Secondary forest management
From 1981 to 1990, the rate of tropical deforestation was 17 million ha/yr. By 1990, half of the tropics (900 million ha, or about 1.1 times the size of Brazil) was in secondary forests. Latin America alone has 335 million ha of secondary forests (about 1.2 times the size of Argentina). While primary tropical forests continue to disappear, consumption of tropical hardwoods is projected to double during the last quarter of the 20th century. Potential problems associated with these trends are loss of the 8 billion dollar trade in tropical timbers, global warming, climatic change on a regional basis, loss of biodiversity, and degradation of soil and water resources. Secondary tropical forests may be conveniently divided into residual (previously logged) and volunteer (arising after agriculture). Five stages may be recognized in the long history of secondary forest management: (1) Before 1850, characterized by migratory agriculture and fallow forests; (2) Indo-Burman phase (1850-1900), characterized by European techniques and taungya; (3) Africa-Malaysia phase (1900-1950), characterized by girth limit selection, shelterwood, improvement fellings, and enrichment plantings; (4) Exploitive phase (1950-1980), where the Malayan Uniform System and Uganda's monocyclic system gained prominence; and (5) Post 1980, characterized by environmental concerns as well as continual degradation tropical forests. Throughout these different phases, loggers selection (removing the best timber without subsequent management) was a prevalent extraction method. The long record of management experience in residual secondary forests contrasts with a limited experience in managing volunteer secondary forests. Secondary forests are characterized by several factors that favor management. These include natural regeneration, rapid recovery and site restoration, fairly uniform composition including some species of economic value, and proximity to markets. In contrast, uneven regeneration, numerous undesireable species, variable growth form, and a possible delay before silviculture is feasible, cause problems for management. Despite the slow volume increment of commercial timber, the management of residual tropical forests has been successful. Most failures have been due to political, economic, social or administrative problems. At least 14 management projects in Latin America are concerned with sustained yield of forest products. These projects, however, are mainly experimental and of relatively short duration. Future attempts at secondary forest management should build on past experience and emphasize conservation of the resource base while yielding forest products. Among the topics that should receive future attention are: land-use planning, protection of genetic resources, secondary forest management systems, enrichment planting, agroforestry, plantations, soil and water conservation, wildlife, eco-tourism, and secondary forest industries.
| Main Authors: | , , , , |
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| Format: | biblioteca |
| Published: |
Río Piedras, Puerto Rico (EUA)
1995
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| Subjects: | MANEJO FORESTAL, SISTEMAS SILVICULTURALES, REGENERACION NATURAL, INVESTIGACION, BOSQUE SECUNDARIO, PUERTO RICO, BRASIL, |
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