One of the major challenges for agriculture today is to manage soil properties and their spatial distribution to optimize productivity and minimize environmental impacts, such as diffuse pollution. To identify best management practices, the effects of different agricultural management practices on pollutant sources, mobilization, transfer and delivery to water bodies need to be understood. Grasslands managed for dairy and meat production, despite being widespread, have received less research attention than other agricultural land uses. Therefore, this thesis studies the effects of different grassland management practices on soil properties and their spatial distribution and the mobilization and delivery of multiple diffuse pollutants. As a grassland case study, monitoring for this thesis was conducted across three fields (6.5 – 7.5 ha) on the North Wyke Farm Platform, a grassland experimental farm in the UK. First, the effects of permanent grassland management (permanent for at least 6 years, but different grassland management > 6 years ago) were characterized as a baseline, followed by quantifying the short-term effects of ploughing and reseeding of permanent grassland fields. Throughout those management periods, i) a range of soil physical (bulk density [BD]) and chemical (soil organic matter [SOM], total N [TN], total phosphorus [TP], total carbon [TC]) soil properties and their spatial distribution were sampled and analysed by geostatistics, and ii) hydrological characteristics and multiple pollutant fluxes (suspended sediment [SS] and the macronutrients: total oxidized nitrogen-N [TONN], total phosphorus [TP], and total carbon [TC]) were monitored at high temporal resolution (monitoring up to every 15 minutes). The permanent grassland fields (or areas within fields) can be considered to be functioning differently. Past management legacy (more than 6 years ago) has affected soil properties and their distribution with subsequent effects on sediment and macronutrient delivery from the fields to surface waters. Overall, permanent grasslands were found to contribute significantly to agricultural diffuse pollution. The estimated erosion and macronutrient losses were similar to or exceeded the losses reported for other grasslands, mixed land use and even arable sites, and sediment and TP concentrations exceeded those recommended by EU / UK water quality guidelines. Ploughing and reseeding did not homogenize spatial variation and did not override past management effects. Long-term management differences affected soil properties and altered soil processes, so that the fields subsequently responded differently to ploughing and reseeding. All nutrient concentrations were significantly reduced in the older grassland field (no ploughing for 20 years), but not in the younger grassland field (no ploughing for 6 years). Ploughing and reseeding significantly accelerated the losses of sediment and macronutrients and sediment, TP and TONN exceedance frequencies of EU / UK water quality guidelines increased. Additionally, ploughing and reseeding caused a shift in the relative importance of nutrients, by increasing the relative importance of N. Such large sediment and nutrient losses from intensively managed grasslands should be acknowledged in land management guidelines and advice for future compliance with surface water quality standards. The between-field and within-field variation highlights the importance of baseline characterization and paired catchment studies. The long-term effects of management still acting on soil properties and subsequently water quality indicates how long it may take to see soil and water quality improvements after implementing mitigation measures. Therefore, long-term management history always has to be included when interpreting soil and water quality data.

Originalmente, a teoria de nicho ecológico fundamenta-se em indivíduos de uma espécie sendo ecologicamente equivalentes por utilizarem os recursos de forma similar. Portanto, o nicho de uma espécie é definido em termos do uso médio de recursos. Porém, a qualidade e abundância de recursos consumidos, sexo, idade ou morfotipo do consumidor influenciam o comportamento alimentar individual. Estudos recentes sobre forrageamento ótimo tem foco de interesse na variação interindividual no uso de recursos. Ao longo da sua área de distribuição são reconhecidas populações da toninha Pontoporia blainvillei (Cetacea) e no litoral paulista, possivelmente hajam três subpopulações dessa espécie: norte, centro e sul. Meu primeiro objetivo foi investigar se há variação na dieta entre essas três subpopulações de toninha. Adicionalmente, investiguei quais fatores entre sazonalidade, sexo e idade dos indivíduos poderiam estruturar a dieta em uma dessas subpopulações (central). Utilizei 58 indivíduos provenientes de captura acidental no litoral paulista, com representantes das regiões norte, centro e sul. A amostra incluiu juvenis e adultos de ambos os sexos, capturados em todas as estações do ano. Identifiquei as espécies nos conteúdos estomacais usando os otólitos de peixes e os bicos de lulas. Estimei o tamanho das presas utilizando regressões com as medidas dessas estruturas e investiguei a estruturação da dieta usando um índice de variação da dieta. Houve uma clara variação na dieta ente as subpopulações paulistas, possivelmente devido à diferença espacial na disponibilidade de presas. Para a subpopulação central não houve variação na dieta decorrente da sazonalidade ou do sexo. A ausência de variação sazonal pode ser devido à pouca alteração na abundância da principal presa, P. harroweri, no ambiente ao longo do ano. A ausência de variação decorrente do sexo pode ser devido a seleção de presa estar mais relacionada a características de corpo mole e fácil digestão e não ao tamanho da presa, sendo essa seleção comum para ambos os sexos. Indivíduos de idades diferentes possuem dietas distintas, com juvenis consumindo mais espécies que os adultos. Essa mudança de nicho alimentar pode ser devida ao período de aprendizado. Finalmente, mesmo descontando os efeitos da