Navegando por Assunto "Impacto ambiental - Amazônia"

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Acesso aberto (Open Access)
Impactos da pastagem na estrutura taxonômica e funcional de peixes de riachos amazônicos
(Universidade Federal do Pará, 2018-01-19) CANTANHÊDE, Lorrane Gabrielle; MONTAG, Luciano Fogaça de Assis; http://lattes.cnpq.br/4936237097107099
In recent years, increasing economic development has promoted high rates of deforestation and land use change that negatively impact terrestrial and aquatic ecosystems around the world. Therefore, this study aimed to assess how the taxonomic structure and functional diversity of the stream fish assemblages of eastern Amazonia respond to impacts caused by pasture. We sought to answer the following questions: (i) What is the effect of pasture on the environmental characteristics of streams?; (ii) How do they affect the taxonomic structure and functional diversity of the ichthyofauna?; (iii) What functional attributes will be related to the environmental variables that characterize the streams that drain pasture and forest areas? The sampling were carried out between the years of 2012 and 2015, in the dry season, with 13 streams in forested areas and 13 streams in pasture areas. Through a PCA the set of environmental variables related to forest and pasture areas were verified. The taxonomic structure was compared among the environments through the richness, composition and abundance of species. Functional diversity was measured through the components of richness, evenness and functional divergence. The significance of the results of the indices with Student's t-test was tested. RLQ ordering analysis and the fourth-corner component were used to determine the relationships between environmental variables of each treatment and functional attributes. A higher number of artificial shelters and a higher percentage of riffles were found in pastures and the higher canopy cover formed by large trees (DAP> 0.3 m) in forest areas. It was verified that the pasture negatively affects the taxonomic structure and the functional divergence of the ichthyofauna, favoring the presence of generalist species. The highest amount of canopy cover benefited benthic species. Although the Brazilian Forest Code provide for the maintenance of riparian vegetation around the streams, grazing generated negative effects on the physical habitat of streams, taxonomic structure and functional divergence of assemblages of fish from streams in the Eastern Amazon. To conserve the diversity of fish in Amazonian streams, there should be stricter laws and increased enforcement regarding the maintenance of riparian vegetation.
Acesso aberto (Open Access)
Impactos de mudanças climáticas e desmatamento na distribuição geográfica de Cebus kaapori (Primates: Cebidae) na Amazônia
(Universidade Federal do Pará, 2018-04-02) GOMES, Letícia Braga; FREDERICO, Renata Guimarães; http://lattes.cnpq.br/3156181119549976; OLIVEIRA, Ana Cristina Mendes de; http://lattes.cnpq.br/1199691414821581
Climate change and deforestation are among the greatest threats to biodiversity. In the Amazon, the establishment of Protected Areas is an important tool to reduce the negative impacts of these threats, favoring the protection of biodiversity. Amazonia holds the largest number of primates in the world. Primates are highly sensitive to forest loss and habitat modification, which directly threatens the survival of their populations. The Ka’apor Capuchin Cebus kaapori is considered the rarest and most threatened primate species in the Amazon, and is classified as Critically Endangered by the International Union for the Conservation of Nature. Here, we evaluated the impacts of climate change and deforestation on Cebus kaapori distribution area. We modeled the distribution of the species under current and future (2050) climates and overlapped these models with established protect areas as well as current forest cover and that expected for 2050 in two different economic scenarios acoording to a land-use model. We found that climate change might lead to up to 97% of loss of climatic suitable area for Cebus kaapori within the next 30 years. The situation worsens when considering current forest loss and future deforestation projections, both under a governance scenario and in under the business-as-usual scenario. We show that the restricted distribution of Cebus kaapori, coupled with likely high reduction in suitable areas for species occurrence, low coverage in protected areas and fragmentation of potential adaptive areas for occurrence in the future, might reduce species’ populations to an unviable level of survival in nature.