A Novel Strategy to Reconstruct NDVI Time-Series with High Temporal Resolution from MODIS Multi-Temporal Composite Products

Vegetation indices (VIs) data derived from satellite imageries play a vital role in land surface vegetation and dynamic monitoring. Due to the excessive noises (e.g., cloud cover, atmospheric contamination) in daily VI data, temporal compositing methods are commonly used to produce composite data to minimize the negative influence of noise over a given compositing time interval. However, VI time series with high temporal resolution were preferred by many applications such as vegetation phenology and land change detections. This study presents a novel strategy named DAVIR-MUTCOP (DAily Vegetation Index Reconstruction based on MUlti-Temporal COmposite Products) method for normalized difference vegetation index (NDVI) time-series reconstruction with high temporal resolution. The core of the DAVIR-MUTCOP method is a combination of the advantages of both original daily and temporally composite products, and selecting more daily observations with high quality through the temporal variation of temporally corrected composite data. The DAVIR-MUTCOP method was applied to reconstruct high-quality NDVI time-series using MODIS multi-temporal products in two study areas in the continental United States (CONUS), i.e., three field experimental sites near Mead, Nebraska from 2001 to 2012 and forty-six AmeriFlux sites evenly distributed across CONUS from 2006 to 2010. In these two study areas, the DAVIR-MUTCOP method was also compared to several commonly used methods, i.e., the Harmonic Analysis of Time- Series (HANTS) method using original daily observations, Savitzky–Golay (SG) filtering using daily observations with cloud mask products as auxiliary data, and SG filtering using temporally corrected composite data. The results showed that the DAVIR-MUTCOP method significantly improved the temporal resolution of the reconstructed NDVI time series. It performed the best in reconstructing NDVI time-series across time and space (coefficient of determination (R2 = 0.93 ~ 0.94) between reconstructed NDVI and ground-observed LAI). DAVIR-MUTCOP method presented the highest robustness and accuracy with the change of the filtering parameter (R2 = 0.99 ~ 1.00, bias = 0.001, root mean square error (RMSE) = 0.020). Only MODIS data were used in this study; nevertheless, the DAVIR-MUTCOP method proposed a universal and potential way to reconstruct daily time series of other VIs or from other operational sensors, e.g., AVHRR and VIIRS

Ecologia reprodutora e padrões migratórios de uma ave migradora afro-paleártica insetívora, o Abelharuco (Merops Apiaster)

