A silvicultural analysis of secondary succession in the Montane Oak forest belt, Cordillera de Talamanca, Costa Rica
This forest inventory was carried out in order to investigate secondary succession of Costa Rican montane oak forests. The study area is situated at the Pacific side of the Cordillera de Talamanca, in the valley of the Rio Savegre along the road from the Carretera Interamericana to San Gerardo de Dota, at altitudes oscillating between 2700 and 2800 m. The climate is considered as very humid, with moderate temperatures. The soils are shallow, acid and poor in nutrients. Most deforestation occurred between the early sixties and mid seventies, when de Los Santos forest reserve was established. Present land uses include pastureland, orchards and some blackberry cultivation. For our inventory, plots of 20 * 25 m were established in secondary forest and all trees (DBH > 50 mm) were measured. In each of these plots, two subplots of 5 * 5 m were established in order to facilitate the measurement of all saplings (DBH < 50 mm, h> 1.50 m). Besides these plots, four subplots of 2 * 2 m were established for the stock-taking of the seedlings (h < 1.50 m). The investigated secondary forests can be divided in two groups; one which is dominated by Quercus spp. (forest type A) and one that is not (forest type B). Preliminary Basal Area (BA) and Mean Annual Increment (M.A.I.) curves were drawn for forest type A and for Quercs spp. Type B forest were too heterogeneous to draw such curves. Importance Value Indices (I.V.I.) were calculated for the most abundant tree species in forest type A and in forest type B, and for both together. Values found for forest type A appear quite similar to those found in primary forest (Jiménez and Miranda, 1986). The majority of forest of type B are now dominated by pioneer species, but examination of the sapling stock suggests that these forests will be dominated by more valuable species in the near future. Forest type a occurred only in proximity to mature oak trees (e.g. > 50 year) Mature oaks are probably indispensible for a succesful regeneration of oak forests. The absence of Quercus spp. in forest type B indicates that acorns are not dispersed very far from the parent tree. If oak seedlings are present from the very start of the secondary succession, they seem to be able to compete successfuly with other, more aggressive (heliophytic) forest vegetation. If these secondary forest are to be managed for timber, it is of great importance to mountain a protective vegetation cover in order to avoid erosion. A plycyclic selection system might be the most appropriate management system for these forest; forest type A probably having a rotation period of 70 years and forest type B possibly a shorter one. Another possible use of these forest might be firewood production by means of coppice systems.
| Main Authors: | , |
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| Format: | biblioteca |
| Published: |
Heredia (Costa Rica)
1989
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| Subjects: | QUERCUS, AGRICULTURA, SUCESION ECOLOGICA, SISTEMAS SILVICULTURALES, CARACTERISTICAS DEL SITIO, MANEJO FORESTAL, CORDILLERA DE TALAMANCA, COSTA RICA, |
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| Summary: | This forest inventory was carried out in order to investigate secondary succession of Costa Rican montane oak forests. The study area is situated at the Pacific side of the Cordillera de Talamanca, in the valley of the Rio Savegre along the road from the Carretera Interamericana to San Gerardo de Dota, at altitudes oscillating between 2700 and 2800 m. The climate is considered as very humid, with moderate temperatures. The soils are shallow, acid and poor in nutrients. Most deforestation occurred between the early sixties and mid seventies, when de Los Santos forest reserve was established. Present land uses include pastureland, orchards and some blackberry cultivation. For our inventory, plots of 20 * 25 m were established in secondary forest and all trees (DBH > 50 mm) were measured. In each of these plots, two subplots of 5 * 5 m were established in order to facilitate the measurement of all saplings (DBH < 50 mm, h> 1.50 m). Besides these plots, four subplots of 2 * 2 m were established for the stock-taking of the seedlings (h < 1.50 m). The investigated secondary forests can be divided in two groups; one which is dominated by Quercus spp. (forest type A) and one that is not (forest type B). Preliminary Basal Area (BA) and Mean Annual Increment (M.A.I.) curves were drawn for forest type A and for Quercs spp. Type B forest were too heterogeneous to draw such curves. Importance Value Indices (I.V.I.) were calculated for the most abundant tree species in forest type A and in forest type B, and for both together. Values found for forest type A appear quite similar to those found in primary forest (Jiménez and Miranda, 1986). The majority of forest of type B are now dominated by pioneer species, but examination of the sapling stock suggests that these forests will be dominated by more valuable species in the near future. Forest type a occurred only in proximity to mature oak trees (e.g. > 50 year) Mature oaks are probably indispensible for a succesful regeneration of oak forests. The absence of Quercus spp. in forest type B indicates that acorns are not dispersed very far from the parent tree. If oak seedlings are present from the very start of the secondary succession, they seem to be able to compete successfuly with other, more aggressive (heliophytic) forest vegetation. If these secondary forest are to be managed for timber, it is of great importance to mountain a protective vegetation cover in order to avoid erosion. A plycyclic selection system might be the most appropriate management system for these forest; forest type A probably having a rotation period of 70 years and forest type B possibly a shorter one. Another possible use of these forest might be firewood production by means of coppice systems. |
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