disponibilidade temporal e espacial de presas, do sexo e da idade, houve variação interindividual da dieta na subpopulação central. Somente estudos com marcadores isotópicos poderão investigar se essa variação é devida à especialização individual em toninhas / Ecological niche theory is originally based on the assumption that individuals of a species use similar resources and therefore are ecologically equivalents. Under this framework, the niche of the species can be defined in terms of average resource use. However, factors such as quality and quantity of prey resources in the environment, consumer gender, age or morphotype may influence the individual feeding behavior. Considering that possible interindividual variation, recently studies under optimal foraging theory have variation among individuals as a focus of interest. The species P. blainvillei is partionated in populations along its range and probably, subpopulations can be found in the Sao Paulo state coast: northern, central and southern. Hence, my first goal was to investigate if there is diet variation among the three franciscana subpopulations from Sao Paulo coast. Additionally, I searched for which factors would be the diet structure defined within one of the subpopulations (the central one). I have considered the seasonality, individual gender and sex as possible factors influencing the diet structure within the central subpopulation. I had 58 franciscana specimens obtained from bycatch in the Sao Paulo coast, being them from northern, central and southern regions. They were juveniles and adults of both genders and bycaught in all the seasons. I identified the prey species from the gut contents with fish otholits and squid beaks. I estimated prey length and weight using regressions with that structures measures and I investigated the diet structure using a diet variation index. Within the central subpopulation I found no diet variation based on seasonality or individual gender, instead I found diet variation for individuals from different ages. Probably, most of the diet variation among subpopulations is due to prey availability spatial difference. The lack of diet variation based on seasonality may be due to little seasonal variation in the abundance of the main prey, P. harroweri. The lack of variation due to gender is probably related to the prey selection on soft body and easy digestion instead of prey size, being this type of selection common for both genders. Juveniles franciscana preyed on more species than the adults and that niche shift as an age effect can be consequence of forraging skills development. Enclosing, even discarding the effects of the spacial and temporal prey availability, individual gender and age, I found interindividual-level diet variation within the central subpopulation, which can points out to franciscana individual specialization, but isotopic studies are required to infer that specialization

Submitted by (lucia.rodrigues@ufrpe.br) on 2016-08-31T11:53:10Z No. of bitstreams: 1 Maria Amanda Menezes Silva.pdf: 547959 bytes, checksum: 467ca75982c62d926e339766fc3075fe (MD5) / Made available in DSpace on 2016-08-31T11:53:10Z (GMT). No. of bitstreams: 1 Maria Amanda Menezes Silva.pdf: 547959 bytes, checksum: 467ca75982c62d926e339766fc3075fe (MD5) Previous issue date: 2010-02-19 / The edge effects alter structure and vegetation dynamics in forest fragments, from the hypothesis was quantified the influence of edge in the canopy and understory of a fragment of Atlantic Forest in Igarassu, PE. We used two transects of 10 × 100 m, perpendicular to the edge and a 20 × 50 m within the fragment divided into plots of 10 × 10 m was collected soil samples from 0 to 20 cm depth for chemical and physical analysis. The sample was divided into edge (0-50m), an intermediate (50-100m) and interior (280 m from the tree line), measured and tagged all individuals living with stem diameter at breast height (DBH)> 4 , 77 cm. In one corner of the plots of 10 × 10 m plots were plotted for 5 × 5 m for analysis of understory woody, plants with stem diameter at ground level > 0.96 cm and <4.77 cm. The canopy had a higher number of individuals and greater wealth at the edge, while in the understory woody, number of individuals, basal area and richness were higher in the interior. The more dynamic, both in the canopy and the understory was inside due to the entry of individuals and the further growth of remaining. A canonical correspondence analysis showed that the soil did not affect the distribution of species. The results indicate that the edge of the fragment is sealed, since most of the assumptions raised were confirmed. / O efeito de borda altera estrutura e dinâmica da vegetação em fragmentos florestais, a partir da hipótese foi quantificada a influência de borda no dossel e no sub-bosque de um fragmento de Mata Atlântica em Igarassu, PE. Foram utilizados dois transectos de 10 × 100 m, perpendiculares à borda e um de 20 × 50 m no interior do fragmento, divididos em parcelas de 10 × 10 m, onde foram coletadas amostras de solo entre 0 e 20 cm de profundidade para análises químicas e granulométricas. A amostragem foi dividida em borda (0-50m), situação intermediária (50-100m) e interior (280 m do limite florestal), sendo medidos e etiquetados todos os indivíduos vivos com diâmetro do caule a altura do peito (DAP) > 4,77 cm. Em um dos vértices das parcelas de 10 × 10 m foram plotadas parcelas de 5 × 5 m para análise do sub-bosque lenhoso: plantas com diâmetro do caule ao nível do solo > 0,96 cm e DAP < 4,77 cm. O dossel apresentou maior número de indivíduos e maior riqueza na borda, enquanto que, no sub-bosque lenhoso, número de indivíduos, área basal e riqueza foram maiores no interior. A maior dinâmica, tanto no dossel quanto no sub-bosque, foi no interior, devido à entrada de indivíduos e o maior crescimento dos remanescentes. A análise de correspondência canônica mostrou que o solo não interferiu na distribuição das espécies. Os resultados indicam que a borda do fragmento encontra-se selada, uma vez que a maioria das premissas levantadas foram confirmadas.

