Дисертації з теми "Écologie des régions tropicales – Brésil"
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Bétard, François. "Montagnes humides au cœur du Nordeste brésilien semi-aride : le cas du massif de Baturité (Ceará) : apports d’une approche morphopédologique pour la connaissance et la gestion des milieux." Paris 4, 2007. http://www.theses.fr/2007PA040232.
Повний текст джерелаThe humid mountains of Northeast Brazil, locally named Brejos de altitude, form islands of humidity where evergreen forest (mata atlântica) contrasts with the semi-arid conditions of the surrounding plain (Sertão). Despite the ecological, cultural and socio-economic importance of such humid mountains across a wide semi- arid area (‘Polígono das secas’), the high diversity of their physical environment has so far been poorly characterised. This study outlines the relevance of a pedogeomorphological approach to the understanding and management of landscape systems. Here the Baturité massif (Ceará) showcases the methodology used in this study, which involves i) a detailed field survey based on a combined description of landforms, weathering mantles and soils ; ii) the analytical characterization of soils and weathering materials based on a wide range of complementary pedological, sedimentological and geochemical laboratory methods ; and iii) the processing and spatial analysis of field and laboratory data in a GIS, with an aim to develop a modernised method of pedogeomorphic mapping applicable to the study of other mountains. The main results are presented in the form of an original inventory of pedogeomorphic landscape units for the Baturité massif and its piedmont. These results are placed within a more global scientific debate centred on the evolution of tropical landscapes, and the hypotheses are tested against geographic comparisons in Brazil and on other continents (Africa, India). The potential for agricultural development of the land systems of the humid mountains and their surrounding semi- arid plains are discussed in the light of the original results of this study
Moreira, Martins Alves Maria Manuel. "Essai de régionalisation écologique en milieu tropical semi-aride : Ribeira do Pombal (Agreste baiano, Nordeste du Bresil)." Toulouse 2, 1985. http://www.theses.fr/1985TOU21003.
Повний текст джерелаMiranda, José Roberto. "Écologie des peuplements de Reptiles du tropique semi-aride brésilien (région d'Ouricuri-PE)." Montpellier 2, 1986. http://www.theses.fr/1986MON20154.
Повний текст джерелаBarros, Lidia Almeida. "Etude terminologique et traitement terminographique du vocabulaire des espaces protégés du Brésil." Lyon 2, 1997. http://www.theses.fr/1997LYO20024.
Повний текст джерелаIn this work we carry out a terminological study and give a terminographic treatment to the vocabulary of the conceptual field "protection of the environnement of Brasil", more specifically, from Brazil's protected areas. We have therefore elaborated a specialised encyclopedic vocabulary the functions of which are as follows : a synthesis of the most important information on the linguistic level and of knowledge of the terminology in the chosen domain ; b. Conveying the information which could help relations between organised sectors of brasilian and french societies interested by the conservaation of nature in Brazil. Therefore we propose a model of macrostructure, macrostructure microstructure and of returning system adapted to the type of directory. We have also organised the terminology into a unified system of terms and notions. In this thesis we propose some definition models adapted each time to the type of vocabulary and to the domain studied; we observe the principal theoreticl problems of the translation into french of the vocabulary of Brazil's protected areas. From a terminological (lexicological) point of view, we analyse the morpho-syntaxic and lexico-semantic of the terminology that is dealt with; we identify the principal process of creation and of lexical renewal into the protected areas of Brazil and finally we analyse the principal relations of established meaning between terminological unities studied
Machado, Carlos José Saldanha. "La dynamique de la recherche scientifique en Amazonie : les acteurs face aux enjeux et limites de la production de la connaissance sur la nature." Paris 5, 1998. http://www.theses.fr/1998PA05H029.
