202 resultados para Paisagens fragmentadas


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Matrix can be defined as a portion of the landscape, that somewhere in time suffered intense human disturbance, such as decreasing of native vegetation. The matrix surrounding the forest fragments may create a certain resistance to the movements of individuals (RICKETTS, 2001). The Atlantic rainforest present in the Corumbataí river basin lost about 89% of its original vegetation, leading to a highly fragmented landscape (VALENTE e VETTORAZZI, 2005). In this context, this study aimed to evaluate the effect of the matrix and the characteristic capacity of two forest birds, Dysithamnus mentalis and Basileuterus flaveolus, moving around the landscape. With this aim, six fragments were selected, three with sugar cane matrix, three with Eucalyptus sp. matrix. The methodology utilized to evaluate the response of the birds was playback technique. First the vocalizations were carried out at the forest matrix boundary, in the edge, attracting individuals to the matrix. As the responses were generated, the playback was moved increasingly inside the matrix, observing the distances traveled by the species. The control trials were conducted inside the fragments, the playback was played at the edge and as the responses were observed, the vocalizations were carried out inside the fragment until the moment that individuals ceased answers. It could be observed that for individuals of D. mentalis the matrix generated a high resistance, because no individual entered the matrix. For B. flaveolus the average distance traveled in both matrices was 70 meters, indicating statistically high resistance of the sugar cane matrix and Eucalyptus sp. Considering the characteristics of different matrices, it was found that both matrices generate similar resistance in the movement of these species

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This paper aims to study the proposal of ecological corridors as integration solution spaces that present fragmentation of vegetation. The geographic space is composed of physical and human characteristics and interrelation between the different variables result in different landscapes. The landscape ecology provides an understanding of the heterogeneous landscape, which combines the space and ecosystem components. The spatial fragmentation of vegetation and is often the result of a number of factors. This new landscape composition presents different forms of economic exploitation of the soil (agriculture, pasture). The corridors are considered optional connection of plant debris, providing greater flow of species of fauna and flora reconstituting somehow Ecosystem site. The research aims to propose the restoration of an area devoid of natural plant its constitution, becoming restoration tool in a particular area of vegetation fragmented

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Diversos estudos têm evidenciado os efeitos da defaunação e fragmentação sobre processos mutualísticos chaves, como polinização e dispersão de sementes. Áreas fragmentadas ou defaunadas possuem um desequilíbrio nas populações resilientes, sendo que algumas populações aumentam drasticamente sua abundância, um fenômeno chamado de “density compensation”. Se por um lado é bem conhecido esse fenômeno, por outro lado, existe uma lacuna em nosso conhecimento sobre as mudanças comportamentais dos dispersores de sementes em áreas com baixa competição intra-específica e alta específica. Na Mata Atlântica, o palmito juçara (Euterpe edulis) produz frutos carnosos consumidos por diversas aves e mamíferos. Nesse projeto, pretendemos entender como a defaunação (perda de grandes dispersores de sementes como Ramphastídeos) pode alterar a efetividade de dispersão de sementes. Para o registro de frugivoria, foi utilizado o método de observação focal que se consiste da observação direta da planta com frutificação madura, no caso o indivíduo palmito-juçara (Euterpe edulis), identificando as espécies visitantes e anotando seus comportamentos pertinentes. Nossa hipótese a ser testada, é que áreas com baixa riqueza de frugívoros e alta abundância de algumas espécies como sabiás (Turdus spp.) acarretará maior competição e menor efetividade de dispersão dessa palmeira

