Navegando por Autor "Campos, Prímula Viana"

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Ecological drivers of plant diversity in Rupestrian Grassland Complex of brazilian tepuis (Roraima, north Amazonia)
(Universidade Federal de Viçosa, 2020-07-17) Campos, Prímula Viana; Schaefer, Carlos Ernesto Gonçalves Reynaud; http://lattes.cnpq.br/3526618002508130
The table mountains (called tepuis), located in the Guayana Shield region, with singular biota and high endemism, are characterized as cradles of Neotropical biodiversity. Studies about pedological heterogeneity, biogeographic patterns, evolutionary processes, ecology of populations and communities, are still scarce. In this context, we aimed to evaluate the effect of environmental drivers (altitude, climate and soil) on the composition, structure and diversity (taxonomic and phylogenetic) of plant communities associated with tepuis’ rocky outcrops. The study was performed on three table mountains, located in the northern South America: Roraima, Tepequém, and Uei. Three phytophysiognomies were sampled: Forest (Tepequém), shrublands and rupestrian grasslands (Roraima, Tepequém and Uei). In the first chapter, we tested the fine-scale effects of abiotic (i.e. soil physicochemical properties and depth) filters on species richness and community composition at the Roraima; in the second chapter, we evaluated the effect of fine-scale geoenvironmental gradient on phylogenetic diversity and structure of plant communities at the Roraima; in the third chapter, we investigated how taxonomic and phylogenetic patterns of plant communities change along a local-scale edaphic and topographic gradient at the Tepequém; in the fourth chapter, to evaluate the effects of fine-scale geoenvironmental filtering on taxonomic richness and composition, and evolutionary history of plant communities at the Uei; finally, in the fifth chapter, we evaluate how lineages composition of plant communities changes along an environmental gradient (i.e. climate and soil properties) across three tepuis. Our results showed that soil properties at the local scale consistently explained most of the variations in richness, composition, diversity, and evolutionary history of plant communities associated with tepuis' rocky outcrops. However, neutral processes, density-dependent factors (competition) and/or other environmental filters, such as altitude, topography, flood and fire regime, may be responsible for the taxonomic and phylogenetic patterns found in this study. In addition, the climate at the regional scale was one of the main drivers of the composition of the lineages, and probably of the turnover between tepuis. Keywords: Rupestrian grasslands. Geoenvironments. Pantepui. Plant-soil relationship.
Interação solo-altitude-vegetação em campos de altitude no sudeste do Brasil
(Universidade Federal de Viçosa, 2016-02-25) Campos, Prímula Viana; Neri, Andreza Viana; http://lattes.cnpq.br/3526618002508130
O estudo avaliou padrões de diversidade, estrutura e formas de vida em três comunidades vegetais associadas a afloramentos rochosos nos campos de altitude do Parque Nacional (PARNA) do Caparaó, MG/ES, Brasil, bem como a influência da altitude e solo nos mesmos parâmetros vegetacionais em três comunidades no Parque Estadual Serra do Brigadeiro (PESB), MG, Brasil. Foram alocadas 100 parcelas de 1x1 m distribuídas ao acaso em cada um dos três ambientes (300 em cada parque). Foram calculados os parâmetros quantitativos clássicos, os índices de diversidade e equabilidade, similaridade florística, curvas de rarefação e dominância-diversidade, bem como análise dos espectros biológicos e vegetacionais, usando as formas de vida de Raunkiaer. Para análise químicas e físicas coletou-se uma amostra simples de solo (0-10 cm). No PARNA Caparaó, foram amostradas 58 espécies, pertencentes a 49 gêneros e 32 famílias. As curvas de rarefação apresentaram tendência à estabilização da assíntota aproximadamente a partir das 75 unidades amostrais em todas as áreas. Entre as áreas existem diferenças significativas entre a riqueza, abundância e cobertura. O índice de diversidade de Shannon-Wiener permaneceu entre 3,00-2,76 e equabilidade de Pielou com dois valores 0,77 e 0,75. As curvas de dominância-diversidade apresentaram distribuição log-normal e geométrica. A proporção do número de espécies por forma de vida foi similar entre as áreas, ao contrário do espectro vegetacional, com destaque para as espécies hemicriptófitas. No PESB, foram amostrados 9.276 indivíduos, pertencentes a 39 famílias e 102 espécies. Entre as áreas existem diferenças significativas entre a riqueza, abundância, cobertura, bem como nos parâmetros edáficos. O índice de diversidade de Shannon-Wiener permaneceu entre 3,07-3,20 e equabilidade de Pielou (0,74-0,79). A CCA indicou dois grupos distintos formados para abundância e cobertura, indicando a concentração das espécies em habitats preferenciais, em função da altitude, bem como da fertilidade e textura do solo. A partir do GLM, a riqueza de espécies foi correlacionada com atributos químicos do solo, assim como ambos os parâmetros estruturais da vegetação, que além de apresentar relação com variáveis químicas do solo, foram influenciados pela altitude. Os resultados apontam a falta de informações em relação aos fatores abióticos que possam reger nesses ambientes.
Phylogenetic structure is determined by patch size in rock outcrop vegetation on an inselberg in the northern Amazon region
(Acta Amazonica, 2018-07) Villa, Pedro Manuel; Gastauer, Markus; Martins, Sebastião Venâncio; Carrión, Juan Fernando; Campos, Prímula Viana; Heringer, Gustavo; Meira-Neto, João Augusto Alves; Rodrigues, Alice Cristina
Although inselbergs from around the world are iconic ecosystems, little is known on the underlying mechanisms of community assembly, especially in their characteristic patchy outcrop vegetation. Environmental constraints are expected to cause phylogenetic clustering when ecological niches are conserved within evolutionary lineages. We tested whether vegetation patches from rock outcrops of the Piedra La Tortuga Natural Monument, in the northern Amazon region, are phylogenetically clustered, indicating that environmental filtering is the dominant driver of community assemblage therein. We classified all patches according to their size as very small (< 1 m 2 ), small (1-4 m 2 ), medium-sized (4-8 m 2 ), and large patches (8-15 m 2 ). From each class, we randomly selected 10 patches, totalizing 40 patches covering 226 m 2 . All individuals found in the 40 isolated patches were identified to the species level. We also correlated measurements of phylogenetic community structure with patch size. We found that species from patches are restricted to the clades monocots, fabids, malvids, and lamiids. We conclude that vegetation in this rock outcrop is phylogenetically clustered. Furthermore, we found that phylogenetic turnover between pairs of patches increases with patch size, which is consistent with a scenario of higher environmental stress in smaller patches. Further research is necessary to identify nurse species in inselberg vegetation, which is pivotal for conservation and restoration of this particular ecosystem.