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  • 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

Biological and Biochemical Transformation of Nutrients in Agricultural Soils of Yucatan, Mexico / Biologische und Biochemische Transformation der Nährstoffe in landwirtschaftlich genutzten Böden in Yukatan, Mexiko

Campos González, Adriana José 31 January 2008 (has links)
No description available.
2

Application of geographic Information system and remote sensing in multiple criteria analysis to identify priority areas for biodiversity conservation in Vietnam

Vu, Xuan Dinh 11 February 2021 (has links)
There has been an increasing need for methods to define priority areas for biodiversity conservation since the effectiveness of biodiversity conservation in protected areas planning depends on available resources (human resources and funds) for the conservation. The identification of priority areas requires the integration of biodiversity data together with social data on human pressures and responses. However, the deficit of comprehensive data and reliable methods are key challenges in zoning where the demand for conservation is most urgent and where the outcomes of conservation strategies can be maximized. In order to fill this gap, the environmental model Pressure–State–Response (PSR) was applied to suggest a set of criteria to identify priority areas for biodiversity conservation. The empirical data have been compiled from 185 respondents, categorizing into three main groups: Governmental Administration, Research Institutions, and Protected Areas in Vietnam, by using a well-designed questionnaire. Then, the Analytic Hierarchy Process (AHP) theory was used to identify the weight of all criteria. These results show that three main factors could identify the priority level for biodiversity conservation: Pressure, State, and Response, with weights of 41%, 26%, and 33%, respectively. Based on the three factors, seven criteria and 17 sub-criteria were developed to determine priority areas for biodiversity conservation. In addition, this study also indicates that the groups of Governmental Administration and Protected Areas put a focus on the “Pressure” factor while the group of Research Institutions emphasized the importance of the “Response” factor in the evaluation process. Then these suggested criteria were applied by integrating with Geographic Information System (GIS) and Remote Sensing (RS) to define priority areas for biodiversity conservation in a particular conservation area (Pu Luong-Cuc Phuong area) in Vietnam. The results also reveal the proportion of very high and high priority areas, accounting for 84.9%, 96%, and 65.9% for Cuc Phuong National Park, Pu Luong Nature Reserve, and Ngoc Son Ngo Luong Nature Reserve, respectively. Based on these results, recommendations were provided to apply the developed criteria for identifying priority areas for biodiversity conservation in Vietnam.:Acknowledgement I Abstract III Table of contents IV List of figures VI List of tables X Acronyms and Abbreviations XII Chapter 1. Introduction 1 1.1. Problem statement and motivation 1 1.2. Research objectives and questions 2 1.3. Study contribution 3 1.4. Thesis structure 6 Chapter 2. Literature review 8 2.1. Background information on Vietnam 8 2.2. Environmental Pressure-State-Response model 11 2.3. Defining criteria for biodiversity conservation 13 2.4. Application of GIS and RS for biodiversity conservation 16 Chapter 3. Research methodology 19 3.1. Study areas 19 3.2. Data collection 23 3.3. Analytic Hierarchy Process 25 3.4. Remote Sensing 27 3.5. Geography Information System 35 3.6. Climate change scenarios 40 Chapter 4. Establishment of criteria 42 4.1. Summary of responses 44 4.2. Statistic of pairwise comparison 46 4.3. Weights of criteria based on all respondents 48 4.4. Weights of criteria based on groups 60 Chapter 5. Application of Criteria 64 5.1. Mapping criteria 64 5.2. Synthesis of multiple criteria 144 Chapter 6. Conclusions and recommendations 158 6.1. Establishment of criteria 158 6.2. Application of criteria 161 6.3. Recommendations 165 References 167 Appendix I. Questionnaire 197 Appendix II. Establishment of criteria 207 Appendix III. Application of criteria 234
3

Response of endangered bird species to land‑use changes in an agricultural landscape in Germany

