Evaluating ipe (Tabebuia, Bignoniaceae) logging in Amazonia: Sustainable management or catalyst for forest degradation?

摘要

Prized for their dense, rot-resistant wood, Tabebuia impetiginosa and T. serratifolia (vernacular name=ipe) are among the most valuable Amazonian timbers. We analyzed the geographical extent, spread and trajectory of ipe logging in Brazilian Amazonia, and evaluated harvest pressure on this forest resource. We also examine Tabebuia population response to reduced-impact logging, a more ecologically benign alternative to destructive conventional harvest practices in Amazonia. Based on eight years of population monitoring at multiple sites in the eastern Brazilian Amazon, we project second harvest ipe yields in forests logged using RIL under legally allowable (90% of commercial stems) and reduced (70%) harvest intensities. In recent years ipe harvests have declined or ceased in the majority of old logging frontiers in eastern Amazonia while spreading to new logging frontiers in central and southwestern Amazonia. With current timber market prices, transportation infrastructure and harvesting costs, logging of ipe would be profitable in an estimated 63% of the Brazilian Amazon; in the more remote logging frontiers only logging of ipe and a few other high-value timbers is currently profitable. All populations of T. impetiginosa and T. serratifolia in northeastern forests showed drastic population declines over multiple RIL harvests in simulations, with no indication of population recovery over the long term. We conclude from study of Tabebuia populations in eastern Amazonia and modeling of response to logging that these two species are endangered by logging activity and merit additional protection under forest legislation.