947 resultados para lowland forests
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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O tapir ou anta, descrito como o maior mamífero terrestre brasileiro, pertence à ordem Perissodactila, subordem Hippomorfa, superfamília Tapiroidea e família Tapiridae. Na floresta úmida está envolvido com a dispersão de sementes em função das características do tubo digestivo. O acompanhamento do ciclo estral permite avaliar e compreender a atividade reprodutiva nas espécies animais. Nos animais silvestres, o estresse da contenção pode interferir na própria ciclicidade gonadal, uma das alternativas é o acompanhamento dos hormônios gonadais nas excretas. Buscamos neste trabalho o acompanhamento periódico da atividade gonadal através da quantificação de progesterona no leite. Utilizamos uma fêmea recém-parida no Zoológico de Araçatuba, da qual colhemos leite, esfregaço vaginal e temperatura retal. A progesterona foi quantificada por radioimunoensaio de fase sólida (Coat-a-Count, DPC®) com curva padrão fornecida pela F.A.O. O ensaio mostrou sensibilidade de 1,25 nmol/l com coeficiente de variação intra-ensaio de 15,36%. Durante a fase de lactação, a fêmea não apresentou níveis detectáveis de progesterona por 158 dias (de novembro a abril). O primeiro pico de produção foi de 2,3 nmol/l e apresentou duração de 5 dias. O segundo pico de 3,54 nmol/l teve uma duração de 23 dias. Setenta e quatro dias após o aparecimento da progesterona no leite a lactação cessou. Podemos concluir que a fêmea de tapir apresentou um período de anestro lactacional de aproximadamente 5 meses e voltou a ciclar no outono (abril) sugerindo pouca influência do fotoperíodo. A quantificação da progesterona no leite mostrou-se útil para o acompanhamento do ciclo estral na espécie, porém a variação da citologia vaginal e temperatura retal não apresentaram correlação com os níveis hormonais.
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A large number of newly published and unpublished hectare plots in Amazonia and the Guiana Shield area allow an analysis of family composition and testing of hypotheses concerning alpha-diversity in the south American rain forest. Using data from 94 plots the family-level floristic patterns in wet tropical South America are described. To test diversity patterns, 268 plots are used in this large area. Contrary to a widely held belief, western Amazonian plots are not necessarily the most diverse. Several central Amazonian plots have equal or even higher tree diversity. Annual rainfall is not a good estimator for tree diversity in the Amazonia area and Guiana shield. Plots in the Guiana Shield area (and eastern Amazonia) usually have lower diversity than those in central or western Amazonia. It is argued that this is not because of low rainfall or low nutrient status of the soil but because of the small area of the relatively isolated rain forest area in eastern Amazonia and the Guiana Shield. The low diversity on nutrient-poor white sand soils in the Amazon basin is not necessarily due to their Low nutrient status but is, at least partly, caused by their small extent and fragmented nature.
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This is the first report of the interaction between the two entomophagous agents Mantispa minuta Fabricius (Mantispidae) and Parawixia bistriata Rengger, an orb-weaver spider (Araneidae). From egg sacs kept in the laboratory we observed the emergence of adult neuropterans followed by the emergence of a high number of spiderlings. This association illustrates the interactions among the invertebrate predators coexisting in Eucalyptus plantations managed without chemical treatment, in the State of São Paulo, Brazil.
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We compared the relative contribution of blackwater inundation forest (igapo) and unflooded (terra firme) forest for regional bird species diversity in the lower Rio Negro region. For analyses of habitat preference we used mist-net samples and an unpublished bird species check-list. The igapo forest had lower bird species diversity than the terra firme forest. However, some 14% of the forest bird species in the region are restricted to igapo forest. Species composition was found to be distinct between the understories of the two forest types. Common forest bird guilds in the Neotropics such as ant-following birds avoid igapo forest. The differential habitat selection among birds in the inundated and unflooded forest is likely to result from vegetation structure and biological interactions such as aggressive behaviour. Since the inundated forest has a typical biota, conservation efforts needs to be directed to protect these habitats. Unfortunately, inundation forests are threatened by several human actions, especially dam construction. The extent of protected areas in the Brazilian Amazon is insufficient for the adequate protection of the inundated habitats, because it includes only 3% of the total area.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Understanding tropical forest succession is critical for the development of tropical forest conservation strategies worldwide, given that tropical secondary forests can be considered the forests of the future. Tropical dry forests (TDF) are among the most threatened tropical ecosystems, there are more secondary forests and forest restoration efforts that require a better understanding of successional processes. The main goal of this synthesis for this special issue on the ecology and management of tropical dry forests in the Americas is to present a summarized review of the current knowledge of the ecology and management implications associated to TDF succession. We explore specific issues associated to tropical dry forest succession with emphasis on the use of chronosequences, plant diversity and composition, plant phenology and remote sensing, pollination, and animal-plant interactions; all under the integrating umbrella of ecosystem succession. We also emphasize the need to conduct socio-ecological research to understand changes in land-use history and its effects on succession and forest regeneration of TDF. We close this paper with some thoughts and ideas associated with the strong need for an integrating dimension not considered until today: the role of cyberinfrastructure and eco-informatics as a tool to support sound conservation, management and understanding of TDF in the Americas. (C) 2009 Elsevier B.V. All rights reserved.
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Body temperatures and thermoregulatory behaviour of the teiid lizard Ameiva ameiva inhabiting the edge and the understory were studied in Central Amazonian forests Despite of differences in the thermal profile of the habitates. the mean body temperature was the some for active lizards observed at the edge or inside the forest. where only slight peculiarities in thermoregulatory behaviour were observed. A. ameiva is capable of maintaining body temperature significantly above microhabitat temperature.
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Ants are often attracted to diaspores not adapted for dispersal by ants. These diaspores may occasionally benefit from this interaction. We selected six nonmyrmecochorous plant species (Virola oleifera, Eugenia stictosepala, Cabralea canjerana, Citharexylum myrianthum, Alchornea glandulosa and Hyeronima alchorneoides) whose diaspores differ in size and lipid content, and investigated how these features affect the outcome of ant-diaspore interactions on the floor of a lowland Atlantic forest of Southeast Brazil. A total of 23 ant species were seen interacting with diaspores on the forest floor. Ants were generally rapid at discovering and cleaning the diaspore pulp or aril. Recruitment rate and ant attendance were higher for lipid-rich diaspores than for lipid-poor ones. Removal rate and displacement distance were higher for small diaspores. The large ponerine ant Pachycondyla striata, one of the most frequent attendants to lipid-rich arillate diaspores, transported the latter into their nests and discarded clean intact seeds on refuse piles outside the nest. Germination tests with cleaned and uncleaned diaspores revealed that the removal of pulp or aril may increase germination success in Virola oleifera, Cabralea canjerana, Citharexylum myrianthum and Alchornea glandulosa. Gas chromatography analyses revealed a close similarity in the fatty acid composition of the arils of the lipid-rich diaspores and the elaiosome of a typical myrmecochorous seed (Ricinus communis), corroborating the suggestion that some arils and elaiosomes are chemically similar. Although ant-derived benefits to diaspores - secondary dispersal and/or increased germination - varied among the six plant species studied, the results enhanced the role of ant-diaspore interactions in the post-dispersal fates of nonmyrmecochorous seeds in tropical forests. The size and the lipid-content of the diaspores were shown to be major determinants of the outcome of such interactions.