Modeling the long-term impacts of logging on genetic diversity and demography of hymenaea courbaril

Abstract

Although selective logging is a common practice for timber production in the Brazilian Amazon, very little is known about its impacts on genetic diversity and demography of the harvested species. This study explores the sustainability of current forest management systems in the Brazilian Amazon by modeling harvesting cycles and examining the impacts on the genetic diversity and demography of the highly valued species Hymenaea courbaril. Using extensive field data, we introduced a two-step modeling procedure for EcoGene software that allowed us to identify optimal felling cycles that were later used for testing and defining sustainable logging parameters. The results show that logging cycles for H. courbaril should be approximately of 110 years, as opposed to the 30-year cycle currently used in Brazil, and harvesting levels should consider a combination of larger minimum cutting diameters (75-100 cm) and lower logging intensities (10-50%). We conclude that current practices in Brazil (30-year cycle, logging intensities of 90%, and minimum cutting diameters of 50 cm) are unsustainable for H. courbaril and that the current practice of using general logging prescriptions for all species does not deliver sustainable forest management in the Amazon. Brazilian forest harvesting regulations need to move toward species-specific prescriptions to ensure real sustainability in the long term. © 2013 by the Society of American Foresters.