Teses / dissertações sobre o tema "Habitat (écologie) – Modèles mathématiques"
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El, Maksoud Walid. "Estimation de fonctions de sélection des ressources : échantillonnage et analyse de données". Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28356/28356.pdf.
Texto completo da fontePichancourt, Jean-Baptiste. "Modéliser la dynamique de population à différents niveaux d'observation, et le long de gradients d’évolution du paysage : le cas d'Abax parallelepipus (Coleoptera, Carabidae)". Rennes 1, 2006. http://www.theses.fr/2006REN1S102.
Texto completo da fontePuzin, Charlène. "Influence of habitat configuration on arthropod life history traits : a multi-scale approach in spatially structured systems". Paris, Muséum national d'histoire naturelle, 2014. http://www.theses.fr/2015MNHN0002.
Texto completo da fonteVariations in organism life history traits allow assessing the impact of human activities on individual biology, but also on entire populations. Human activities actually modify the landscape configuration of an environment: habitat surface and degree of isolation, habitat and surrounded matrix suitability… Salt marshes, because of their rare, linear and fragmented configuration along coasts and their fragmented condition due to human activities, are thus ideal systems to study the influence of habitat configuration on life history traits of arthropods that inhabit them, at both population and community levels. These species, according to their ecological preference in terms of habitat and diet, their size, or their dispersal ability, indeed react in different ways in terms of fitness and abundance
Benouari, Ouassima. "Critère de sélection de variables pour les modèles de régression logistique conditionnelle mixte lorsque la structure des effets aléatoires est inconnue". Master's thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/36598.
Texto completo da fonteWe assess the perfomance of the recently proposed criterion meanAIC as a variable selection criterion for mixed conditional logistic regression models. It is a criterion based on Akaike’s information, computable when the model is fitted with a two-step estimation method. In addition, the calculation of meanAIC does not require the specification of the random effects structure; it is thus of great use as a first covariates filter in the early stage of the analysis when the random effects structure is typically unknown. This work is motivated by applications in ecology where the model selection is traditionally based on information criteria rather than on regularization. These studies use animal movement telemetric data collected using a matched case-control sampling design that are analyzed with a mixed conditional logistic regression model. We conduct a simulation study to assess the ability of meanAIC to correctly identify potentially important covariates and illustrate its use by analyzing habitat selection data collected on caribou.
Violet, Clément. "Approches quantitatives pour comprendre et prédire l'écologie, la distribution et la biodiversité des habitats benthiques dans l'Anthropocène". Electronic Thesis or Diss., Brest, 2023. http://www.theses.fr/2023BRES0092.
Texto completo da fonteThis thesis aims at better understanding and predicting coastal benthic biodiversity with a specific focus on the role of biogenic habitats in maintaining ecosystem structure and functioning. This thesis explored how different innovative and complementary numeric tools and pipelines can address these objectives at different scales: 1) joint species distribution modelling across two biogenic habitats at a regional scale, and 2) using Machine Learning approaches, defining and modelling the distribution of benthic habitats states at a global and at a national scale. These complementary approaches quantify the relative influence of the environmental and anthropogenic factors (including marine heatwaves and fishing intensity) that determinecoastal biodiversity and the state of benthic habitats. While in both case studies the predictability of the considered species or states was low, these studies have identified future avenues to optimise models inference and prediction of benthic communities. Thus, this thesis provides a critical perspective on existingapproaches available to study and characterise coastal biodiversity; and on the future developments required to better anticipate future ecological responses related to anthropogenic impacts
Prima, Marie-Caroline. "Utilisation de l'espace par les grands herbivores dans un environnement hétérogène et dynamique : méthodologie et applications". Doctoral thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/34748.
