Patterns of variation in tree composition and richness in Neotropical Non‐Flooded Evergreen Forests

AbstractQuestionsWe investigated tree floristic variation among the Neotropical Non‐Flooded Evergreen Forests (NEF). We addressed the following questions: (a) which are the floristic groups among NEF and how are they correlated with environmental variables; (b) how many species, genera and families are shared between these floristic groups and which species are unique and indicative of each one; and (c) how does species richness vary between NEF groups?LocationNeotropical region.MethodsWe used cluster and ordination analyses based on 518,004 tree occurrence data available in the NeoTropTree database to identify floristic groups throughout NEF. From the floristic groups identified here, we (a) verified correlations between floristic composition and precipitation, temperature, altitude, and latitude; (b) calculated the number of shared species, genera and families, and identified taxa unique to each group; and (c) obtained indicator species and estimated species richness for these floristic groups.ResultsWe recorded 172 families, 1,276 genera and 15,134 species in 1,885 sites of NEF. The families most rich in species were Fabaceae, Rubiaceae and Myrtaceae. We identified nine groups among the NEF, which broadly correspond to floristic provinces reported in the literature. Altitude and annual mean temperature were associated with a species turnover gradient from Amazon to Andean Cloud Forest. Atlantic Forest (south) and Mesoamerica plus Caribbean (north) represented the extremes of a latitudinal gradient. The Atlantic Forest presented the largest number of exclusive and indicator species (2,477 and 265, respectively), while the Amazon showed the highest species richness (6,167 species).ConclusionsAlthough it was possible to separate NEF into distinct floristic groups, this floristic dissociation seems to be recent, since it found support only in species data. The floristic groups identified in this study are largely congruent with their geographic distribution and spatial/ecological isolation, and seem to reflect historical, geological and climatic events that occurred in the Neotropics.