Assessing trade-offs in multiple-objective tropical forest management.

摘要

While tropical forests continue to be cleared at alarming rates, the debate over how best to conserve them often proceeds without a clear understanding of the trade-offs that result from different management alternatives. Because timber is the most valuable product of tropical forests, substantial effort has been directed to harmonizing timber production and other goals, especially carbon sequestration and biodiversity conservation. Unfortunately, the nature and magnitude of the trade-offs between timber production and these objectives remain unclear and depend on numerous factors. By elucidating the key biophysical factors that influence forest management trade-offs, I aimed to better inform the quest to manage tropical forests for multiple benefits.; I assessed the trade-offs between timber production and fire susceptibility in a seasonally dry forest in lowland Bolivia subjected to four silvicultural treatments of increasing intensity aimed at achieving sustained timber yields (STY). By quantifying treatment effects on fuel loads, vegetative cover, dry-down rates of 10-h fuels, and fire spread, I found that the treatments had little effect on fire susceptibility; this forest is fire-prone for about 130 days per year, even in the absence of logging. Fire severity, however, would likely be greater with intensive management due to increases in 1,000-h fuels.; Using a simulation model (SYMFOR) to project the effects of the silvicultural treatments on future timber yields, forest structure and composition, and biomass, I found that none of the treatments came close to achieving STY, indicating that silviculture would probably need to be intensified to secure STY. Neither forest structure nor species composition changed appreciably over two cutting cycles (60 years) in any of the treatments.; By contrasting the Bolivian forest with eastern Amazon and Borneo forests, I found that the trade-offs resulting from intensive silviculture to secure STY paled in comparison to the loss of forests. If maintenance of productive forest for both timber and carbon with a full complement of biodiversity is the goal, then fire (and not silviculture) is the menace. Fire prevention must complement silvicultural treatments to achieve sustained yields if tropical forests are to serve both production and conservation goals.