Orientador: Paulo Sérgio Moreira Carvalho de Oliveira / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-17T09:19:12Z (GMT). No. of bitstreams: 1 Bottcher_Claudia_D.pdf: 2277526 bytes, checksum: fd9c885535eb1d45ead71daf14f43c8a (MD5) Previous issue date: 2010 / Resumo: A grande quantidade de frutos carnosos e a diversidade e abundância de formigas em ambientes tropicais faz com que a interação entre formigas e diásporos seja bastante comum. Atualmente sabe-se que estas interações envolvem dezenas de espécies de plantas e formigas em uma comunidade ecológica. Dentre as espécies da fauna de formigas que interagem com diásporos, Pachycondyla striata e Odontomachus chelifer destacam-se como dispersores de sementes caídas no solo e as características físicas e químicas de seus ninhos freqüentemente promovem o estabelecimento de plântulas. Contudo, apesar da reconhecida importância dessas formigas para algumas espécies de plantas, nada se sabe sobre a influência desses diásporos no desenvolvimento e reprodução de suas colônias. Com base nesse cenário, esta tese foi dividida em duas partes relacionadas. Na primeira parte, Capítulo I, investigamos as interações entre formigas e diásporos não-mirmecocóricos em três diferentes fisionomias florestais da Ilha do Cardoso (restinga, planície e encosta), sudeste do Brasil. Durante dois anos de amostras mensais 517 interações envolvendo 53 espécies de formigas e 48 espécies de diásporos foram observadas. A maior parte das interações ocorreu em floresta de planície (54.62%), e menos da metade ocorreu nas demais áreas, encosta (31.33%) e restinga (14.06%). Myrmicinae teve o maior número de espécies em interação (39 espécies), totalizando 436 interações (82.20%). Seis espécies da subfamília Ponerinae foram responsáveis por 33 interações (6,4%). Myrtaceae foi a família de planta mais numerosa nas interações (14 espécies). Na segunda parte da tese, capítulos II e III, foi dado ênfase às duas espécies de formigas da subfamília Ponerinae (Pachycondyla striata e Odontomachus chelifer) onde investigamos a importância dos frutos na ecologia de forrageamento e desenvolvimento das colônias. No capítulo II nós estudamos como a estrutura dos ninhos, demografia das colônias, ritmo diário de atividades, dieta e área de vida dessas espécies variam espacial e sazonalmente em restinga e planície. Operárias de O. chelifer e de P. striata caçam de modo oportunista incluindo uma ampla variedade de itens alimentares, forrageando mais intensamente no período úmido quando alados são mais abundantes e as condições ambientais são mais favoráveis. A atividade de forrageamento apresentou variação entre as espécies de formigas, o que poderia ser associada com fatores físicos e disponibilidade de alimentos, mostrando que o comportamento de forrageamento de O. chelifer e P. striata corresponde a variabilidade temporal e espacial da Mata Atlântica. Para testar a hipótese de que o consumo de diásporos não-mirmecocóricos beneficiaria colônias de formigas, no Capítulo III nós testamos o efeito do consumo de sementes de C. canjerana, com arilos ricos em lipídeos, em colônias de O. chelifer sob condições controladas em laboratório. Constatamos que larvas de formigas alimentadas com diásporos de C. canjerana foram em média maiores e se desenvolveram melhor que larvas controle. Em conclusão, os resultados desta tese reforçam a importância da dispersão secundária por formigas para sementes primariamente dispersas por vertebrados. Os dados evidenciam também a importância do estudo da ecologia de forrageamento e da influência do consumo de frutos na sobrevivência e crescimento de colônias de formigas. / Abstract: The large number of fleshy fruits and the diversity and abundance of ants in tropical environments makes the ant-diaspore interaction very common. Currently it is known that these interactions involve a large number of plants and ants species in an ecological community. Among the ant species interacting with diaspores, Pachycondyla striata and Odontomachus chelifer stand out as main dispersers of seeds encountered on the forest ground. Moreover, the physical and chemical characteristics of their nests often promote the establishment of seedlings. However, despite the recognized importance of these ants for some species of plants, nothing is known about the influence of the consumption of fleshy diaspores in the development and reproduction of the ant colonies. Based on this scenario, this thesis was divided into two related parts. In the first part, Chapter I, we investigated the interactions between ants and nonmyrmecochorous diaspores in three different physiognomic forest of Cardoso