On the floristic identity of Amazonian vegetation types

The Amazon forest is far from uniform, containing different types and even savannas, but quantitative analyses of this variation are lacking. Here, we applied ordination to test the floristic differentiation among Amazonian vegetation using data for virtually all known tree species occurring in (8224), distributed across 1584 sites. We also performed multiple regressions assess role climate substrate shaping continental-scale patterns community composition Amazonia. find that traditional classification consistent with composition. High elevation extremes substrate-related factors underpin segregation environmentally “marginal” terra firme forests climatic being relatively unimportant. These hold at continental scales, sites similar showing higher similarity between them regardless geographic distance, which contrasts idea large-scale regions (e.g., Guiana Shield southwestern Amazon) representing dominant pattern Amazon. In contrast other tropical biomes South America, including Mata Atlântica (second largest rain biome neotropics), main units not geographically separated, edaphically driven spatially interdigitated Two thirds restricted type, while marginal types, only white-sand (campinaranas) have a substantial proportion species, sharing large numbers species.