996 resultados para Forest remnant


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Aim: To quantify the consequences of major threats to biodiversity, such as climate and land-use change, it is important to use explicit measures of species persistence, such as extinction risk. The extinction risk of metapopulations can be approximated through simple models, providing a regional snapshot of the extinction probability of a species. We evaluated the extinction risk of three species under different climate change scenarios in three different regions of the Mexican cloud forest, a highly fragmented habitat that is particularly vulnerable to climate change. Location Cloud forests in Mexico.
Methods: Using Maxent, we estimated the potential distribution of cloud forest for three different time horizons (2030, 2050 and 2080) and their overlap with protected areas. Then, we calculated the extinction risk of three contrasting vertebrate species for two scenarios: (1) climate change only (all suitable areas of cloud forest through time) and (2) climate and land-use change (only suitable areas within a currently protected area), using an explicit patch-occupancy approximation model and calculating the joint probability of all populations becoming extinct when the number of remaining patches was less than five.
Results: Our results show that the extent of environmentally suitable areas for cloud forest in Mexico will sharply decline in the next 70 years. We discovered that if all habitat outside protected areas is transformed, then only species with small area requirements are likely to persist. With habitat loss through climate change only, high dispersal rates are sufficient for persistence, but this requires protection of all remaining cloud forest areas.
Main conclusions: Even if high dispersal rates mitigate the extinction risk of species due to climate change, the synergistic impacts of changing climate and land use further threaten the persistence of species with higher area requirements. Our approach for assessing the impacts of threats on biodiversity is particularly useful when there is little time or data for detailed population viability analyses.

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The resilience of mangroves is dependent on their regeneration capacity. Patchy mid-19th century clearing dramatically affected this capacity, creating stable vegetated and unvegetated states in a fragmented temperate mangrove ecosystem. Mechanisms of mediation between states were tested by monitoring the survival and growth of planted mangrove seedlings and propagules on formerly forested bare mudflats and inside patches of existing forest. Survival (1 to 76%) and growth (-0.83 to 10.45 mm mo-1 increase in plant height) of seedlings was affected by (1) differing levels of exposure found at varying proximities to remnant forest and (2) differing inundation regimes both within and between sites that were randomly selected from locations that varied in aspect relative to prevailing winds. Increases in hydrodynamic energy within and between sites corresponded to a decrease in survival that was much more pronounced at locations that were exposed to prevailing winds. Growth rates were also generally lower at sites in exposed locations, but inundation regime was a more important determinant within sites, where growth was reduced at lower heights on the shore. Results suggest that stability of the bare mudflat state (caused by historical clearance of the mangrove forest) is dependent on level of exposure to hydrodynamic energy, and a return to a forested state is more likely where this exposure is lower. These results have implications for planning and implementing mangrove restoration projects and illustrate the role that physical factors can play in determining the resilience of disturbed temperate mangrove ecosystems.

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Privacy-preserving data mining has become an active focus of the research community in the domains where data are sensitive and personal in nature. For example, highly sensitive digital repositories of medical or financial records offer enormous values for risk prediction and decision making. However, prediction models derived from such repositories should maintain strict privacy of individuals. We propose a novel random forest algorithm under the framework of differential privacy. Unlike previous works that strictly follow differential privacy and keep the complete data distribution approximately invariant to change in one data instance, we only keep the necessary statistics (e.g. variance of the estimate) invariant. This relaxation results in significantly higher utility. To realize our approach, we propose a novel differentially private decision tree induction algorithm and use them to create an ensemble of decision trees. We also propose feasible adversary models to infer about the attribute and class label of unknown data in presence of the knowledge of all other data. Under these adversary models, we derive bounds on the maximum number of trees that are allowed in the ensemble while maintaining privacy. We focus on binary classification problem and demonstrate our approach on four real-world datasets. Compared to the existing privacy preserving approaches we achieve significantly higher utility.

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Illegal logging causes a number of environmental and social damages in countries where wood is sourced from native forests. Logging in protected areas is an act of irresponsibility that exacerbates the loss of biodiversity. In addition, uncontrolled deforestation and bushfires may aggravate climate change, not to mention the negative effects they impose on local populations, such as the impoverishment of rural communities whose livelihoods depend on forest products. Several studies show that Brazil ranks high in terms of irresponsible use of natural resources, including native wood from the Amazon. Even more worrisome is the fact that the state, despite being responsible for regulating logging activities, is one of the largest consumers of native wood, which subverts the goals of any government committed to sustainable environmental management. By monitoring the development and impacts of illegal timber production and consumption around the world, the Friends of the Amazon Network – an initiative by the Getulio Vargas Foundation with support from the British Government and the European Commission – identified a need to describe and evaluate, in a brief and instructive manner, the different mechanisms the state has available to reverse this predatory practice. One of the aspects discussed in this book is the role of civil servants in major efforts aimed at repressing illegal logging and timber production, as well as identifying products derived from these activities in order to prevent their consumption. This is the purpose of this publication, which uses detailed infographics and a journalistic approach, including interviews and true stories, to outline the complexity of Amazon timber’s chain of custody – from logging, processing and transportation to commercialization in the Brazilian market.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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As florestas secundárias e plantações de espécies exóticas estão se expandindo nas paisagens tropicais. No entanto, nossa compreensão sobre o valor destas florestas para a conservação da biodiversidade de invertebrados ainda é incipiente. Neste trabalho, usamos a fauna de formigas de serapilheira para avaliar a diversidade desses insetos entre três florestas de Eucalyptus, sendo uma comercial (quatro anos de idade) e duas abandonadas em diferentes idades de regeneração (16 e 31 anos) e uma área de Mata Atlântica secundária. A riqueza total foi mais alta na floresta secundária e nos plantios de Eucalyptus abandonados há mais tempo. A densidade de espécies na floresta secundária foi significativamente maior quando comparado as plantações de Eucalyptus, mas não difere entre eucaliptais; análise de ordenação revelou diferenças na composição de espécies entre as plantações de Eucalyptus com subbosque ausente e com subbosque desenvolvido ou em desenvolvimento. Ainda, foi constatada uma sobreposição acentuada entre amostras de serapilheira das florestas de eucaliptos abandonadas há mais tempo e a floresta secundária. em geral, plantações de eucalipto foram caracterizadas pela presença de espécies generalistas e de ampla distribuição. Nossos resultados indicam que embora o subbosque de plantações de eucaliptos com maior idade de regeneração suporte um conjunto relativamente alto de espécies generalistas de formigas, é improvável que eucaliptais conservem a maioria das espécies de florestas primárias, especialmente predadores especializados, Dacetini e espécies nômades.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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

