Common species distribution and environmental determinants in South American coastal plains

Abstract

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.

Aridity, soil and biome stability influence plant ecoregions in the Atlantic Forest, a biodiversity hotspot in South America

“…This also suggests that local community composition and structure are influenced by niche and dispersal mechanisms acting at geographical as well as at local scales, as suggested by metacommunity theory (Leibold et al 2004, Ricklefs 2006. At smaller geographical scales soil texture variation, specifically, seems to pose a strong environmental filter to the colonization of sandy, loose and nutrient-poor soils that are common in the northern parts of the Atlantic Forest, and specially along the coastline, where Restinga heath vegetation occurs (Marques et al 2011, Santos et al 2012, Silva and Souza 2018b. Work by Santos et al (2007) and Carnaval et al (2014) identified two divergent bioclimatic domains within the Atlantic Forest and high vertebrate turnover around the Doce River, with correspondingly different endemism patterns in the northern and southern portions of the domain.…”

“…Abundance ecoregions, on their turn, portray dominance patterns linked to variation in the prevalence of ecological strategies related to competitive resource acquisition, stress and disturbance tolerance (Grime and Pierce 2012). Abundance ecoregions are thus more clearly linked to ecosystem structure and function and the distribution of groups of species with similar niches (Silva and Souza 2018b) than occurrence ecoregions.…”

“…This picture points to a broad-scale effect of environmental variables on the assembling of whole biotas in eastern South America. At smaller geographical scales soil texture variation, specifically, seems to pose a strong environmental filter to the colonization of sandy, loose and nutrient-poor soils that are common in the northern parts of the Atlantic Forest, and specially along the coastline, where Restinga heath vegetation occurs (Marques et al 2011, Santos et al 2012, Silva and Souza 2018b. It is notable that extensive patches of stressful sandy soils occurring as far south as the coasts of Rio de Janeiro and Espírito Santo (Veloso et al 1991, Hiruma et al 2010), seemed to have selected species sets characteristic of the northern floristic zone.…”

“…Factors linked to productivity like climate and soil variation directly influences the distribution of species through species-specific physiological effects like metabolic rates and performance, and indirectly through suitability to natural enemies or competitors (Reis et al 2015). Marked compositional variation has been found along the above-mentioned gradients in several sectors of the Atlantic Forest (Oliveira-Filho and Fontes 2000, Marques et al 2011, Gonçalves and Souza 2014, Kamimura et al 2017, Silva and Souza 2018b. Productivity variation also influences the relative success of different ecological strategies (Grime and Pierce 2012) and population size, and thus extinction probabilities, floristic gradients, species occurrences and dominance patterns (González-Orozco et al 2014, Fine 2015, Neves et al 2015.…”

Woody plant subregions of the Amazon forest

“…Tree species show great variation in both drought and flooding sensitivity, which result in different distribution and vegetation type patterns at larger spatial scales (e.g. the forest-savanna boundaries), which may represent ecophysiological barriers to many lineages (Butt, Malhi, Phillips, & New, 2008;Esquivel-muelbert et al, 2017;Silva & Souza, 2018b).…”