History of logging and silvicultural treatments in the western Venezuelan plain forests and the prospect for sustainable forest management
详细信息   
摘要
Venezuela’s logging history is poorly documented, although this country is endowed with one of the largest tracts of forests in Latin America. In this paper, we reviewed the history of natural forest management (NFM) in the western plains where commercial logging began as early as 1920. In the first few decades, logging was highly selective, focusing on mahogany (Swietenia macrophylla) and cedar (Cedrela odorata). From the 1950s until recent times, saqui–saqui (Bombacopsis quinata) was the most important timber species not only in the study area but also for all of Venezuela. Early logging was based on annual permits, resulting in the eventual conversion of natural forests into pasture. In the 1950s and 1960s, the Venezuelan government set aside four permanent forest estates (PFEs; covering ca. 1Mioha) in the study area to sustain timber production. However, NFM under long-term lease contracts (up to 40 years) did not commence until 1970. Conventional logging operations, removing all valuable timber species above the legal size, leave a highly damaged residual stand. Growth modelling suggests that the anticipated 30-yr cutting cycles do not provide sustainable yields under the current logging regime. On suitable sites, teak (Tectona grandis) is a promising species for monocultures. Due to the invasion of landless farmers, the area of PFEs has declined to some 250000ha (230000ha logged or unlogged forest, 20000ha monocultures). The remaining forest can only be preserved as timber production area if: (1) NFM is improved, (2) underpricing of forest resources is surmounted, and (3) disparity in land tenure and the trend to extensifying agriculture is overcome.