Litter fall and decomposition in primary, secondary and plantation forests in the Brazilian Amazon

Litter fall and leaf decomposition represent important functional processes, yet we have a limited understanding of these processes in disturbed and regenerating tropical habitats. Litter production, litterfall phenology and leaf decomposition were examined in primary forests, 14-19-year-old secondary forests and 4-5-year-old Eucalyptus urophylla plantations in the north-east Brazilian Amazon. Total annual litter fall was similar in primary and secondary forests, and lower in plantations. Leaf fall in primary and secondary forests was negatively associated with rainfall, and was highest in the dry season. Leaf fall in Eucalyptus plantations showed an opposite response, and peaked during the wet season. Decomposition experiments were carried out in the three habitats using 1200 litter bags (1 mm mesh) filled separately with leaves from four different species of tree, including an exotic plantation species (E. urophylla) and trees typical of secondary (Bellucia spp. and Vismia spp.) and primary forests (Bertholettia excelsa). Litter bags were re-weighed at 3-month intervals 3, 6, 9 and 12 months after being placed on the forest floor. A repeated measures General Linear Model showed that litter decomposition was similar in the primary and secondary forest, and slowest in the Eucalyptus plantations. Leaves decomposed, from fastest to slowest, in the following order: E. urophylla > B. excelsa > Vismia spp. > Bellucia spp. There was no significant interaction between leaf species and habitat type. Our results indicate that secondary forests regenerating on abandoned and degraded Amazonian lands can be effective at restoring ecosystem processes such as litterfall and decomposition. (c) 2007 Elsevier B.V. All rights reserved.