Texto completo da fonteIn my thesis, I develop mechanistic models of space use based on animal movement, to understand and to predict population distribution in heterogeneous and dynamic landscapes. Used and developed methodologies couple mathematical modelling of the spatio-temporal dynamics of animal movement together with statistical analysis of simulated and empirical movement datasets. In my first chapter, I proceed in a series of simulations to clarify how many clusters are needed when using generalized estimating equations to correctly account for the correlation in movement data and to obtain robust inference on habitat selection. My simulations reveal that 30 independent individuals, each assigned to a cluster, are sufficient to avoid biased evaluation of the uncertainty on habitat selection along movement in heterogeneous environments. When less than 30 individuals are available, destructive sampling can be used but solely when temporal correlation is present and inter-individual heterogeneity is low in the data. In my second chapter, I develop a statistical movement model that allows to identify successive behavioral phases (e.g., foraging phase, inter-patch movement) together with behavior-specific habitat selection parameters, over the whole population and using temporally irregular data. Analysis of simulated and empirical movement data from three large herbivores including plains bison (Bison bison bison), mule deer (Odocoileus hemionus) and plains zebra (Equus quagga) show the robustness and the high predictive capacity of the model. This statistical tool is also flexible since I assess multiple ecological processes from those datasets such as foraging behavior, migratory behavior or prey-predator interactions. In addition, I show how accounting for behavioral phases in habitat selection analysis is crucial to correctly characterize habitat selection along animal movement. In my third chapter, I develop a mathematical framework to couple movement of individuals among a network of resource patches with residency time in patches to mechanistically predict space use in heterogeneous landscapes. In addition, I illustrate a methodology to identify and predict the most representative theoretical network for the target species. I show from model application on data of plains bison that the theoretical network topology is crucial to correctly infer population space use and implement realistic management and conservation planning. In my chapter 4, I empirically assess the robustness of a network of resource patches following landscape fragmentation from anthropogenic source. The analysis shows that woodland caribou (Rangifer tarandus caribou) reconnect some patches, thus causing robustness in their spatial networks. However, predictions on space use from the mechanistic model developed in chapter 3 reveal that, despite the rewiring, patch use change following the fragmentation. Moreover, this change is stronger when the most connected patches (i.e., the hubs) are impacted. My thesis provides a methodological contribution to better account for correlation in movement data and integrate behavioral phases in habitat selection analysis in heterogeneous landscapes. Besides, my work links network theory and space use to mechanistically predict population distribution in heterogeneous and dynamic environments. My research also assesses the context in which network theory can be applied to spatial ecology. Finally, my thesis improves our mechanistic understanding of animal movement in four species of large herbivores.
De, Cubber Lola. "Etude des traits de vie de annélides polychète Arenicola marina et A. defodiens : développement d’un modèle de type "Dynamic Energy Budget" (DEB) et conservation de ces espèces". Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1R052.
Texto completo da fonteArenicola spp. are marine benthic polychaetes displaying a complex bentho-pelagic life cycle with two larval dispersal phases, only partially described up to now, and intensively dug for bait by anglers on many foreshores of the Eastern English Channel. Without regulation, this activity can lead to the decrease of lugworms’ population while affecting the physical characteristics of the beach and the associated biodiversity. First, we identified through morphology and genetics two species of lugworms, Arenicola marina and A. defodiens, and assessed their abundance and spatial distribution at four studied sites, as well as some life-history traits such as the spawning periods and the size at first maturity. These data were compared to lugworms’ collection data to estimate its sustainability and to provide potential management measures (De Cubber et al., 2018). At one studied site, A. marina was present in large numbers on the higher and middle shore, whereas A. defodiens occupied the lower shore. At the other sites, both species cooccurred on the lower shore, and A. marina individuals were less numerous and lacking recruits. Spawning periods for A. marina occurred in early autumn and in late autumn for A. defodiens. One site appeared in need for management when linking abundance data with bait collection, where harvest was above the carrying capacity of the beach for A. marina. Second, a Dynamic Energy Budget (DEB) model was applied to the species combining the former as well as new field data, experimental data (growth and oxygen consumption data), and literature data in order to reconstruct the life cycle and growth of A. marina under in situ environmental conditions (De Cubber et al., in press). The reconstruction of the early life-stages chronology by the DEB model for A. marina according to in situ environmental conditions indicated a first dispersal phase of 5 days followed by a 7 months’ temporary settlement before a second dispersal phase in spring, at the end of metamorphosis, which appeared consistent with field observations. Finally, we followed-up the population size structure of A. marina at one studied site during 1.5 year to explore the down shore migration of lugworms recorded by several authors. To do so, we adapted a sediment temperature model from a mud temperature model (Guarini et al., 1997), measured the nitrogen content and tested several proxys for the food sources. The metabolic responses of lugworms to food (scaled functional response) and temperature (temperature tolerance range and Arrhenius temperature) were then assessed. We combined those data with the former DEB model to explore the effects of the fine changes in temperature and food conditions met by the individuals along the foreshore gradient and according to the depth of their galleries. The follow-up of the population size structure of A. marina showed clearly a migration pattern. The effect of sediment temperature alone when migrating did not allow significantly higher growth and egg production, while an increase of food concentrations down the shore did. Other factors might be taken in consideration in further studies such as desiccation and anaerobic metabolism during emersion periods at low tide. All these data constitute valuable information for conservation managers to better understand and regulate the lugworm populations. Further combination of the DEB model developed in this study with an individual-based model and a larval dispersal model could enable to understand the dynamics of the local lugworm populations
Capra, Hervé. "Amélioration des modèles prédictifs d'habitat de la truite Fario : échelles d'échantillonnage : intégration des chroniques hydrologiques". Lyon 1, 1995. http://www.theses.fr/1995LYO10306.
Texto completo da fonteMercier, Pascal. "Etude des relations espèces-environnement et analyse de la co-structure d'un couple de tableaux". Lyon 1, 1991. http://www.theses.fr/1991LYO10140.
Texto completo da fonteLaurence, Edward. "La résilience des réseaux complexes". Doctoral thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/66989.
