Diversity and composition of tropical forest plant communities in the Golfo Dulce region

The Golfo Dulce region located in southwestern Costa Rica represents one of the
remnant global biodiversity hotspots containing the largest Pacific lowland tropical
forest in Central America. Recent biogeographical analyses revealed a close relation of
taxonomic tree species composition to northern South America. However, the underlying factors leading to the extraordinary taxonomic richness of the region have so far
remained elusive. In this study, we analyzed the composition of tropical forest plant
communities (trees, lianas and palms with a diameter at breast height ≥10 cm) occurring in one-hectare permanent forest inventory plots. To that end, we established 20
forest sites across the Golfo Dulce region, i.e. 5 geographic locations each comprising
4 forest habitat types in ridge, slope and ravine positions, as well as in secondary forest
stands. Our study highlights the oligarchic dominance of tropical forest plant communities in the Golfo Dulce region, and further suggests that plant species composition is associated with topography, disturbance history and edaphic properties. The
finding that oligarchic and rare species are affected by environmental filtering has
important implications for assessment and modeling of important ecosystem functions, such as carbon storage and productivity, as well as nutrient cycling and trophic
interactions and thus could potentially improve biodiversity conservation and management strategies.