Amelioration of degraded rain forest soils by plantations of native trees.

Abstract

In 1988 eight native tree species: Hyeronima alchorneoides, Inga edulis, Pentaclethra macroloba, Pithecellobium macradenium, Stryphnodendron microstachyum, Virola koschnyi, Vochysia guatemalensis, and Vochysia ferruginea and three exotic tree species: Acacia mangium, Gmelina arborea, and Pinus tecunumanii [P. patula subsp. tecunumanii] were planted on abandoned pasture land in NE Costa Rica cleared of rain forest 25 yr earlier. Four replicates of 0.25-ha plots of the 11 species and a control were established in a randomized complete block design. All species survived fairly well, but some grew much better than others. The soil was thoroughly sampled before trees were planted and again 4 yr after trees were established. Although bulk density decreased significantly beneath eight of the 11 species, organic C increased significantly under only three species. Significant increases in base cations also occurred beneath the majority of species. Nitrogen did not increase as much as expected beneath the N₂-fixing legumes; however, the availability of P was significantly enhanced beneath both species of Vochysia. The changes in soil properties were marked, and significant amelioration of these degraded soils occurred in a short time beneath the majority of species.