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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.
121

A conservação de grandes mamíferos e o planejamento de uso e ocupação da terra no Estado de São Paulo/Brasil / Large mammals\' conservation and land use planning in São Paulo State/Brazil

Cíntia Camila Silva Angelieri 30 September 2015 (has links)
Os grandes carnívoros necessitam de vastos territórios para sobreviver em longo prazo, sendo que sua coexistência com humanos é fundamental, porém gera conflitos. O objetivo geral dessa tese é integrar a conservação de grandes carnívoros ao processo de planejamento de uso e ocupação da terra do estado de São Paulo. Para isso os objetivos específicos são: (1) sistematizar, espacializar e analisar a ocorrência de grandes carnívoros, estabelecendo correlações com os padrões de uso e ocupação da terra, variáveis climáticas e topográficas; (2) estabelecer áreas prioritárias para conservação de grandes carnívoros no estado de São Paulo; e (3) caracterizar os padrões de uso e conservação da terra nos municípios indicando necessidades e oportunidades para conservação (ênfase em Brotas-SP). O delineamento desse estudo foi feito buscando a aplicação de Modelos de Distribuição de Espécies - MDEs (espécies estudadas: Chrysocyon brachyurus, Leopardus Pardalis e Puma concolor) em uma abordagem de Planejamento Sistemático da Conservação - PSC. Para isso, foi aplicado o algoritmo MAXENT para as análises de distribuição das espécies e o algoritmo ZONATION para análises de priorização espacial e identificação de áreas prioritárias para conservação. Os modelos gerados mostraram alto desempenho (AUCs ≥ 0.8) e foram significantes (p ≤ 0.05) para o limite de corte mais inclusivo considerado \"minimum training presence\". Apesar da plasticidade das espécies estudadas, a variável porcentagem de vegetação nativa foi uma das três mais importantes para os modelos gerados. A distribuição das espécies abrange tanto paisagens naturais quanto paisagens antropizadas, porém as áreas com alta adequabilidade ambiental (acima de 0.5) se concentram em regiões com vegetação nativa remanescente e em sua maior parte não estão protegidas em Unidades de Conservação de Proteção Integral. Os resultados das análises de priorização espacial mostraram prioridades altas para os carnívoros concentradas na região central do estado de São Paulo, onde existem conflitos entre a demanda por áreas para conservação e a demanda por áreas para desenvolvimento humano. Recomenda-se a ampliação das UCPIs nessa região e ações de manejo e conservação em propriedades privadas (ex. Reservas Legais e Áreas de Preservação Permanente). Tanto as prioridades para conservação como as prioridades para desenvolvimento são muito diferentes entre os municípios do estado de São Paulo. Sendo assim, as estratégias precisam ser elaboradas caso a caso em escala municipal. Brotas possui localização estratégica na conservação de grandes carnívoros com alta porcentagem de áreas núcleo e alto potencial ecoturístico, sendo recomendada a expansão de UCPIs e a restauração da vegetação nativa para ampliar a proteção de grandes carnívoros. Os resultados desse estudo devem informar o processo de tomada de decisão (Ex. Planos de Ação para Conservação de Espécies Ameaçadas; Zoneamentos; Avaliações de Impactos Ambientais) e a abordagem metodológica serve como um modelo para orientar processos semelhantes que visam à conservação de espécies em outras regiões. / Large carnivores need large territories to survive in long term, requiring the use of existing protected areas and private properties with many land uses types and human occupation levels for dispersion and as additional habitat. Thus, the coexistence between large carnivores and humans is essential. However, it leads to conflicts of interest. The overall objective of this thesis is to integrate the conservation of large mammals to land use planning process in São Paulo State, Brazil. For this, the specific objectives are: (1) to systematize, to spatialize and to analyze the occurrence of large mammals, establishing correlations between large mammals distribution and land use patterns, climatic and topographic variables; (2) to establish priority areas for conservation of large mammals in São Paulo State; and (3) to characterize the land use and conservation patterns in São Paulo\'s municipalities (emphasis in Brotas-SP). The design of this study aimed to apply Species Distribution Models tools (species studied: Chrysocyon brachyurus, Leopardus Pardalis and Puma concolor) in an approach of Systematic Conservation Planning. For this, MAXENT algorithm was applied for species distribution modelling and Zonation algorithm was applied for spatial prioritization analysis and conservation priority areas identification. All models were significant (p ≤ 0.05) considering the minimum training presence threshold showing high performance (AUC ≥ 0.8). Despite the plasticity of the species, the variable percentage of native vegetation was one of the top three most important for all models. The distribution of the species covers both natural and disturbed landscapes, but high environmental suitability areas (up to 0.5) concentrate in regions with native vegetation fragments. However the most part of these areas are not protected by law. Spatial prioritization results showed high priorities for carnivores concentrate in the central region of São Paulo, where there are conflicts there are both high demand for carnivore conservation and high demand for human development. Conservation strategies need to be developed case by case because both priorities for conservation and priorities for development were showed very different between the municipalities. For example, Brotas is strategic for carnivore\'s conservation, having high percentage of core areas in its territory and high ecotourism potential. However the percent of native vegetation cover is low. Therefore, it is recommended protected areas expansion and native vegetation restoration to increase the protection of large carnivores in Brotas. This study highlights the importance of a landscape planning approach to improve the conservation outlook for large mammals, including not only the establishment and management of protected areas, but also native habitat conservation and management on private lands. Importantly, the results may inform environmental policies and land use planning in São Paulo State, Brazil (e.g. Action Plan for Conservation of Endangered Species; Zoning; Reviews of Environmental Impacts), and it serves as a useful model to guide similar process for other large-carnivore species world-wide.
122

