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Belo Horizonte, Brazil

Silveira F.A.O.,Federal University of Minas Gerais | Negreiros D.,Federal University of Minas Gerais | Barbosa N.P.U.,Federal University of Minas Gerais | Buisson E.,Aix - Marseille University | And 21 more authors.
Plant and Soil | Year: 2015

Background: Botanists, ecologists and evolutionary biologists are familiar with the astonishing species richness and endemism of the fynbos of the Cape Floristic Region and the ancient and unique flora of the kwongkan of south-western Australia. These regions represent old climatically-buffered infertile landscapes (OCBILs) that are the basis of a general hypothesis to explain their richness and endemism. However, few ecologists are familiar with the campo rupestre of central and eastern Brazil, an extremely old mountaintop ecosystem that is both a museum of ancient lineages and a cradle of continuing diversification of endemic lineages. Scope: Diversification of some lineages of campo rupestre pre-dates diversification of lowland cerrado, suggesting it may be the most ancient open vegetation in eastern South America. This vegetation comprises more than 5000 plant species, nearly 15 % of Brazil’s plant diversity, in an area corresponding to 0.78 % of its surface. Reviewing empirical data, we scrutinise five predictions of the OCBIL theory, and show that campo rupestre is fully comparable to and remarkably convergent with both fynbos and kwongkan, and fulfills the criteria for a classic OCBIL. Conclusions: The increasing threats to campo rupestre are compromising ecosystem services and we argue for the implementation of more effective conservation and restoration strategies. © 2015 Springer International Publishing Switzerland

Do Carmo F.F.,Instituto Pristino | Do Carmo F.F.,Federal University of Minas Gerais | Jacobi C.M.,Federal University of Minas Gerais
Plant and Soil | Year: 2015

Aims: We investigated how outcrops of different geological origins enhance the plant megadiversity of the Atlantic rainforest hotspot. Methods: We collected vegetation, topographic, and soil fertility data from 50 2 m2 plots in each of nine rock outcrops (three ironstones -or cangas, three quartzites and three granitoids) in the Iron Quadrangle, SE Brazil. We examined the response of community diversity and structure patterns to edaphic and topographic gradients by means of diversity profiles, clustering and ordination analyses. Species were organized into nine functional groups. Results: We inventoried 17,690 individuals belonging to 352 species. Functional groups with largest cover were sclerophytic shrubs (in cangas), graminoid and poikilohydric herbs (in both granitoids and quartzites). Granitoid plant communities were the least diverse, on account of fewer substrate types leading to more xeric conditions. The multivariate analyses sorted the outcrops by geological origin, although within-lithotype similarity was low. There was stronger similarity between cangas and quartzites, separated from granitoids. Soil was nutrient-poor, and variables most influencing this pattern were number of substrates, topographic heterogeneity, soil depth, and aluminum saturation. Conclusions: Saxicolous plant communities responded more strongly to microtopographic than soil fertility parameters. Each lithotype contributes differently to the high alpha- and especially beta-diversity within the Atlantic Rainforest matrix. © 2015 Springer International Publishing Switzerland

do Carmo F.F.,Federal University of Minas Gerais | do Carmo F.F.,Instituto Pristino | de Campos I.C.,Federal University of Minas Gerais | de Campos I.C.,Instituto Pristino | Jacobi C.M.,Federal University of Minas Gerais
Journal of Vegetation Science | Year: 2016

Questions: To what extent do fine-scale substrate variations affect the structure and diversity of rock outcrop vascular plant communities? How can we define the appropriate scale to measure fine-scale substrate heterogeneity in rocky systems? Location: Nine rock outcrops in the Iron Quadrangle, a priority area for biodiversity conservation in southeast Brazil. Methods: Geomorphology and rock mechanics methods were adapted to determine the appropriate scale to measure rock surface heterogeneity on granitoid, quartzitic and ironstone (canga) outcrops. Then, a roughness index was calculated from 60 microtopographic profiles in each lithotype to investigate the response of the plant community to this scale. The relation between surface heterogeneity and plant community richness, abundance, total plant cover and dominant species cover was quantified through linear regressions. A cluster analysis compared the percentage cover of functional groups in each outcrop, and diversity profiles were built based on Rényi's alpha. PERMANOVA was used to test for significant difference in the relative cover among the functional groups. Results: The roughness index, scaled at 1 cm, had the best power to diagnose the presence of vascular plants. High surface heterogeneity was caused by high frequency of fissures, cracks and rock fragments. Linear regression models indicated that the community parameters are strongly related to variations in surface roughness. The community patterns revealed by the cluster analysis and the diversity profiles matched those of the roughness analysis. Dominant functional groups differed strongly between 'smooth' and 'coarse' microtopography. Desiccation-tolerant species prevailed in smooth outcrops, while sclerophytes and graminoids were better represented in coarse outcrops. Conclusions: The composition of plant functional groups was affected by rock microrelief, and roughness was a significant predictor of plant community parameters. Functional group proportions reflected different adaptive plant strategies to two main stressful bedrock features: water shortage and mechanical resistance to root growth. © 2016 International Association for Vegetation Science.

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