Повний текст джерелаThe fact that we have been attributing increasing importance to scientific research on the tropical rain forest, specially on the amazon, means that we should study these activities that became strategie. The objective of this work is to contribute to our understanding of those scientific practices, their dynamics and organization at the amazon region. Our focus is on the construction of knowledge and the build up of a research infrastructure and for doing that we use two series of interviews (in Brazil and France), one case study and examination of the scientific literature. This inquiry allow us to advancie the thesis that those actions of one researche actors posses one unique dynamics because each step forward reveal the conformation of the object of study that is renewes accordind to place, time and scale of observation. The combination of specific factors generated form different situations that does not maintaint the relionship among them. A dynamic view of the context and environment where research is conducted take us to the conclusion them the word amazon acquires various meanings, and that the scientific knowledge produced on/from this region results in a multitude of cognitive practices where the concrete realizations do not let themselves harmonize easily
Rascalou, Guilhem. "Écologie, évolution et contrôle des maladies tropicales négligées." Phd thesis, Université de Perpignan, 2012. http://tel.archives-ouvertes.fr/tel-00940064.
Повний текст джерелаMaurin, Leslie. "Ecologie des nématodes marins libres et symbiotiques en milieu tropical : développement de la microspectrométrie Raman comme outil de caractérisation des organismes thiotrophiques." Antilles-Guyane, 2009. http://www.theses.fr/2009AGUY0278.
Повний текст джерелаFree-Iiving marine nematodes are the most important taxon in shallow-water sediments. In tropical environments nematodes colonize preferentially the calcareous sand of Thalassia testudinum seagrass beds and mud sediments of mangrove swamp. The results presente demonstrate by SEM analysis and by molecular hybridization FISH/CARD-FISH, the presence of extracellular bacteria belonging to the y proteobacteria and localized on the body surface of eight species of nematodes belonging to the genera Eubostrichus, Robbea and Stilbonema (Stilbonematinae family). The analysis conducted in Raman microspectrometry have revealed the presence of elemental sulfur S8 in the bacterial coat associate of nematodes and more specifically to the sulfur granules translucent observed by MET in the periplasmic space of bacteria. The Raman microspectrometry has proven a powerful tool for the detection of sulfo-oxidizing symbioses and more generally for the detection of thiotrophic metabolism among mangrove meiofauna organisms. The study of the mangrove nematofauna has revealed a f1uctuating dynamic of the population, either monospecific or diverse, colonizing a heterogeneous and reduced sulfur (1mM to 10mM) sediment. Nematodes of mangroves are dominated by deposit feeders and sorne genera such as Terschellingia, Daptonema and Gomphionema constitute the basic nematofauna in this environment with more specific nematodes such as Eubostrichus, Croconema and Pseudochromadora
Martin, Agnès. "Effet des vers de terre tropicaux géophages sur la dynamique de la matière organique du sol dans les savanes humides." Paris 11, 1989. http://www.theses.fr/1989PA112201.
Повний текст джерелаMoreno, François. "Organisation et fonctionnement hydrobiologique d'écosystèmes estuariens tropicaux : variabilité spatio-temporelle." Montpellier 2, 2003. http://www.theses.fr/2003MON20197.
Повний текст джерелаGaidet, Nicolas. "Étude de la dynamique des populations d'ongulés en zone tropicale : contribution du modèle d'une population exploitée d'impalas (Aepyceros melampus)." Lyon 1, 2005. http://www.theses.fr/2005LYO10100.
Повний текст джерелаGlemarec, Yannick. "Definition d'indicateurs d'environnement pour le developpement durable des hautes terres tropicales etude de cas de la province de thai nguyen au viet nam." Paris 7, 2000. http://www.theses.fr/2000PA070028.
Повний текст джерелаGuirlet, Elodie. "Etude des facteurs écologiques et écotoxicologiques impliqués dans la réussite d’incubation chez la tortue luth Dermochelys coriacea de Guyane Française." Paris 11, 2008. http://www.theses.fr/2008PA112108.
