Phylogenetic community structure reveals differences in plant community assembly of an oligotrophic white-sand ecosystem from the Brazilian Atlantic Forest

Abstract

Mussununga, an oligotrophic sandy savanna ecosystem, comprises distinct physiognomies along fi re, water and nutrient availability gradients. Grasslands and woodlands are constrained at the opposite poles of these gradients, with grasslands occurring in areas with poorer soils and higher levels of both water-stress and fi re intensity. According to the stress-dominance hypothesis, one might expect the importance of competition for community assembly to increase from grasslands to woodlands. Assuming conservation of ecological niches within evolutionary lineages, this should increase phylogenetic overdispersion from grasslands towards woodlands. To test this, we calculated phylogenetic diversity and community structure using diff erent null models as well as the phylogenetic signal of life form as a proxy of niche space. All indices indicate phylogenetic clustering for grasslands and phylogenetic overdispersion for woodlands. Considering that most life-forms showed a signifi cant phylogenetic signal, fi ndings indicate that competition and further density dependent factors may play a larger role in community assembly of physiognomies in less harsh positions along the gradient, while environmental fi ltering dominates the harsher positions. Our results indicate that the entire gradient should receive conservation priority in order to guarantee the eff ective conservation of this endangered ecosystem, including its species richness and ecological processes such as community assembly.

Community assembly as a basis for tropical forest restoration in a global change scenario

“…DispersalNRI values significantly greater than zero (more than 1.96 sd, and more than -1.96 sd) indicate phylogenetic signal. Phylogenetic signal of dispersal type was considered significant when the observed MPD or MNTD occurred in the lowest 2.5% of the null models (significance of 0.05) (Gastauer et al 2017).…”

Roads as conduits of taxonomic, functional and phylogenetic degradation in caatinga vegetation

“…Phylogenetic signal was tested using two methods: the ‘aotf’ function in Phylocom 4.2 (Webb et al, 2011) for the quantitative traits (maximum diameter, maximum height and relative coverage), and calculating the traitNRI for the qualitative traits (Gastauer et al, 2017), except for Selaginella convoluta , which was not considered in the tests of the phylogenetic signal so as not to create bias caused by imbalanced phylogenetic trees because of the large phylogenetic distance (566 myr) between this only pteridophyte species and all the others (see Duchêne et al, 2015; Holman, 2005). For the endozoochory trait, maximum diameter and maximum height only the species of the woody component were considered (n=87).…”

“…One thousand randomizations were performed and evaluated through null model. If traitNRIs or traitNTIs were lower than – 1.96 or higher than 1.96 (p<0.05), they were considered significant (Gastauer et al, 2017).…”

The spatial patterns of taxonomic and phylogenetic diversity of seed plants with the climate factors across Ethiopia and Eritrea

“…Biogeographically and evolutionary histories, habitat heterogeneities, edaphic heterogeneities, climatic variability and the in uences of biotic factors such as interspeci c interactions among the species in the community have been reported as some of these factors [5,9,16,17]. The associations among plant diversity and climatic factors have been observed by several researchers [e.g.…”