Dissertationen zum Thema „Compétition (botanique) – Modèles mathématiques“
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Monroy, Ata Arcadio. „Installation de plantes pérennes de la zone aride soumises à des contraintes hydriques contrôlées et à des coupes“. Montpellier 2, 1989. http://www.theses.fr/1989MON20025.
Der volle Inhalt der QuelleDumas, Noé. „La végétation concurrente de la régénération forestière : évaluation des surfaces colonisées, modélisation de l'abondance et de l'impact sur la régénération ligneuse à l'échelle de la France“. Electronic Thesis or Diss., Paris, AgroParisTech, 2022. http://www.theses.fr/2022AGPT0015.
Der volle Inhalt der QuelleForest renewal is a key stage in the life of forest stands as it allows the long-term maintenance of the forest and its associated ecosystem services. Among the factors likely to have a negative impact on forest renewal, colonisation by competitive species can slow down tree regeneration, or even block it for several decades.The objective of this thesis is to estimate the impact of competitive vegetation on tree regeneration on a regional to national scale. The thesis is mainly based on the use of French National Forest Inventory (NFI) data.A first step, using the results of a survey of forest managers, was to establish a list of the main competing species for tree regeneration, and to determine the areas where each species is present with a high abundance. Bramble (Rubus fruticosus), Eagle Fern (Pteridium aquilinum) and Purple Moor-grass (Molinia caerulea) are the main competitive species in France, and are each present with a high abundance in more than 300,000 ha of forests with open canopies in France.In order to better understand the ecology of competitive species, the role of canopy openness on the probability of presence and high abundance of competitive species was studied. For a majority of species, canopy cover has a weak effect on the probability of presence of species. Conversely, species abundance was strongly correlated with canopy cover, with high canopy cover being associated with lower abundance for most competitive species.The effect of competitive vegetation on tree regeneration cover was then modelled at the scale of France for the three main species. High abundance of P. aquilinum and M. caerulea is associated with a relative decrease in tree regeneration cover of about 30% and 40% respectively, compared to situations where these species are present at low abundance. Conversely, R. fruticosus has a more ambivalent effect on tree regeneration. Woody regeneration cover increases slightly on average at intermediate R. fruticosus abundances, and decreases significantly at high abundance of this species.Finally, the probability of presence and high abundance of the three main competing species was modelled, in order to identify the conditions of high abundance and to predict the location of the areas potentially impacted by the appearance of these three species when the canopy is opened. The difficulty of accurately modelling the presence and, more importantly, the level of abundance of these species led to models with poor predictive abilities, which did not allow for robust estimates of the conditions at high risk of colonisation by the three species studied.In conclusion, this thesis has shown that tree regeneration problems related to competitive vegetation species are present on significant areas in French forests. P. aquilinum and M. caerulea have a marked negative effect on tree regeneration regardless of their abundance, whereas the effect of R. fruticosus is only negative at high abundances. Finally, this thesis also demonstrated the importance of modelling presence and abundance separately, and identified the main factors that need to be taken into account to better model species abundance
Baup, Stéphane. „Elimination de pesticides sur lit de charbon actif en grain en présence de matière organique naturelle : élaboration d'un protocole couplant expériences et calculs numériques afin de simuler les équilibres et les cinétiques compétitifs d'adsorption“. Poitiers, 2000. https://tel.archives-ouvertes.fr/tel-00983252.
Der volle Inhalt der QuelleMeredieu, Céline. „Croissance et branchaison du pin laricio (Pinus nigra Arnold ssp laricio (Poiret) Maire) : élaboration et évaluation d'un système de modèles pour la prévision de caractéristiques des arbres et du bois“. Lyon 1, 1998. http://www.theses.fr/1998LYO10242.
Der volle Inhalt der QuelleFekih-Salem, Radouane. „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-00940100.
Der volle Inhalt der QuelleFekih, 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.