Повний текст джерелаLeatherback turtles, Dermochelys coriacea, have relatively low hatching success in comparison to other marine turtle’s species. This low hatching rate is largely a result of high embryonic mortality rather than infertility, but the specific cause remains unknown. Long lived species such as leatherbacks are more vulnerable to excessive adult mortality that results in dramatic population decline. However, low hatching success could result in long term declines caused by a recruitment of juveniles too low. Leatherbacks populations have already suffered from dramatic decline. On the Yalimapo beach, in French Guiana, hatching success is lower than on other nesting sites for this species, stressing the problem of recruitment of the population. Therefore, understanding causes of low hatching success would be an important conservation step towards preventing extinction in this species. During my thesis, I investigated the role of ecological (predation and nest site location) and ecotoxicological factors (blood and egg contamination in trace elements and organochlorine compounds) on the hatching success of nests. First, nest location has been shown to have an important effect on predation and inundation rate that decreased hatching success. Second, a maternal transfer of contaminants from females to their eggs was assessed, raising the question of deleterious effects of environmental contaminants on embryos development, a very sensitive stage to contaminants. Dose-effects relationships between contaminants and hatching success need to be assessed to establish risk of environmental pollution for leatherbacks. The use of stable isotope analysis in females differing in the number of years between two reproductive seasons made possible to highlight different feeding areas used by those females. These feeding grounds differed in their geographical location, but also in the quality of the preys available in terms of level of contamination by environmental pollutants raising the question of adult contamination. This thesis confirmed the importance of ecological factors for hatching rate and highlighted the existence of ecotoxicological factors, which have not been studied yet for the leatherback turtle
Carvalho, Vitor Celso de. "Structure et dynamique de la végétation en milieu tropical semi-aride : la Caatinga de Quixaba (Pernambouc, Brésil) du terrain à l'analyse des données MSS/LANDSAT." Toulouse 2, 1986. http://www.theses.fr/1986TOU20031.
Повний текст джерелаSatellite remote sensing is more used as a tool for monitoring the tropical semiarid ecosystems. In this work we propose to do an estimation of practicability and limits of mss landsat datas, from a test region of brazilian nordeste, north of Petrolina (pe) the first part deals with the finalization of a structural classification of the steppe (Caatinga) vegetation and its application to the test region. Then, a 1 100 000 scale structural mapping, drawn from the 1955,1965 and 1983 aerial photographs, allows to discuss the signification of aerial photographic structure perception, and to analyse the 1955-1983 caatinga evolution. At last, the results of four mss landsat scenes (1973,1974 and 1983) numerical processing, are estimated, by comparison to vegetation structure maps : while in these maps, 15 thematic classes are distinguished, only 7 are available on the classified picture. In practice, the whole analysis show that the main characteristics of 1955-1983 landcape evolution are : a clear expansion of agricultural area (mainly after 1974) and, in all probability, a notable stability of Caatinga
Jardim, Arruda André. "Seed ecology and grassland resilience : the case of campo rupestre How have we studied seed rain in grasslands and what do we need to improve for better restoration?" Thesis, Avignon, 2019. http://www.theses.fr/2019AVIG0353.
Повний текст джерелаOur knowledge of tropical old-growth grassland resilience (i.e. resistance to degradation and capacity for recovery) remains limited relative to our knowledge of temperate grasslands. Although highly resilient to endogenous disturbances such fires, the vegetation dynamics in old-growth fire-prone tropical grasslands seems hampered by anthropogenic disturbances, especially topsoil degradation. After topsoil disturbance, the internal species pool (i.e. remaining vegetation and the seed bank) is often depleted or even absent, and natural regeneration depends mainly on seed dispersal from surrounding sites via the seed rain. However, plant communities on areas disturbed by soil removal can remain very different from preserved sites many years after degradation, with almost no recovery of the natural vegetation. Despite extremely relevant, seed dispersal dynamics and resilience of tropical old-growth grasslands after soil disturbance remains much overlooked. In this thesis, I carried out a review and three experimental studies about seed rain and diaspore removal dynamics in grasslands. In CHAPTER1, I did a systematic literature survey about seed rain studies in global grasslands. I (1) assessed where, how and why research on seed rain has been carried out; (2) examined how methodological design and results have been reported; and (3) provided guidelines for future research on seed rain in grasslands. I found a remarkable unbalance in the numbers of studies between grassland types, which becomes even more dissimilar across global climatic ranges when the area covered by each grassland type is take into consideration. I identified significant knowledge gaps in grassland seed rain research. I also found a great disparity of methods and data being reported across studies. Additionally, I found that only a few attempts have been made to assess the seed trap efficiency and no studies to date have proposed any protocol