MultiModel Projections for Evaluating Sustainable Timber and Seed Harvest of Carapa guianensis

Ecological models are increasingly used to forecast the long-term fate of populations after management interventions. The uncertainty associated with forecasts is important to investigate. Because model choice is one component of uncertainty, we compared projections of Carapa guianensis population growth rate (lambda) from matrix population models (MPMs) and integral projection models (IPMs). We also compared lambda projections for C. guianensis seed and timber harvest scenarios to those from previous MPMs for this economically valuable multiple-use tree species. Changes in the time interval of the MPM resulted in larger changes in lambda than changes in environmental conditions between years. The only exception to this trend was when representing impacts of a 2005 fire. Fire had a more severe impact on lambda when modeled with IPMs. The lambda(IPM) estimated in 2005-9 was 0.8122, almost 0.1 lower than the lambda(MPM) of 0.9115. The management implications of this research were mixed. Both MPM and IPM results indicated declining populations of C. guianensis even before simulated harvests. However, the annualized income from seed oil and timber harvests, although not ecologically sustainable, was comparable or higher than per-hectare earnings from rubber and other nontimber forest products in the Amazon.