Amazon forest dieback: assessing vulnerabilities and threats
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2016-05-16
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Universidade Federal de Goiás
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In recent years, it is increasing evidences about Amazon vunerability due to land use and climate
changes. Because of a positive feedback system, in which impacts intensify other impacts, some
models project to the end of the century a replacement of the Amazon forest by savanna formations
or semi-arid (forest dieback). Several evidence has indicated a high vulnerability of the Amazon to
global climate change and local environmental impacts triggered by human activities (eg
conversion to agricultural areas, construction of roads and burns). However, they are still deeply
unknown the general mechanisms and standards about how these impacts affect the forest. In this
thesis, I developed works that aim contribute to discussions of the subject. In each chapter, I will
consider a threat that is contributing to the degradation of the Amazon. Each of the three threats
discussed in the following chapters are often cited as important drivers of forest dieback. In the
first chapter I evaluated the impact of forest fires at different levels of diversity of trees in a forest
area next to the Amazon-Cerrado transition. Our results suggest that communities of trees in
burned areas are losing more phylogenetic and functional diversity per unit of species than in
unburned areas. My results indicate the existence of selection of species based on phylogenetic and
functional characteristics, representing a major force of change and impoverishment (functional
and phylogenetically) of these communities. In the second chapter, using high resolution images
(LiDAR and hyperspectral), I evaluated the impact of a intense drought in forest areas near Madre
de Dios, Peru. Thus, my results support the idea that changes in regional climate may change the
structure and function of the forest. In the third chapter, I evaluated how the construction of roads
in the Brazilian Amazon has contributed to deforestation in an important group of protected areas
of the Amazon: the Indigenous Lands. Based on the analysis of observed impacts, I propose the
establishment of buffer zones (buffers) around these reserves to reduce the negative impacts of
road construction planned to be built.
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NOBREGA, C. C. Amazon forest dieback: assessing vulnerabilities and threats. 2016. 125 f. Tese (doutorado em Ecologia e Evolução) - Universidade Federal de Goiás, Goiânia, 2016.