to evaluate the effectiveness of seed sorting methods. Then, in CHAPTER 2, I ran a field experiment to propose a simple standard protocol to evaluate the efficiency of two seed trap types (sticky and funnel traps) and of a seed sorting method to assess the efficient of the methods prior to seed rain studies. As a case of study, in CHAPTER 3 and 4, I studied seed rain and secondary diaspore removal dynamics in preserved areas and in areas degraded by gravel exploitation for road construction in campo rupestre vegetation, a megadiverse edaphic grassland in southeastern Brazil. The small number of seeds captured in the seed rain, indicates seed limitation and suggests a close causal relationship between seed dispersal limitation and the low resilience after soil disturbance. The identification of some relatively abundant species in the seed rain places these species as good targets for reintroduction in future restoration projects. Topsoil removal changed the identity of ants interacting with diaspores, resulting in contrasting outcomes from ant-diaspore interactions. The lack of diaspore removal towards degraded areas indicates that establishment limitation is a factor hampering natural regeneration. Our findings help to explain, at least partially, why natural regeneration is compromised after soil removal, which strongly influences diaspore fate and interactions with potential ground-dwelling dispersers, resulting in different ecological outcomes and strong influencing vegetation dynamics and regeneration. I expect that these results will guide future research on seed dispersal and resilience in grasslands, underpinning decisions on restoration and conservation practices on these threatened environments
O nosso conhecimento sobre a resiliência (isto é, resistência à degradação e capacidade de recuperação) de savanas tropicais permanece muito aquém do nosso conhecimento já adquirido sobre as savanas temperadas. Savanas tropicais, embora altamente resilientes à perturbações endógenas, como o fogo, se mostram extremamente vulneráveis à certas perturbações antrópicas como a degradação do solo, a quais podem ocasionar drástica alteração da dinâmica da vegetação. Após a perturbação da camada superficial do solo, o conjunto interno de espécies (isto é, a vegetação remanescente e o banco de sementes) são frequentemente reduzidos ou até mesmo completamente eliminados. Nestes casos, a regeneração natural depende principalmente da dispersão de sementes da vegetação do entorno através da chuva de sementes. No entanto, comunidades vegetais em áreas perturbadas pela remoção do solo podem permanecer, mesmo após vários anos ao distúrbio original, muito diferentes do ecossistema de referência, apresentando baixíssima capacidade de regeneração natural. A dinâmica de dispersão de sementes em savanas tropicais, apesar de extremamente relevantes para uma melhor compreensão sobre a resiliência desses ecossistemas frente a ações antrópicas, permanece pouco estudada. Nesta tese, realizei uma revisão e três estudos experimentais sobre a dinâmica da chuva de sementes e da remoção de diásporos no campo rupestre, uma savana tropical natural, megadiversa e muito antiga localizada no sudeste do Brasil. No primeiro capítulo, realizei uma pesquisa bibliográfica sistemática sobre estudos de chuva de sementes em áreas não florestais no mundo com os seguintes objetivos: (1) avaliar onde, como e por que as pesquisas sobre chuva de sementes foram realizadas; (2) examinar como o desenho metodológico e os resultados foram relatados; (3) fornecer diretrizes para futuras pesquisas sobre chuva de sementes em áreas não florestais. Nesta revisão, eu encontrei um notável desequilíbrio no número de estudos entre os tipos diferentes tipos de áreas não florestais, o qual se torna ainda mais notável em relação à distribuição dos estudos entre as faixas climáticas globais e em relação à área total recoberta por cada ecossistema (ex. savanas tropicais). Neste estudo, foram identificadas algumas importantes lacunas de conhecimento relativas a estudos sobre a chuva de sementes em áreas não florestais. Foi evidenciado também uma grande disparidade entre os métodos de estudo de chuva de semente e sobre a maneira de reportar os dados observados, o que dificulta comparações entre estudos. Verificamos que apenas algumas tentativas foram feitas para avaliar a eficiência das armadilhas de captura de sementes e que nenhum estudo até o momento propôs algum protocolo para avaliar a eficácia dos métodos de captura de sementes utilizando armadilhas de sementes para áreas não florestais. No segundo capítulo, foi proposto e testado um protocolo simples para avaliar a eficiência de dois tipos de armadilhas de sementes (armadilhas pegajosa e de funil) e a eficácia de um método de busca e triagem de sementes coletas em armadilhas de funil, os quais podem ser realizados previamente aos estudos de chuva de semente. Como casos de estudo, no terceiro e quarto capítulos, pesquisei a dinâmica da chuva de sementes e de remoção secundária de diásporos em áreas preservadas e em áreas degradadas pela exploração de cascalho para a construção de estradas na vegetação do campo rupestre. O pequeno número de sementes capturadas na chuva de sementes indica limitação na dispersão de sementes e sugere uma estreita relação causal entre a limitação de dispersão de sementes e a baixa resiliência observada nestas áreas degradadas após a perturbação do solo.A identificação de espécies relativamente abundantes na chuva de sementes coloca essas espécies como potenciais alvos para futuros projetos de restauração visando a reintrodução de espécies
Joseph, Philippe. "Dynamique, éco-physiologie végétales en bioclimat sec à la Martinique (Antilles françaises)." Antilles-Guyane, 1997. http://www.theses.fr/1997AGUY0020.
