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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.
151

Landscape Transformation of Cyprus from 1970 through 2070

January 2013 (has links)
abstract: This dissertation investigates spatial and temporal changes in land cover and plant species distributions on Cyprus in the past, present and future (1973-2070). Landsat image analysis supports inference of land cover changes following the political division of the island of Cyprus in 1974. Urban growth in Nicosia, Larnaka and Limasol, as well as increased development along the southern coastline, is clearly evident between 1973 and 2011. Forests of the Troodos and Kyrenia Ranges remain relatively stable, with transitions occurring most frequently between agricultural land covers and shrub/herbaceous land covers. Vegetation models were constructed for twenty-two plant species of Cyprus using Maxent to predict potentially suitable areas of occurrence. Modern vegetation models were constructed from presence-only data collected by field surveys conducted between 2008 and 2011. These models provide a baseline for the assessment of potential species distributions under two climate change scenarios (A1b and A2) for the years 2030, 2050, and 2070. Climate change in Cyprus is likely to influence habitat availability, particularly for high elevation species as the relatively low elevation mountain ranges and small latitudinal range prevent species from shifting to areas of suitable environmental conditions. The loss of suitable habitat for some species may allow the introduction of non-native plant species or the expansion of generalists currently excluded from these areas. Results from future projections indicate the loss of suitable areas for most species by the year 2030 under both climate regimes and all four endemic species (Cedrus brevifolia, Helianthemum obtusifolium, Pterocephalus multiflorus, and Quercus alnifolia) are predicted to lose all suitable environments as soon as 2030. As striking exceptions Prunus dulcis (almond), Ficus carica (fig), Punica granatum (pomegranate) and Olea europaea (olive), which occur as both wild varieties and orchard cultigens, will expand under both scenarios. Land cover and species distribution maps are evaluated in concert to create a more detailed interpretation of the Cypriot landscape and to discuss the potential implications of climate change for land cover and plant species distributions. / Dissertation/Thesis / Ph.D. Geography 2013
152

Natural Desert and Human Controlled Landscapes: Remote Sensing of LULC Response to Drought

January 2014 (has links)
abstract: Droughts are a common phenomenon of the arid South-west USA climate. Despite water limitations, the region has been substantially transformed by agriculture and urbanization. The water requirements to support these human activities along with the projected increase in droughts intensity and frequency challenge long term sustainability and water security, thus the need to spatially and temporally characterize land use/land cover response to drought and quantify water consumption is crucial. This dissertation evaluates changes in `undisturbed' desert vegetation in response to water availability to characterize climate-driven variability. A new model coupling phenology and spectral unmixing was applied to Landsat time series (1987-2010) in order to derive fractional cover (FC) maps of annuals, perennials, and evergreen vegetation. Results show that annuals FC is controlled by short term water availability and antecedent soil moisture. Perennials FC follow wet-dry multi-year regime shifts, while evergreen is completely decoupled from short term changes in water availability. Trend analysis suggests that different processes operate at the local scale. Regionally, evergreen cover increased while perennials and annuals cover decreased. Subsequently, urban land cover was compared with its surrounding desert. A distinct signal of rain use efficiency and aridity index was documented from remote sensing and a soil-water-balance model. It was estimated that a total of 295 mm of water input is needed to sustain current greenness. Finally, an energy balance model was developed to spatio-temporally estimate evapotranspiration (ET) as a proxy for water consumption, and evaluate land use/land cover types in response to drought. Agricultural fields show an average ET of 9.3 mm/day with no significant difference between drought and wet conditions, implying similar level of water usage regardless of climatic conditions. Xeric neighborhoods show significant variability between dry and wet conditions, while mesic neighborhoods retain high ET of 400-500 mm during drought due to irrigation. Considering the potentially limited water availability, land use/land cover changes due to population increases, and the threat of a warming and drying climate, maintaining large water-consuming, irrigated landscapes challenges sustainable practices of water conservation and the need to provide amenities of this desert area for enhancing quality of life. / Dissertation/Thesis / Ph.D. Geography 2014
153

As unidades de conservação no cerrado frente ao processo de conversão / The conservation units in cerrado facing the conversion process