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A extensa fragmentação das florestas tropicais e conseguinte perda da fauna de dispersores e predadores de sementes trazem importantes consequências às interações planta-animal. A predação de sementes, que representa uma etapa crítica no recrutamento de plantas tropicais, é um dos processos que sofrem com este impacto. A falta dos agentes dispersores e predadores de sementes pode alterar a dinâmica natural dessa interação trófica ao ponto de não corresponder mais ao modelo de Janzen-Connell, que prediz que quanto mais próximo da planta parental, maior a probabilidade de predação e, por conseqüência, menor será a dispersão. Esse estudo avaliou em três fragmentos com níveis diferenciado de defaunação (Mata São José, Reserva Municipal Santa Genebra e Estação Ecológica dos Caetetus) a predação (e/ou dispersão) de sementes de palmito juçara (Euterpe edulis Martius) abaixo e longe da planta-mãe, buscando testar o modelo Janzen-Connell. Em cada área cinco sementes foram dispostas em tratamento aberto e cinco em tratamento fechado, abaixo e distante 10 metros do parental em 15 palmeiras e avaliado o destino das sementes após 30 dias. Os resultados não oferecem suporte ao modelo, uma vez que apenas em um dos fragmentos pequenos e defaunados a predação abaixo do parental foi maior que distante, ou seja, nos demais fragmentos a distância da planta mãe não aumentou a sobrevivência das sementes. Nas áreas defaunadas a predação ocorreu principalmente por invertebrados e patógenos, enquanto que na área menos defaunada a predação foi feita principalmente por vertebrados. Diferenças significativas na predação de sementes entre os tratamentos só foram obtidas na área menos defaunada, o que mostra a importância dos predadores vertebrados de médio e grande porte na predação e/ou dispersão de sementes de E. edulis neste fragmento.

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The Brazilian fauna has been constantly threatened by deforestation and forest fragmentation. As a result, many populations become isolated and small which negatively impacts their genetic diversity, putting them at a higher risk of extinction than large and stable populations. The aim of this work was to estimate the genetic diversity of white-lipped peccaries (Tayassu pecari) in the region of Taboco (Corguinho, MS), a fragmented area; and to compare these estimates with that obtained previously for two populations from Brazilian Pantanal, which is considered a relatively well-preserved biome and where the species is not threatened. A total of 18 blood and 72 hair samples of white-lipped peccaries had their DNA extracted and amplified for five polymorphic microsatellite loci. With the individuals identified, genetic diversity indicators (such as number of alleles, allelic richness, expected end and observed) and the inbreeding coefficient FIS were calculated. In addition, to verify if the population suffered a recent population bottleneck, we used the tests implemented in the program Bottleneck. The population of Taboco showed no evidence of recent population bottleneck (p > 0.05) or inbreeding (FIS = 0.008; p > 0.022). In addition, the levels of genetic diversity in this population (mean number of alleles = 2.60; mean allelic richness = 2.56 mean observed and expected heterozygosities = 0.45 and 0.47, respectively) were statistically similar to those found previously for the two populations from Pantanal (p > 0,05); although the region of Taboco is more impacted than the Pantanal. Even though we showed no evidence of loss of genetic diversity, it does not mean that the population is not suffering with fragmentation; but that there was not sufficient time to evidence the genetic changes. In addition, may be occurring gene flow with populations of nearby fragments, which is maintaining... (Complete abstract click electronic access below)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Habitat loss and fragmentation of landscapes endanger the planet’s biodiversity. Strategies for identify priority areas for conservation and restoration of biodiversity rich areas becomes essential for the planning of the management of these landscape become successful. This study aims to propose a novel, transparent and replicable method for choosing priority areas for restoration, and includes the following steps: (a) identification of regional biodiversity hotspots for conservation; (b) identification of priority areas for restoration with the greatest potential to increase the connectivity of the fragments already existing; (c) estimate the potential richness of understory birds before and after restoration, analyzing the gain of species for the future scenario. In order to identify the corridors to be restored in a future scenario we considered the approach of multiple corridors, which aimed to connect the main fragments within the region through analysis of multi-paths. Already existing regression models were applied to estimate the richness of the landscape considering three models: a) species richness as a function of patch area of the fragment selected as hotspots; b) richness as a function of areas connected by structural corridors and c) connected area for species which are able to access nearby fragments within 20m. The gain of species for future scenario which consider the potential restoration of selected areas was estimated. Based on our results we observed that species that use corridors showed the highest increment of species richness of understory birds. As a result it had to restore corridors to model species with the ability to use forest corridors was the highest gain potential species richness of understory birds. The methods proposed method in this study appears provide new ways to ensures a better cost / benefit relationship for restoration projects by increasing the chances of better reach high levels of...

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Pós-graduação em Ciências Biológicas (Zoologia) - IBRC

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Agronomia (Energia na Agricultura) - FCA

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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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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)