Texto completo da fonteReal complex systems are often driven by external perturbations toward irreversible transitions of their dynamical state. With the rise of the human footprint on ecosystems, these perturbations will likely become more persistent so that characterizing resilience of complex systems has become a major issue of the 21st century. This thesis focuses on complex systems that exhibit networked interactions where the components present dynamical states. Studying the resilience of these networks demands depicting their dynamical portraits which may feature thousands of dimensions. In this thesis, three contrasting methods are introduced for studying the dynamical properties as a function of the network structure. Apart from the methods themselves, the originality of the thesis lies in the wide vision of resilience analysis, opening with model-based approaches and concluding with data-driven tools. We begin by developing an exact solution to binary cascades on networks (forest fire type) and follow with an optimized algorithm. Because its practical range is restricted to small networks, this method highlights the limitations of using model-based and highly dimensional tools. Wethen introduce a dimension reduction method to predict dynamical bifurcations of networked systems. This contribution builds up on theoretical foundations and expands possible applications of existing frameworks. Finally, we examine the task of extracting the structural causesof perturbations using machine learning. The validity of the developed tool is supported by an extended numerical analysis of spreading, population, and neural dynamics. The results indicate that subtle dynamical anomalies may suffice to infer the causes of perturbations. It also shows the leading role that machine learning may have to play in the future of resilience of real complex systems.
Chiarello, Ernest. "Pyramide stochastique et écologie du paysage : modélisation des structures spatiales par images de synthèse". Lyon 1, 1994. http://www.theses.fr/1994LYO10078.
Texto completo da fonteFaivre, Bruno. "Coexistence et écologie de deux espèces jumelles d'hippolais". Dijon, 1992. http://www.theses.fr/1992DIJOS014.
Texto completo da fonteLeger, Jean-Benoist. "Modelling the topology of ecological bipartite networks with statistical models for heterogeneous random graphs". Paris 7, 2014. http://www.theses.fr/2014PA077185.
Texto completo da fonteAn ecological network is a representation of the whole set of interactions between species in a given context. Ecological scientists analyse the topological structure of such networks, in order to understand the underlying processes. The identification of sub-groups of highly-interacting species (usually called communities, or compartments) is an important stream of research. The most popular method for the search of communities in ecological networks is the modularity optimization method. However this popularity is more due to the first paper published on this topic than to a rational choice based on solid grounds. There are many other clustering methods that could be used to delimit communities in ecological networks. The analysis of complex networks is indeed a rapidly growing topic with many applications in several scientific fields. To our knowledge, no comparison of different clustering methods is available in the case of ecological networks. Here we reviewed the whole set of methods available for clustering networks and we compared them using an ecological benchmark. In order to assess the relative contribution of several processes to the network structure, we integrated exogenous information in the clustering model. We analysed two bipartite antagonistic networks with this method, a tree-fungus and tree-insect network. The results are still preliminary but the method seems to us very promising for future ecological studies. Finally we searched communities in a different kind of network, a mating network between individuals belonging to two hybridizing tree species. We used our results to discuss a concept which is central in ecology, the species concept
Blanc, Laurence. "Données spatio-temporelles en écologie et analyses multitableaux : examen d'une relation". Lyon 1, 2000. http://www.theses.fr/2000LYO10044.
Texto completo da fonteDelattre, Thomas. "Influence de la structure du paysage et des conditions météorologiques sur le comportement de dispersion de Maniola jurtina (Lepidoptera : Nymphalidae, L. ) dans un agroécosystème bocager". Rennes 1, 2010. http://www.theses.fr/2010REN1S217.
Texto completo da fonteDispersal is the movement of individuals with potential consequences on gene flow. The distribution patterns of metapopulations and communities in the landscapes result from the inter and intra-individual variations of dispersal. The selection pressures due to human-driven landscape changes cause the apparition of specific movement strategies, with a growing contrast between strategies adapted to resource searching inside patches, and patch searching inside landscapes. The quantitative analysis of M. Jurtina dispersal behaviour allowed us to highlight a strategy adapted to long distance dispersal, the “direct moves”, which is different from the “foray loops” strategy that was known for this species, and is adapted to local short-distance exploration. Besides, in ectotherms activity is strongly dependant on meteorological conditions. We showed that this effect applies to dispersal too, that the dispersal strategies of M. Jurtina are differently affected, and that it changes the functional connectivity at the landscape scale. Moreover, we examined the dispersal behaviour of M. Jurtina along a gradient of agricultural intensification, and showed how dispersal is affected by habitat loss and environmental stochasticity. Finally, we estimated the potential corridor role of an agri-environment scheme set up in European landscapes: the grassy field margins. We used a combination of individual-based simulations of movement, and field surveys of movement inside grassy field margins and habitat patches to estimate this corridor function
Beffy, Jean-Luc. "Approche des structures ternaires en écologie par l'analyse en composantes principales à trois modes". Lyon 1, 1993. http://www.theses.fr/1993LYO10057.
Texto completo da fonteChevenet, François. "Un environnement coopératif de résolution de problèmes pour l'analyse statistique en écologie". Lyon 1, 1994. http://www.theses.fr/1994LYO10074.
