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 b y farmers presents conditions distinct from those for which traditiona l plantation forestry species have been selected, i.e., low intensity site management, compacted soils and high year-round rainfall. The ada ptation of 14 exotic (proven plantation species in other tropical regi ons) and 66 potential native plantation timber species to these condit ions was tested in a 6-year-old trial in the lowland humid tropics of Costa Rica. Two exotic species, Gmelina arborea and Acacia mangium, ha d the highest growth rates, but both were subject to pest attacks that limited the life of the stand. Other exotic species (Pinus spp. and E ucalyptus spp.) did not express the high growth rates typical of these species in other regions. Native species within the top 20 overall sp ecies tended to have higher survival, fewer pests, but lower growth ra tes than exotics of similar wood qualities. Of the natives tested, onl y about 10 species had sufficiently high growth rates and good form to be attractive as potential plantation species, these included Vochysi a spp., Stryphnodendron excelsum and Terminalia amazonia. Two native s pecies with high growth rates but poor form were Goethalsia meiantha a nd Sclerolobium guianensis. The native potential plantation species ap peared to be well adapted to the low input forestry practiced by farme rs in the lowland humid tropics, while the traditional forestry specie s (exotic to this region) probably require more intensive production s ystems. If a wide range of production systems is considered, e.g., agr oforestry, 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.