Santos, Sara Alves dos 27 April 2018 (has links)
Submitted by Liliane Ferreira (ljuvencia30@gmail.com) on 2018-05-23T12:15:12Z No. of bitstreams: 2 Dissertação - Sara Alves dos Santos - 2018.pdf: 7361072 bytes, checksum: c8222e95975a740e21f7c7a748bff29b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-05-23T12:27:32Z (GMT) No. of bitstreams: 2 Dissertação - Sara Alves dos Santos - 2018.pdf: 7361072 bytes, checksum: c8222e95975a740e21f7c7a748bff29b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-05-23T12:27:32Z (GMT). No. of bitstreams: 2 Dissertação - Sara Alves dos Santos - 2018.pdf: 7361072 bytes, checksum: c8222e95975a740e21f7c7a748bff29b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-04-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The Brazilian Savannah (Cerrado) is the second Brazilian Biome in area of conservation units (CU), a protection strategy to face the intense conversion to land use. These units are benefited by national environment policies that have been promulgated in the last few decades. However, many of these CU do not receive suitable effort to enhance their effectiveness. At the same time, the pressure of land use conversion in their surroundings also affects their effectiveness. This research proposes evaluates the relationship of spatial structure and spatial distribution of Federal and State Conservation Units in the Brazilian Savannah to the conversion of changes in land use that occurred over the last five decades. As a main result a thematic mapping of time-space distribution of CU is proposed. To archive this objective, a quantitative analysis of temporal and spatial distribution of UC is carried out as well as the evaluation of the representativeness of each phytophysiognomy in the CU facing the land use conversion. The database applied were obtained from government agencies. The Results revealed that considerable part of the protected areas are located in places inappropriate for agribusiness, while so-called areas more "enjoyable" have already been converted. The distribution of UC in the Cerrado is not regular, some focus on certain areas, while in others there are big gaps. In General, the largest UC are located at least anthropic of Cerrado and have recent creation, from the Decade of 1980. The East portion, are older, are in better fitness, agricultural area larger and present significant conflict of use in your interior. Ten main UC-compartments are identified in the Cerrado, proving that time and space are important variables to understand the role played by conservation policies in the Brazilian Savannah. Protected areas constitute an alternative for conservation, however you must think your location and connection, so that they can ensure the maintenance of ecosystems and are in fact effective. / O Cerrado é o segundo bioma brasileiro em área de unidades de conservação (UC). A condição de conservação é estratégia de proteção para enfrentar a intensa conversão do uso da terra. Essas unidades são beneficiadas pelas políticas ambientais nacionais que foram promulgadas nas últimas décadas, no entanto, muitas dessas UC não recebem um esforço adequado para aumentar sua eficiência. Ao mesmo tempo, a pressão da conversão do uso da terra em seu entorno também afeta sua eficiência. A presente pesquisa propõe-se a avaliar a relação entre a estrutura e a distribuição espacial das unidades de conservação do Cerrado com as mudanças no uso da terra ocorridas nas últimas cinco décadas. Para atingir esse objetivo, fez-se uma análise quantitativa da distribuição temporal e espacial das UC, levando-se em conta aspectos físicos da paisagem, bem como a avaliação da representatividade de cada fitofisionomia nas UC frente à conversão do uso da terra. A base de dados utilizada foi obtida de diversas agências governamentais. Os resultados revelaram que parte considerável das áreas protegidas localiza-se em locais inadequados para o agronegócio, enquanto as chamadas áreas mais "agradáveis" já foram convertidas. A distribuição da UC no Cerrado não é regular, algumas se concentram em certas áreas, enquanto em outras há grandes lacunas. Em geral, as maiores UC estão situadas em porções menos antropizados do Cerrado e têm criação recente, a partir da década de 1980. As da porção leste, são mais antigas, apresentam melhor aptidão, área agrícola maior e apresentam significativo conflito de uso em seu interior. Dez principais compartimentos de UC foram identificados no Cerrado, provando que o tempo e o espaço são variáveis importantes para entender o papel desempenhado pelas políticas de conservação no Cerrado brasileiro. As áreas protegidas constituem uma alternativa para conservação, porém deve-se pensar sua localização e conexão, para que possam garantir a manutenção dos ecossistemas e sejam de fato eficazes.
154

Mapeamento da cobertura do solo ao longo da faixa de domínio de trem metropolitano: Linha F em São Paulo. / Land cover mapping of the metropolitan railway right of way: Line F in São Paulo.