Der volle Inhalt der QuelleTamasi, Elisabetta. „Analisi e modellizzazione dell'architettura radicale di giovani piante arboree soggette a stress meccanico“. Bordeaux 1, 2002. http://www.theses.fr/2002BOR12492.
Der volle Inhalt der QuelleTiedemann, Florian, und Florian Tiedemann. „Étude sur la relation compétition-densité de l'épinette noire au Québec“. Master's thesis, Université Laval, 2014. http://hdl.handle.net/20.500.11794/24779.
Der volle Inhalt der QuelleUn modèle intégrant des guides de gestion de la densité décrit l'«effet de compétition-densité» étant l'effet négatif du nombre d'arbres (densité) sur le volume moyen V . Pour les peuplements naturels d'épinette noire (Picea mariana (Mill.) BSP) au Québec, Tremblay et collab. (2000) constatent que le modèle simple d'Ando (1968) manque de précision. L'ajout du coefficient de distribution, défini comme le taux d'occupation des cellules subdivisant une placette échantillon en autant de cellules qu'il s'y trouvent d'arbres, a significativement amélioré un modèle simplifié de l'effet de compétition-densité (critère d'information d'Akaike) pour 63 placettes échantillons situées dans les régions Saguenay{Lac-St-Jean et Côte-Nord. Un faible CD, indicateur d'une dispersion spatiale en bouquets des arbres, a un effet négatif sur le V . En utilisant 8197 placettes échantillons du ministère des Ressources naturelles, nous avons significativement amélioré (critère d'information bayesien) le modèle simple d'Ando (1968) par l'ajout simultané de (1.a) l'indicateur de distribution diamétrale «RD4», qui est le rapport entre le diamètre moyen quadratique et le diamètre dominant, (1.b) W, qui est de 1 dans les sous-domaines bioclimatiques de l'ouest, et de 0 dans ceux de l'est et (1.c) RE2, qui est de 1 pour la végétation potentielle RE2 et de 0 pour l'autre végétation potentielle (RE3). Avec une racine d'erreur quadratique moyenne (RMSE) de 1,055 et un coeffiction de déterminantion (R2) de 0,936, nous avons obtenu une véritable amélioration de la précision du modèle réduit (RMSE = 1; 369 et R2 = 0; 787), tout en n'utilisant que des variables qui sont à la fois faciles à mesurer sur le terrain et qui se prêtent bien, en plus, à être utilisees dans les autres modèles composants d'un guide de gestion de la densité. Le modèle complétée par (2) la classe de pourcentage de couverture est également significativement meilleur (critère d'information bayesien) et plus précis (RMSE = 1; 303 et R2 = 0; 81) que le modèle réduit.
Dupuy, Lionel. „Modélisation de l'ancrage racinaire des arbres forestiers“. Bordeaux 1, 2003. http://www.theses.fr/2003BOR12788.
Der volle Inhalt der QuelleAndré, Jean-Baptiste. „Niveaux de sélection chez les microparasites : virulence, coopération, mutation“. Montpellier 2, 2003. http://www.theses.fr/2003MON20172.
Der volle Inhalt der QuelleYadi, Karim. „Perturbations singulières : approximations, stabilité pratique et applications à des modèles de compétition“. Phd thesis, Université de Haute Alsace - Mulhouse, 2008. http://tel.archives-ouvertes.fr/tel-00411503.
Der volle Inhalt der QuelleGrange, Sophie. „Le grand dilemme des équidés sauvages : coexister avec les bovidés et éviter les grands prédateurs“. Poitiers, 2006. http://www.theses.fr/2006POIT2319.