Texto completo da fonteRobinet, Christelle. "Modélisation mathématique des phénomènes d'invasion en écologie : exemple de la chenille processionnaire du pin". Paris, EHESS, 2006. http://www.theses.fr/2006EHES0077.
Texto completo da fonteThis thesis reports a mathematical modelling of a spatio-temporal dynamic of a population responding to climate change. Several approaches are gathered to study the northward expansion of a defoliator insect, the pine processionnary moth. The delayed Ricker model proves that the outbreak cycle is 6-year periodic. The expansion dynamics in the Paris Basin is described by the model coupled to a climatic constraint and a diffusion model wich takes into account the pines distribution. We show that the climate change is really involved in the process of expansion even if the heterogeneity of the environnement is a key factor of the speed of propagation, and we finally suggest an expansion scenario for the next years
Nowak, James. "Integrated Population Models and Habitat Metrics for Wildlife Management". Doctoral thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/26023.
Texto completo da fonteSuccessful management of harvested species critically depends on an ability to predict the consequences of corrective actions. Ideally, managers would have comprehensive, quantitative and continuous knowledge of a managed system upon which to base decisions. In reality, wildlife managers rarely have comprehensive system knowledge. Despite imperfect knowledge and data deficiencies, a desire exists to manipulate populations and achieve objectives. To this end, manipulation of harvest regimes and the habitat upon which species rely have become staples of wildlife management. Contemporary statistical tools have potential to enhance both the estimation of population size and vital rates while making possible more proactive management. In chapter 1 we evaluate the efficacy of integrated population models (IPM) to fill knowledge voids under conditions of limited data and model misspecification. We show that IPMs maintain high accuracy and low bias over a wide range of realistic conditions. In recognition of the fact that many monitoring programs have focal data collection areas we then fit a novel form of the IPM that employs random effects to effectively share information through space and time. We find that random effects dramatically improve performance of optimization algorithms, produce reasonable estimates and make it possible to estimate parameters for populations with very limited data. We applied these random effect models to 51 elk management units in Idaho, USA to demonstrate the abilities of the models and information gains. Many of the estimates are the first of their kind. Short-term forecasting is the focus of population models, but managers assess viability on longer time horizons through habitat. Modern approaches to understanding large ungulate habitat requirements largely depend on resource selection. An implicit assumption of the resource selection approach is that disproportionate use of the landscape directly reflects an individual’s desire to meet life history goals. However, we show that simple metrics of habitat encountered better describe variations in elk survival. Comparing population level variation through time to individual variation we found that individual variation in habitat used was the most supported model relating habitat to a fitness component. Further, resource selection coefficients did not correlate with survival.
Ezzahiri, Mustapha. "Application de l'analyse numérique à l'étude phytoécologique et sylvicole de la cédraie du Moyen-Atlas tabulaire : exemple de la cédraie de Sidi-Mguild". Aix-Marseille 3, 1989. http://www.theses.fr/1989AIX30031.
Texto completo da fonteVirgili, Auriane. "Modelling distributions of rare marine species : the deep-diving cetaceans". Thesis, La Rochelle, 2018. http://www.theses.fr/2018LAROS003/document.
Texto completo da fonteDeep-diving cetaceans, sperm- and beaked whales Physeteridae, Kogiidae and Ziphiidae, are rare marine species. Due to their low densities, wide distribution ranges and limited presence at the water surface, visual surveys usually result in low sighting rates. This paucity of data challenges the modelling of their habitat, prerequisite for their conservation. Models have to cope with a great number of zeros that weakens the ability to make sound ecological inferences. Consequently, this thesis aimed at finding a methodology suitable for datasets with a large number of zeros, determining how environmental variables influence deep-diver distributions and predicting areas preferentially used by these species. By testing the predictive performance of various habitat models fitted to decreasing numbers of sightings, I selected the most suitable model and determined that at least 50 sightings were needed to provide reliable predictions. However, individual surveys can rarely provide sufficient deep-diver sightings thus I merged many visual survey datasets to produce the first basin-wide deep-diver density maps in the North Atlantic Ocean and the Mediterranean Sea. Highest densities were predicted in waters from 1500-4000 m deep and close to thermal fronts ; hotspots were predicted along the continental slopes, particularly in the western North Atlantic Ocean. In addition, a model transferability analysis highlighted that habitat drivers selected by the models varied between contrasted large ecosystems. Finally, I discussed challenges related to statistical modelling applied to rare species and the management applications of this thesis
Lamouroux, Nicolas. "Hydraulique statistique et prédiction de caractéristiques du peuplement piscicole : modèles pour l'écosystème fluvial". Lyon 1, 1997. http://www.theses.fr/1997LYO10198.
Texto completo da fonteGosselin, Frédéric. "Modèles stochastiques d'extinction de population : propriétés mathématiques et leurs applications". Paris 6, 1997. http://www.theses.fr/1997PA066358.