Jungandreas, Anne, Roilo, Stephanie, Strauch, Michael, Václavík, Tomáš, Volk, Martin, Cord, Anna F. 02 February 2024 (has links)
Land-use intensification in agroecosystems has led to population declines in many taxonomic groups, especially farmland birds. Two contrasting conservation strategies have therefore been proposed: land sharing (the integration of biodiversity conservation in low-intensity agriculture) and land sparing (the spatial separation of high-yielding agriculture and areas for conservation). Despite the large academic interest in this field, only few studies have taken into account stakeholders’ perspectives of these strategies when assessing conservation implications. We modeled the effects of three land-use scenarios (a business-as-usual, a land-sharing, and a land-sparing scenario), developed together with regional stakeholders, on the habitat area of 13 regionally endangered bird species in the Middle Mulde River Basin (Saxony, Germany). We used random forest models based on environmental variables relating to land-use/cover, climate and soil characteristics, occurrence of linear landscape elements (hedges and tree rows), and distance to water and major roads. Responses to the three land-use scenarios were species-specific, but extensively managed permanent grassland and the density of forest edges were positively associated with the occurrence of most bird species. Overall, the land-sharing scenario provided the largest breeding habitat area: 76% of the species had a significant (p < 0.05) increase in breeding habitat, and none showed a significant decrease. Our findings confirm that balancing the different, often contrasting habitat requirements of multiple species is a key challenge in conservation and landscape management. Land sharing, which local stakeholders identified as the most desirable scenario, is a promising strategy for the conservation of endangered birds in agricultural landscapes like our study region.
4

Understanding geographies of threat: Impacts of habitat destruction and hunting on large mammals in the Chaco

Romero-Muñoz, Alfredo 23 September 2021 (has links)
Die Hauptursachen für die derzeitige weltweite Krise der biologischen Vielfalt sind Lebensraumzerstörung und Übernutzung. Wir wissen jedoch nicht, wie sich diese beiden Faktoren einzeln und zusammen auf die verschiedenen Aspekte biologischer Vielfalt auswirken und wie sie sich im Laufe der Zeit verändern. Da beide Bedrohungen weit verbreitet sind, verhindern dies die Entwicklung wirksamer Schutzstrategien. Das übergeordnete Ziel dieser Arbeit war räumliche und zeitliche Veränderungsmuster der Auswirkungen von Lebensraumzerstörung und Übernutzung auf die biologische Vielfalt zu verstehen. Ich habe diese Bedrohungsgeographien mit hoher räumlicher Auflösung und über drei Jahrzehnte hinweg für verschiedene Aspekte biologischer Vielfalt untersucht: Arten, Lebensgemeinschaften und taxonomische, phylogenetische und funktionale Facetten biologischer Vielfalt. Ich konzentrierte mich auf den 1,1 Millionen km² großen Gran Chaco, den größten tropischen Trockenwald der Welt und einen globalen Entwaldungs-Hotspot. Meine Ergebnisse zeigen, dass sich im Laufe von 30 Jahren die räumlichen Auswirkungen der einzelnen Bedrohungen auf größere Gebiete ausdehnten als nur auf die abgeholzte Fläche. Dies führte zu einem Verlust an hochwertigen und sicheren Gebieten für den Jaguar, die gesamte Großsäugergemeinschaft und alle Facetten der Säugetiervielfalt. Beide Bedrohungen trugen wesentlich zum Rückgang biologischer Vielfalt bei, ihre relative Bedeutung variierte jedoch je nach Art und Facette der biologischen Vielfalt. Zudem haben die Gebiete, in denen beide Bedrohungen zusammenwirken, im Laufe der Zeit zugenommen, was den Verlust der biologischen Vielfalt wahrscheinlich noch verschlimmert hat. Diese Arbeit unterstreicht, wie wichtig es ist, die Auswirkungen mehrerer Bedrohungen im Laufe der Zeit gemeinsam zu bewerten, um den menschlichen Einfluss auf die biologische Vielfalt besser verstehen zu können und wirksame Schutzstrategien zu finden. / The main drivers of the current global biodiversity crisis are habitat destruction and overexploitation. Yet, we lack understanding of their individual and combined spatial impact on different aspects of biodiversity, and how they change over time. Because both threats are common, these knowledge gaps preclude building more effective conservation strategies. The overarching goal of this thesis was to understand how the impacts of habitat destruction and overexploitation on biodiversity change in space and over time. I assessed these geographies of threat at high spatial resolutions and over three decades for different biodiversity aspects: species, communities, and the taxonomic, phylogenetic, and functional facets of biodiversity. I focused on the 1.1 million km² Gran Chaco, the largest tropical dry forest globally, and a global deforestation hotspot. Results reveal that over 30 years, the spatial impacts of each threat expanded over larger areas than the area deforested. This resulted in widespread losses of high-quality and safe areas for the jaguar, the entire larger mammal community and for all facets of the mammalian diversity. Such declines suggest a generalized biotic impoverishment that includes the loss of species, evolutionary history, and ecological functions across much of the Chaco. Both threats contributed substantially to biodiversity declines, and their relative importance varied among species and biodiversity facets. Moreover, the areas where both threats synergize increased over time, likely exacerbating biodiversity losses. For each biodiversity aspect, I identified priority areas of safe and high-quality habitats, and hotspots of high threat impacts, which could guide more effective complementary proactive and reactive conservation strategies. This thesis highlights the importance of jointly assessing the impact of multiple threats over time to better understand the impact of humans on biodiversity and to identify effective ways to mitigate them. / Los principales factores de la actual crisis de la biodiversidad global son la destrucción del hábitat y la sobreexplotación. Sin embargo, desconocemos su impacto espacial, tanto individual como combinado, sobre los diferentes aspectos de la biodiversidad, y cómo cambian en el tiempo. Como ambas amenazas son comunes, estos vacíos de conocimiento impiden elaborar estrategias de conservación más eficaces. El objetivo general de esta tesis fue comprender cómo los impactos de la destrucción del hábitat y la sobreexplotación en la biodiversidad cambian en el espacio y en el tiempo. Evalué estas geografías de las amenazas a altas resoluciones espaciales y a lo largo de tres décadas para diferentes aspectos de la biodiversidad: especies, comunidades y las facetas taxonómica, filogenética y funcional de la biodiversidad. Me centré en el Gran Chaco, de 1,1 millones de km², el mayor bosque seco tropical del mundo y un foco global de deforestación. Los resultados revelan que, a lo largo de 30 años, los impactos espaciales de cada una de las amenazas se extendieron por areas mayores que la superficie deforestada. Esto dio lugar a pérdidas extendidas de áreas seguras y de alta calidad para el jaguar, la comunidad de mamíferos grandes y para todas las facetas de la diversidad de mamíferos. Estos declives sugieren un empobrecimiento biótico generalizado que incluye la pérdida de especies, historia evolutiva y funciones ecológicas en gran parte del Chaco. Ambas amenazas contribuyeron sustancialmente al declive de la biodiversidad, y su importancia relativa varió entre especies y facetas de la biodiversidad. Además, las áreas en las que ambas amenazas sinergizan aumentaron en el tiempo, probablemente exacerbando las pérdidas de biodiversidad. Para cada aspecto de la biodiversidad, identifiqué áreas prioritarias de hábitats seguros y de alta calidad, y focos de alto impacto de las amenazas, que podrían orientar estrategias de conservación complementarias más eficaces, tanto proactivas como reactivas. Esta tesis destaca la importancia de evaluar conjuntamente el impacto de múltiples amenazas a lo largo del tiempo para comprender mejor el impacto de los humanos en la biodiversidad e identificar vías eficaces para mitigarlas.
5

