Les patrons de variation au sein des espèces d'arbres résultent d'évolutions complexes dont certaines sont particulièrement liées à la condition d'arbre. Si les facteurs expliquant cette variabilité ont été abordés pour les espèces des zones tempérées, ils restent encore peu connus pour des espèces fruitières des zones tropicales sèches offrant des particularités sur le plan adaptatif et relevant d'un processus de domestication ancien. Pour répondre à cet enjeu, l'objectif scientifique de cette thèse est de mieux comprendre l'impact des facteurs évolutifs sur la variabilité au sein d'une espèce d'arbre en zone soudano-sahélienne. Nous nous sommes intéressés à Vitellaria paradoxa (karité), une espèce jouant un rôle économique majeur par la production de beurre à partir des graines, dont l'aire de distribution s'étend du Sénégal à l'Ouganda sous la forme de peuplements naturels et agroforestiers. Dans une approche phylogéographique basée sur l'analyse du polymorphisme de marqueurs moléculaires supposés neutres (microsatellites chloroplastiques et nucléaires, et régions intergéniques du chloroplaste) et sur la modélisation des niches écologiques du Karité à différentes périodes du Quaternaire, nous mettons en évidence l'impact des perturbations liées aux dernières glaciations (il y a 20000 ans) sur la diversité génétique de l'espèce. Dans une seconde approche méthodologique, nous étudions l'impact des déterminants environnementaux sur la variabilité des constituants chimiques des graines de Karité, permettant d'énoncer de nouvelles hypothèses. Enfin, nous nous intéressons à l'expression du polymorphisme de gènes candidats, codant les enzymes stéaroyl-ACP-désaturase (SAD) et homogentisate phytyltransférase (HPT), en relation avec la variabilité de la composition chimique en acides gras et en tocophérols des graines. Les résultats obtenus permettent notamment de discuter de l'impact de la sélection naturelle, de la domestication et de la dérive génétique, et d'apporter des hypothèses évolutives et fonctionnelles potentielles expliquant la variabilité observée. / Patterns of variation within tree species are the result of complex evolutionary changes, some of which are particularly related to the condition of trees. If the factors explaining this variability were discussed for species in temperate zones, they remain little known for fruit tree species of dry tropics, which show special adaptive features and result from an old domestication process. To meet this challenge, the scientific purpose of this thesis is to improve our understanding of evolutionary factors affecting the variability within a tree species in the Sudano-Sahelian zone. We got interested in Vitellaria paradoxa (Shea tree), a species which plays a major economic role for the production of butter from seeds and whose distribution range extends from Senegal to Uganda. In a phylogeographic approach based on the analysis of polymorphism supposedly neutral molecular markers (chloroplast and nuclear microsatellites and chloroplast intergenic regions) and based on ecological niche modelling of Shea tree at different periods of the Quaternary, we shape the role of last glacial maximum (20.000 YBP) on the genetic diversity of the species. In a second methodological approach, we study the impact of environmental determinants on the variability of Shea nuts chemical constituents, stating novel hypotheses. Finally, we investigate the polymorphism of candidate genes, encoding enzymes stearoyl-ACP-desaturase (SAD) and homogentisate phytyltransférase (HPT), in connection with the variability of relative fatty acids compositions and tocopherols contents in seeds. Through the results obtained, we discuss the impact of natural selection, domestication and genetic drift, and provide evolutionary and functional hypotheses that potentially explain the varia bility observed.

