RESUMEN
BACKGROUND: A large proportion of the tropical rain forests of central Africa undergo periodic selective logging for timber harvesting. The REDD+ mechanism could promote less intensive logging if revenue from the additional carbon stored in the forest compensates financially for the reduced timber yield. RESULTS: Carbon stocks, and timber yields, and their associated values, were predicted at the scale of a forest concession in Gabon over a project scenario of 40 yr with reduced logging intensity. Considering that the timber contribution margin (i.e. the selling price of timber minus its production costs) varies between 10 and US$40 m -3, the minimum price of carbon that enables carbon revenues to compensate forgone timber benefits ranges between US$4.4 and US$25.9/tCO 2 depending on the management scenario implemented. CONCLUSIONS: Where multiple suppliers of emission reductions compete in a REDD+ carbon market, tropical timber companies are likely to change their management practices only if very favourable conditions are met, namely if the timber contribution margin remains low enough and if alternative management practices and associated incentives are appropriately chosen.
RESUMEN
The effect of Phragmanthera capitata (Sprengel) Balle, an epiphytic Loranthaceae, on latex production of three clones of rubber tree, Hevea brasiliensis (Müll. Arg.), was studied in the industrial plantation of Mitzic, in Gabon. The 22-year-old trees, presenting the largest trunk circumference, were the most parasitized and at the same time the best producers of latex. At first, this would suggest that mistletoe parasitism could have a favourable effect on latex yield. However, an accurate statistical analysis showed that, in fact, parasitism had no significant effect on latex yield. These data, discussed in relation to the biology of flowering parasitic plants, suggest that there is no urgency to eradicate Phragmanthera capitata for the moment.