Damage and yield change in cocoa crops due to harvesting of timber shade trees in Talamanca, Costa Rica

摘要

A computer model was developed for the economic analysis of the damage caused to cocoa plants (Theobroma cacao) due to the harvest of timber shade trees (Cordia alliodora), based on field estimations from cocoa farms in the indigenous region of Talamanca, in the south east of Costa Rica. An economic cost-benefit analysis was carried out considering cocoa planting densities, yields, timber volumes and both cocoa and timber prices. Damage to cocoa plants was quantified in terms of severity levels and then translated into yield losses and their corresponding economic values. From the 49 harvested timber trees observed, 196 cocoa plants were affected, of which 4% required replanting and 38% coppicing. Tree trunks were involved in 55% of the damage cases (109) and tree crowns in 45% (89). Nevertheless, the revenue obtained from timber sales easily offset the costs of damage to the cocoa crop. The economic analysis showed that on average, the net gain derived from timber harvesting was around US$316 per tree. For all considered scenarios, the timber market price that would balance discounted costs and benefits to zero ranged between US$22 and US$66 mpd (current market price for C. alliodora is US$128 mpd). There would be lower margins due to higher costs of cocoa damage in high yielding, high price cocoa scenarios. However, the study shows that damage due to tree felling should not be a major objection of farmers to the use of timber shade trees in cocoa farms even in these scenarios.