Important habitats crucial to animal reproduction and survival are being transformed at an increasing rate and at the same time, climate change is altering ecological patterns in both time and space. Migratory species are currently experiencing severe declines as they move within a network of interconnected areas that are often undergoing different rates of change. Understanding the factors that influence population dynamics in migratory species therefore requires not only knowledge on breeding ecology and drivers of breeding success, but also on how events during one period of the annual cycle carry over to influence events in subsequent seasons. The overall objective of this thesis was to increase the knowledge about the breeding ecology and migratory patterns of the European bee-eater (Merops apiaster), an Afro-Palearctic long-distance migrant. More specifically, this thesis focused on increasing the knowledge on trophic ecology as well as providing a first insight of bee-eater’s migratory patterns, at population and individual levels. This work also explored, for the first time, the link between migratory performance and productivity in an Iberian population of this species. Finally, it was investigated if productivity is influenced by age and pair-fidelity. The first two chapters were developed based on the need of the application of the described methods in the subsequent chapters. First, I developed discriminant functions to sex adult bee-eaters. This work was the first using biometrics of molecularly sexed birds to generate population specific, as well as, general discriminant functions for sexing adult European bee-eaters. Then, I also developed a photographic guide to estimate the age of nestling bee-eaters and presented a protocol that proposes visiting nests at 12 day intervals, while achieving the highest accuracy in nestling aging with the smallest disturbance and logistic investment. This thesis showed that the diet of bee-eaters during the breeding season varies across colonies in distinct habitats and seasons, and between what is consumed by adults and provided to nestlings. The results revealed distinct migration patterns of European Bee-eaters from three breeding populations (Iberia, Germany and Bulgaria) showing that individuals from Bulgaria migrate on an eastern route to southern Africa while the other two populations take a western route. It also provided evidence for different timings of migration between the three populations. At individual level, departure from the wintering area and travel duration seemed to be the most apparent factors influencing arrival to the breeding areas in Iberia. In this study, it was reported a positive relationship between arrival and laying dates. Additionally, the relationship between laying date and productivity was year specific: in 2017, the number of fledglings decreased throughout the season, contrary to 2016, when laying was earlier in the year and productivity remained constant. Finally, the results showed that older females (but not males) lay eggs earlier and have higher productivity than first breeding females. Moreover, older couples seemed equally likely to maintain their pair bond during two consecutive seasons than first breeding pairs and productivity does not seem to be influenced by mate retention. Inter-annual variation in productivity may affect populations in the long term if the frequency of poor (or good) environmental conditions increases, as these induce fluctuations in demographic rates. Therefore, this study urges for long-term monitoring of bee-eater populations, and other Afro-Palearctic migrants, to predict their population level responses to environmental change and optimize conservation strategies accordingly.Os habitats essenciais para a reprodução e sobrevivência animal têm vindo a ser transformados a um ritmo crescente e ao mesmo tempo, as alterações climáticas têm vindo a alterar espacialmente e temporalmente os padrões ecológicos. Muitas espécies migradoras estão, actualmente, em declínio severo devido ao facto de ocuparem áreas conectadas entre si que muitas vezes são alteradas a diferentes velocidades. Assim, para compreender os factores que influenciam a dinâmica populacional das espécies migradoras é necessário, não só, aprofundar o conhecimento sobre a sua ecologia reprodutora e os factores que determinam o sucesso reprodutor, mas também perceber de que modo os eventos que ocorrem durante um determinado período do ciclo anual se traduzem em carry-over effects e influenciam os eventos nas épocas subsequentes. O principal objectivo desta tese foi aumentar o conhecimento sobre a ecologia reprodutora e padrões migratórios do Abelharuco (Merops apiaster), um migrador Afro-paleártico de longa distância. Mais concretamente, esta tese focou-se em aprofundar o conhecimento sobre a ecologia trófica, assim como investigar pela primeira vez os padrões migratórios do Abelharuco, a nível populacional e individual. Este trabalho também investigou pela primeira vez a relação entre a performance migratória e a produtividade de uma população desta espécie que nidifica na Península Ibéria. Finalmente investigou-se se a produtividade é influenciada pela idade e fidelidade do casal. Os primeiros dois manuscritos foram desenvolvidos devido à necessidade de aplicar esses métodos nos capítulos seguintes. Primeiro, desenvolvi funções discriminantes para determinar o sexo de Abelharucos adultos. Este trabalho foi o primeiro que utilizou biometrias de Abelharucos, nos quais o sexo foi identificado molecularmente, para produzir funções discriminantes aplicáveis ao nível da população mas também para a espécie em geral. Desenvolvi também um guia de fotografias para determinar a idade das crias de Abelharuco e apresento um protocolo que propõe visitar os ninhos em intervalos de 12 dias de modo a atingir a precisão máxima na determinação da idade das crias, minimizando a perturbação e o investimento logístico. Esta tese mostrou que a dieta do Abelharuco durante a época reprodutora varia entre colónias localizadas em habitats distintos, entre épocas e entre o que é consumido pelos adultos e fornecido às crias. Os resultados revelaram distintos padrões migratórios do Abelharuco entre três populações reprodutoras (Ibéria, Alemanha e Bulgária), indicando que os indivíduos da Bulgária migram através de uma rota este para o sul de África, enquanto as outras duas populações migram por uma rota oeste. Também demonstrou que as três populações exibem diferentes timings de migração. Ao nível individual, a partida da área de invernada e a duração da migração parecem ser os principais factores que influenciam a data de chegada à área de reprodução na Ibéria. Neste estudo, foi estabelecida uma relação positiva entre a chegada à área de reprodução e as datas de postura. Adicionalmente, a relação encontrada entre a data de postura e a produtividade variou entre anos: em 2017, o número de crias voadoras diminuiu ao longo da época reprodutora; mas tal não aconteceu em 2016, quando as datas de postura ocorreram mais cedo e a produtividade permaneceu constante ao longo da época. Finalmente, os resultados mostraram que fêmeas mais velhas (mas não machos) colocam os ovos mais cedo e têm maior produtividade do que as fêmeas que se reproduzem pela primeira vez. Adicionalmente, os casais mais velhos parecem ter a mesma probabilidade de se manter juntos durante duas épocas reprodutoras consecutivas comparado com os casais que se reproduzem pela primeira vez. A produtividade não parece ser influenciada pela manutenção do parceiro. A variação inter-anual na produtividade pode afectar as populações a longo termo através da indução de flutuações nas taxas demográficas, se a frequência de más (ou boas) condições ambientais aumentar. Deste modo, este estudo apela à monitorização a longo prazo das populações de Abelharucos, e outros migradores afro-paleárcticos, de forma a prever as respostas das populações às alterações ambientais e optimizar medidas de conservação.Programa Doutoral em Biologi