Alessandra Mariane Knopik Beltrame 12 August 2008 (has links)
O transporte ferroviário de passageiros ganha importância estratégica na melhoria do trânsito e qualidade de vida dos grandes centros urbanos, mas no Brasil enfrenta sérios problemas operacionais, como obsolescência da infra-estrutura e invasão da faixa de domínio, comprometendo sua segurança e operacionalidade. O objetivo central deste trabalho é o mapeamento da cobertura do solo ao longo da faixa de domínio de uma linha de trem metropolitano. A área de estudo concentra-se nas adjacências da Linha F de trem metropolitano de São Paulo, operada pela CPTM Companhia Paulista de Trens Metropolitanos, com 38,8 km de extensão, cruzando as zonas central e leste da capital paulista, estendendo-se até outros municípios da Grande São Paulo. A metodologia adotada compreende o uso de imagem de satélite de alta resolução espacial IKONOS II, e técnica de classificação baseada em regiões. Os classificadores por regiões utilizam, além de informação espectral de cada pixel, a informação espacial que envolve a relação entre os pixels e seus vizinhos. Através da interpretação visual, foram identificadas doze classes de coberturas do solo, cujas feições nortearam os parâmetros da segmentação. A imagem segmentada foi então classificada usando o algoritmo de Bhattacharyya e pós-classificada utilizando regras e critérios definidos para cada classe, de acordo com seus atributos e contextualização. O desempenho da classificação final foi avaliado com base no coeficiente Kappa tendo atingido nível aceitável de correspondência. O mapa de cobertura do solo gerado a partir da classificação, demonstra que o entorno da linha é composto, predominantemente, por materiais impermeáveis como asfalto e concreto mas possui presença significativa de elementos naturais como vegetação e água. Desta forma, comprova-se a aplicabilidade de imagem de satélite de alta resolução e técnicas de processamento de imagem como suportes ao planejamento e gerenciamento do entorno da ferrovia. / The rail transport of passengers has strategic importance in the traffic and quality of life improvement in the downtowns, but in Brazil it faces serious operational problems such as obsolete infrastructure and invasion of the right of way, compromising its safety and operability. The principal aim of this paper is the mapping of land cover area of metropolitan railway right of way. The study focuses on the outskirts of the Line F metropolitan train in Sao Paulo, operated by CPTM - Companhia Paulista de Trens Metropolitanos, with 38,8 km long, crossing the central and eastern areas of São Paulo, extending to other cities in the Metropolitan Region of Sao Paulo. The methodology includes the use of the high spatial resolution satellite image - IKONOS II, and regions-based classification. The regions-based classifiers use, besides spectral information of each pixel, the spatial information that involves the relationship between the pixels and its neighbours. Through visual interpretation, were identified twelve classes of land covers, which features guided the segmentation parameters. The segmented image was classified using Bhattacharyya distance and post-classified using rules and criteria established for each class, according to their attributes and contextualization. The performance of the final classification was evaluated based on Kappa coefficient, resulting acceptable level of correspondence. The mapping of land cover generated from the classification, shows that the outskirts of the metropolitan railway`s right way is predominantly composed by impermeable materials - such as asphalt and concrete - but has significant presence of natural elements - such as vegetation and water. Thus, is evident the applicability of high spatial resolution satellite image added to classification methods for remotely sensed data for planning and management of the railway right of way.
155

Avaliação da influência da infraestrutura de transporte nas mudanças de uso e cobertura da terra através de modelagem dinâmica espacial. / Evaluation of influence of transport infrastructure on land use change and coverage through dynamic spatial modeling.