Globally fish production has continued to increase during recent years at a rate exceeding that of human population growth. However the contribution from capture fisheries has remained largely static since the late 1980s with the increase in production being accounted for by dramatic growth in the aquaculture sector. As of 2012 aquaculture accounted for approximately 42% of total fisheries production and 78% of inland fish production. In view of these figures it is unsurprising that for a number of regions aquaculture represents an important source of both food security and income. The use of Geographical Information Systems (GIS) and spatial data have seen substantial developments in recent years with the help of increasingly affordable computing capacity. From an aquaculture perspective the use of GIS has shown significant potential as a means of combining varied data sources, including those acquired via remote sensing, into models to provide decision support in relation to site selection. A common theme amongst site suitability assessments is the incorporation of climate variables relating to temperature and water availability. These factors in turn can have a significant influence on aquaculture in terms of water availability and quality, and temperature modulated growth performance. There is now a strong consensus that during the 20th century, and especially during recent decades, the earth has experienced a significant warming trend. There is also strong agreement that this warming trend is at least partially a consequence of anthropogenic greenhouse gas emissions and that some degree of further warming is inevitable. While global warming is typically discussed in terms of degrees centigrade of average global temperature increase the full effects in terms of climate changes will be varied both in terms of location and season. The current project focuses on site suitability for aquaculture in relation to changing climate conditions. Significant use is made of GIS and a range of spatial data including remotely sensed data and output from a series of climate models. The project consists of a number of key components: 1. Vulnerability of aquaculture related livelihoods to climate change was assessed at the global scale based on the concept of vulnerability to climate related impacts as a function of sensitivity to climate change, exposure to climate change, and adaptive capacity. Use was made of national level statistics along with gridded climate and population data. Climate change scenarios were supplied using the MAGICC/SCENGEN climate modelling tools. Analysis was conducted for aquaculture in freshwater, brackish, and marine environments with outputs represented as a series of raster images. A number of Asian countries (Vietnam, Bangladesh, Laos, and China) were indicated as most vulnerable to impacts on freshwater production. Vietnam, Thailand, Egypt and Ecuador stood out in terms of brackish water production. Norway and Chile were considered most vulnerable to impacts on Marine production while a number of Asian countries (China, Vietnam, and the Philippines) also ranked highly. 2. Site suitability for pond-based aquaculture was modelled at the global scale using a 10 arcsecond grid. Data from an ensemble of 13 climate models was used to model pond temperature and water availability for rain fed ponds under late 20th century conditions and for a 2°C global warming scenario. Two methods are demonstrated for combining data with a focus on the culture of warm water species. Results suggest both positive and negative impacts in relation to the 2°C warming scenario depending on location and season. Some areas are projected to see negative effects from maximum temperatures during the warmest parts of the year while for many regions there are likely to be potential increases in growth performance during colder months with possible expansion into previously unsuitable areas. 3. Methods for detecting surface water using remotely sensed data were investigated for Bangladesh. Use was made of data from the Moderate-resolution Imaging Spectroradiometer (MODIS) and Landsat ETM+ instruments with accuracy assessed against ground truth data collected in the field. A time series was constructed using all available MODIS data (approximately 13 years with an 8 day temporal resolution) to show areas of: surface water, land, and mixed land and water. The time series was then analysed to produce a layer showing the percentage of the total time series where surface water is indicated thus providing a spatial representation of flood prevalence. 4. A land cover data set was produced using 9 Landsat ETM+ scenes to cover the majority of Bangladesh. 10 different classification routines were evaluated including a decision tree approach unique to the current study. Classification results were assessed against two sets of ground control points produced: one based on field collected ground truth data and the other using a stratified random sampling procedure in association with visual analysis of high resolution true colour satellite images and ETM+ composites. The most accurate classifications were provided by the decision tree method developed for the current study and a Multi-Layer Perceptron (MLP) neural network based classifier. 5. Site suitability for pond-based aquaculture within Bangladesh was assessed using a GIS in combination with the ETM+ based land cover data, the MODIS based surface water time series, and components of the global site suitability assessment including modelled pond temperature data. Assessments were made based on late 20th century conditions and a 2°C global warming scenario. The MODIS surface water time series was also used to show the effects of storm surge flooding in relation to cyclone Aila that struck Bangladesh on 25th May 2009. The south and east of the country were considered most suitable for aquaculture due to more favourable cold season temperatures and higher water balance values. The north west of the country was considered least favourable due to higher maximum modelled pond temperatures and lower water balance values. The effect of the 2°C warming scenario was to enhance these trends. To date the potential spatial implications of changing climate for aquaculture has been significantly under researched. In this respect the current study provides a highly useful indication of where aquaculture related livelihoods may be vulnerable. In addition valuable and unique insights are provided into the distribution of areas of both potential increased, as well as decreased, suitability for existing aquaculture and further aquaculture development.

