Dynamics and diversity of flooded and unflooded forests in a Brazilian Atlantic rain forest: a 16-year study

Abstract

Background: Disturbance and small-scale variation in environmental conditions are potential factors that influence structure and diversity in tropical forest communities. In the coastal lowland vegetation in Brazil, forests that differ in flooding regimes could differ in these metrics, although long-term data are usually lacking.

Aims: Our aim was to determine if a stand in an unflooded forest and a stand in a flooded forest had distinct structural characteristics and patterns of change over a 16-year period.

Methods: Individuals ≥4.44 cm in diameter at breast height were recorded on two 0.3-ha plots in 1991 and 2007. The differences in stem density, species richness, community-level mortality and recruitment, and stem growth rates were assessed.

Results: The unflooded forest plot had a higher density of smaller individuals, but a substantially lower basal area than the flooded forest plot. Basal area increased by 4% and 20% over 16 years in the flooded and unflooded plots, respectively. Species richness per area was twice as high in the flooded forest plot than in the unflooded plot.

Conclusions: These data provide tentative support for the hypothesis that enhanced tree turnover contributes to maintenance of small-scale differences in diversity at the landscape scale. We conclude that flooded and unflooded habitats provide distinct environments that support contrasting communities of woody plants.

Keywords:

• Atlantic rain forest
• Brazil
• disturbance
• diversity
• flooding
• growth
• mortality
• recruitment

Acknowledgements

We are grateful to all students from the Laboratory of Plant Ecology for their assistance in the field work and data organisation and the Instituto Ambiental do Parana (IAP) for permission to work in Ilha do Mel. We thank the Brazilian Research Council (CNPq) for supporting this research and the Brazilian Education Council (CAPES) for the grant to prepare the paper during a period of sabbatical leave.