Island (sandy, lowland and hillside), southeastern Brazil. During two years of monthly samples 517 interactions involving 53 ant species and 48 species of seeds were observed. Most interactions occurred in lowland Forest (54.62%), and less than half occurred in the two other areas, hillside (31.33%) and sandy Forest (14.06%). Myrmicinae had the highest species number in interaction (39 species), totaling 436 interactions (82.20%). The six species of the Ponerinae subfamily were observed exploring diaspores accounted for 33 interactions (6.4%). Myrtaceae was the most numerous plant family in interactions (14 species). In the second part of this thesis, Chapter II and III, we emphasized two species of Ponerinae (Pachycondyla striata and Odontomachus chelifer), investigating the importance of fruits in their foraging ecology and the development of their colonies. In Chapter II we studied how nest structure, colonies demography, daily activities, diet and home range of these two species vary spatially and seasonally in sandy and lowland forest. Odontomachus chelifer and Pachycondyla striata workers hunt opportunistically including a wide variety of food items. They forage more intensively during the wet season when alates are more abundant and environmental conditions are more favorable. The foraging activity showed variation among the ant species, which could be associated with physical factors and food availability, showing that the foraging behavior of O. chelifer and P. striata correspond to temporal and spatial variability of the Atlantic Forest. To test the hypothesis that the consumption of non-myrmecochorous diaspores benefit ant colonies, in Chapter III we tested the effect of consumption of seeds of Cabralea canjerana, with lipid-rich arils, in colonies of O. chelifer under controlled laboratory conditions. We found that ant larvae fed with diaspores of C. canjerana were on average larger and grew better than control larvae. In conclusion, the data presented here reinforce the importance of secondary dispersal by ants for seeds primarily dispersed by vertebrates. Our results also indicate the importance of studying the foraging ecology and the influence of fruit consumption on survival and growth of colonies of ants. / Doutorado / Ecologia / Doutor em Ecologia

Submitted by Luanna Matias (lua_matias@yahoo.com.br) on 2015-03-26T13:29:15Z No. of bitstreams: 2 Tese - Deomar Plácido da Costa - 2014.pdf: 4099062 bytes, checksum: 621b8aac23edc39c2891c18ea16f400c (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luanna Matias (lua_matias@yahoo.com.br) on 2015-03-26T13:45:01Z (GMT) No. of bitstreams: 2 Tese - Deomar Plácido da Costa - 2014.pdf: 4099062 bytes, checksum: 621b8aac23edc39c2891c18ea16f400c (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-03-26T13:45:01Z (GMT). No. of bitstreams: 2 Tese - Deomar Plácido da Costa - 2014.pdf: 4099062 bytes, checksum: 621b8aac23edc39c2891c18ea16f400c (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-11-28 / Leaf entomofauna variation in eleven Caryocar brasiliense populations from central Brazilian Cerrado was analyzed based on total phenolic contents, as well as edaphic and spatial parameters of the sampling sites. Insects of the order Coleoptera had low occurrence in leaves that showed high levels of total phenols and tannins. However, they were found in leaves of plants growing on soils with higher micronutrient contents. Insects of the orders developed galls on plants with high levels of total and hydrolysable tannins. Hemiptera showed a homogeneous distribution, whereas species of the orders Neuroptera, Diptera, and Orthoptera behaved as visiting insects, without establishing any relationship with C. brasiliense during field observations. Approximately 97% of the entomofauna variability was explained by edaphic, chemical, and spatial data sets as predictor variables, whose contributions were 64.5%, 22.7%, and 60.6% of the total variation, respectively. Most of the residual variance (2.9%) was attributed to the anthropization of sampling sites. / A variação da entomofauna nas folhas de onze populações de Caryocar brasiliense do centro Cerrado brasileiro foi analisada com base no teor de compostos fenólicos totais, bem como de parâmetros edáficos e espaciais dos locais de amostragem. A ordem de insetos Coleoptera apresentou uma baixa ocorrência em folhas que continham altos níveis de fenóis totais e taninos. No entanto, eles foram encontrados em folhas de plantas que cresceram em solos com teores de micronutrientes mais elevados. Insetos da ordem Hymenoptera formou galhas em plantas com altos níveis de taninos totais e taninos hidrolisáveis. Hemiptera mostrou uma distribuição homogênea, enquanto que as espécies das ordens Neuroptera, Diptera e Orthoptera se comportaram como insetos visitantes, sem estabelecer qualquer relação com C. brasiliense durante as observações de campo. Aproximadamente 97% da variabilidade da entomofauna podem ser explicadas pelos conjuntos de dados edáficos, químicos e espaciais como variáveis preditoras, cujas contribuições foram de 64,5%, 22,7% e 60,6% da variação total, respectivamente. A maior parte da variância residual (2,9%) foi atribuída à antropização nos locais de amostragem.