Texto completo da fontePradel, Roger. "Estimation et comparaison de probabilités de survie par suivi individuel et utilisation en biologie des populations". Montpellier 2, 1992. http://www.theses.fr/1992MON20152.
Texto completo da fonteRavigné, Virginie. "Etude théorique des évolutions conjointes de traits : les exemples de la spécialisation écologique et de la dispersion chez les plantes". Montpellier 2, 2003. http://www.theses.fr/2003MON20200.
Texto completo da fonteLe, Fur Jean. "Modélisation numérique des transferts de radioéléments artificiels en mer de Manche : processus hydrodynamiques, biologiques et sédimentaires". Lyon 1, 1989. http://www.theses.fr/1989LYO10129.
Texto completo da fonteCarre, Catherine. "Transfert de radionucléides dans les organismes vivants : analyse de données et modélisation : application au domaine de la Manche". Lyon 1, 1996. http://www.theses.fr/1996LYO10238.
Texto completo da fonteLardeux, Frédéric. "Biologie, écologie et dynamique de population de l'éperlan (Osmerus eperlanus, L. ) (poisson, clupéiforme, L. ) dans l'estuaire de la Loire (France)". Brest, 1986. http://www.theses.fr/1986BRES2031.
Texto completo da fonteLeclère, Jérémy. "Modèles prédictifs des peuplements de juvéniles 0+ de poisson en grands cours d'eau : outil pour la gestion et la restauration". Paris, Muséum national d'histoire naturelle, 2013. http://www.theses.fr/2013MNHN0006.
Texto completo da fonteRiver management is supported by the use of numerous biological indicators in order to assess ecosystems condition, to identify the origin of disturbances and to provide valuable information on the possible restoration measures. In large river systems, some limitations have been highlighted for the fish-based indicators, which are usually built on adult populations. These limitations are related to their ability to disentangle disturbance sources and to assess the effectiveness of river bank rehabilitation works, which represent a large part of current restoration acts in these systems. Indicators based on young-of-the-year (YOY) fishes should overcome these limitations since YOYs are strongly sensitive to their environment and occupy specific habitat reflecting their biological requirements. This thesis aims to develop a preliminary multi-metric index, strictly based on young-of-the-year fishes, in order to assess the ecological integrity of riparian habitats of large river systems
Poreau, Brice. "Biologie et complexité : histoire et modèles du commensalisme". Phd thesis, Université Claude Bernard - Lyon I, 2014. http://tel.archives-ouvertes.fr/tel-01063917.
Texto completo da fonteMabrouk, Nabil. "Analyzing individual-based models of microbial systems". Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2010. http://tel.archives-ouvertes.fr/tel-00712153.
Texto completo da fonteFekih, Salem Radhouane. "Modèles mathématiques pour la compétition et la coexistence des espèces microbiennes dans un chémostat". Phd thesis, Université Montpellier II - Sciences et Techniques du Languedoc, 2013. http://tel.archives-ouvertes.fr/tel-01018600.
Texto completo da fonteGirard, Virginie. "Modèles d'habitat statistiques comme outils d'aide à la gestion des débits des rivières insulaires tropicales : Guadeloupe, Martinique, Mayotte, Réunion". Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10055/document.
Texto completo da fonteHydraulic habitat models are frequently used for predicting the ecological impacts of flow management in stream reaches. Their hydraulic component describes microhabitat hydraulics within the reach (e.g. velocity, depth); their biological component describes the "preferences" of aquatic taxa for microhabitat hydraulics. Statistical habitat models involve the modelling of the frequency distributions of hydraulic variables in reaches. Their application requires simple data, but such models are not available for insular tropical streams. We developed hydraulic preference models for 15 diadromous taxa of tropical islands (shrimps and fishes), and statistical hydraulic models for steep streams with large bed particle size. Our models are based on five available biological data sets (~8350 electrofishing units, 52 streams) and original hydraulic measurements (44 streams, 69 site×date) collected in four islands in the Caribbean region (Guadeloupe, Martinique) and the Indian Ocean (Reunion, Mayotte), in collaboration with local partners. Our hydraulic models improve the predictions of observed velocity and depth distributions when compared with previous models developed in continental Europe. Our biological models reflect that hydraulics contribute less to microhabitat selection in tropical islands than elsewhere. Nevertheless, some taxa have significant hydraulic preferences that are comparable among data sets and we illustrate a potential application of our results for guiding low flow management in tropical insular streams
Le, Mezo Priscilla. "Variabilité des écosystèmes marins de l'échelle inter-annuelle au dernier cycle glaciaire-interglaciaire". Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLV003.
