Native species: a resource for the diversification of forestry production in the lowland humid tropics

Reforestation of abandoned pastures in the lowland per humid tropics by farmers presents conditions distinct from those for which traditional plantation forestry species have been selected, i.e., low intensity site management, compacted soils and high year-round rainfall. The adaptation of 14 exotic (proven plantation species in other tropical regions) and 66 potential native plantation timber species to these conditions was tested in a 6-year-old trial in the lowland humid tropics of Costa Rica. Two exotic species, Gmelina arborea and Acacia mangium, had the highest growth rates, but both were subject to pest attacks that limited the life of the stand. Other exotic species (Pinus spp. and Eucalyptus spp.) did not express the high growth rates typical of these species in other regions. Native species within the top 20 overall species tended to have higher survival, fewer pests, but lower growth rates than exotics of similar wood qualities. Of the natives tested, only about 10 species had sufficiently high growth rates and good form to be attractive as potential plantation species, these included Vochysia spp., Stryphnodendron excelsum and Terminalia amazonia. Two native species with high growth rates but poor form were Goethalsia meiantha and Sclerolobium guianensis. The native potential plantation species appeared to be well adapted to the low input forestry practiced by farmers in the lowland humid tropics, while the traditional forestry species (exotic to this region) probably require more intensive production systems. If a wide range of production systems is considered, e.g., agroforestry, fuel wood lots, and mixed plantations, the biodiversity of native species provides a resource to potentially fill these different production niches. (C) 1998 Elsevier Science B.V.