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A produção de liteira fina foi monitorada em 15 parcelas permanentes da grade do Programa de Pesquisas em Biodiversidade (PPBio) localizada no Parque Nacional do Viruá, Roraima. Foram instalados 5 coletores de 0, 25 m2 por parcela, monitorados em intervalos quinzenais de fevereiro de 2012 a fevereiro de 2013. Após a coleta, as amostras foram secas em estufa a 60o C até o peso constante, separadas e pesadas em diferentes frações: folhas, galhos menores do que 2 cm de diâmetro, flores, frutos/sementes e material não-identificado. O estudo investigou (i) a relação entre a produção mensal de liteira fina e a precipitação mensal e (ii) o efeito da variação espacial na textura e fertilidade do solo na produção de liteira fina. A produção total de liteira fina variou de 5, 86 t ha ano a 12, 10 t ha ano com média de 8, 83 t ha ano. A fração foliar contribuiu com 66, 55% da produção total, seguida por galhos (21, 94%), frutos (6, 32%), flores (2, 96%) e material não identificado (2, 23%). A produção mensal de liteira fina não foi correlacionada com a precipitação mensal (rs = 0, 27; p = 0, 33). Somente a produção de frutos/sementes (rs= 0, 13; p = 0, 05) e galhos (rs= 0, 20; p < 0, 01) foi correlacionada com a precipitação. A variação espacial na produção de liteira fina não foi relacionada com a textura ou fertilidade do solo na Campinarana. Da mesma forma, não houve relação entre a produção de liteira fina e a textura do solo na Floresta ombrófila. Entretanto, houve uma relação positiva entre a produção e a fertilidade do solo na floresta (r = 0, 39; p = 0, 05). A abertura do dossel afetou a produção de liteira fina, mas seu efeito foi dependente da fitofisionomia. Em áreas de floresta ombrófila, a produção não foi relacionada a abertura do dossel. Por outro lado, em áreas de campinarana, a produção da liteira fina foi diretamente relacionada a abertura do dossel (r = 0, 93; p = 0, 01). / Annual production of fine litter was measured between February 2012 and February 2013 in a campinarana-terra-firme forest ecotonein Viruá National Park, Roraima. This study investigated the relationship between the monthly production of fine litter and monthly precipitation, and evaluated the effect of spatial variation in texture and soil fertility in the production of fine litter. The production of fine litter was monitored in 15 1-hectare permanent plots located in the grid of Brazilian Biodiversity Research Program (PPBio). Five 0. 25m2 litter collectors were installed in each plot and were monitored bimonthly. After collection, samples were dried at 60o C for 48 hours, separated into different fractions (leaves, branches thinner than 2 cm in diameter, flowers, fruits/seeds and materials not identified) and weighed. The total production of fine litter ranged from 5, 86 t /ha/year to 12, 10 t/ ha/ year with an average of 8, 83 t/ ha/ year. There were no significant differences between the annual production of fine litter in areas of terra-firme forest and campinarana. Most of the litter was composed of leaves which represented 66, 55% of the total, followed by twigs (21, 94%), fruits (6, 32%), flowers (2, 96%) and unidentified materials (2, 23%). Monthly production of fine litter was not correlated with monthly rainfall (rs = 0, 27, p = 0, 33). Only the production of fruits / seeds (rs = 0, 13, p = 0, 05), and branches (rs = 0, 20, p <0, 01) was correlated with precipitation. The spatial variation in litter production was not related to texture or soil fertility in the campinarana. Likewise, there was no relationship between the production of fine litter and texture in the terra-firme forest. However, there was a relationship between production and soil fertility (r = 0, 39; p = 0, 05). Canopy openness affected the production of fine litter, but its effect was dependent on the vegetation type. In areas of terra-firme forest, the production was not related to canopy openness. On the other hand, in the campinarana production was directly related to canopy openness (r = 0, 93; p = 0, 01).