Texto completo da fonteClimate variability influences marine primary productivity and marine species distribution over all timescales, from seasonal to interannual variability and glacial-interglacial cycles. The links between climate and marine ecosystems are still sparsely known so that the predictions of futur changes are difficult. Moreover, because paleoclimate recorders extracted from marine archives are often linked to the functionning of the ecosystem, this lack of knowledge limits our ability to reconstruct past climate variability.This thesis work aims at improving our knowledge of these links between climate and marine ecosystems : we have looked into marine productivity changes during the last glacial-interglacial cycle, but we also examined the "end-to-end" ecosystem response to inter-annual to decadal variability in a pre-industrial climate. This work uses a climate model (IPSL-CM), a bio-geochemical model (PISCES) and a model of high trophic levels (APECOSM).First, we show that the link between Indian summer monsoon intensity and marine primary productivity in the Arabian Sea is indirect. Indeed, it appears necessary to consider the monsoon pattern, such as the Findlater Jet position, which drives the Ekman dynamics in the region, as well as its intensity to understand the productivity changes.Second, we study the marine productivity changes off the Congo river mouth and their links with the river runoff and the African atmospheric dynamics. This work shows that the relationship between monsoon intensity and trade winds intensity, often used to reconstruct past changes, is not always verified. Depending on the climate, thermal or dynamical effects are more or less prominent drivers of the simulated changes in precipitation and winds. Productivity off the Congo river mouth, which is mainly located in the subsurface, seems more affected by the ocean and atmosphere dynamics than by the river supply in nutrients.Third, we study the inter-annual variability effects over past productivity changes and over the climatic signal potentially recorded in the biological climate proxies.Finally, the last part of the thesis focuses on high trophic levels marine organisms response to climate variability at different frequencies. This study shows that marine organisms response to environmental changes varies with the organism' size and habitat
Maigrot, Jean-Louis. "La relation homme-territoire à de grandes échelles d'espace : (contribution à la mise au point d'un modèle permettant, à un niveau communal, de localiser des enjeux territoriaux)". Dijon, 1997. http://www.theses.fr/1997DIJOL020.
Texto completo da fonteDerville, Solène. "Écologie spatiale des baleines à bosse en zone de reproduction : habitats, distribution et mouvements dans le Pacifique Sud". Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS374.
Texto completo da fonteUnderstanding the social and environmental drivers of the distribution and movements of marine megafauna is essential to their conservation. Cetaceans are elusive and mobile species, whose management requires an improved understanding of habitat use patterns. This thesis is aimed at investigating the spatial ecology of an endangered population of humpback whales (Megaptera novaeangliae) in the South Pacific Ocean. Using a multidisciplinary dataset collected between 1995 and 2018 in New Caledonia and Oceania, this thesis addressed three objectives, 1) investigate best practices to cetacean species distribution modeling, 2) acquire fundamental knowledge on the distribution, habitats and movements of humpback whales in Oceania breeding grounds, and 3) predict priority conservation areas and potential threats to humpback whales. Modeling the distribution of a migratory large whale from non-systematic visual survey and citizen science data provided valuable space-use predictions when uneven survey effort and statistical overfitting were specifically addressed. Generalized Additive Models were favored for their complexity trade-off, ecological interpretability and transferability. Models of habitat use revealed a preference for a diversity of shallow habitats (low island and atoll lagoons, barrier reef and high island slopes, banks and seamounts) spread over a relatively large thermal range over Oceania. Shallow seamounts and banks were identified as major breeding and nursing habitats and play a key role in the connectivity within and between populations. This unique and unexpected use of pelagic waters has important consequences for the spatial management of humpback whales. The predictions of present and future suitable humpback whale breeding habitats at multiples scales provide science-based evidence for priority conservation areas, and enable mitigation of threats from anthropogenic activities and climate change in the South Pacific
Lévi, Laurent. "Modélisation par des problèmes hyperboliques de perturbations d'écosystèmes hydriques". Pau, 1994. http://www.theses.fr/1994PAUU3004.
Texto completo da fonteDinaharison, Jean Bienvenue. "Conception d’une approche spatialisée à base d’agent pour coupler les modèles mathématiques et informatiques : application à la modélisation du processus écosystémique du sol". Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS184.
Texto completo da fonteSoil is a highly heterogeneous environment in which many processes interact to provide ecosystem services. Model coupling approaches propose to define such system by using a modular architecture in which various processes, represented by models, communicate to reproduce different aspects of a phenomenon such as soil functioning. In this thesis project, we develop such an approach for the purpose of modelling soil functioning. The challenges of such a scheme lie in solving representation problems of soil processes. These representation problems originate from the fact that models from various disciplines are reused to describe the processes. By representations problems, we mean model description which can be (individual or equation based), the temporal execution settings and data resolution. These coupling constraints are addressed by a number of approaches in the literature. All of them propose satisfactory solutions to these constraints in their respective application fields. In our approach, we use the agent paradigm to encapsulate the various soil processes. Then processes will communicate through the space by using resources inside it. The behaviour of the processes then depends on the availability of resources. A coordination problem can arise from this type of coupling, as processes may consume the resource simultaneously while the resource may not support this demand. To overcome that matter, we use an action-theoretic technique called Influence-Reaction to define strategies to manage this type of situation. We used algorithms suggested by the abbundant litterature to manage any processes temporality issues. This coupling approach was applied to a model of organic matter decomposition in which several processes (earthworms, microbes and roots) compete for soil ressources. The results suggest that the use of our approach is suitable for modelling soil functioning, but also gives more accurate indications of resource availability
Bled, Florent. "Tests d'hypothèses en dynamique des populations fragmentées : développement et applications de modèles d'occupation des sites". Toulouse 3, 2010. http://thesesups.ups-tlse.fr/1087/.
