Plant diversity and community structure of Brazilian Páramos

In Eastern South America, high altitude grasslands represent a mountain system that has a high number of endemic species. However, studies on the ecology of plant communities in these environments remain scarce. We aimed to evaluate the patterns of biodiversity and structure of plant communities from rocky outcrops in high altitude grasslands of three areas at the Caparaó National Park, southeastern Brazil, by sampling 300 randomly distributed plots. Then, we compared the floristic composition, relative abundance, and biological and vegetation spectra among areas. We classified species as endemic and non-endemic and verified the occurrence of endangered species. Species richness was evaluated by rarefaction analysis on the sampling units. The importance value and species abundance distribution(SAD) models were assessed. We also performed an indicator species analysis. We sampled 58 species belonging to 49 genera and 32 families. The number of species decreased with increasing altitude, with significant differences being observed among areas regarding richness, abundance, and cover. Of the total number of species, 10 are endemic to the Caparaó National Park and 17 are listed on the Brazilian Red List of endangered species. The dominant families on all peaks were Asteraceae and Poaceae. The SAD models showed lognormal and geometric distributions, corroborating the fact that 10 species that were common to all three areas were also the most dominant ones in the communities and showed the highest importance values, which ranged between 35% and 60%. Indicator species analysis revealed that 28 species(48.27%) were indicators. Of these, 42.85% had maximum specificity, meaning that they occurred only in one area. Thus, the number of species per life form ratio was similar among areas, yet vegetation spectra differed, especially for hemicryptophytes. The altimetric difference among the areas showed to be a very important driver in the community assembly, influencing the evaluated variables, however, other drivers as soil depth, slope and water could also influence the community structure on a smaller and local spatial scale.

How do altitude and soil properties influence the taxonomic and phylogenetic structure and diversity of Brazilian páramo vegetation?

Altitude and environmental variables such as edaphic properties are considered determinants of species distribution and community composition in mountain ecosystems.Here,we aimed to outline the effects of distinct mountain peaks,altitude and soil properties on community composition,species density,phylogenetic structure and diversity of angiosperm páramo communities from the Serra do Brigadeiro State Park,Minas Gerais,southeastern Brazil.For that,we identified all angiosperm species found in 300 plots(1 m×1 m)from three mountain peaks,measured soil depth and analyzed soil fertility and texture in each plot.To reduce the number of soil variables and species composition,we computed principal coordinates based on soil properties and principal coordinates based on species-plot matrix for each plot.Furthermore,we computed the standard effect sizes of the mean phylogenetic pairwise distance and the mean nearest phylogenetic taxon distance for each plot to investigate differences in the degree of relatedness among coexisting species.We compared differences in response variables between peaks and modelled them in function of altitude and principle components of soil properties using mixed effect models.Species density and phylogenetic diversity differed between peaks,but,contrary to the previous findings,no relationships between species richness or phylogenetic diversity and altitude or soil properties were found,indicating that further investigations are necessary to understand the altitude-biodiversity relationship in Brazilian páramo vegetation.Community composition differed between peaks and depended on altitude,soil properties and interactions between them,indicating that upward shifting of bioclimatic conditions due to climate changes may alter communities of this ecosystem.Phylogenetic structure differed between peaks and was influenced by altitude and soil properties.As phylogenetic clustering increased with altitude,eventual upward movements of species in Brazilian páramo vegetation due to climate change may alter community composition and the degree of relatedness among coexisting species,increasing the risk of species from higher altitudes to disappear.Therefore,conservation priorities arise for higher landscape portions,where these high altitude species may find refuges.

Soil and altitude drive diversity and functioning of Brazilian Páramos(campo de altitude)

Aims the vegetation on Brazilian Páramos consists of assemblages that are driven mainly by the influence of strong environmental filtering.It is very important to understand the effect of environmental varia-tion on taxonomic diversity and on functional diversity.considering the lack of information about the functional diversity in Brazilian Páramos,we analyzed for the first time the effects of altitude and edaphic attributes on functional traits,as well as on taxonomic and functional diversity.We also wanted to answer the questions:Which ecological strategies are favorable in high-altitude grassland?Does soil attributes determine distributions of traits in high-altitude grassland?considering the studied altitudinal gradient is altitude an important variable in the community assembly?Methods the study was conducted on three mountains:Mammoth(1850 m),Elephant(1790 m)and totem(1690 m)in Serra do Brigadeiro State Park,Minas Gerais State,Brazil.those mountains represent the‘Serra das cabeças’,a smaller ridge that is surrounded by the Atlantic Forest,one of the 25 hotspot of biodiversity.the samples were taken using 100 plots of 1 m2 per mountain that were randomly distributed.All plants except mosses were sampled.the taxonomic diversity was evaluated using richness,Shannon diversity,effective number of species and Pielou evenness.For the functional diver-sity,we considered the functional richness,functional evenness and functional divergence.Generalized linear models(GLM/Poisson and quasi-Poisson)were used to evaluate the effect of abiotic variables(altitude,soil depth and soil chemical attributes)on biotic variables(number of species and individuals,life form,dispersal and fruit type)and ordinary least squares regression to evaluate the effect of abiotic variables on the functional and taxonomic diversity.Important Findingsthe soil variables presented a considerable edaphic gradient associated with altitude.the soil in Serra das cabeças plays an important role for the plant diversity:richness and diversity index were positively related with fertility.With regard to the life form,nanophanerophytes tended to increase with altitude and soil depth,while therophytes tended to decrease with altitude.the dispersal type was also associated with the abiotic variables:autochory decreases with altitude,while zoochory increases.Functional richness increases with fertility and the functional evenness with altitude.the studied gradient showed that altitude is working as a filter for functional traits and indices and is,together with soil attributes,an important determinant for the distribution of plants on Brazilian Páramos.