Forecasting the Spread and Invasive Potential of Apple Snails (Pomacea spp.) in Florida

Reilly, Stephanie A 07 December 2017 (has links)
Forecasting the potential range of invasive species is a critical component for risk assessment, monitoring, and management. However, many of these invasive species are not yet at equilibrium which can be problematic for many modelling approaches. Using the climate matching method, MaxEnt, a series of species distribution models (SDMs) and risk analysis maps were created for select apple snail species in Florida: Pomacea canaliculata, P. diffusa, and P. maculata. Apple snails, freshwater gastropods in the family Ampullariidae, are native to South America and were introduced to the United States via the pet trade approximately 40 years ago. These highly invasive species have already been introduced in ten states and established in at least seven. The models and risk analysis in this study show the majority of Florida was at least moderately suitable for all apple snails modeled, with P. maculata posing the greatest threat.
123

Ensemblemodellering av piggvarens habitat utgående från provfiske- och miljödata / Ensemble modelling of the habitat of turbot based on video analyses and fish survey data

Erlandsson, Mårten January 2016 (has links)
Piggvarens (Scophthalmus maximus) val av habitat i Östersjön har modellerats utifrån provfiskedata och miljövariabler. Vid totalt 435 stationer i Östersjön har data samlats in i form av provfiske, CTD-mätningar (konduktivitet, temperatur och djup) och videofilmer. Genom att analysera videofilmerna från havsbotten i Östersjön har den klassificerats efter fyra olika förklaringsvariabler: täckningsgrad mjukbotten, strukturbildande växter, övriga alger och täckningsgrad blåmusslor. Ytterligare sex förklaringsvariabler har samlats in från mätningar och befintliga kartor: bottensalinitet, bottentemperatur, djup, siktdjup, vågexponering och bottenlutning. Dessa tio förklaringsvariabler har använts i tio olika enskilda statistiska modelleringsmetoder med förekomst/icke-förekomst av piggvar som responsvariabel. Nio av tio modeller visade på bra resultat (AUC > 0,7) där CTA (Classification Tree Analysis) och GBM (Global Boosting Model) hade bäst resultat (AUC > 0,9). Genom att kombinera modeller med bra resultat på olika sätt skapades sex ensemblemodeller för att minska varje enskild modells svagheter. Ensemblemodellerna visade tydligt fördelarna med denna typ av modellering då de gav ett mycket bra resultat (AUC > 0,949). Den sämsta ensemblemodellen var markant bättre än den bästa enskilda modellen. Resultaten från modellerna visar att största sannolikheten för piggvarsförekomst i Östersjön är vid grunt (< 20 meter) och varmt (> 10 oC) vatten med hög vågexponering (> 30 000 m²/s). Dessa tre variabler var de med högst betydelse för modellerna. Täckningsgrad mjukbotten och de två växtlighetsvariablerna från videoanalyserna var de tre variabler som hade lägst påverkan på piggvarens val av habitat. Med en högre kvalitet på videofilmerna hade de variablerna kunnat klassificeras i mer specifika grupper vilket eventuellt gett ett annat resultat. Generellt visade modellerna att denna typ av habitatmodellering med provfiske och miljödata både är möjlig att utföra. / The turbots’ (Scophthalmus maximus) selection of habitat in the Baltic Sea has been modeled on the basis of fish survey data and environmental variables. At a total of 435 stations in the Baltic Sea, data was collected in the form of fish survey data, CTD (Conductivity, Temperature and Depth) measurements and videos. By analyzing the videos from the seabed of the Baltic Sea, four different explanatory variables have been classified: coverage of soft bottom, structure-forming plants, other algae and coverage of mussels. Another six explanatory variables have been collected from measurements and existing rasters: salinity, temperature, depth, water transparency, wave exposure and the bottom slope. These ten explanatory variables have been used in ten different species distribution modeling methods with the presence/absence of turbot as a response variable. Nine out of ten models showed good results (AUC > 0.7) where the CTA (Classification Tree Analysis) and GBM (Global Boosting Model) performed the best (AUC > 0.9). By combining the models with good performance in six different ensemble models each individual models’ weaknesses were decreased. The ensemble models clearly showed strength as they gave a very good performance (AUC > 0.94). The worst ensemble model was significantly better than the best individual model. The results of the models show that the largest probability of occurrence of turbot in the Baltic Sea is in shallow (< 20 m) and warm (> 10 ° C) water with high wave exposure (> 30,000 m²/s). These three variables were those with the highest significance for the models. Coverage of soft bottom and the two vegetation variables, from the video analyzes, had the lowest impact on the turbots’ choice of habitat. A higher quality of the videos would have made it possible to classify these variables in more specific groups which might have given a different result. Generally, the models showed that this type of modeling of habitat is possible to perform with fish survey and environmental monitoring data and generates useful results.
124

