• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • Tagged with
  • 3
  • 3
  • 2
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Cenários de priorização na conservação de sítios insubstituíveis da flora na Cadeia do Espinhaço em Minas Gerais, Brasil / Priorization scenarios in conservation of the irreplaceable sites of flora in the Espinhaço Mountain Range of Minas Gerais, Brasil

Silva, Patricia Köster e 06 June 2017 (has links)
A crise de extinções antropogênicas é um problema planetário que erode a biodiversidade a taxas muito superiores àquelas registradas pelos eventos geológicos de extinção. Essa grande perda de espécies pode desencadear a sexta onda de extinções em massa, ocasionando um empobrecimento na evolução mundial e comprometer os processos de especiação. Nas últimas décadas surgiram muitas iniciativas de conservação que atuam em diferentes esferas para proteger a biodiversidade mundial. No entanto, locais insubstituíveis onde ocorrem espécies microendêmicas ameaçadas de extinção deve ser a prioridade em medidas de conservação, pois representam a \"ponta do iceberg\" na crise das extinções. Fatores de ameaça contribuem na vulnerabilidade das espécies microendêmicas, intensificando seu risco de extinção. A Cadeia do Espinhaço em Minas Gerais, inserida no bioma Cerrado, é reconhecidamente uma região de microendemismos da flora e está sujeita a muitos fatores de ameaça como a mineração, a agropecuária e o extrativismo. A identificação das áreas mais vulneráveis às ameaças, bem como, a identificação dos sítios prioritários, onde ocorrem espécies de único refúgio, pode evidenciar a necessidade de conservação de uma região única com biodiversidade exclusiva. Portanto, os objetivos gerais deste estudo são: identificar as espécies-alvo da flora e mapear seus sítios prioritários, avaliar o estado de conservação da Cadeia do Espinhaço em Minas Gerais, identificar as principais ameaças e sua vulnerabilidade e testar a eficiência dos sítios prioritários das espécies microendêmicas típicas como indicadores de espécies ameaçadas. Para isto, foram utilizadas bases cartográficas e imagens de satélite processadas em Sistema de Informação Geográfica, informações de herbários e coordenadas para caracterizar a distribuição das espécies e a aplicabilidade da metodologia da Aliança para Extinção Zero (AZE), identificando os sítios prioritários para conservação. Foram identificadas as principais ameaças que ocorrem nos sítios por meio da análise de uso e ocupação das terras, revisão sistemática da literatura e levantamento das ameaças que afetam diretamente as espécies para calcular os índices de vulnerabilidade dos sítios mapeados. Com isto, foram identificadas 22 espécies-alvo distribuídas em sete sítios prioritários no Espinhaço mineiro, cujas principais ameaças são mineração, agropecuária, queimadas, extrativismo, visitação predatória e expansão urbana. Os resultados monstraram ainda que as ameaças secundárias são muito importantes na região, tornando os sítios de Serra do Cipó, Diamantina e Águas Vertentes os mais vulneráveis a essas perturbações. Os sítios prioritários representam cerca de 83% das espécies ameaçadas no Espinhaço mineiro possibilitando, ações em conservação eficazes nestas áreas. O Brasil é o primeiro País a mapear sítios prioritários para espécies-alvo típicas da flora e testar o estado de conservação destas áreas, revelando quais locais são mais vulneráveis e que necessitam de ações de conservação urgentes / The crisis of anthropogenic extinctions is a planetary problem that erodes biodiversity at rates much higher than those recorded by geological extinction events. This great loss of species can trigger the sixth wave of mass extinctions, causing an impoverishment in world evolution and compromising the processes of speciation. In the last decades many conservation initiatives have emerged that act in different spheres to protect the world\'s biodiversity. However, irreplaceable sites where microendemic species are threatened with extinction should be the priority in conservation measures, as they represent the \"top of the iceberg\" in the crisis of extinctions. Threat factors contribute to the vulnerability of microendemic species, intensifying their risk of extinction. The Espinhaço Mountain Range in Minas Gerais, is part of the Cerrado biome, recognized as a microendemism region of flora and is subject to many threat factors such as mining, farming and extractivism. Identification of areas most vulnerable to threats, as well as identification of priority sites where trigger species occur, may highlight the need for conservation of a unique region with exclusive biodiversity. Therefore, the general objectives of this study are: to identify the target species of the flora and to map their priority sites, to evaluate the conservation status of the Espinhaço Mountain Range in Minas Gerais, to identify the main threats, their vulnerability and to test the efficiency of the priority sites of the typical microendemic species as indicators of endangered species. For this, cartographic bases and satellite images processed in Geographic Information System, herbarium and coordinate information were used to characterize the distribution of species and the applicability of the Alliance for Zero Extinction (AZE) methodology, to