A two-year analysis of pollen rain was conducted in the Pretoria-Witwatersrand-Vereeniging district of the Transvaal, South Africa. Poaceae WaS the major component of the pollen assemblage, comprising 52% regionally. Of the total pollen count, 58.8% was non-seasonal and present throughout the year. During the analysis it became apparent that fungal spores dominated the atmospheric content, accounting for 94% of total airspora, considered here to incl ude pollen and fUngal spores.[Abbreviated Abstract. Open document to view full version]. / AC2017

A Área de Proteção Ambiental (APA) Capivari-Monos no sul do município de São Paulo, sub-distrito de Parelheiros, é uma área de Mata Atlântica que abriga importantes mananciais. Devido à urbanização desorganizada, alterações das condições ecológicas naturais dessa área propiciam o contato entre humanos, patógenos e culicídeos. Pouco se sabe sobre a ecologia de mosquitos vetores de patógenos nessa localidade, o que instigou a pesquisa na região. Nesse sentido, o presente estudo investigou a fauna culicídeos presentes em ambiente silvestre e antrópico na APA Capivari-Monos, determinando-se indicadores de biodiversidade e relacionando-os a fatores ambientais. Para tal, por 12 meses foram capturados mensalmente culicídeos adultos e imaturos de ambiente silvestre e antrópico usando-se diferentes técnicas de captura. Foram utilizados indicadores de diversidade para avaliar a riqueza, dominância, abundância e equabilidade dos diferentes ambientes. Um total de 9.403 mosquitos adultos foram capturados de maio de 2009 a junho de 2010. As espécies prevalentes entre as coletadas no ambiente silvestre foram Anopheles (Kerteszia) cruzii, Culex (Melanoconion) seção Melanoconion e Aedes serratus, enquanto as mais comuns no ambiente antrópico foram Coquillettidia chrysonotum / albifera, Culex (Culex) grupo coronator e An. (Kerteszia) cruzii. A riqueza de mosquitos adultos foi semelhante entre os ambientes, e a abundância variou entre as espécies. Ao comparar os padrões de diversidade entre os ambientes, a região antrópica apresentou maior riqueza e uniformidade, o que sugere que o estresse ambiental aumentou o número de nichos favoráveis para culicídeos e promoveu maior diversidade. A espécie An. cruzii apresentou correlação positiva com pluviosidade e temperatura no ambiente antrópico, mas no ambiente silvestre essa espécie não esteve associada aos fatores climáticos. Dos 2443 mosquitos imaturos coletados, 1507 (61,7 por cento ) foram encontrados no ambiente antrópico e 936 (38,3 por cento ) no ambiente silvestre. Os mosquitos imaturos foram distribuídos em 62 categorias taxonômicas, e sua riqueza e abundância foram maiores no ambiente antrópico que no silvestre. Os indivíduos Culex (Microculex) grupo Imitator foram os que apresentaram maior abundância e foram encontrados com maior frequência no ambiente antrópico e silvestre. / The Environmental Protection Area (APA) Capivari-Monos in the Parelheiros sub-district, in South São Paulo, is an Atlantic Forest area that comprises important springs. Owing to the disorganized urbanization, changes in the natural ecological conditions of the APA promoted human-Culicidae-pathogen contact. The lack of information on the ecology of mosquito vectors in the APA motivated the present study, which investigated the Culicidae fauna wild and anthropic zones of the Capivari-Monos APA, determining biodiversity indicators and relating them to environmental factors. To that end, adult and immature Culicidae were monthly collected from the wild and from