Der volle Inhalt der QuelleThe Plains zebra is currently the most widespread wild equid; however there is still little information on the regulation/limitation of their populations. Comparative studies on the relative abundance and the population dynamics of Plains zebras and grazing bovids support the hypothesis that predation has a greater impact on the number of zebras in African ecosystems, and probably also play an important role in the limitation of some zebra populations. Given these findings, it will be necessary to link population models of zebra and their main predators. However a major problem is the lack of accurate data on zebra survival rates. The study on the population dynamics of Plains zebra in Hwange National Park (Zimbabwe) is the first one to use a capture-mark-recapture method based on photo-identification. After only one year and a half, this method already proves to be promising to study zebra population dynamics. This thesis also shows that the feralization of domestic horses leads to an unnatural population dynamics, which means that Camargue horses cannot be used as surrogates of wild equids to restore natural ecosystems. In terms of species conservation it is therefore now important to acquire a good knowledge on the regulating/limiting factors acting on current wild equid populations in order to facilitate translocations and reintroductions in their natural ecosystems
Le, Cadre Hélène. „Contributions à la modélisation et tarification dans un contexte de compétition dans le secteur des télécommunications“. Rennes 1, 2009. http://www.theses.fr/2009REN1S083.
Der volle Inhalt der QuelleThis thesis aims at developing a whole revenue management system, enabling the telecommunications operator to increase his profit under competition and uncertainty on the consumers' preferences and on his rivals' marketing strategies. At first, we infer the consumers' preferences. Then, under horizontal competition, we determine the most appropriate marketing strategy to use under uncertainty on the rival's marketing strategy. Second, we study the interactions resulting from the competition between the operators sharing a scarce ressource, while a regulator supervizes the whole system. Various contract performances are studied. Finally, we characterize power relation and consumers' loyalty influence on the operators' learning rate when the ressource sharing mechansim is hidden and we study the system resulting organization
Ravaz, Nathalie. „Croissance de populations levuriennes mixtes : effet Killer : analyse et modélisation“. Toulouse, INPT, 1992. http://www.theses.fr/1992INPT058G.
Der volle Inhalt der QuellePerez-Guevara, Fermin. „Production de schizosaccharomyces pombe. Physiologie et paramètres de culture“. Toulouse, INPT, 1992. http://www.theses.fr/1992INPT053G.
Der volle Inhalt der QuelleJourdan, Christophe. „Modélisation de l'architecture et du développement du système racinaire du palmier à huile (Elaeis guineensis Jacq. )“. Montpellier 2, 1995. http://www.theses.fr/1995MON20208.
Der volle Inhalt der QuelleSpataro, Thierry. „De l'individu à la population : étude théorique de l'influence, au niveau de la population, de traits d'histoire de vie et de comportements individuels dans les systèmes hôte-parasitoïde“. Lyon 1, 2001. http://www.theses.fr/2001LYO10083.
Der volle Inhalt der QuelleMasci, Pierre. „Control and optimization of ecosystems in bioreactors for bioenergy production“. Nice, 2010. http://www.theses.fr/2010NICE4064.
Der volle Inhalt der QuelleSome alternative biofuels, produced by microbial ecosystems, are presently studied with the aim of limiting the unreasoned resource consumption of energetic resources, and greenhouse gases emissions which modify the climate. In this thesis we have considered bioreactors based on oleaginous microalgae, and on anaerobic bacterial ecosystems which degrade wastes and produce methane. The aims of these works were to better understand these processes and to improve their performances. First we have developed and studied models of microalgal cultures in photobioreactors, in which algal pigments cause strong light attenuation. For anaerobic digestion we have used an existing model. By rigorous mathematical analysis of these models, we proposed strategies for optimizing their productivity. Then the study of natural selection between several microbial species, in these two ecosystems, leads to the protection of the species which wins the competition. And finally we showed how it’s possible in each ecosystem to control competition and drive natural selection, in order to advantage species which efficient characteristics, inducing better performances
Pradel, 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.
Der volle Inhalt der QuelleRuby, Anne. „Contribution à la méthodologie de l'analyse de la performance sportive : application à la situation de compétition en ski de fond“. Lyon 1, 1995. http://www.theses.fr/1995LYO10184.
