Navegando por Assunto "Diversidade taxonomica"

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Efeitos da inundação e da antropização sobre padrões de diversidade de árvores da floresta de várzea amazônica
(Universidade Federal do Pará, 2019-05-29) MAGALHÃES, Jose Leonardo Lima; LOPES, Maria Aparecida; http://lattes.cnpq.br/3377799793942627; https://orcid.org/0000-0002-6296-5487
The white-water floodplain forest in Amazon (locally várzea) is a highly heterogeneous floodplain ecosystem that encompasses a large number of adapted species. It is distributed along the entire length of the main channel of the Amazon River and of tributaries of Andean origin. In addition, due to periodic flooding by waters with high sediment load, it has high fertility when compared to other Amazonian systems. What on the one hand is important for high primary productivity also makes it the target of human colonization for its benefits to food production. In this sense, because it presents continental dimensions and crosses almost all the biome from East to West, it has been the main access route of present and previous human populations to the most distant points of the basin. All these factors contribute to these forests being an important model for testing diversity patterns along natural and anthropogenic gradients. This thesis is presented in two chapters that use distinct approaches, focusing on different aspects of forest diversity and structure. Chapter 1 examines the phylogenetic structure of the arboreal component of floodplain forests in the Central and Eastern macro-regions and investigates whether the current human presence has modified it, specifically reducing the number of tree lineages present and leading to the phylogenetic homogenization of these forests. Chapter 2 investigates whether the taxonomic diversity and the local and regional tree species found today in the macro-regions of the study are associated with historical patterns of human density since the arrival of Europeans in the region. To reach the objectives, seven areas were sampled along the 2,400 km stretch of the Brazilian portion of the Amazon River, which covers different flood regimes and human influences. Thus, tree individuals with DBH ≥ 10 cm were sampled and data were collected in situ and in databases available to be used as predictors variables in modeling tree diversity at different scales. With the results, it was detected that the flood regime is the main factor that influences the phylogenetic structure whereas the human density of almost three centuries ago is responsible for the patterns of taxonomic diversity that are currently found. The diversity patterns were detected in the evolutionary and ecological scale, where it was shown that human influences may have a long-delayed response after they have occurred. Because várzea is a system of relatively easy access in the region and has few protected areas, it is necessary to understand how these forests are important for the maintenance of essential ecosystem services, even though they have been affected by human influence for a long period.