the anthropic zones for 12 months and using different capture techniques. Diversity indicators were used to assess richness, dominance, evenness and abundance in the different environments. A number of 9,403 adult mosquitoes were collected from May 2009 to June 2010. The main species collected in the wild environment were Anopheles (Kerteszia) cruzii, the Melanoconion section of Culex (Melanoconion) and Aedes serratus, whereas the most common species in the anthropic zone were Coquillettidia chrysonotum/albifera, Culex (Culex) Coronator group and An. (Ker.) cruzii. Mosquito richness was similar between the zones, and their abundance varied according to the species. Compared to the wild zone, the anthropic zone exhibited higher richness and evenness, suggesting that environmental stress increased the number of favorable niches for culicids, promoting diversity. An. cruzii occurrence was positively correlated with rainfall and temperature in the anthropic zone, but in the wild zone it was not associated with climatic factors. From the 2,443 immature mosquitoes collected, 1,507 (61.7 per cent ) were found int the anthropic zone and 936 (38.3 per cent ) in the wild zone. The immature mosquitoes were distributed into 62 taxonomic categories, and their richness and abundance were higher in the anthropic than in the wild zone. Culex (Microculex) Imitator group was the prevailing species in both environments.

Snowmelt is one of the major sources of surface water supply and ground-water recharge in high elevation areas and can also cause flooding in snow dominated watersheds. Direct estimation of daily snowmelt requires daily snow water equivalent (SWE) measurements that are not always available, especially in places without monitoring stations. There are two alternative approaches to modeling snowmelt without using direct measurements of SWE, temperature-based and energy-based models. Due to its simplicity, computational efficiency, and less input data requirement, the temperature-based method is commonly used than the energy-based method. In the temperature-index approach snowmelt is estimated as a linear function of average air temperature, and the slope of the linear function is called the degree-day factor (DDF). Hence, the DDF is an essential parameter for utilizing the temperature-based method to estimate snowmelt. Thereby, to analyze the spatial properties of DDF, 10 years DDF from the entire state of Colorado was calculated for this research. Likewise, to study the temporal properties, DDFs for 27 years from the White Yampa water basin and the Colorado Headwaters water basin were calculated. As a part of the spatial analysis, the calculated DDFs were correlated with spatial variables (slope, aspect, latitude and elevation) and a spatial correlation graph was created to observe the possibility of predicting DDF. Also a multivariate regression model was prepared using these spatial variables to predict the DDF using spatial variables. Further, the DDFs calculated from Colorado headwaters and the White Yampa water basins were correlated for annual temporal variation, daily variation, variation with peak snow water equivalent and variation with important temporal cycles like accumulation period and melting period of snowmelt. The result obtained from this study showed that the variability of DDF is more dependent upon temporal factors compared to the spatial factors. Also, the results showed that predicting DDF is a difficult process and requires complex methods than simple linear models or multivariate models.