Henrique Alessandro de Almeida Ramos 29 September 2017 (has links)
A dinâmica das paisagens e as consequentes alterações no uso e cobertura da terra podem ser analisadas a partir de modelagens espaciais, que auxiliam na interpretação das variáveis responsáveis pelas alterações na paisagem, bem como viabilizam a criação de cenários distintos visando ao conhecimento do impacto produzido pela inserção ou supressão de variáveis na simulação de mudanças da paisagem. Em Guarulhos, a instalação de grandes rodovias conectando o município de São Paulo ao Vale do Paraíba e, posteriormente, de um terminal aeroportuário, em consonância com diferentes períodos de crescimento econômico e expansão urbana, impactaram fortemente na formação da paisagem encontrada neste município, principalmente com a instalação dos grandes pátios industriais e bairros residenciais de média e baixa renda. Com isso, a presente pesquisa buscou avaliar as mudanças no uso e cobertura da terra a partir de produtos de sensoriamento remoto para identificar a influência advinda da instalação dos grandes pontos de conexão do município, por meio de modelagem com autômatos celulares (cellular automata - CA). Dentre os principais resultados obtidos está a influência positiva nas transições para a classe residencial regular exercida pela instalação do aeroporto no primeiro período de análise (1986 a 1993), e a repelência a essa transição nos anos seguintes. Resultados similares foram obtidos na avaliação da influência das grandes vias de acesso na implantação dos parques industriais e galpões logísticos. A modelagem dinâmica, por meio do software Dinamica-EGO, mostrou-se uma ferramenta bastante versátil para avaliação da influência das variáveis espaciais na dinâmica das paisagens urbanas. / The dynamics of landscapes and the consequent changes in land use and land cover can be analyzed according to spatial models, which helps the interpretation of the variables responsible for territorial changes, as well as enables the creation of distinct scenarios in order to know the impact produced by the insertion or suppression of variables in the simulation of landscape changes. In the municipal area of Guarulhos, the installation of large highways linking the municipality of São Paulo to the Paraíba Valley and an airport terminal afterwards, in accordance with different periods of economic growth and urban expansion, had a strong impact on the landscape found in this municipality, mostly because of the installation of large industrial yards and residential neighborhoods of medium and low income. Hence, this research aimed to evaluate the changes in land use and land cover according to remote sensing products, and it also aimed to try to identify the influence of the installation of big connection points of the municipality through modeling with cellular automata (CA). Among the main results obtained are the positive influence on the transitions to the regular residential class exercised by the airport installation in the first period of analysis (1986 to 1993), and the repellency of this transition in the following years. A similar result was obtained in the evaluation of the influence of the great access roads in the implantation of industrial parks and logistic sheds. Thus, the dynamic modeling through the Dynamica-EGO software proved to be a very versatile tool to evaluate the influence of spatial variables on the dynamics of urban landscapes.
156

Diversificação de commodities no uso da terra na agricultura do Estado do Paraná, Brasil