identify the priority conservation sites. The main threats that occurred in the sites were identified through analysis of land use and occupation, systematic review of the literature and identification of the threats that directly affect the species to calculate the vulnerability indexes of the mapped sites. Were identifyed 22 trigger species distributed in seven priority sites in the Espinhaço of Minas Gerais, whose main threats are mining, farming, burning, extractivism, predatory visitation and urban expansion. The results also showed that secondary threats are very important in the region, making the Serra do Cipó, Diamantina and Aguas Vertentes sites the most vulnerable to these disturbances. The priority sites represent about 83% of the threatened species in the Espinhaço Mountain Range of Minas Gerais, enabling effective conservation actions in these areas. Brazil is the first country to map priority sites for typical target species of the flora and to test the conservation status of these areas, revealing which sites are most vulnerable and requiring urgent conservation actions
2

Using Bird Distributions to Assess Extinction Risk and Identify Conservation Priorities in Biodiversity Hotspots

Ocampo-Penuela, Natalia January 2016 (has links)
<p>Habitat loss, fragmentation, and degradation threaten the World’s ecosystems and species. These, and other threats, will likely be exacerbated by climate change. Due to a limited budget for conservation, we are forced to prioritize a few areas over others. These places are selected based on their uniqueness and vulnerability. One of the most famous examples is the biodiversity hotspots: areas where large quantities of endemic species meet alarming rates of habitat loss. Most of these places are in the tropics, where species have smaller ranges, diversity is higher, and ecosystems are most threatened.</p><p> Species distributions are useful to understand ecological theory and evaluate extinction risk. Small-ranged species, or those endemic to one place, are more vulnerable to extinction than widely distributed species. However, current range maps often overestimate the distribution of species, including areas that are not within the suitable elevation or habitat for a species. Consequently, assessment of extinction risk using these maps could underestimate vulnerability.</p><p>In order to be effective in our quest to conserve the World’s most important places we must: 1) Translate global and national priorities into practical local actions, 2) Find synergies between biodiversity conservation and human welfare, 3) Evaluate the different dimensions of threats, in order to design effective conservation measures and prepare for future threats, and 4) Improve the methods used to evaluate species’ extinction risk and prioritize areas for conservation. The purpose of this dissertation is to address these points in Colombia and other global biodiversity hotspots.</p><p>In Chapter 2, I identified the global, strategic conservation priorities and then downscaled to practical local actions within the selected priorities in Colombia. I used existing range maps of 171 bird species to identify priority conservation areas that would protect the greatest number of species at risk in Colombia (endemic and small-ranged species). The Western Andes had the highest concentrations of such species—100 in total—but the lowest densities of national parks. I then adjusted the priorities for this region by refining these species ranges by selecting only areas of suitable elevation and remaining habitat. The estimated ranges of these species shrank by 18–100% after accounting for habitat and suitable elevation. Setting conservation priorities on the basis of currently available range maps excluded priority areas in the Western Andes and, by extension, likely elsewhere and for other taxa. By incorporating detailed maps of remaining natural habitats, I made practical recommendations for conservation actions. One recommendation was to restore forest connections to a patch of cloud forest about to become isolated from the main Andes.</p><p>For Chapter 3, I identified areas where bird conservation met ecosystem service protection in the Central Andes of Colombia. Inspired by the November 11th (2011) landslide event near Manizales, and the current poor results of Colombia’s Article 111 of Law 99 of 1993 as a conservation measure in this country, I set out to prioritize conservation and restoration areas where landslide prevention would complement bird conservation in the Central Andes. This area is one of the most biodiverse places on Earth, but also one of the most threatened. Using the case of the Rio Blanco Reserve, near Manizales, I identified areas for conservation where endemic and small-range bird diversity was high, and where landslide risk was also high. I further prioritized restoration areas by overlapping these conservation priorities with a forest cover map. Restoring forests in bare areas of high landslide risk and important bird diversity yields benefits for both biodiversity and people. I developed a simple landslide susceptibility model using slope, forest cover, aspect, and stream proximity. Using publicly available bird range maps, refined by elevation, I mapped concentrations of endemic and small-range bird species. I identified 1.54 km2 of potential restoration areas in the Rio Blanco Reserve, and 886 km2 in the Central Andes region. By prioritizing these areas, I facilitate the application of Article 111 which requires local and regional governments to invest in land purchases for the conservation of watersheds.