Originalmente, a teoria de nicho ecológico fundamenta-se em indivíduos de uma espécie sendo ecologicamente equivalentes por utilizarem os recursos de forma similar. Portanto, o nicho de uma espécie é definido em termos do uso médio de recursos. Porém, a qualidade e abundância de recursos consumidos, sexo, idade ou morfotipo do consumidor influenciam o comportamento alimentar individual. Estudos recentes sobre forrageamento ótimo tem foco de interesse na variação interindividual no uso de recursos. Ao longo da sua área de distribuição são reconhecidas populações da toninha Pontoporia blainvillei (Cetacea) e no litoral paulista, possivelmente hajam três subpopulações dessa espécie: norte, centro e sul. Meu primeiro objetivo foi investigar se há variação na dieta entre essas três subpopulações de toninha. Adicionalmente, investiguei quais fatores entre sazonalidade, sexo e idade dos indivíduos poderiam estruturar a dieta em uma dessas subpopulações (central). Utilizei 58 indivíduos provenientes de captura acidental no litoral paulista, com representantes das regiões norte, centro e sul. A amostra incluiu juvenis e adultos de ambos os sexos, capturados em todas as estações do ano. Identifiquei as espécies nos conteúdos estomacais usando os otólitos de peixes e os bicos de lulas. Estimei o tamanho das presas utilizando regressões com as medidas dessas estruturas e investiguei a estruturação da dieta usando um índice de variação da dieta. Houve uma clara variação na dieta ente as subpopulações paulistas, possivelmente devido à diferença espacial na disponibilidade de presas. Para a subpopulação central não houve variação na dieta decorrente da sazonalidade ou do sexo. A ausência de variação sazonal pode ser devido à pouca alteração na abundância da principal presa, P. harroweri, no ambiente ao longo do ano. A ausência de variação decorrente do sexo pode ser devido a seleção de presa estar mais relacionada a características de corpo mole e fácil digestão e não ao tamanho da presa, sendo essa seleção comum para ambos os sexos. Indivíduos de idades diferentes possuem dietas distintas, com juvenis consumindo mais espécies que os adultos. Essa mudança de nicho alimentar pode ser devida ao período de aprendizado. Finalmente, mesmo descontando os efeitos da disponibilidade temporal e espacial de presas, do sexo e da idade, houve variação interindividual da dieta na subpopulação central. Somente estudos com marcadores isotópicos poderão investigar se essa variação é devida à especialização individual em toninhas / Ecological niche theory is originally based on the assumption that individuals of a species use similar resources and therefore are ecologically equivalents. Under this framework, the niche of the species can be defined in terms of average resource use. However, factors such as quality and quantity of prey resources in the environment, consumer gender, age or morphotype may influence the individual feeding behavior. Considering that possible interindividual variation, recently studies under optimal foraging theory have variation among individuals as a focus of interest. The species P. blainvillei is partionated in populations along its range and probably, subpopulations can be found in the Sao Paulo state coast: northern, central and southern. Hence, my first goal was to investigate if there is diet variation among the three franciscana subpopulations from Sao Paulo coast. Additionally, I searched for which factors would be the diet structure defined within one of the subpopulations (the central one). I have considered the seasonality, individual gender and sex as possible factors influencing the diet structure within the central subpopulation. I had 58 franciscana specimens obtained from bycatch in the Sao Paulo coast, being them from northern, central and southern regions. They were juveniles and adults of both genders and bycaught in all the seasons. I identified the prey species from the gut contents with fish otholits and squid beaks. I estimated prey length and weight using regressions with that structures measures and I investigated the diet structure using a diet variation index. Within the central subpopulation I found no diet variation based on seasonality or individual gender, instead I found diet variation for individuals from different ages. Probably, most of the diet variation among subpopulations is due to prey availability spatial difference. The lack of diet variation based on seasonality may be due to little seasonal variation in the abundance of the main prey, P. harroweri. The lack of variation due to gender is probably related to the prey selection on soft body and easy digestion instead of prey size, being this type of selection common for both genders. Juveniles franciscana preyed on more species than the adults and that niche shift as an age effect can be consequence of forraging skills development. Enclosing, even discarding the effects of the spacial and temporal prey availability, individual gender and age, I found interindividual-level diet variation within the central subpopulation, which can points out to franciscana individual specialization, but isotopic studies are required to infer that specialization