Texto completo da fonteClassical approaches to the development of spatial models for binary processes of species distribution (i. E. Occupancy processes) present three important deficiencies. I) They do not explicitly accommodate sampling uncertainty. Ii) There is a lack of spatio-temporal occupancy models, especially in the framework of hierarchical modeling. Iii) Most of existing models are phenomenological and do not explicitly consider underlying ecological mechanisms. This thesis develops spatio-temporal occupancy models for dynamical ecological processes in order to respond to these limitations while incorporating scientific knowledge in every modeling step. Those models are applied to critical ecological topics ranging from the spread of invasive species to habitat selection via climate changes. Understanding range and occupancy dynamics will permit prediction of occupancy changes that are likely to accompany future changes and hopefully will permit informed attempts to mediate changes in occupancy
Hébrard, Olivier. "Stratégie de prévision des humidités de surface sur un bassin versant agricole en milieu méditerranéen". Montpellier 2, 2004. http://www.theses.fr/2004MON20076.
Texto completo da fonteCazelles, Bernard. "Modélisation d'un écosystème lotique : dynamique du carbone organique dissous et des microorganismes benthiques dans un cours d'eau cours". Lyon 1, 1987. http://www.theses.fr/1987LYO10068.
Texto completo da fonteGeorgescu, Vera. "Classification de données multivariées multitypes basée sur des modèles de mélange : application à l'étude d'assemblages d'espèces en écologie". Phd thesis, Université d'Avignon, 2010. http://tel.archives-ouvertes.fr/tel-00624382.
Texto completo da fonteHouballah, Mojtaba. "Modeling multi-functional forest management through a social-ecological system framework-based analysis". Thesis, Université Clermont Auvergne (2017-2020), 2019. http://www.theses.fr/2019CLFAC083.
Texto completo da fonteThe usefulness of forests is spread from their exploitation for timber, tourism, and other functions to maintenance of wildlife, ecological balance, and prevention of soil erosion. In achieving these goals, the essential factor is proper forest management. However, with the increasingly perceived idea that forests are characterized by complex interactions related to biological and social aspects, forest management is facing a challenge, which consists in integrating interrelations between ecological and social systems. While sustainable forest management is originally seen as a constant yield of wood supply, modern ideas of sustainability are broader in scope, embracing all goods and services of the forest. Increasingly, forests are being managed as multi-functional ecosystems. In this vein, forests are progressively seen as complex social-ecological systems (SESs), requiring adaptive and multi-functional management. In this Ph.D. thesis, we consider that the question of management application can be tackled by understanding how shared infrastructures mediate the interaction between human and ecological environment. In particular, for sustainable and multi-functional forest management, the relation between the capacity for production as well as multi-functional use is highlighted with the concept of forest’s shared infrastructures that are mainly composed of roads (accessibility utilities). However, dilemmas associated with their provision pose some problems when it is applied in a context of different forest functions with conflicting objectives. Therefore, to fully understand and integrate the role of infrastructure and their governance into ecosystem science, we base our research on three parts. We first combine the use of Ostrom’s SES framework and Anderies’ robustness framework and apply it to a specific case study (Quatre-Montagne forest, Vercors, France) to highlight how forestry institutions affect forest ecosystem, its functions, and its social arrangements. With this, we link the concept of multi-functional forest management to the multi-functionality of infrastructures. We then develop a mathematical model, based on the first partition, which analyzes the evolution of the forest system and its functions when impacted by decisions of infrastructure provision. We highlight the role of governance calling to attention their role in fostering multi-functional forest management. Finally, we apply mathematical tools such as viability theory to identify management techniques and approaches that define a first step in characterizing adaptive managements for safe operating spaces in multi-functional forests
Mannocci, Laura. "Distribution of cetaceans and seabirds in tropical oceans : roles of physiographic, oceanographic and biological factors". Thesis, La Rochelle, 2013. http://www.theses.fr/2013LAROS419/document.