Der volle Inhalt der QuelleSellier, Damien. „Analyse numérique du comportement mécanique d'arbres sous sollicitation aérodynamique turbulente“. Bordeaux 1, 2004. http://www.theses.fr/2004BOR12911.
Der volle Inhalt der QuelleFaivre, Bruno. „Coexistence et écologie de deux espèces jumelles d'hippolais“. Dijon, 1992. http://www.theses.fr/1992DIJOS014.
Der volle Inhalt der QuelleMarsac, Rémi. „Contrôle de la spéciation des terres rares par les acides humiques : rôle de l'hétérogénéité des sites de complexation et de la compétition entre cations“. Rennes 1, 2011. https://tel.archives-ouvertes.fr/tel-00674929.
Der volle Inhalt der QuelleEtte thèse a permis de mieux comprendre les mécanismes de complexation des terres rares par les acides humiques afin d’expliquer la variabilité des spectres de terres rares observée dans les eaux riches en matière organique. Cette étude montre que l’hétérogénéité des groupements fonctionnels complexants des acides humiques peut induire différents types de spectres de complexation des terres rares en fonction des conditions physico-chimiques. En effet, à pH acide, lorsque le rapport terres rares/acides humiques augmente, les terres rares se lient majoritairement à des sites carboxyliques multidentates puis monodentates qui ont, respectivement, une plus forte affinité pour les terres rares lourdes et intermédiaires. Lorsque le pH augmente, la participation de sites phénoliques devient plus importante pour les terres rares lourdes tandis que les légères restent liées à des sites carboxyliques. Des expériences de compétition entre les terres rares et le fer ou l'aluminium pour la complexation par les acides humiques ont également été réalisées. A pH neutre, Al est un plus fort compétiteur pour les terres rares légères, et se lie donc préférentiellement à des sites carboxyliques, tandis que Fe est un compétiteur pour toutes les terres rares, et se lie donc aussi bien aux sites carboxyliques que phénoliques. Ainsi, le rapport cation dissous/acides humiques, le pH et la natures des cations compétiteurs peuvent expliquer la variabilité des spectres de terres rares observée dans les eaux naturelles. De plus, les terres rares peuvent être utilisées comme sonde des mécanismes de complexation des cations par les acides humiques, comme ici pour Al et Fe
Al, Kotob Moubine. „Compétition entre instabilités globales et locales lors de la ruine de structures aéronautiques“. Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEM002/document.
Der volle Inhalt der QuelleAeronautical engineers are constantly challenged to provide lighter structures in order to reduce fuel consumption, and thus the environmental impact and flight costs. At the same time, the design of aeronautical structures is subjected to strict regulation aimed at ensuring the integrity of the aircraft and the safety of the passengers. To tackle this challenge, the limits of structural and material mechanics are consistently explored which in turn leads to the development of new, mathematical, numerical, experimental and manufacturing tools.There are numerous metallic parts in the most critical aeronautical structures, like landing gears, engine shafts, or mechanical lugs. These parts are subjected to extreme loading conditions due to the thermal environment or to the intense mechanical ultimate or cyclic loading. The failure of these elastoplastic structures is generally caused by the initiation and propagation of cracks or by the emergence of local instabilities, such as plastic strain localization, or global instabilities, such as buckling.In the present work, we focus on the detection of local and global elastoplastic instabilities in a finite deformation framework. While they are generally studied separately, it was chosen to study both phenomena together in order to analyze and better understand the competition between localization and buckling in elastoplastic structures. For this purpose, multiple analytical developments are presented founded on Hill's global stability criterion (1958) and Rice's strain localization criterion (1976). The new "weakened stability analysis" has been introduced in order to analyze the sensitivity to the type of prescribed boundary conditions. All these criteria have been implemented in the finite element software Zset, which allowed us to analyze the emergence of elastoplastic instabilities in various experimental samples, tubes loaded in torsion, and a lug loaded in tension
Le, Chevalier Vincent. „Cadres formels pour la simulation des peuplements hétérogènes de plantes en compétition pour les ressources“. Phd thesis, Ecole Centrale Paris, 2010. http://tel.archives-ouvertes.fr/tel-00493525.