Watanabe, Melissa January 2009 (has links)
As civilizações humanas iniciaram o seu desenvolvimento a partir do uso da terra nas atividades agrícolas. Esse uso da terra na agricultura está condicionado às questões biofísicas, atividades socioeconômicas e contextos culturais das populações da qual dependem. O Estado do Paraná tem se apresentado com uma agricultura forte e vinculada diretamente às principais commodities agrícolas mundiais com uma produção agrícola diversificada, que espelha a evolução dos agronegócios do Brasil. O presente estudo busca analisar a evolução das principais culturas agrícolas do Estado do Paraná de 1996 a 2006 e relacioná-las aos fatores reconhecidos como determinantes do uso da terra, estimando a repercussão desse uso nas respectivas condições socioeconômicas prevalentes nos municípios. Observou-se que as culturas agrícolas da soja, milho e trigo apresentaram ampliação de áreas principalmente em regiões de solos mais férteis. O café teve uma significativa retração em área, principalmente nas regiões mais a noroeste do Estado, mas, em contrapartida, a cana-de-açúcar apresentou uma grande expansão, principalmente nas regiões próximas a Maringá e Paranavaí. As áreas de pastagens no Estado do Paraná sofrem retração ou aumento em decorrência das oportunidades de mercado que as principais commodities apresentam. As matas e florestas, em 1996, apresentavam-se mais concentradas na região sudeste do estado, e, observou-se que, em 2006, esta concentração foi diminuída e suas áreas tornaram-se mais presentes em todo o Estado do Paraná. Após, calculou-se o Índice de Diversificação das Commodities Agrícolas (IDCA) e o Índice de Desenvolvimento Municipal (IDM) para cada município do Estado do Paraná nos anos de 1996 e 2006. O IDCA apresentou maiores valores nos municípios das regiões do estado apresentando solos mais férteis e sem uma grande restrição climática. De 1996 para 2006, houve um aumento de 9,6 % nos valores médios de IDCA no estado, mostrando, assim, um aumento de sua diversificação. O Índice de Desenvolvimento Municipal (IDM) apresentou-se de uma forma homogênea, o que mostra uma ausência de regiões com maior ou menor desenvolvimento, nos anos de 1996 e 2006. A correlação entre o IDCA e o IDM revelou-se baixa, mostrando uma ausência de relação direta entre a diversificação das commodities agrícolas nos muncípios, IDCA, e seu respectivo desenvolvimento municipal, IDM. Após esta análise, separou-se o Estado do Paraná em duas regiões edáficas distintas: a região A que apresenta solos, em sua maioria, de origem sedimentar ou metamórfica e a região B com solos basálticos, reconhecidamente mais férteis. Com o teste de diferença mínima significativa (5% de nível de significância) nas médias dos indicadores IDCA e IDM entre as regiões A e B, observou-se diferença entre médias para o IDCA e uma igualdade para o IDM. A produção das commodities agrícolas paranaenses responde aos mercados internacionais influenciados pela oferta e demanda mundiais e pelos seus respectivos preços e cotações internacionais. Os incrementos verificados no indicador de diversificação agrícola utilizado sugerem que, na última década, ocorreu um aumento da resiliência do Estado do Paraná frente às oscilações do mercado. / Agricultural land-use is related to the environmental, biophysical conditions and to the cultural and socioeconomical context of the populations, which depend upon it. The Parana State, Brazil, is charaterized by a vigorous agriculture that responds directly to fluctuations of the world commodities markets. Its agriculture is diversified and follows the Brazilian agribusiness trends. This study aims towards the analysis of the evolution of the major cultures of the Parana State between the years of 1996 and 2006 and relates it to the main, recognized drivers of land-use, trying to establish its eventual effects on the socioeconomical conditions prevalent in the municipalities of the Parana State, taken here as analytical grid cells. It was seen that in the past decade the areas of cultivation of soybean, corn and wheat expanded, mostly in the regions of more fertile soils. Coffee presented a significant reduction of cultivation area, mostly in the northwest of the state, contrasting with sugarcane fields that expanded into this area. Pasture areas in the Parana State have changed as a result of the new opportunities of the world market for grain commodities. In 1996 wild and cultivated forests were more concentrated in the southeast of the Parana State. In 2006 this concentration was reduced and the forests were more spread throughout the state. In an attempt to relate the agricultural diversification of the Parana State with the local, prevalent socioeconomical conditions, an Agricultural Commodities Diversification Index (ACDI) and a Municipal Development Index (MDI) were calculated for each municipal grid cell, for both the years 1996 and 2006. ACDI values were higher for the municipalities located in the regions of more fertile soil, with no markedly climatic restrictions for agriculture. From 1996 to 2006 average values for ACDI in the State of Parana soared around 9.6 %, suggesting an increase in agricultural diversification. MDI values throughout the Parana State are quite homogeneous, showing an absence of regions of markedly diffentiated level of development. The calculated correlation between ACDI and MDI was low, suggesting an absence of direct relationship between the agricultural commodities diversification and the socioeconomic development of the municipalities of the Parana State. There are two distinct, edafic regions in this state. One presents mostly sedimentary or metamorphic soils, the other presents mostly basaltic, markedly more fertile soils. A test for significant minimal difference (5 % significance level) was carried out with the average values for ACDI and MDI for the two distinct, edafic regions. A significant difference was found between the average values for ACDI, but no difference between the average values for MDI. As a whole, it was concluded that the production of agricultural commodities in the Parana State responds to international markets, and is mostly affected by supply and demand and by the international commodities prices. The increments of the index for agricultural diversification suggest that in the last decade the agriculture of the Parana State became more resilient towards the unstabilities and uncertainties of the global commodities markets.
157

Ecological Responses of Avian Species to Land Cover Metrics at the Landscape-Level and Across Broad Spatial Extent