Повний текст джерелаIn the sight of the vegetable world in its natural state, the insularity is synonymous with biocenotic, physionomic and landscaped diversity. When the anthropic energy which increases the climatic risks is added, this biodiversity rises noticeably and is shown by a great compexity of the high natural environments. The questionning and the ways of researching defined gave access to an approach of the main functional modalities of the vegetation, on the constituent vegetale elements (autoecology) level and on the vegetable communities they produce (synecology) level as well. Those latters, according to their place on the vegetable succession scale, give birth to inside environments specified by strict ecophysiologic characteristics. The last evolution of the vegetable sheet is shown by the sylvatic organisation setting up which can offer various floristic, ecosystemic and landscaped aspects. Those ones depend on the caribbean islands geomorgphology. The result is a kind of floristic gradient in the mountainous islands (allowing spatial movements, in the primitive climacic state) wihch component is the ecosystemic analogue of the flat islands vegetation. Maximal potentiality of the vegetable carpet known (sylvatic organization), the occurence of succession has been halved into two important parts : successional extra-sylvatic cycles and successional intra-sylvatic cycles which at each period is linked with a specific factorial space noticeable in the view point of their most reductible elements which are the setting of installation and expansion which linked formations, have an inside environment or caracteristic microclimate of the considered dynamic period and able to regulate in some cases, the macroclimayic variations
Pouyaud, Bernard. "Contribution à l'évaluation de l'évaporation de nappes d'eau libre en climat tropical sec : exemples du lac de Bam et de la mare d'Oursi (Burkina-Faso), du lac Tchad et d'Açudes du Nordeste brésilien." Paris 11, 1985. http://www.theses.fr/1985PA112388.
Повний текст джерелаJaquemet, Sébastien. "Rôle des oiseaux marins tropicaux dans les réseaux trophiques hauturiers du Sud-Ouest de l'océan Indien." La Réunion, 2005. http://tel.archives-ouvertes.fr/tel-00464182/fr/.
Повний текст джерелаTropical seabirds show a hierarchical distribution depending on the position of their colonies and their dispersion capability. At macro-scale it reflects the boundaries of their habitats, at meso-scale the presence of structures aggregating prey, and at micro-scale the presence at the surface of prey driven by predatory schools. In the South-West Indian Ocean, more than 6 millions of birds are present, of which 99% are sooty terns. They breed seasonally in austral winter in the Seychelles and at Europa, in austral summer at Juan de Nova. The high chlorophyll concentration around colonies favours the development of food web leading to the terns. The location of Glorieuses favours a sub-annual breeding regime, led by the presence of prey around the colony all year round. Biomass removed by terns in the Mozambique Channel is estimated to 55,000 tons, by breeding season
Bourgoin, Clément. "A framework for evaluating forest ecological vulnerability in tropical deforestation fronts from the assessment of forest degradation in a landscape approach : Case studies from Brazil and Vietnam." Electronic Thesis or Diss., Paris, Institut agronomique, vétérinaire et forestier de France, 2019. http://www.theses.fr/2019IAVF0027.