Der volle Inhalt der QuelleBichara, Derdeï. „Etude de modèles épidémiologiques : stabilité, observation et estimation de paramètres“. Electronic Thesis or Diss., Université de Lorraine, 2013. http://www.theses.fr/2013LORR0011.
Der volle Inhalt der QuelleThe purpose of this thesis is on the one hand to study stability of equilibria of some epidemic models and secondly to construct an observer to estimate the non-measured states and a key parameter in a within host model. We propose extensions of classical models SIR, SIRS and SIS and we study the global stability of their equilibria. In presence of multiple pathogen strains, we proved that competitive exclusion principle holds: the strain having the largest threshold wins the competition by eliminating the others. It turns out that the winning strain is the one for which the equilibrium gives the minimum of the susceptible host population. This can be interpreted as pessimization principle. By considering the same model with two strains and a frequency-dependent type of the contact law, we prove that dynamics changes and a coexistence equilibrium exists and it is globally asymptotically stable under some conditions. The asymptotic behavior of the two other boundary equilibria is also established. The stability study of equilibrium states is mainly done by construction Lyapunov functions combined with LaSalle's invariance principle. We consider an age-structured within-host model of the Plasmodium falciuparum parasite with a general infection force. We develop a method to estimate the total parasite burden that cannot be measured by the current methods. To this end, we use some tools from control theory, more precisely observers with unknown inputs, to estimate the non measured states from the measured ones (data). From this, we deduce a method to estimate an unknown parameter that represents infection rate of healthy reed blood cells by the parasites
Bichara, Derdeï. „Etude de modèles épidémiologiques : stabilité, observation et estimation de paramètres“. Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0011/document.
Der volle Inhalt der QuelleThe purpose of this thesis is on the one hand to study stability of equilibria of some epidemic models and secondly to construct an observer to estimate the non-measured states and a key parameter in a within host model. We propose extensions of classical models SIR, SIRS and SIS and we study the global stability of their equilibria. In presence of multiple pathogen strains, we proved that competitive exclusion principle holds: the strain having the largest threshold wins the competition by eliminating the others. It turns out that the winning strain is the one for which the equilibrium gives the minimum of the susceptible host population. This can be interpreted as pessimization principle. By considering the same model with two strains and a frequency-dependent type of the contact law, we prove that dynamics changes and a coexistence equilibrium exists and it is globally asymptotically stable under some conditions. The asymptotic behavior of the two other boundary equilibria is also established. The stability study of equilibrium states is mainly done by construction Lyapunov functions combined with LaSalle's invariance principle. We consider an age-structured within-host model of the Plasmodium falciuparum parasite with a general infection force. We develop a method to estimate the total parasite burden that cannot be measured by the current methods. To this end, we use some tools from control theory, more precisely observers with unknown inputs, to estimate the non measured states from the measured ones (data). From this, we deduce a method to estimate an unknown parameter that represents infection rate of healthy reed blood cells by the parasites
Njimi, Hassane. „Mise en oeuvre de techniques de modélisation récentes pour la prévision statistique et économique“. Doctoral thesis, Universite Libre de Bruxelles, 2008. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210441.
Der volle Inhalt der QuelleBlanc, Emmanuelle. „Modélisation des conséquences évolutives de la compétition pour la lumière dans des populations composites de blé“. Thesis, université Paris-Saclay, 2021. http://www.theses.fr/2021UPASB013.
