuel wood and saw-wood) and after four years of growth, 74 percent of the initial basal area were reached, but species diversity is lower than the other treatments. At this time there is numerical superiority of pioneer and early secondary species, b) Species composition observed in 1988, at the treatments 1,3 and 4 is similar to that one observed in 1986. Treatment 2 showed an irregular unsteady pattern in the period under consideration, c) The number of plots to study natural regeneration was lower than the necessary (10 percent sampling error with 95 percent probability level), but it was possible to get statistical significance among treatments, d) The growth increment expressed as number of trees and basal area, was greater in diameter class form 5 to 20 cm, for all treatments, e) It was not possible to recommend anyone treatment, because the period of observation (four years) is not enough to reach stability, f) It is suggested a development of a sampling scheme to monitor natural regeneration under several thinning intensities, and a demostration program for forest management in the Amazon. |
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