Ecological drivers of plant diversity in Rupestrian Grassland Complex of brazilian tepuis (Roraima, north Amazonia)

• Ano de defesa: 2020
• Autor(a) principal: Campos, Prímula Viana
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa; Botânica
• Palavras-chave em Português: Comunidades vegetais; Plantas das montanhas; Plantas e solo; Fitogeografia; Botânica
• Link de acesso: https://locus.ufv.br//handle/123456789/30105

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.