Tropical leguminous species for acid soils: studies on plant form and growth

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references: p. 71-77.Issued also on microfiche from Lange Micrographics.Many forest plantations in the humid neo-tropics are established on degraded soils in abandoned pasture land, and with some exceptions, the species planted have not grown successfully. Few studies of adaptability and growth under these conditions have been conducted to test the potential of native species for reforestation and agroforestry in acid, infertile soils. Results are presented from a three-year species screening trial with 25 legume species, of which most were tree species of potential multipurpose value: 8% were exotic N2-fixing trees, 60% (some of which were N2-fixers) were indigenous to the region, and 32% (some of which were N2-fixers) were native to other areas of Costa Rica. Survival (including damage indices), growth, tree form and N2fixing ability were analyzed for species at four abandoned pasture sites at the La Selva Biological Station, Sarapiqui, Costa Rica. Survival of the majority of the species after 3 years was high. Pithecellobium idiopodum, Inga edulis, A lbizia guichapele, Pithecellobium elegans and Dalbergia retusa had greater than 90% survival at all sites. There were significant differences in growth measures among species. The native species with the highest stem volume after A. mangium in Site I (sun) were S. microstachyum (0.044 M3 per tree) and I. edulis (0.025 M3 per tree), and in Site 4 (sun) L edulis (0.029 ml per tree) and S. microstachyum (0.025 ml per tree ). In Site 2 (sun) and Site 3 (shade) native N2-fixing S. microstachyum was the greatest. Across sun sites L edulis had the highest crown volume (>Ioo M3 ) after A. mangium. Inga edulis, P. idiopodum, L coruscans and P. macroloba failed to form straight single stems. The results of acetylene reduction assay at Site 4 showed that L edulis, A. mangium, Albizia guichapele, and L coruscans had the highest nitrogenase activity. This study indicated that some N2-fixing tree species are adapted to acidic, infertile soils high in Al and Mn. These species have higher growth potential than most species currently used in agroforestry and reforestation in the tropics on such soils