Earth’s climate is intricately linked to the carbon cycle through the radiative effect of atmospheric carbon dioxide. The ocean plays a central role in this climate-carbon system; as oceans store ∼50 times more carbon than the atmosphere, even small changes in ocean chemistry could greatly affect global climate. Understanding how the oceanic carbon reservoir has evolved across changing climates is thus critical for both constraining mechanisms of climate change and predicting impacts from anthropogenic carbon addition. This dissertation contributes to knowledge of the ocean carbon reservoir’s evolution across the last 1.5 million years of Earth’s history, with a particular focus on two key intervals of climatic change: 1) Present day, when a large, human-sourced perturbation to the carbon cycle is underway, the effects of which are not yet fully realized; and 2) The mid-Pleistocene transition (MPT; ∼900,000 years ago), when natural cycles of global warming and cooling increased in intensity and duration. Without direct observations for both these time intervals, I focus on documenting changes to ocean carbon chemistry using proxies for seawater composition. The primary tools for this purpose are boron concentrations (B/Ca ratios) and the boron isotopic composition (δ11B) of carbonate skeletons produced by marine organisms. These tools are rooted in the aqueous chemistry of boron, in which the speciation and isotopic composition of boron compounds change with seawater pH. To test present-day changes in the oceanic carbon reservoir, I measured δ11B on the calcitic skeletons of deep-sea corals (genus Keratoisis). Results show that while coral δ11B does correlate with deep ocean pH, δ11B variations within coral skeletons are too large to be explained by changes in deep ocean pH over the corals’ lifespan. These variations most likely reflect the biology of the coral organism, suggesting that δ11B measurements in Keraotisis cannot be utilized to track ocean pH until coral growth mechanisms are better understood. To complement these δ11B data, I measured the radiocarbon (14C) content of Keratoisis skeletons. Results show that coral skeletal 14C tightly correlates to the 14C content of the deep ocean, and that bamboo corals live for 50 to 300 years with radial growth rates of 10 to 80 μm per year. This supports the use of 14C for generating bamboo coral ages and growth rates, and for tracking perturbations to the 14C content of the deep ocean. Through my deep-sea coral study, I learned the importance of accurate and precise δ11B measurements for sound interpretations of ocean carbon chemistry. These interpretations necessitate highly specialized analysis protocols. While two protocols are commonly applied for δ11B measurements, existing comparisons found relatively large offsets between both protocols. To trace the cause and implications of this offset, I established a new δ11B measurement protocol and performed an internal comparison between the new and existing measurement protocols. Results confirm that carbonate δ11B values are significantly offset between techniques. Although the nature of this offset remains enigmatic, I show that both techniques show the same δ11B-to-pH sensitivity, and consistent pH estimates are obtained when a protocol-specific constant offset is applied. This suggests that both δ11B analysis protocols can be applied for reconstructing pH with equal confidence. To test for changes in the ocean carbon reservoir across the MPT, I investigated the B/Ca and Cd/Ca composition of the benthic foraminifer Cibicidoides wuellerstorfi to track deep ocean carbonate saturation state (∆[CO32−]) and nutrient inventories. At 4.3 km water depth in the South Atlantic Ocean, B/Ca abruptly decreased by 20% and Cd/Ca increased by 40% between 950 and 900 ka, equivalent to a 60 μmol/kg increase in abyssal ocean carbon storage. Coincident shifts in deep ocean circulation and atmospheric pCO2 around 900 ka suggest that a new regime of deep ocean carbon sequestration developed during the MPT. I argue that this regime was intricately linked with the increased magnitude and duration of glacial cycles following the MPT.

Dimethylsulphoniopropionate (DMSP) and dimethylsulphoxide (DMSO) (collectively DMSP/O) are produced by marine algae, including symbiotic algae within corals. These sulphur compounds are important not only in sulphur cycle dynamics but also in potentially mediating atmospheric conditions, alleviating the effects of climate change and contributing to reef health. Most research has focused on the production of DMSP and its major degradation product, the climatically active gas, dimethylsulphide (DMS) by Acropora corals in the Great Barrier Reef. However, mechanisms for the production and release of DMSP/O by different reef taxa is poorly understood. Recently the importance of mesophotic reefs as refugia for shallow water corals has been postulated, however their role in the marine sulphur cycle is unknown. This research aimed to improve our understanding of the contemporary and climate change induced seawater and tissue production of DMSP/O in a range of reef environments and taxa. This was achieved through a combination of laboratory and field - based studies, using modern and established techniques. An effect of both elevated temperature and OA on increased tissue and seawater concentrations of DMSP/O production is reported in field and laboratory studies. Contrasting effects of benthic cover on tissue DMSP/O distributions and seawater DMSP are also noted. The importance of the physical and hydrodynamic environment on biogeochemical connectivity both within a reef and between neighbouring reefs is also focussed on. Crucially, however, the novel tissue and seawater data from mesophotic sites suggests that deeper reefs could affect the biogeochemistry of their shallow water counterparts. The key finding from this work is that climate change will result in increased seawater DMSP concentrations via two mechanisms; through the increase of cellular production of DMSP/O in all reef taxa, and by increasing the biomass of prolific DMSP producers as reefs transition to a fleshy/macroalgal assemblage. Whilst this could potentially mediate the effects of climate change, it will probably also worsen overall reef health, lead to a restructuring of reef communities from the microbial level upwards and will have possibly permanent and deleterious effects on overall ecosystem function.