Ecological analysis of large floristic and plant-sociological datasets – opportunities and limitations

Goedecke, Florian 04 May 2018 (has links)
No description available.
125

Ecological knowledge towards sustainable forest management:habitat requirements of the Siberian flying squirrel in Finland

Hurme, E. (Eija) 18 November 2008 (has links)
Abstract Maintaining biodiversity in boreal forest landscapes in conjunction with forestry is a challenging task. This requires ecological understanding that is based on empirical research. In this thesis, I examined spatial and temporal occupancy patterns as well as predictability of the occurrence of the Siberian flying squirrel (Pteromys volans L.) in Finland. I used thematic maps which matched habitat requirements of the flying squirrel in forested landscapes and data on species presence and absence, which were gathered in suitable forest habitats. The results of this thesis provide applications for landscape management. First, the preferred habitat characteristics of the flying squirrel were linked to available forest data. In addition, some predictive habitat models could be used to estimate the distribution of the flying squirrel within a region. Second, based on a five year study the forests were classified as continuously occupied, continuously unoccupied and variable-occupancy patches. The dynamic occupancy pattern emphasizes the need for repeated surveys to also locate the seldom-used suitable habitats in a landscape. Third, a comparison of simulated future scenarios in long-term forest planning suggested that flying squirrel habitat might be maintained without considerable loss of timber in a landscape. Thus, a combination of ecological and economic goals in forestry planning is an encouraging alternative. Fourth, there were more polypore species in forests occupied by the flying squirrel. This suggests that conservation of the flying squirrel habitats would protect other naturally co-occurring species, and thus the flying squirrel could be assigned as an umbrella species in mature spruce-dominated forests. Based on these findings, I suggest that the flying squirrel could be used as one of the target species for forest management in boreal forest landscapes. Further research challenges are related to the examination of habitat thresholds and to the projection of future scenarios where ecological, economic and social aspects are combined to assist in complex decision making processes.
126