</p><p>Chapter 4 dealt with elevational ranges of montane birds and the impact of lowland deforestation on their ranges in the Western Andes of Colombia, an important biodiversity hotspot. Using point counts and mist-nets, I surveyed six altitudinal transects spanning 2200 to 2800m. Three transects were forested from 2200 to 2800m, and three were partially deforested with forest cover only above 2400m. I compared abundance-weighted mean elevation, minimum elevation, and elevational range width. In addition to analyzing the effect of deforestation on 134 species, I tested its impact within trophic guilds and habitat preference groups. Abundance-weighted mean and minimum elevations were not significantly different between forested and partially deforested transects. Range width was marginally different: as expected, ranges were larger in forested transects. Species in different trophic guilds and habitat preference categories showed different trends. These results suggest that deforestation may affect species’ elevational ranges, even within the forest that remains. Climate change will likely exacerbate harmful impacts of deforestation on species’ elevational distributions. Future conservation strategies need to account for this by protecting connected forest tracts across a wide range of elevations.</p><p> In Chapter 5, I refine the ranges of 726 species from six biodiversity hotspots by suitable elevation and habitat. This set of 172 bird species for the Atlantic Forest, 138 for Central America, 100 for the Western Andes of Colombia, 57 for Madagascar, 102 for Sumatra, and 157 for Southeast Asia met the criteria for range size, endemism, threat, and forest use. Of these 586 species, the Red List deems 108 to be threatened: 15 critically endangered, 29 endangered, and 64 vulnerable. When ranges are refined by elevational limits and remaining forest cover, 10 of those critically endangered species have ranges < 100km2, but then so do 2 endangered species, seven vulnerable, and eight non-threatened ones. Similarly, 4 critically endangered species, 20 endangered, and 12 vulnerable species have refined ranges < 5000km2, but so do 66 non-threatened species. A striking 89% of these species I have classified in higher threat categories have <50% of their refined ranges inside protected areas. I find that for 43% of the species I assessed, refined range sizes fall within thresholds that typically have higher threat categories than their current assignments. I recommend these species for closer inspection by those who assess risk. These assessments are not only important on a species-by-species basis, but by combining distributions of threatened species, I create maps of conservation priorities. They differ significantly from those created from unrefined ranges.</p> / Dissertation
3

Biogeografia da conservação frente à expansão agrícola: conflitos e prioridades / Conservation Biogeography faced with agricultural expansion: conflicts and priorities

DOBROVOLSKI, Ricardo 10 April 2012 (has links)
Made available in DSpace on 2014-07-29T16:23:34Z (GMT). No. of bitstreams: 1 Tese Ricardo Dobrovolski.pdf: 1981880 bytes, checksum: 8c60352c3d999171ab957f065b32a9db (MD5) Previous issue date: 2012-04-10 / Agriculture is the human activity with the greatest impact on the environment. Specifically, it represents the greatest threat to biodiversity. In the future, this activity should expand due to population growth, increased consumption and production of biofuels from food. To understand the possible impacts of this expansion on biodiversity, we used scenarios of land use change between 1970 and 2100 from IMAGE (Integrated Model to Access Global Environment) to test the following hypotheses: (i) areas considered as global priorities for conservation by international NGOs will be preferentially impacted by agricultural expansion in the XXI century, (ii) there is a conflict between the priority areas for carnivores conservation and agricultural expansion, and this conflict can be reduced by incorporating information on agricultural expansion in the prioritization process, (iii) the integration among countries for conservation planning may benefit both biodiversity and agricultural productivity, (iv) Brazilian protected areas will be impacted by agricultural expansion in the future and this impact will differ between protected areas of integral protection and those of sustainable use. We found that: (i) the impact on priority areas for conservation depends on the criteria by which they were set, so that areas defined by its high vulnerability are currently most affected than those of low vulnerability. Throughout the XXI century this impact is expected to increase, although the difference between the two types of priorities remains, except for High Biodiversity Wilderness Areas, defined by their low vulnerability in current time, but for which most pessimistic scenarios forecast an impact similar to priority areas of high vulnerability, (ii) there is a high spatial congruence