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The ovarian remnant syndrome (ORS) is an iatrogenic disorder in bitches and queens, which is characterized by recurrence of estrus following surgical spay, due to the presence of a piece of ovarian tissue within the abdominal cavity. In most cases, the remnant ovary is found in the right ovarian pedicle, due to its topographic position, deeper and more cranial than the left ovary. The main clinical signs of ORS in small animals are the heat behavior and the presence of vaginal swelling/secretion, especially in canines. The diagnosis should be performed by means of vaginal cytology when attraction of males is detected, serum estrogen and progesterone levels and/or by challenging test with GnRH or hCG administration. However, vaginal citology is the most suitable and less expensive diagnostic tool. Nowadays the treatment of choice is a new laparotomy or laparoscopy, followed by removal of the remnant ovarian tissue. The surgical treatment has more chances of success if it is performed in the diestrus (i.e., between 15 and 60 days after the detection of attraction of males). Furthermore, a careful and accurate surgical procedure aided by advanced visualization techniques during ovariohysterectomy or ovariectomy is the best way to prevent ORS in companion animals.

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The survey presented here describes the bacterial diversity and community structures of a pristine forest soil and an anthropogenic, terra preta from the Western Amazon forest using molecular methods to identify the predominant phylogenetic groups. Bacterial community similarities and species diversity in the two soils were compared using oligonucleotide fingerprint grouping of 16S rRNA gene sequences for 1500 clones (OFRG) and by DNA sequencing. The results showed that both soils had similar bacterial community compositions over a range of phylogenetic distances, among which Acidobacteria were predominant, but that terra preta supported approximately 25% greater species richness. The survey provides the first detailed analysis of the composition and structure of bacterial communities from terra preta anthrosols using noncultured-based molecular methods. (c) 2006 Elsevier Ltd. All rights reserved.

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

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Some Eucalyptus species are widely used as a plantation crop in tropical and subtropical regions. One reason for this is the diversity of end uses, but the main reason is the high level of wood production obtained from commercial plantings. With the advancement of biotechnology it will be possible to expand the geographical area in which eucalypts can be used as commercial plantation crops, especially in regions with current climatic restrictions. Despite the popularity of eucalypts and their increasing range, questions still exist, in both traditional planting areas and in the new regions: Can eucalypts invade areas of native vegetation, causing damage to natural ecosystems biodiversity?The objective of this study it was to assess whether eucalypts can invade native vegetation fragments in proximity to commercial stands, and what factors promote this invasive growth. Thus, three experiments were established in forest fragments located in three different regions of Brazil. Each experiment was composed of 40 plots (1 m(2) each one), 20 plots located at the border between the forest fragment and eucalypts plantation, and 20 plots in the interior of the forest fragments. In each experimental site, the plots were paired by two soil exposure conditions, 10 plots in natural conditions and 10 plots with soil exposure (no plant and no litter). During the rainy season, 2 g of eucalypts seeds were sown in each plot, including Eucalyptus grandis or a hybrid of E. urophylla x E. grandis, the most common commercial eucalypt species planted in the three region. At 15, 30, 45, 90, 180, 270 and 360 days after sowing, we assessed the number of seedlings of eucalypts and the number of seedlings of native species resulting from natural regeneration. Fifteen days after sowing, the greatest number of eucalypts seedlings (37 m(-2)) was observed in the plots with lower luminosity and exposed soil. Also, for native species, it was observed that exposed soil improved natural germination reaching the highest number of 163 seedlings per square meter. Site and soil exposure were the factors that have the greatest influence on seed germination of both eucalypt and native species. However, 270 days after sowing, eucalypt seedlings were not observed at any of the three experimental sites. The result shows the inability of eucalypts to adapt to condition outside of their natural range. However, native species demonstrated their strong capacity for natural regeneration in forest fragments under the same conditions where eucalypts were seeded. (C) 2011 Elsevier B.V. All rights reserved.

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