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Common species distribution and environmental determinants in South American coastal plains

Silva, Karla J. P., Souza, Alexandre F.
Ecosphere 2018 v.9 no.6 pp. e02224
biogeography, biomass, coastal plains, coasts, community structure, ecosystems, edaphic factors, models, plant communities, statistical analysis, vegetation, woody plants
Common species correspond to most of the structure and biomass of ecosystems, but the determinants of their distributions and the extent of their overlap are still a matter of debate. Here, we tested the hypotheses that (1) common herbaceous and woody species do not respond individualistically to environmental factors, but rather form groups of species with similar environmental affinities (archetypes), and (2) if local communities comprised cohesive systems, then archetypes of common species will occupy distinct portions of the coast with little or no overlap. We used a large set of climatic and soil variables in restinga heath vegetation along ~9000 km of eastern South American coastal plains. We used species archetype models, a new statistical approach that clusters species based on their environmental responses. We found five herbaceous species archetypes and 11 woody species archetypes, all responsive significantly although weakly to a mixture of climatic and soil variables. In most cases, there was considerable spatial overlap of different archetypes rather than separation along the coastline. Common species form groups with similar environmental affinities, but that did not respond strongly to environmental factors. This suggests an important role for dispersal in the explanation of heath vegetation floristic variation. Local community composition is influenced by groups of species that are not unique to any region and overlap extensively. Restinga heath vegetation communities seem to be considerably individualistic rather than cohesive systems.