Der volle Inhalt der QuelleIntra-specific diversity, mobilized at the scale of the field (cultivar mixtures and composite populations) should play an important role in the agroecological transition, contributing to the adaptation and resilience of low input cropping systems, more prone to stresses. However, many questions are raised by the complex plant-to-plant interactions occurring in such heterogeneous canopies, and there is a growing need to develop modelling approaches to improve their design and management. Thus, our study focuses on the use of functional-structural plant modelling to study the impact of the aerial architecture of plants on the performance and the evolution of heterogeneous wheat populations. The thesis project is based on WALTer : a pre-existing functional-structural plant model that simulates the development of a wheat field from sowing to maturity and the plasticity of tillering (i.e. branching) in response to competition for light. In a first step, modifications were made to WALTer to reduce the computational cost of simulations, enhance its realism and improve its ability to simulate complex heterogeneous stands. The functioning of this new version of WALTer was then characterized by analysing the impact of stochasticity on the simulations and by performing a sensitivity analysis on homogeneous plots. Furthermore, on the basis of field observations, an automatic calibration method, which is rarely developed for this type of model, was applied to WALTer in order to estimate the values of the parameters previously identified as important by the sensitivity analysis. Thanks to a sensitivity analysis of balanced binary mixtures, WALTer was then used to identify the traits of the aerial architecture (described by their mean values in the mixture and the values of the differences between the 2 varieties) that have the most impact on the performance of the plots. The analysis thus revealed the preponderant role of tillering capability and dimensions of the leaves as determinants of the performance of the simulated mixtures. Thanks to an optimization phase, the combinations of traits that are the most favourable for the performance of the simulated mixtures were identified. The results of the simulations highlighted the importance of carefully selecting combinations of traits to associate in mixtures, showing the potential interest of a diversity of architecture in heterogeneous stands, but also the possible adverse effects of such diversity. Finally, WALTer was coupled to a population genetics model to simulate the evolution of heterogeneous wheat stands along generations of resowing. The coupling was used to simulate the dynamic management of a population presenting a large diversity of plant height. The genetic and phenotypic evolution of the population over 20 generations of resowing could thus be compared with experimental data to confirm the good functioning of the coupling. This thesis allowed the development of methods and tools for the functional-structural modelling of heterogeneous wheat stands. The simulations carried out have also improved our understanding of the impact of the aerial architecture on the competition for light in these stands. Ultimately, this work will be useful for the design and management of heterogeneous wheat stands adapted to farmers' needs
Madec, Sten. „Hétérogénéité spatiale en dynamique des populations“. Phd thesis, Université Rennes 1, 2011. http://tel.archives-ouvertes.fr/tel-00600942.
Der volle Inhalt der QuelleBousqué, Isabelle. „Étude de la respiration racinaire : conséquences de l'asphyxie racinaire sur la culture du blé“. Toulouse, INPT, 1992. http://www.theses.fr/1992INPT017A.
Der volle Inhalt der QuelleShili-Touzi, Inès. „Analyse du fonctionnement d'une association de blé d'hiver (Triticum aestivum L. ) et d'une plante de couverture sur une échelle annuelle par modélisation et expérimentation“. Phd thesis, AgroParisTech, 2009. http://pastel.archives-ouvertes.fr/pastel-00606113.
Der volle Inhalt der QuelleLanchier, Nicolas. „Systèmes de particules multicolores“. Rouen, 2005. http://www.theses.fr/2005ROUES019.