Landscape-level heterogeneity of agri-environment measures improves habitat suitability for farmland birds

Roilo, Stephanie, Engler, Jan O., Václavík, Tomáš, Cord, Anna F. 21 May 2024 (has links)
Agri-environment schemes (AESs), ecological focus areas (EFAs), and organic farming are the main tools of the common agricultural policy (CAP) to counteract the dramatic decline of farmland biodiversity in Europe. However, their effectiveness is repeatedly doubted because it seems to vary when measured at the field-versus-landscape level and to depend on the regional environmental and land-use context. Understanding the heterogeneity of their effectiveness is thus crucial to developing management recommendations that maximize their efficacy. Using ensemble species distribution models and spatially explicit field-level information on crops grown, farming practice (organic/conventional), and applied AES/EFA from the Integrated Administration and Control System, we investigated the contributions of five groups of measures (buffer areas, cover crops, extensive grassland management, fallow land, and organic farming) to habitat suitability for 15 farmland bird species in the Mulde River Basin, Germany. We used a multiscale approach to identify the scale of effect of the selected measures. Using simulated land-use scenarios, we further examined how breeding habitat suitability would change if the measures were completely removed and if their adoption by farmers increased to meet conservation-informed targets. Buffer areas, fallow land, and extensive grassland were beneficial measures for most species, but cover crops and organic farming had contrasting effects across species. While different measures acted at different spatial scales, our results highlight the importance of land-use management at the landscape level—at which most measures had the strongest effect. We found that the current level of adoption of the measures delivers only modest gains in breeding habitat suitability. However, habitat suitability improved for the majority of species when the implementation of the measures was increased, suggesting that they could be effective conservation tools if higher adoption levels were reached. The heterogeneity of responses across species and spatial scales indicated that a mix of different measures, applied widely across the agricultural landscape, would likely maximize the benefits for biodiversity. This can only be achieved if the measures in the future CAP will be cooperatively designed in a regionally targeted way to improve their attractiveness for farmers and widen their uptake.

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