Texto completo da fonteMarine top predators, here cetaceans and seabirds, must develop optimal strategies of resource and habitat utilization. The main goal of this dissertation was to investigate cetacean and seabird strategies of habitat utilization in relation to their energetic costs of living. We hypothesized that predators with high costs of living should be constrained to high quality habitats, whereas less active predators could cope with habitats of lesser quality. We studied the habitats of cetacean and seabird guilds defined according to their likely costs of living. We relied on sightings collected from aerial surveys in three tropical regions (the western tropical Atlantic, the Southwest Indian Ocean and French Polynesia). We built generalized additive models based on a range of physiographic (e.g. depth), oceanographic (e.g. mesoscale activity) and biological variables (e.g. chlorophyll concentration and micronekton) to describe the quality of pelagic habitats. We first modeled cetacean and seabird habitats at the regional scale. Energetically costly cetaceans appeared to be constrained to the highest quality habitats, whereas less active cetaceans exploited habitats of lesser quality. Seabird distributions primarily reflected colony locations and their dependences on habitat quality were less clear. We then highlighted generic properties of cetacean distributions and provided predictions at the circumtropical scale. This dissertation gave new insights on top predator strategies of habitats utilization in light of their costs of living. These spatial predictions have significant implications for the management of these species and of their pelagic ecosystems
Alleaume-Benharira, Mariane. "Étude théorique et expérimentale de l'évolution des aires de répartition des espèces dans un contexte de changements globaux". Montpellier 2, 2005. http://www.theses.fr/2005MON20143.
Texto completo da fonteDelogu, Émilie. "Modélisation de la respiration du sol dans les agro-écosystèmes". Toulouse 3, 2013. http://thesesups.ups-tlse.fr/2301/.
Texto completo da fonteAround 1/3 of the Earth land surface is used for croplands. Their role in the carbon cycle is a crucial issue for scientists today. In the context of global warming, understanding the factors influencing carbon fluxes of agricultural soils and their components is essential for implementing efficient mitigation practices. The CO2 produced at the soil surface results from several respiratory processes making the evaluation of the existing methods complicated. Understanding the soil respiration sources and their dynamics are crucial issues to estimate the potential for carbon sequestration into soils via efficient cultural practices. Because of its major role in carbon loss over croplands, soil respiration modeling received much attention to quantify the fluxes (empirical modeling), to highlight the lack of knowledge and to guide researches (mechanistic modeling). In this study, empirical and semi-mechanistic models were carried out depending on how precise, generic or real the model should be. Using abiotic and biotic factors was essential to properly model respiration among five sites with different soil and climate. The Rh sensitivity to Ts and ?s was adequate to obtain satisfying predictions over bare soils but the dependency of Rs on an indicator of the vegetation growth (GPP) was necessary to improve the predictions during crop periods. The empirical approach could not allow a good and reliable estimation of the contributions of the different components of Rs. Semi-mechanistic model was tested on 3 sites with various climatic and soil conditions. This approach allowed a good assessment on the heterotrophic and autotrophic contributions since it described more carefully the soil respiration and its underlying processes. Rh accounted for 63 % to 66 % of Rs for winter wheat culture whereas it accounted for 52 % to 56 % for a spring wheat rotation. Rs represented 33 % to 43 % of the total ecosystem respiration balance during winter wheat season and about 50 % for spring wheat. The semi-mechanistic model was developed to simulate the effects under different cultural practices as fertilization (manure) and tillage systems. It was concluded that carbon sequestration and carbon dioxide fluxes were more affected by soil organic matter inputs than by the tillage system itself
Lacas, Jean-Guillaume. "Processus de dissipation des produits phytosanitaires dans les zones tampons enherbées : étude expérimentale et modélisation en vue de limiter la contamination des eaux de surface". Montpellier 2, 2005. http://www.theses.fr/2005MON20127.
Texto completo da fonteJarry, Vincent. "Etude pluridisciplinaire en écologie lagunaire (étang de Thau, France) : stratégie d'échantillonnage et organisation spatiale du phytoplancton". Montpellier 2, 1990. http://www.theses.fr/1990MON20204.
Texto completo da fonteArancio, Marc. "Etude théorique des interactions entre des dinoflagellés et des parasitoïdes eucaryotes en environnement mélangé : persistance du système et succession phytoplanctonique". Electronic Thesis or Diss., Lille 1, 2014. http://www.theses.fr/2014LIL10223.
Texto completo da fonteMany species of autotrophic dinoflagellates can be parasitized by multiple eukaryotic parasitoids. These parasitoids have a specific life cycle resulting in the death of the host and the release of hundreds of zoospores that can infect a new host. Several studies have demonstrated their potential to control the host population in a few days as well as their great diversity and suggests a very complex dynamics of infection in this kind of environment. The objective of this thesis is to understand the parasitoid-dinoflagellates infection dynamics in a highly mixed estuary and a better understanding of the different interactions taking place within this system. To address this problem, we used the modeling approach (IBM). This approach has enabled to show that the hosts excystment process, also used by the parasites to survive the winter, helps to explain the persistence of the system. It has also demonstrated the potential influence of different types of parasitoid on the dynamics infection and succession of dinoflagellates species, with increased diversity of the host population in the presence of specialists and decreased with generalists. The estimation improvement of the parameter used to calculate the rate of encounter between hosts and parasites with experimental and numerical methods was also attempted. The results showed a significant change in this parameter depending on behavior and the need to take it into account for a better parameterization
Garde, Laurent. "Ressources pastorales en Haute-Provence et modélisation de la relation végétation-troupeau". Aix-Marseille 3, 1990. http://www.theses.fr/1990AIX30022.
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