Der volle Inhalt der QuelleMost mathematical models in the biological literature that describe inherently spatial phenomena of interacting populations consist of systems of ordinary differential equations obtained under global dispersion assumptions, thus leaving out any spatial structure. Interacting particle systems are Markov processes with state space FS where F is a finite set of colors and where S is a spatial structure, typically Zd. They are ideally suited to study the consequences of the inclusion of a spatial structure in the form of local interactions. We investigate the mathematical properties (stationary distribution, geometry of the configurations, phase transitions) of various multicolour particle systems defined on Zd. Each of these systems is intended to model local interactions within a spatially structured community of populations. More precisely, the biological processes we investigate are ecological succession, allelopathy or competition between an inhibitory species and a susceptible species, multi-species host-symbiont interactions, and persistent gene flow from transgenic crops to wild relatives through pollination in a heterogeneous environment. The mathematical techniques are probabilistic, including coupling, duality, multiscales arguments, oriented percolation, asymptotic properties of random walks, and large deviations estimates
Kerfriden, Baptiste. „Variabilité environnementale et botanique de la densité du bois des espèces forestières et variabilité temporelle de la biomasse aérienne des forêts françaises : une analyse sur un échantillon systématique de l’inventaire forestier national“. Electronic Thesis or Diss., Paris, AgroParisTech, 2021. http://www.theses.fr/2021AGPT0006.
Der volle Inhalt der QuelleContext. Wood density (kg/m3) is a functional trait linked to the strategy of forest species and its variations convey the ability to adapt to an environment resulting in both an interspecific and intraspecific recognized variability. But it also enables forest biomass estimation and carbon sequestration potential in forests.Aims. We try to understand what structures wood density variability. To assess that, we first seek the factors of the intraspecific variability of wood density. Then, we look at methods to estimate this variability in a context of quantifying forest biomass. Next, along environmental gradients, we seek to identify the share of interspecific and intraspecific variations. Finally, we examine the structure of wood density variability with botanical levels and in species growth-wood density trade-off.Approach. The national forest inventory ensures a systematic coverage and without any bias of all metropolitan France. The XyloDensMap project made it possible to collect wood increment cores extracted at 1,30 m on inventoried trees for 2016 and 2017, that is to say 55 000 increment cores. Massive wood density measurements conducted with an X-ray scanner, furthermore combined with the forest information from the inventory, enabled this work.Results. For the first time, we quantified the wood density and its variability for all inventoried forest species. Wood density variability has been estimated operationally by an imputation method over the period of 2005-2018, making it possible to produce a sequence of metropolitan aboveground forest biomass, and to reassess the stock of biomass and carbon in French forests upwards, with a constant trend regarding the annual carbon sink over the period. We showed that wood density variability is structured on a large scale by soil water holding capacity, soil basicity index and elevation. This variability is mostly interspecific. Finally, the botanical levels of class, order and species structure the variability in wood density between species, with order being the most important level, while the wood structure organizes the growth-wood density trade-off.Conclusion. This thesis, which is the first exploitation of the wood density data obtained by the XyloDensMap project, made it possible to progress in the understanding of the intraspecific and interspecific variability structure of this variable but also in forest carbon accounting. There are many prospects for this new dataset which include the production of models of wood density variation, the estimation of forest biomass in the past and in the deep past, the analysis of the forest management effect on biomass production or even the link with wood anatomy
Laghdir, Aziz. „Modélisation de la fissuration en bout de grumes liée aux contraintes de croissance : application aux eucalyptus“. Montpellier 2, 2000. http://www.theses.fr/2000MON20079.
Der volle Inhalt der QuelleNaudin, Christophe. „Nutrition azotée des associations Pois-Blé d'hiver (Pisum sativum L. – Triticum aestivum L. ) : Analyse, modélisation et propositions de stratégies de gestion“. Phd thesis, Université d'Angers, 2009. http://tel.archives-ouvertes.fr/tel-00482632.
Der volle Inhalt der QuelleLavorel, Sandra. „Structure spatiale, perturbations, et dynamique de la coexistence des espèces végétales : de l'expérimentation à la modélisation : l'exemple de friches méditerranéennes“. Montpellier 2, 1991. http://www.theses.fr/1991MON20006.
Der volle Inhalt der QuelleTeixeira, Alves Mickael. „Des interactions indirectes entre les proies : modélisation et influence du comportement du prédateur commun“. Phd thesis, Université Nice Sophia Antipolis, 2013. http://tel.archives-ouvertes.fr/tel-00833242.
Der volle Inhalt der Quelle