Viability of combined timber and non-timber harvests for one species: A Carapa guianensis case study

Abstract

There is growing consensus that sustainable use has a significant role to play in global conservation. Tropical forests are no different, and managing them for multiple products is envisioned as a preferable alternative to timber-dominant management models. Limited research, however, has tested coupling timber and non-timber harvests in multiple-use species for both economic gain and long-term species conservation. We employ matrix population models and the extinction time cumulative distribution function to examine one such species, Carapa guianensis. We investigated sustainable harvests of C. guianensis in two forest types in which it occurs naturally in western Amazonia, testing whether differences between forest types affect population responses to harvest under measured environmental stochasticity regimes. Our results indicated that some C. guianensis populations may be suitable for extraction of seeds, timber, or a combination of both. In upland or terra firme forest sites, model projections suggested that no tested levels of seed and timber extraction were sustainable. In contrast, we found the potential for compatibility between seed and timber harvest in occasionally inundated forests. In these sites, which are ecologically similar to wet areas where Carapa thrives throughout its range, our results suggested that 10% annual seed harvests were compatible with 100% timber harvests of trees ≥50cm twice a century, the equivalent of approximately two trees per hectare. Application of this research approach to other economically important tropical species could increase the diversity of Amazonian management and conservation options.