Gammaridean Amphipods as Bioindicators in Subtropical Seagrass Ecosystems

Sweatman, Jennifer L 28 June 2016 (has links)
Anthropogenic disturbances are ubiquitous in coastal marine ecosystems. As such, more intensive monitoring efforts are necessary to conserve these valuable habitats. Bioindicators, organisms that predictably respond to changes in environmental variables, may be utilized in monitoring efforts to assess ecosystem functioning. To incorporate organisms into monitoring programs as bioindicators managers need to first understand the difference between the natural phenology of the focal organisms and their responses to different forms of anthropogenic disturbance. To determine if gammaridean amphipods could be used as indicators of changes in environmental quality in sub-tropical seagrass ecosystems, I conducted spatial and temporal surveys of amphipod communities in south Florida. Amphipod community structure varied significantly across sites and seasons. Variation in community structure was largely driven by macrophyte biomass, food availability, seasonally variable factors (epiphyte abundance, dissolved oxygen, salinity, and temperature), water-column nitrogen concentration, and factors related to freshwater input, including low Thalassia testudinum and high Halodule wrightii densities, and salinity. Amphipods are also susceptible to mechanical damage in seagrass habitats and could be used as indicators of ecological functioning of a region. A major source of mechanical damage in seagrass ecosystems is caused by boat propellers. I simulated propeller scars in continuous seagrass beds to investigate the effects of scarring on seagrass ecosystem functioning. Seagrasses located adjacent to propeller scars experienced a shift in the limiting resource from light to phosphorus. Amphipod community structure, however, was not impacted by scarring, but amphipod density was reduced in fragmented patches. To determine if plant-herbivore interactions were impacted by propeller scarring, we removed amphipods from half of the experimental plots and measured epiphyte biomass and community composition. Top-down control on epiphyte biomass or community composition by amphipods was not affected by fragmentation, despite reduced amphipod densities. My dissertation research demonstrates that amphipods could be incorporated into existing management programs in sub-tropical seagrass ecosystems as environmental indicators. Reduced amphipod densities in fragmented seagrass beds suggests that amphipods could also be used as ecological indicators, but more research is needed to determine the extent of the impacts of fragmentation on higher trophic levels.
127

Habitat Suitability Modeling for the Eastern Hog-nosed Snake, 'Heterodon platirhinos', in Ontario

Thomasson, Victor January 2012 (has links)
With exploding human populations and landscapes that are changing, an increasing number of wildlife species are brought to the brink of extinction. In Canada, the eastern hog-nosed snake, 'Heterodon platirhinos', is found in a limited portion of southern Ontario. Designated as threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), this reptile has been losing its habitat at an alarming rate. Due to the increase in development of southern Ontario, it is crucial to document what limits the snake’s habitat to direct conservation efforts better, for the long-term survival of this species. The goals of this study are: 1) to examine what environmental parameters are linked to the presence of the species at a landscape scale; 2) to predict where the snakes can be found in Ontario through GIS-based habitat suitability models (HSMs); and 3) to assess the role of biotic interactions in HSMs. Three models with high predictive power were employed: Maxent, Boosted Regression Trees (BRTs), and the Genetic Algorithm for Rule-set Production (GARP). Habitat suitability maps were constructed for the eastern hog-nosed snake for its entire Canadian distribution and models were validated with both threshold dependent and independent metrics. Maxent and BRT performed better than GARP and all models predict fewer areas of high suitability when landscape variables are used with current occurrences. Forest density and maximum temperature during the active season were the two variables that contributed the most to models predicting the current distribution of the species. Biotic variables increased the performance of models not by representing a limiting resource, but by representing the inequality of sampling and areas where forest remains. Although habitat suitability models rely on many assumptions, they remain useful in the fields of conservation and landscape management. In addition to help identify critical habitat, HSMs may be used as a tool to better manage land to allow for the survival of species at risk.
128

The ecology and conservation of Juliana’s golden mole (Neamblysomus julianae)

Jackson, Craig Ryan 28 July 2008 (has links)
Despite an IUCN conservation status of critically endangered, Juliana’s golden mole (Neamblysomus julianae) has received no ecological research attention to date. The species urgently requires conservation attention, but a poor understanding its biology, ecology and distribution makes effective conservation planning almost impossible. In light of this, a thorough understanding of the habitat requirements for this habitat specific species was needed. Additionally, the cryptic lifestyle of Juliana’s golden mole has resulted in very few distribution records for the species. Little was known about the animals’ daily and seasonal activity patterns or movement patterns. This study revealed that Juliana’s golden mole is range restricted on account of sandy soils that have a uniform particle size distribution. This feature limits substrate compaction, making tunnelling far easier for these small mammals. In comparison to uninhabited areas, occupied habitat had greater vegetation cover provided by trees and shrubs, and this would be expected to provide a cooler and moister microenvironment. The ecological parameters associated with the species presence were then used, in addition to existing GIS data, to predict regions of potentially suitable habitat. This process revealed large potentially inhabitable areas in the northern parts of South Africa. Preliminary ground-truthing has shown the model to be relatively accurate with three potentially new populations having been identified. Contrary to what has been reported in the literature, Juliana’s golden mole does not appear to be strictly nocturnal. Instead, an adaptive pattern of activity was observed, governed by soil temperature. Body temperature was found to fluctuate to some degree with that of the soil temperature, but fluctuations were regulated by behavioural thermoregulation. Seasonal activity is highly correlated with rainfall. Rain moistens the soil making it significantly softer and far easier to tunnel through. Using this and other information acquired through the course of the study, the thesis culminates with an evaluation of conservation concerns and proposed conservation management actions. Copyright / Dissertation (MSc)--University of Pretoria, 2009. / Zoology and Entomology / unrestricted
129

