To advance our understanding of the processes that govern the assembly of palm communities and the local coexistence of numerous palm species, we here synthesize available information in the literature on species diversity and growth-form composition in palm communities across the Americas. American palm communities surveyed had 4-48 (median 16) species in study plots covering 0.09-7.2 ha. Climate, soils, hydrology, and topography are the main factors determining palm community species richness. Tropical lowland terra firme rain forests are the most species-rich whereas forests that are inundated or grow on sandy soils or in areas with seasonal climate have much fewer species. Palm communities in the central-western Amazon and in Central America are significantly richer than the average region and those in the Caribbean significantly poorer in species. As for branching, the 789 species of tropical American palms belong to Corner's model (solitary, 268 species, 33%), Tomlinsons model (cespitose, 521 species, 66%) and Schoute's model (dichotomous branching, three species, <1%). We assigned the species to eight different growth forms: (i) Large tall-stemmed Palms (102 spp), (ii) Large-leaved medium-short-stemmed Palms (31 spp), (iii) Medium-sized Palms (95 spp), (iv) Medium/Small Palms with Stout Stem (42 spp), (v) Small Palms (423 spp), (vi) Large acaulescent Palms (28 spp), (vii) Small acaulescent Palms (56 spp), and (viii) Climbing Palms (12 spp). The eight growth forms are differently represented in the palm communities, and the categories Small Palms and Large tall-stemmed Palms dominate the communities both in terms of species richness and in number of individuals.
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Acknowledgements We would like to thank our colleagues in the PALMS project for inspiring discussions and for help in the field and elsewhere. We are especially grateful to Rodrigo Bernal and Gloria Galeano who facilitated field work in Colombia, to Renato Valencia, Hugo Navarrete and Rommel Montufar for making several arrangements in Ecuador, and Cesar Grández for organizing our field work in Peru, and to Monica Moraes and Narel Paniagua for paving the way for our work in Bolivia. John Dransfield, Fred Stauffer, Andrew Henderson, Jean-Christophe Pintaud, Euridice Honorio, Gloria Galeano and Olivia Sylvester kindly read and commented on the manuscript. The PALMS project is supported by the European Commission (contract no. 212631 to Henrik Balslev) for which we are most grateful. We also acknowledge the financial support from the Danish Council for Independent Research—Natural Sciences (grant no. 10–83348 to HB). The Faculty of Science, Aarhus University supported TK’s PhD study.
- Functional Diversity
- Habitat Specialization
- Species Richness
- Tropical Forest
- Tropical Trees