between areas with high agricultural use in the future and priority areas for conservation of carnivores. This conflict can be reduced if the prioritization process include information on agricultural expansion; this incorporation, however, causes a profound change in the distribution of priority areas and reduces the number of protected carnivore populations, (iii) the integration of countries to create a set of priority areas for conservation that represents 17% of the land surface can protect 19% more mammal populations without reducing food production, compared to a strategy in which each country seeks to protect its territory independently, and (iv) the impact of agriculture in Brazil is expected to increase until the end of the century, threatening even the protected areas and their surroundings. This impact, however, should not be different between areas of sustainable use and those of integral protection. We conclude that agricultural expansion should remain a major threat to biodiversity in the future, even in areas of special interest for conservation. Conservation actions should be planned taking into account this threat in order to reduce their potential impacts. For this, countries like Brazil should strengthen its surveillance on agricultural expansion and on how this activity is developed. Furthermore, the integration of international conservation efforts should be pursued, given its benefits for biodiversity and food production. Finally, humanity must choose methods of agricultural production that reduce its impacts, including avoiding its future expansion, so as to meet the increasing needs of a human population globally. / A agricultura é a atividade humana com maior impacto sobre o ambiente. Particularmente, ela representa a maior ameaça à biodiversidade. No futuro, essa atividade deve expandir-se com o aumento populacional humano, o aumento do consumo e a produção de biocombustíveis a partir dos alimentos. Para entender os possíveis impactos dessa expansão sobre a biodiversidade, nós utilizamos cenários de mudança de uso do solo entre 2000 e 2100 do IMAGE (Integrated Model to Access Global Environment) para testar as seguintes hipóteses: (i) as áreas consideradas como prioridades globais de conservação pelas ONGs internacionais serão preferencialmente impactadas pela expansão agrícola no século XXI; (ii) há um conflito entre áreas prioritárias para a conservação de carnívoros e a expansão agrícola e esse conflito pode ser reduzido com a incorporação da informação sobre expansão agrícola no processo de priorização; (iii) a integração entre os países para o planejamento da conservação pode ser favorável à proteção da biodiversidade e à produção agrícola; (iv) no Brasil, as áreas protegidas serão impactadas pela expansão agrícola no futuro e esse impacto será diferente entre áreas de proteção integral e áreas de uso sustentável. Nós encontramos os seguintes resultados: (i) o impacto sobre as áreas prioritárias para a conservação depende dos critérios pelos quais elas foram definidas, assim, as áreas definidas por sua alta vulnerabilidade estão atualmente mais impactadas do que áreas de baixa vulnerabilidade. Ao longo do século XXI, o impacto geral da agricultura deve aumentar, mas a diferença entre os dois tipos de prioridades se mantém, exceto para as High Biodiversity Wilderness Areas, definidas por sua baixa vulnerabilidade, mas que nos cenários mais pessimistas podem ter um impacto agrícola semelhante ao das áreas de alta vulnerabilidade; (ii) há uma alta congruência espacial entre áreas com elevado uso agrícola no futuro e áreas prioritárias para a conservação de carnívoros; esse conflito pode ser reduzido se o processo de priorização incluir as informações sobre a expansão agrícola; a incorporação dessa informação, entretanto, provoca uma profunda alteração na distribuição das áreas prioritárias e reduz o número de populações de carnívoros protegidas; (iii) a integração entre os países para a criação de um conjunto de áreas prioritárias para conservação que represente 17% da superfície terrestre pode proteger 19% mais populações de mamíferos sem reduzir a produção de alimentos, se comparada a uma estratégia em que cada país busque proteger seu território independentemente; (iv) o impacto da agricultura no Brasil deve aumentar até o fim do século XXI, ameaçando inclusive as áreas protegidas e o seu entorno. Esse impacto, porém, não deve ser diferente entre as áreas de uso sustentável e aquelas de proteção integral. Assim, a expansão agrícola deve continuar a ser uma importante ameaça à biodiversidade no futuro, atingindo inclusive áreas de especial interesse para a conservação. As ações de conservação devem ser planejadas levando em consideração essa ameaça, a fim de reduzir seus impactos potenciais. Para isso, países como o Brasil devem reforçar sua vigilância sobre a expansão agrícola e a maneira como essa atividade é desenvolvida. Além disso, a integração internacional dos esforços de conservação deve ser buscada, dados seus benefícios para a biodiversidade e para a produção de alimentos. E por fim, a humanidade deve optar por formas de produção agrícola que reduzam seus impactos, inclusive evitando sua expansão futura, mas que possam satisfazer as necessidades da população humana globalmente.

Page generated in 0.147 seconds