Essential oil production increases value of Psiadia altissima fallows in Madagascar's eastern forests

Abstract : Fallow with Psiadia altissima is one of the most common post-'slash and burn' vegetation successions described in the evergreen forests of eastern Madagascar. Some fallows consist of almost pure stands of this species, of which the leaves produce an essential oil offering international commercial interest. The present research aims to evaluate the production potential of essential oil derived from different fallows rich in P. altissima. The study has revealed that fallows aged 4 and 6 years since the last crop abandonment produce the most essential oil (around 20 l ha−1), but relative to fallow duration, the youngest fallows (1- or 2-year-old) are the most productive, respectively producing 12 and 6 l ha−1 year−1. Additionally, the trees from the youngest fallows have a substantial capacity for regeneration from coppice shoots, on condition that the cut is performed well above the root collar. Although farmers earn five times less from harvesting leaves than from cultivating rice from tavy, the possibility is there for them to complement their income and diversify their production. The overall results show that sustainable exploitation of fallows of P. altissima is a conceivable option. However, this can only be achieved through an integrated approach that takes into account the environmental and social constraints associated with the development of this new activity.