food crops and of native fruit and leguminous trees to poor soil and other conditions found in small forest clearings; and to transfer field plots and plant material to Panamanian government agencies responsible for the development of agricultural technology to enable them to continue with the most promising results obtained by this project.
Soils in the project area are very poor, like much soil under tropical forests. They are characterized by very low to medium pH values (4.3–5.4); a low to high aluminum content (traces-7.4 ppm), and low to extremely low phosphorus concentrations (traces-9.5 ppm).
The quality of these soils did not seem to vary with successional stage of vegetation. Seeds of leguminous shrubs, trees, and vines with the required adaptation and performance potential (NRC, 1979) were obtained from several sources. Promising results in terms of vigor, competitiveness, and stress tolerance against drought or impeded drainage were obtained with fast-growing trees, e.g., Sabah salwood (Acacia mangium) in Malaysia, wattle (A. auriculiformis) in Papua New Guinea, and mata raton, madre del cacao (Gliricidia sepium) in Latin America; shrubs, e.g., Desmodium gyroides, Tephrosia candida, and Townsville clover (Stylosanthes guianensis) in Trinidad; and creeping vines, e.g., tropical kudzu (Pueraria phaseoloides) and Desmodium ovalifolium. Of these, only G. sepium and S. guianensis are native to the Neotropics.
The response of Acacia mangium was impressive under the local conditions; no species hitherto proposed for lumber production in similar soil in Panama even approaches the growth figures obtained with this species. The trees showed a striking response to the addition of phosphorus, and rhizobium-induced root nodules were large and prolific. A symbiotic relationship with mycorrhizal fungi was clearly indicated in growth trials using forest and pasture soils. The performance of A. mangium and of other leguminous species under severely adverse soil conditions opens up a wide range of options for the restoration and maintenance of soil fertility and for the development of agroforestry systems.
Results of trials in small forest clearings showed that the following species could constitute the core of a highly productive forest garden in tropical soils of low fertility: arrow root (Maranta arundinacea), tuber-bearing yam (Dioscorea bulbifera), Mexican yam bean (Pachyrhizus erosus), American peach palm (Bactris gasipaes), hardy banana clones (Musa spp.), a shade-tolerant, soil-covering vine (Desmodium ovalifolium), and leguminous shade trees (Erythrina spp. and Gliricidia sepium) (cf. Huxley, 1983).
Native populations in the Neotropical humid forests have traditionally relied on native wildlife for their high-quality protein. Since the advent of firearms and headlamps, more efficient hunting methods combined with habitat destruction have resulted in the extermination of game species in many areas. It is thus urgent to determine the sustainable yield of protein that can be obtained from these forests and to devise the means to manage the game populations appropriately.