De Camargo, Rafael Xavier January 2018 (has links)
Human activities have transformed natural landscapes into human-dominated areas at unprecedented rates in the last centuries. Land cover transformation is associated with loss of natural habitat, thus a threat to biodiversity. Because habitat loss will likely continue in the future due to population growth and increase demand for natural resources, an important question in ecological studies is whether land cover features (i.e. amount, variety, shape, configuration) can be used as predictors to estimate species loss from habitat modification. This thesis investigates the predictive ability of landscape features in predicting species distributions at the landscape level and across large regions. It tests several predictions from classic hypotheses such as the species-area relationship and habitat fragmentation, utilizing a macroecological approach. Response variables (e.g. species richness, species’ probability of occurrence) and independent variables (e.g. proportion of natural areas, metrics of fragmentation, temperature, etc.) are analysed in cell sizes of 25-900km2 covering large regions (e.g. southern Ontario, New York State). Bird species were chosen as the main biological model. Most literature assumes that species richness should vary positively as a function of remaining natural area, following the well-known species–area relationship (i.e. classic SAR). Prior studies have shown that avian species richness has a peaked, rather than a monotonic increasing, relationship with the proportion of natural land cover in landscapes of southern Ontario. The first chapter of the thesis showed improvements in the predictive power of classic SARs by proposing the “Lost-habitat SAR”, which demonstrates that richness of open-habitat species can be predicted when we partition human-dominated land cover into an ‘‘available human-dominated’’ component and ‘‘lost’’ habitat (i.e. parts of the landscape that can no longer be utilized by any species). The second chapter addresses a current contention in the literature about the effect of habitat fragmentation beyond habitat amount at the landscape level. Specifically, I tested the effect of fragmentation (e.g. number of patches) on both avian richness and the probability of occurrence (pocc) of individual species, after controlling for habitat amount in 991 landscapes, each 100-km2, in southern Ontario. The analysis showed that overall species richness responds primarily to habitat amount, and that the effect of habitat fragmentation, holding the total amount of habitat constant, is negligible. The probability of occurrence of a few bird species did relate negatively to the size, number and isolation of the patches within the landscape. We argue that the evidence is inconsistent with the hypothesis that reducing habitat fragmentation would be an effective conservation strategy for birds at the landscape level. Chapter 3 tested the speculation in the climate change literature that habitat loss may impede the colonization or movement of species whose ranges are shifting northwards in response to climate. Using the same 100-km2 landscapes of southern Ontario, I examined individual bird species’ probability of occupancy as a function of the amount of remaining natural land cover for three groups of species: i) those whose northern range limit falls within the study area, ii) those whose southern range limit is in the study area, and iii) those whose ranges cover the entire study area. The results showed that the probability of occupancy of southern-edge species is a positive function of the amount of natural land cover (forest) in the landscape, while the probability of occupancy of northern-edge species is a negative function of natural land cover. Hence, I conclude that at southern range limits species faces the dual stresses of climatic warming and habitat conversion. Whereas, at northern (potentially expanding) range edges, partially disturbed landscapes are more readily occupied than undisturbed landscapes. In the final chapter, I challenge widely accepted hypothesis that habitat loss causes biodiversity loss by testing whether conserving natural land cover would conserve species diversity. More specifically, I tested whether broad-extent relationships between avian species richness and natural land cover are independent of: 1) whether species distribution data come from systematic censuses (atlases) versus range maps, and 2) the grain size of the analysis in grid cells covering southern Ontario, CA, and New York State, US. My findings showed that over regional extents, range-map-based richness relates strongly to temperature, irrespective of spatial grain, and that censused species richness relates to temperature less strongly. Moreover, range-map richness is a negative function of the proportion of natural land cover, while realized richness is a peaked function. Therefore, I conclude that conserving natural land cover would not conserve species diversity in southern Ontario or in New York State, since greater natural cover does not imply higher richness. We argue that habitat loss has become a panchreston. It may be misguiding conservation biology strategies by focusing on a threat that is too general to be usefully predictive.
158

Phytomass and Soil Organic Carbon Inventories Related to Land Cover Classification and Periglacial Features at Ari-Mas and Logata, Taimyr Peninsula