The seasonal variation and landscape regulation of dissolved organic carbon (DOC) concentrations in streams have been studied in two watersheds in the boreal zone. The seasonal variation was found to be highly correlated to variations in runoff. An increase in runoff was always accompanied with an increase in DOC concentration. However, there were indications that the TOC concentration was restricted by the soil TOC pool during snowmelt. The main factors affecting DOC exports varied between seasons. During winter baseflow the spatial variation in DOC exports was strongly influenced by wetland coverage, during snowmelt the exports were correlated to factors describing the size and location of the catchment, and during the snow-free season they were heavily affected by the proportions of wetlands and forests in the catchments. Small headwaters had the highest terrestrial DOC export, per unit area. The properties of the DOC changed during spring flood, towards lower molecular weight and more aliphatic compounds. These changes affected the bioavailability of the DOC, which increased during spring flood. There were also differences in the DOC properties between wetlands and forest soils; the forested soils yielded DOC with lower molecular weight (measured as 254 nm/365 nm light absorbance ratios), largely from superficial layers that were activated during high flow events, while wetland soils generally provided a more constant carbon source with higher molecular weight. The majority of the DOC was exported by wetlands, but most of the short-term bioavailable DOC (BP7) was derived from the forests, during the spring flood period, indicating that bacterial production in streams and lakes is likely to be almost entirely based on DOC exported from forested areas during, and some time after, the spring flood event.

La variation spatiale du mouvement sismique a des effets significatifs sur la réponse dynamique des structures de génie civil de grandes dimensions. Dans la pratique courante, l'excitation du mouvement sismique le long de la fondation de la structure est considérée uniforme, approche cependant inadéquate pour les structures de large portance au sol localisées à proximité des failles ou sur des sites présentant une structure du sous-sol latéralement hétérogène. Cette thèse se propose donc de comprendre les facteurs clefs contrôlant localement la variabilité spatiale du mouvement sismique, avec en ligne de mire la mise en place de recommendations en vue d'incorporer ces effets dans l'estimation de l'aléa sismique et le dimensionnement des structures. La première partie de cette thèse s'intéresse à la composante intra-évènement de l'écart-type de la distribution du mouvement sismique en champ proche à l'aide de simulations numériques du mouvement sismique pour des sources étendues présentnat une cinématique de rupture réaliste. Les résultats suggèrent que la variabilité intra-évènement dépend significativement du type de rupture, cette variabilité augmentant avec la distance pour les ruptures bilatérales et diminuant pour les ruptures unilatérales. La seconde partie traite de la caractérisation de la composition du champ d'onde dans la vallée de Koutavos-Argostoli, qui est une vallée de petite dimension et d'épaisseur sédimentaire faible, située sur l'île – sismiquement active - de Céphalonie en Grèce. Les champs d'onde générés par 46 séismes, ayant des magnitudes variant entre 2 et 5 et des distances épicentrales jusqu'à 200 km, ont été analysés à partir de l'enregistrement par deux réseaux denses de capteurs sismologiques. L'algorithme de traitement d'antenne MUSIQUE est utilisé pour extraire la vitesse, l'azimut, le type et la polarisation des ondes dominantes se propageant à travers le réseau. Les résultats montrent clairement d'importantes diffractions d'ondes de surface aux bords de vallée au-delà de la fréquence de résonance de la vallée. Tandis que les ondes de Love dominent clairement le champ d'ondes proche de la fréquence de résonance, les ondes de Rayleigh dominent à plus haute fréquence dans des gammes de fréquences étroites. Par ailleurs, un excellent accord est observé entre les champs d'onde de surface diffractés localement et les caractéristiques d'amplification du site. La “cohérence décalée” de la partie la plus énergétique du signal a été quantifiée pour chaque paire de stations du réseau. En général, la cohérence calculée sur les composantes horizontales diminue avec la distance entre stations et la fréquence. La cohérence sur la composante verticale indique des valeurs relativement fortes à haute fréquence. Les valeurs de cohérence apparaissent très faiblement corrélées à la magnitude, l'azimut et la distance épicentrale du séisme, mais sont au contraire liées aux caractéristiques géométriques de la vallée. La coherence est systématiquement plus forte pour les couples de capteurs orientés selon la direction parallèle à l'axe de la vallée, et moins forte pour des couples de capteurs orientés dans la direction perpendiculaires. Cette observation est en accord avec les résultats du traitement d'antenne: la prédominance d'ondes de surface diffractées sur les bords de la vallée conduit à des mouvements en phase le long de la direction parrallèle à l'axe de la vallée. Les résultats de cette thèse apporte des elements de compréhension sur la variabilité spatiale du movement sismique et ouvrent de nombreuses perspectives d'application. / Spatial variation of earthquake ground motion over short distances significantly affects the dynamic response of engineered structures with large dimensions. In current practices, the ground motion excitation