Повний текст джерелаThe conservation of tropical forest cover is a key to ensuring sustainable provision of multiple ecosystem services. In human-modified landscapes, forest conservation must also be reconciled with agricultural productivity. However, increasing demography, demand for agricultural products and changes in land uses are affecting forest sustainability through degradation processes. A first step to tailor effective forest management by local decision makers is to identify most vulnerable forests and to characterize what is driving this vulnerability. The objective of this thesis is to develop a multidimensional approach using remote sensing to assess forest degradation and the relations with the broader dynamics of land use/cover towards the evaluation of forest ecological vulnerability. The thesis was applied in old-deforestation fronts of Paragominas (Brazil) and Di Linh (Vietnam) where large-scale deforestation driven by commercial agriculture shaped the landscape into land use mosaics with increasing degradation pressures. In Paragominas, degradation is linked with long-term accumulation of selective logging and fire implying changes in forest structure. We estimated the potential of multisource remote sensing to map forest aboveground biomass (AGB) from large-scale field assessment of carbon stock. We improved the accuracy of AGB mapping compared to pantropical datasets and revealed that 87% of forest was degraded. At a lower scale, we investigated the consequences of 33 years of degradation history from Landsat on forest structures using Unmanned Aerial Vehicle. We found that canopy textures captured canopy grain, heterogeneity and openness gradients, correlated with forest structure variability and could be used as proxies to characterize degraded forests. We also assessed the potential of very high resolution satellite images and derived canopy textures to upscale texture-structure relations at the municipality scale. Based on environmental, geographical factors and landscape structure metrics derived from land use/cover classification, we demonstrated that 80% of forest degradation was mainly driven by accessibility, geomorphology, fire occurrence and fragmentation. The drivers of degradation acted together and in sequence and clustering analysis disentangled different cascades of effects. Changes in landscape structure allowed reconstructing trajectories informing on agricultural frontier dynamics. The combination of current forest state, landscape dynamics and distribution of degradation drivers would be at the basis of ecological vulnerability assessment. In Di Linh, degradation mostly concerns forest edges and is driven by encroachment of coffee-based agriculture. Field inventory of the different forest types and other landscape elements combined with Sentinel-2 images allowed to map with high precision the current land cover. We then mapped land cover changes over 45 years using Landsat time series. We constructed trajectories of landscape structure dynamics from which we characterized the expansion of the agricultural frontier and highlighted heterogeneous agricultural encroachment on forested areas. We also identified degradation and fragmentation trajectories that affect forest cover at different rates and intensity. Combined, these indicators pinpointed hotspots of forest ecological vulnerability. Most vulnerable forest areas were experiencing rapid and recent forest cover loss associated with landscape fragmentation, land use competition due to coffee production and degradation. Through the developed remote sensing approaches and indicators at forest and landscape scales, we provided a holistic diagnosis of forests in human-modified landscapes encompassing forest state and broader dynamics and drivers. This thesis aims to pave the way for tailored and prioritized management of degraded forests at the landscape scale
Huguet, Lucie. "Caractérisation biogéochimique et potentiel de méthylation du mercure de biofilms en milieu tropical (retenue de Petit Saut et estuaire du Sinnamary, Guyane Française)." Thesis, Nancy 1, 2009. http://www.theses.fr/2009NAN10080/document.
