TROPICAL LEGUMINOUS SPECIES FOR ACID SOILS - STUDIES ON PLANT FORM AND GROWTH IN COSTA RICA

Few studies of adaptability and growth of native legume species have b een conducted on degraded acid soils. The lack of data for native spec ies has often precluded their use in incentive-supported reforestation and international agroforestry schemes. A species screening trial tha t included 25 legume species was conducted at three abandoned pasture sites in the Atlantic Lowland of Costa Rica. Most of the leguminous sp ecies were of potential multipurpose value: 8% were exotic N-2-fixing trees, 60% (some of which were N-2-fixers) were indigenous to the regi on, and 32% (some of which were N-2-fixers) were native to other areas of Costa Rica. Survival (including damage indices), growth, tree form and N2-fixing ability were used to evaluate species performance. Surv ival of the majority of the species after 3 years was high. Pithecello bium idiopodum, Inga edulis, Albizia guachapele, Pithecellobium elegan s and Dalbergia retusa had greater than 90% survival at all sites. The re were significant differences in growth measures among species. Acro ss sites Acacia mangium, Stryphnodendron microstachyum and Inga edulis produced the greatest stem volume, and A. mangium, I. edulis, P. idio podum and S.microstachyum had the highest crown volume. Inga edulis, P . idiopodum, I. coruscans and P. macroloba failed to form straight sin gle stems. Acetylene reduction assay at Site 3 showed that I. edulis, A. mangium, A. guichapele, and I. coruscans had the highest nitrogenas e activity among the best growing species. This trial indicates that t here are native leguminous species with excellent potential for refore station and agroforestry on acid soils high in aluminum and manganese. (C) 1998 Elsevier Science B.V.