报告摘要

Regional assembly of the tropical tree flora: insights from field inventories and theory

Abstract

Trees structure tropical forests, the most diverse biome. The vast number of tree species challenges our understanding of their historical assembly, and their response to environmental change. I present two separate studies that aim to document patterns of species abundance across the world's tropical forests. First, we investigated species abundance patterns using inventory data on over one mission trees in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. About 2% of the species comprise 50% of the tropical trees in these regions. This studies points to consistent patterns of species abundance distributions across the continents. Fundamental mechanisms of tree community assembly may apply to all tropical forests, and the neutral theory of biodiversity offers interesting insights into these questions, as exemplified by a comparison between theory and data. Second, extending beyond lowland tropical rain forests, we explored patterns of abundance across ecosystem types in tropical America, based on over 10,000 inventory plots and over four million trees, and document similar patterns of dominance between woodland savannas, dry forests, wet forests, and flooded forests. These results challenge the view that dispersal is a major determinant of the regional assembly of the tropical tree flora, and point to a renewed interest for theory in biodiversity science.