across the foundation of a structure is assumed to be spatially uniform, which becomes inadequate for spatially extended structures in the near-fault region or on sites with lateral inhomogeneity. This PhD thesis seeks to understand the key parameters that locally control the ground motion spatial variability with the intent of putting forth practical propositions for incorporating such effects in seismic design and hazard assessment. The first part of the thesis addresses the within-event component of the standard deviation of ground-motion distribution in near source region by means of numerical simulation of ground motions for extended sources with realistic rupture kinematics. The results suggest that the within-event variability significantly depends on the rupture type, depicting an increase with distance for bilateral ruptures and a decrease for unilateral ruptures. The second part deals with the characterization of seismic wave field at the Koutavos-Argostoli site, a small-size, shallow, alluvial valley located in the seismically active Cephalonia Island in Western Greece. The seismic wave field was investigated from the recordings of a dense seismological array for a set of 46 earthquakes, with magnitude 2 to 5 and epicentral distance up to 200 km. The MUSIQUE array analysis algorithm was used to extract the phase velocity, back-azimuth, type and polarization of the dominant waves crossing the array. The results clearly indicate dominant scattering of seismic surface waves, mainly from the valley-edge directions, beyond the fundamental frequency of the valley. While Love surface waves clearly dominate the wave field close to the resonance frequency, Rayleigh waves strongly dominate only in relatively narrow frequency bands at higher frequency. Besides, an excellent consistency is observed between the dominance of the identified surface wave type in the wave field and the site amplification. The "lagged coherency" of the most energetic part of the ground motion has been quantified for each station-pair within the array. In general, spatial coherency estimated from the horizontal components exhibit decays with frequency and interstation distance. Estimates from the vertical component exhibit rather larger values at some higher frequencies. Although coherency does not show any consistent trend indicating dependence on the magnitude, back-azimuth or site-to-source distance of the event, it seems to be primarily controlled by the site geometry. Larger coherency is systematically observed when the station pair is oriented parallel to the valley axis, while lower values are observed in the perpendicular direction. This observation proves to be consistent with the MUSIQUE analysis results: the predominance of scattered surface waves propagating across the valley implies an in-phase motion along valley-parallel direction and out-of-phase motion along valley-perpendicular direction. The findings of the present research are expected to contribute in enhancing our understanding of spatial variability of ground motion and improving the coherency models used in engineering. This work also opens up new insights and many questions in need of further investigation.

The strength and direction of interactions between organisms vary spatially across the landscape. Traditionally, the focus has been on how trait variation affects the interactions between species. However, differences in abiotic and biotic environmental factors may also alter the distribution, phenology and behavior of the interacting species. To be able to understand why an interaction varies across the landscape, the effects of trait variation has to be separated from the effects of the environmental context. In this thesis, I try to separate the effects of context and trait differences on plant resistance against herbivory, through experimental and observational studies conducted with two cytotypes of the perennial herb Cardamine pratensis and its main herbivore, Anthocharis cardamines. The results show that differences in plant resistance against oviposition under controlled conditions were mainly mediated by flower size; larger flowers were more attractive to the female butterfly. However, among-populations differences in oviposition under natural conditions were not related to the resistance observed under controlled conditions, or to ploidy type, flowering phenology or plant size. Within populations under natural conditions the oviposition patterns by A. cardamines was affected by the plant traits plant size and flowering phenology. The result of this thesis shows that among-population differences in intensity of plant-herbivore interactions were caused by differences in environmental context rather than by herbivore preferences for any phenotypic plant traits, while host plant selection within population was based on plant traits. This suggests that biotic and biotic context can have important effects on the intensity of plant-herbivore interactions. Although genetic traits influenced the outcome of the interaction within populations, it was the environmental context of the populations that determined largely if the interaction took place or not. / <p>At the time of the doctoral defence the following papers were unpublished and had  a status as follows: Paper 2: Manuscript in review in Plos One; Paper 3: Manuscript in review in <em></em>Ecological Entomology; Paper 4: Manuscript</p>