Orientador: Lucila Chebel Labaki / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-09-11T21:19:20Z (GMT). No. of bitstreams: 1 Dacanal_Cristiane_D.pdf: 11178954 bytes, checksum: 264b1339c0c91df1787d0fd078e67c29 (MD5) Previous issue date: 2011 / Resumo: O processo de urbanização é causador de grandes impactos ambientais, dentre eles a extinção da vegetação nativa. Pouco se sabe sobre o efeito de fragmentos florestais no clima local urbano, apesar de haver um consenso em relação aos benefícios da vegetação na modificação do microclima e na melhoria dos níveis de conforto térmico humano. Este estudo tem como objetivos caracterizar o microclima de fragmentos florestais, remanescentes da Floresta Estacional Semidecidual, na cidade de Campinas-SP; quantificar a magnitude e a extensão do efeito de fragmentos florestais urbanos no clima do entorno edificado; e encontrar um percentual mínimo de área de fragmento florestal em relação à área total urbanizada que seja suficiente para modificar o clima local urbano. Para tanto, foram realizados monitoramentos fixos e móveis de variáveis climáticas na microescala e na escala local urbana. Os fragmentos florestais foram caracterizados por meio da abertura do dossel florestal, da área e com base em inventários. A paisagem urbana foi descrita a partir da classificação do uso do solo, sendo possível distinguir as zonas climáticas urbanas e o padrão da fronteira. Os resultados mostram que a estabilidade térmica aumenta com a área dos fragmentos florestais. Ocorrem diferenças térmicas e de umidade do ar no perfil vertical e horizontal das florestas, que são influenciadas pelo ambiente construído. Por outro lado, foi possível constatar que o efeito das florestas sobre a o clima local urbano aumenta com o percentual de área de floresta sobre o total urbanizado (A.V. / A.U.). Sugere-se uma porcentagem mínima de 20% de A.V. / A.U. No tecido urbano, recomenda-se a distribuição homogênea de fragmentos florestais, com formato regular, em uma distância de aproximadamente o dobro da largura média dos fragmentos / Abstract: The urbanization process causes major environmental impacts, among them the native vegetation extinction. Little is known about the effects of forest fragments in an urban environment, although there is a consensus regarding the benefits of vegetation in modifying the microclimate and improving the human thermal comfort. This study aims to characterize the microclimate of the forest fragments, remnants of Semideciduous Seasonal Forest, in the city of Campinas; to quantify the magnitude and extent of the effect of urban forest fragments in the climate of the surrounding buildings; and to find a minimum percentage of forest fragmentation area in relation to the total urbanized area which is sufficient to modify the local urban climate. Thus, observations of climate variables in both micro and local scales were made. The forest fragments were characterized by measurements of forest canopy openness, area and inventories. The urban landscape was described based on land use classification, being possible to distinguish the climatic urban zones and the frontier pattern. The results show that thermal stability increases with the area of forest fragments. There were differences of thermal and air humidity in the vertical and horizontal profile of forests, which are influenced by the built environment. On the other hand, it was possible to conclude that the effect of forests on the local urban climate increases along with the percentage of forest area over the total urbanized area (A.V. / A.U.). It was suggested a minimum percentage of 20% of A.V./A.U. It was recommended a homogenous distribution of forest fragments through the city, in a distance about a double of the medium fragments width / Doutorado / Arquitetura e Construção / Doutor em Engenharia Civil