Predicting Glass Sponge (Porifera, Hexactinellida) Distributions in the North Pacific Ocean and Spatially Quantifying Model Uncertainty

Davidson, Fiona 07 January 2020 (has links)
Predictions of species’ ranges from distribution modeling are often used to inform marine management and conservation efforts, but few studies justify the model selected or quantify the uncertainty of the model predictions in a spatial manner. This thesis employs a multi-model, multi-area SDM analysis to develop a higher certainty in the predictions where similarities exist across models and areas. Partial dependence plots and variable importance rankings were shown to be useful in producing further certainty in the results. The modeling indicated that glass sponges (Hexactinellida) are most likely to exist within the North Pacific Ocean where alkalinity is greater than 2.2 μmol l-1 and dissolved oxygen is lower than 2 ml l-1. Silicate was also found to be an important environmental predictor. All areas, except Hecate Strait, indicated that high glass sponge probability of presence coincided with silicate values of 150 μmol l-1 and over, although lower values in Hecate Strait confirmed that sponges can exist in areas with silicate values of as low as 40 μmol l-1. Three methods of showing spatial uncertainty of model predictions were presented: the standard error (SE) of a binomial GLM, the standard deviation of predictions made from 200 bootstrapped GLM models, and the standard deviation of eight commonly used SDM algorithms. Certain areas with few input data points or extreme ranges of predictor variables were highlighted by these methods as having high uncertainty. Such areas should be treated cautiously regardless of the overall accuracy of the model as indicated by accuracy metrics (AUC, TSS), and such areas could be targeted for future data collection. The uncertainty metrics produced by the multi-model SE varied from the GLM SE and the bootstrapped GLM. The uncertainty was lowest where models predicted low probability of presence and highest where the models predicted high probability of presence and these predictions differed slightly, indicating high confidence in where the models predicted the sponges would not exist.
130

Ecological suitability modelling for anthrax in the Kruger National Park, South Africa

Steenkamp, Pieter Johannes 15 January 2013 (has links)
Bacillus anthracis is the causal agent of anthrax which primarily affects ungulates, occasionally carnivores and less frequently humans. The endospores of this soil-borne bacterium are highly resistant to extreme conditions, and under ideal conditions, anthrax spores can survive for many years in the soil. The bacterium is generally found in soil at sites where infected animals have died. When these spores are exposed, they have the potential to be ingested by a mammalian species which could lead to an anthrax outbreak. Anthrax is almost never transmitted directly from host to host, but is rather ingested by herbivores while drinking, grazing or browsing in a contaminated environment, with the exception of scavengers and carnivores consuming infected prey. Anthrax is known to be endemic in the northern part of Kruger National Park (KNP) in South Africa (SA), with occasional epidemics spreading southward into the non-endemic areas. The aim of this study is to identify and map areas that are ecologically suitable for the harbouring of B. anthracis spores within the KNP. Anthrax surveillance data and selected environmental variables were used as inputs to the maximum entropy (Maxent) species distribution modelling method. Five-hundred and ninety-seven anthrax occurrence records, dating from the year 1988 to 2011, were extracted from the Skukuza State Veterinary Office’s database. A total of 40 environmental variables were used and their relative contribution to predicting suitability for anthrax occurrence was evaluated using Maxent software (version 3.3.3k). Variables showing the highest gain were then used for subsequent, refined model iterations until the final model parameters were established. The environmental variables that contributed the most to the occurrence of anthrax were soil type, normalized difference vegetation index (NDVI), land type and precipitation. A map was created using a geographic information system (GIS) that illustrates the sites where anthrax spores are most likely to occur throughout the Park. This included the known endemic Pafuri region as well as the low lying soils along the Shingwedzi-Phugwane-Bubube rivers and the Letaba-Olifants river drainage area. The outputs of this study could guide future targeted surveillance efforts to focus on areas predicted to be highly suitable for anthrax, especially since the KNP uses passive surveillance to detect anthrax outbreaks. Knowing where to look can improve sampling efficiency and lead to increased understanding of the ecology of anthrax within the KNP. / Dissertation (MMedVet)--University of Pretoria, 2013. / Production Animal Studies / unrestricted

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