Ramage, Justine January 2012 (has links)
The predicted increase in atmospheric temperatures is expected to affect the turnover of soil organic carbon in permafrost soils through modifications of the soil thermal regime. However, the tundra biome is formed of a mosaic of diverse landscape types with differing patterns of soil organic carbon storage and partitioning. Among these, differences in e.g. vegetation diversity and soil movements due to freeze-thaw processes are of main importance for assessing potential C remobilization under a changing climate. In this study, we described the storage of soil organic carbon (SOC) and the aboveground phytomass carbon in relation to geomorphology and periglacial features for two areas on Taymir Peninsula (Arctic Russia). An average of 29.5 kg C m-2, calculated by upscaling with a land cover classification, is stored in the upper soil meter at these two study sites. The mean C phytomass storage amounts to ca.0.406 Kg C m-2, or only 1.38% of the total SOC storage. The topography, at different scales, plays an important role in the carbon partitioning. High amounts of soil organic carbon are found in highland areas and within the patterned ground features found in peatlands. The highest amounts of aboveground phytomass carbon are found in deciduous shrubs and moss layers. The large variability in carbon distribution within land cover types among the sites reveals the challenge of upscaling the carbon storage values over the Arctic and thus highlight the necessity to carry out detailed field inventories in this region.
159

The Effect of Home Range Estimation Techniques on Habitat Use Analysis

Quinton, Brendon 30 June 2016 (has links)
The term “home range” refers to the area in which an animal spends most of its time during everyday activities. This study examined the effects of four different home range estimation techniques on the proportions of habitats located therein. The study utilized a point dataset collected for twenty individual Florida Black Bears (Ursus americanus floridanus), occurring in five different areas throughout the state of Florida. Each dataset was used to create home ranges using the following techniques: (1) Minimum Convex Polygon, (2) Kernel Density Estimation, (3) Characteristic Hull Polygon, and (4) Time-Geographic Density Estimation, a new home range estimator which has not been thoroughly tested prior to this study. A dataset of land cover types was clipped with each home range and the areas of habitats were recalculated. The proportion of each land cover type was evaluated and the results compared first within each dataset, then between all datasets used. Repeated measures analysis of variance (ANOVA) was used to determine whether the four home range estimation techniques produced significantly different areas and proportions of each habitat type. These results were then evaluated to determine whether the method of home range estimation has an effect on which land cover types are most utilized by a species and, therefore, which habitats are considered preferable. While the choice of home range estimation did not have an effect on which habitats were determined to be most frequently visited, it did affect the amount of each habitat found within each home range. Furthermore, there was a statistically significant change in the amount of developed areas, specifically between the characteristic hull polygon and kernel density estimation methods. These results suggest the choice of home range estimator affects habitat analysis and that researchers should use the method best suited for the dataset.
160

Historical Analysis of Riparian Vegetation Change in Response to Shifting Management Objectives on the Middle Rio Grande

Petrakis, Roy, van Leeuwen, Willem, Villarreal, Miguel L., Tashjian, Paul, Dello Russo, Regina, Scott, Christopher 22 April 2017 (has links)
Riparian ecosystems are valuable to the ecological and human communities that depend on them. Over the past century, they have been subject to shifting management practices to maximize human use and ecosystem services, creating a complex relationship between water policy, management, and the natural ecosystem. This has necessitated research on the spatial and temporal dynamics of riparian vegetation change. The San Acacia Reach of the Middle Rio Grande has experienced multiple management and river flow fluctuations, resulting in threats to its riparian and aquatic ecosystems. This research uses remote sensing data, GIS, a review of management decisions, and an assessment of climate to both quantify how riparian vegetation has been altered over time and provide interpretations of the relationships between riparian change and shifting climate and management objectives. This research focused on four management phases from 1935 to 2014, each highlighting different management practices and climate-driven river patterns, providing unique opportunities to observe a direct relationship between river management, climate, and riparian response. Overall, we believe that management practices coupled with reduced surface river-flows with limited overbank flooding influenced the compositional and spatial patterns of vegetation, including possibly increasing non-native vegetation coverage. However, recent restoration efforts have begun to reduce non-native vegetation coverage.

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