Estrututa funcional das comunidades arbóreas de florestas alagáveis na Amazônia Central

Abstract

Understanding the structure of plant communities is essential to make ecological predictions about environmental changes. As tropical floodplains are a growing target for anthropogenic impacts, they require further studies to support effective conservation strategies. In this thesis, we investigated the functional structure of tree communities of várzea and igapó floodplain forests in Central Amazonia, in relation to seasonal flooding and soil properties. Soil properties were good predictors of functional traits variation, differentiating ecological strategies between várzea and igapó communities. Várzea communities were characterized by trait values related to a better use and acquisition of resources and a fast growth, while igapó communities were characterized by trait values related to a better conservation of resources, development of persistent tissues and, consequently, slow growth. Surprisingly, flooding level and duration influenced little traits variation, even within communities with the same soil type. We also found that traits differentiation between várzea and igapó occurred even between species phylogenetically related with the same pattern of differentiation among the strategies of acquisition versus conservation of resources, indicating the process of habitat specialization. Our results also showed that the attribute wood density differs between the stem and the branch, both in the várzea and igapós, compared to the terra firme. This suggests the existence of ecological strategies related to specific abiotic conditions acting on the arboreal community of floodplain ecosystems. Based on our results, we conclude that soil properties in local scale are determinant factors for functional structure in tree communities of floodplain forests, and are responsible for the differentiation in species composition and ecological strategies between these communities, contributing to the increase in species diversity in Amazonian floodplain forests. We recommend that the development of ecological strategies for floodplain forests conservation should be prepared for each forest type, considerating their different functions.