Geoinformatics in Citizen Science

The book features contributions that report original research in the theoretical, technological, and social aspects of geoinformation methods, as applied to supporting citizen science. Specifically, the book focuses on the technological aspects of the field and their application toward the recruitment of volunteers and the collection, management, and analysis of geotagged information to support volunteer involvement in scientific projects. Internationally renowned research groups share research in three areas: First, the key methods of geoinformatics within citizen science initiatives to support scientists in discovering new knowledge in specific application domains or in performing relevant activities, such as reliable geodata filtering, management, analysis, synthesis, sharing, and visualization; second, the critical aspects of citizen science initiatives that call for emerging or novel approaches of geoinformatics to acquire and handle geoinformation; and third, novel geoinformatics research that could serve in support of citizen science

Across Space and Time. Papers from the 41st Conference on Computer Applications and Quantitative Methods in Archaeology, Perth, 25-28 March 2013

This volume presents a selection of the best papers presented at the forty-first annual Conference on Computer Applications and Quantitative Methods in Archaeology. The theme for the conference was "Across Space and Time", and the papers explore a multitude of topics related to that concept, including databases, the semantic Web, geographical information systems, data collection and management, and more

Foraging Behavior of Anopheles Mosquitoes in Nchelenge District, Zambia

Approximately 3.2 billion people worldwide are at risk of contracting malaria. In 2013, there were 200 million cases and close to 600,000 deaths, most of which occurred in sub-Saharan Africa and affected mainly children, denoting the disease as a major public health problem. In Nchelenge District, Zambia, there is holoendemic transmission of Plasmodium falciparum, vectored by Anopheles funestus sensu stricto and An. gambiae s.s. mosquitoes. Since 2006, the Zambian government has provided LLINs, providing approximately one net per person, and has implemented IRS campaigns in Nchelenge. Despite the use of vector control, the prevalence of malaria has not reduced, making it necessary to define and characterize the Anopheles mosquitoes involved in transmission to better develop strategies for control. Therefore, the specific aims of this study were: 1) to identify and characterize the anopheline mosquitoes and their respective roles in P. falciparum transmission both temporally and spatially, 2) to determine the extent of underestimation of Anopheles foraging behavior by standard field methods across the three southern Africa ICEMR field sites, and 3) to investigate multiple blood feeding behavior and human gender preference of human fed mosquitoes, and P. falciparum complexity of infection (COI) in infected anophelines in Nchelenge District. CDC LT and PSC trap methods were performed over three consecutive wet and dry seasons in three villages lakeside and two villages streamside, revealing An. funestus and An. gambiae as the dominant vectors. Both vectors were also highly anthropophilic. Temporally, An. funestus is the primary vector year round, whereas An. gambiae is more abundant during the wet season compared to the dry season. Spatially, during the wet season, An. funestus is the predominant vector inland and along the stream, whereas An. gambiae is the predominant vector along Lake Mweru. Additionally, the abundances of both An. funestus and An. gambiae streamside are higher than lakeside. Throughout all three collections, An. funestus had the highest transmission intensity, indicating its important role in maintaining transmission year round. When investigating the foraging behavior of malaria vectors across the three southern Africa ICEMR sites, it was found that by not including visually “unfed” mosquitoes in host blood meal PCR assays, the overall proportion of fed vectors is underestimated by up to 18.7%, and that this can have potential effects on the human blood index (HBI), human biting rate (HBR), and entomological inoculation rate (EIR). Finally, Anopheles mosquito foraging behavior in Nchelenge was further defined through multiple blood feeding behavior, human gender preference, and COI studies. Both An. funestus and An. gambiae displayed multiple blood feeding rates of 23.2% and 25.7% respectively, rates that are among the highest recorded in sub-Saharan Africa and lead to an underestimation of the EIR. There was a trend towards both vectors feeding on human males more so than females. Furthermore, the P. falciparum COI in infected mosquitoes was 6.4, suggesting a high transmission setting and supports the inoculation of multiple clones in a single mosquito bite in Nchelenge District. The studies described in this dissertation have provided a foundation for future entomological studies on mosquito vectors in Nchelenge District, Zambia, as well as vector control evaluation and development of effective intervention programs