O possível envolvimento de afídeos na transmissão de vírus associados à morte súbita dos citros (MSC) indica a necessidade de monitoramento desses insetos para melhor compreender sua dinâmica populacional e a epidemiologia da doença. Esta pesquisa teve como principal objetivo a determinação das principais espécies de afídeos que colonizam pomares de laranja doce [Citrus sinensis (L.) Osbeck] de um município afetado pela MSC, no Norte do Estado de São Paulo, bem como o estudo da dinâmica populacional destes insetos. Preliminarmente, padronizou-se uma metodologia de amostragem de afídeos, baseando-se em uma análise da distribuição espacial destes insetos na copa de árvores cítricas, em dois pomares de laranja doce, localizados em Comendador Gomes-MG e Santa Cruz do Rio Pardo-SP. Em cada pomar, delimitou-se um talhão com 960 plantas numeradas, no qual 100 plantas foram selecionadas ao acaso, para as avaliações. Cada árvore foi dividida em três estratos: i) inferior (0 - 1,0 m); ii) médio (1,0 - 1,8 m); e iii) superior (>1,8 m). Os estratos foram divididos em quadrantes (Leste, Oeste, Norte e Sul), amostrando-se uma brotação por quadrante, totalizando 12 brotações por planta. Através de análise de variância, observou-se efeito de planta e de estrato na densidade populacional dos afídeos, havendo menor número de afídeos no terço inferior em relação aos terços médio e superior da planta. Não houve efeito significativo de quadrantes nem da interação estrato x quadrante na estimativa populacional de afídeos. Definiu-se que a avaliação de uma brotação de cada quadrante do terço médio da copa, em 150 plantas, seria o procedimento mais adequado para o monitoramento de afídeos, visando-se ao estudo de dinâmica populacional. Utilizando-se este método de amostragem, iniciaram-se avaliações quinzenais de afídeos em dois talhões de laranja doce (‘Valência’ enxertada sobre limão ‘Cravo’) com idades diferentes (4 e 10 anos), no município de Nova Granada-SP, no período de abril/2003 a abril/2005. Simultaneamente, foram realizadas avaliações de brotações nas árvores cítricas, obtendo-se valores médios do número de brotações por m2 e do comprimento das brotações para cada talhão. Através de análises de regressão linear múltipla, os dados populacionais dos afídeos foram correlacionados com variáveis climáticas (temperaturas média, mínima e máxima; umidade relativa do ar e precipitação pluviométrica) registradas 30 dias antes da amostragem dos afídeos, e com variáveis fenológicas (comprimento das brotações e número de brotações/m²) registradas no dia da amostragem. Foram coletados afídeos das espécies Aphis gossypii Glover, A. spiraecola Patch e Toxoptera citricida Kirkaldy, com predominância de colônias de A. gossypii e A. spiraecola no pomar com 4 anos, e de colônias de T. citricida no pomar com 10 anos. A ocorrência desses afídeos em árvores cítricas coincide com períodos de brotações nos pomares, tanto em épocas de estiagem como em épocas de maior precipitação pluviométrica. O número de brotações cítricas/m², o comprimento das brotações e a temperatura são os fatores mais freqüentemente associados ao desenvolvimento das colônias de afídeos em árvores cítricas. A. gossypii, A. spiraecola e T. citricida mostram maiores picos de incidência de formas aladas em ramos cítricos nos meses de inverno (julho a setembro). As espécies T. citricida, A. gossypii e A. spiraecola diferem na capacidade de distorcer folhas e brotações cítricas, sendo que a última é a principal responsável por este tipo de dano direto. / Because aphids are possibly involved in the spread of viruses associated with a new and destructive disease, citrus sudden death (CSD), it is important to know their population dynamics in order to understand disease epidemiology. The goal of this research was to determine the main aphid species that colonize citrus groves [Citrus sinensis (L.) Osbeck] in CSD-affected areas of northern State of São Paulo, as well as to study their population dynamics. In order to establish procedures for sampling aphids that colonize citrus, a preliminary study of spatial distribution of these insects on the canopy of citrus trees was carried out in two sweet orange groves in Comendador Gomes-MG and Santa Cruz do Rio Pardo-SP. In each grove, 100 trees were randomly sampled in an experimental plot with 960 numbered plants. Each tree canopy was divided in three strata: i) lower (0 - 1,0 m); ii) medium (1,0 - 1,8 m); and iii) upper (>1,8 m). The canopy strata were subdivided in quadrants (E, W, N, S). Twelve young branches were sampled from each tree (1 per quadrant; 4 per stratum). By using analysis of variance, significant effects of plant and canopy stratum on aphid population were observed, with lower numbers of nymphs and adults found on the lower stratum than on the medium and upper strata. Aphid population was not influenced by quadrant or stratum x quadrant interaction. It was determined that sampling of 4 young branches (1 per quadrant) of the medium stratum from 150 citrus trees would be an adequate procedure for monitoring aphids on citrus trees, in order to obtain accurate population estimates for the population dynamics study. By using this sampling method, aphid surveys were carried out fortnightly in two sweet orange groves (‘Valência’ grafted on rangpur lime), 4 and 10 years old, in Nova Granada County, from April/2003 to April/2005. Simultaneous observations of mean number of young shoots/m2 of citrus canopy and mean shoot length were also conducted. By using multiple linear regression analysis, aphid numbers were correlated with local climatic variables (minimum, medium and maximum temperatures; relative humidity and rainfall) recorded 30 days before aphid sampling, as well as with phenological variables (mean number of young shoots/m2 and mean shoot length) recorded on the sampling date. Aphis gossypii Glover, A. spiraecola Patch, Toxoptera citricida Kirkaldy were the main aphid species sampled. A. gossypii and A. spiraecola were the prevalent species in the 4-year old grove, whereas T. citricida prevailed in the 10-year old grove. Aphid colonies were detected on citrus trees during periods of young shoot production, in different seasons, with either low (winter) or high (summer) rainfall. Mean number of young shoots/m2, mean shoot length and temperature were the main factors associated with aphid colony development on citrus trees. Peaks of A. gossypii, A. spiraecola and T. citricida alatae on citrus branches occurred during the winter months (July through September). A. spiraecola, A. gossypii and T. citricida differed in the ability to cause severe leaf deformation in the young shoots; this type of direct damage was mostly associated with colonies of the first species.

Urban water use arises from a mix of scale-dependent biophysical and socioeconomic factors. In Portland, Oregon, single-family residential water use exhibits a tightly coupled relationship with summertime weather, although this relationship varies with land use patterns across households and neighborhoods. This thesis developed a multilevel regression model to evaluate the relative importance of weather variability, parcel land use characteristics, and neighborhood geographic context in explaining single-family residential water demand patterns in the Portland metropolitan area. The model drew on a high-resolution panel dataset of weekly mean summer water use over five years (2001-2005) for a sample of 460 single-family households spanning an urban-to-suburban gradient. Water use was found to be most elastic with respect to parcel-scale building size. Building age was negatively related to water use at both the parcel and neighborhood scale. Half the variation in water use can be attributed to between-household factors. Between-neighborhood variation exerted a modest but statistically significant effect. The analysis decomposed household temperature sensitivity into four components: a fixed effect common to all households, a household-specific deviation from the fixed effect, a separate extreme heat effect, and a land use effect, where lot size exaggerated the effect of temperature on water use. Results suggested that land use planning may be an effective non-price mechanism for long-range management of peak demand, as land use decisions have water use implications. The combined effects of population growth, urbanization, and climate change expose water providers to risk of water stress. Modeling fine-grain relationships among heat, land use, and water use across scales plays a role in long-range climate change planning and adaptation.