Повний текст джерелаThe Petit Saut dam was built on the Sinnamary River in French Guiana in 1994 and its flooding has resulted to the final immersion of 350 km² of uncleared tropical rainforest. All immersed surfaces (rocks, immersed tree branches and trunks, roots…) in the reservoir lake and in the downstream are recovered by abundant biofilms. The aim of the present work was to characterize biofilms in terms of elemental composition, organic matter content and microbial communities and to define their role in mercury methylation. A multidisciplinary approach, applied to the biofilms and the nepheloid layer of the reservoir sediment, consisted in (i) assessing carbon, nitrogen, iron, sulfur, manganese, mercury and methylmercury concentrations, (ii) characterizing the nature of organic matter using its carbon and nitrogen isotopic composition (?13C and ?15N), its C/N ratio and its fatty acids composition (focusing on bacterial biomarkers). In the reservoir, suspended particles matter is an important source of accumulating material in biofilms. Reservoir biofilms contain higher refractory organic matter than the biofilms of the estuary and than the reservoir nepheloid layer. Iron, sulfur and manganese, mercury and methylmercury concentration are stratified with depth. Even if the relative contribution of bacterial fatty acids biomarkers was low, Chlorobiaceae was identified above the oxycline, whereas iron reducing bacteria were predominant in the hypolimnion as regards sulphate reducing bacteria. In the estuary, iron weights for the major part of the biofilm and higher IRB amount is present than SRB. The more labile organic matter allows the development of various microbial metabolic groups such as methanotrophs at the Passerelle station. Presence of Firmicutes-Archaea consortia (FISH analysis) in enrichment of Passerelle biofilms and of the reservoir nepheloid layer suggests that methane could also be oxidized under anaerobic synthrophy. This study shows a new application of stable isotope incubation to determine mercury methylation potential in tropical biofilms. Methylation potential is the lowest in the biofilm from the oxycline whereas higher methylation rates are obtained for microorganisms of the water column (planktonic), nepheloid layer, biofilms sampled at -20 m and at the Passerelle station. Adding nutrient enhances mercury methylation, especially in the estuary but it doesn’t only promote growth of methylating microorganisms but also that of demethylating or not involved in Hg transformation microorganisms Differences in methylation potential could be explained by either the bacterial communities diversity and/or by biofilm composition modifying Hg bioavailability
Toro, Perez Catalina. "La biodiversité tropicale, entre gouvernance globale et réalités locales : le cas de la politique de protection de la biodiversité en Colombie." Paris, Institut d'études politiques, 2008. http://www.theses.fr/2008IEPP0052.
Повний текст джерелаIn the early 90s, when the forum of the Earth Summit in Rio took place, tropical countries like Brazil, Colombia, Mexico, Côte d'Ivoire, India, China, were presented as "The Hots Spots": the richest and most threatened areas of biological and cultural diversity of the planet. The loss of tropical biodiversity, as a common concern of humanity will gradually emerge as one of the most widespread consensus in the Forum of the Community of global environmental policy: Three-quarters of the world population use medicines and benefit agricultural development related to the exploitation of tropical plants. However, genetic research in tropical countries is restricted because of the existent mechanisms of control they impose to avoid access to natural resources and traditional knowledge. A principle is then referred to a global resource intervention, necessary and useful for scientific research, and management in the common interest of all. A set of ideas, institutions and interest groups will shape a new system of genetic resources defined in terms of access, property rights and free trade in the tropical countries. The evolution of the political protection of common property under the principle of non-appropriation to a global trade system of genes will become one of the major issues of the global governance of tropical biodiversity. The purpose of this research is to show how the process and re-transmission of biodiversity, as a "common concern of mankind" change ideas, power structures and institutions of nature conservation in the global system and how it is reflected in "tropical" countries, like Colombia
Dahome, Di Ruggiero Michelle. "Evolution, exploitation et amenagement des zones humides littorales dans les petites Antilles Françaises." Antilles-Guyane, 2008. http://www.theses.fr/2008AGUY0240.
Повний текст джерелаThe humid coastal zones (mangroves swamps, marshy forest, marsh meadow) of Guadeloupe and Martinique. Subjects to anthropic pressures, are they ln danger? The traditionals activities detremine a phytologic spatio-temporal dynamic of environment ensuring a newbalance to the system. With the analysis of aerial photographies, field-cheeking, a bibliographie synthesis permitted a typography based on the nature of the back mangrove swamp and a cartography of the spatial evolution of these zones of 1950 to 2004. Ali the diminishedprocesses are seen near urbaniazed areas. The counting ob of biological and physical indicators of the anthropisation convey thecharacteristics of traditionals uses differently applied in the 2 islands. The estimate of the anthropic pressure show the vulnerability of the forests near urbanized zones or roads and meadows and marshes. Surveys conducted in the field define the population of users and the social determinism of the uses. The study of popular regional events 'crab feast, shooting) gives the resources value of these habitats anexplains the economic of humid littoral of uses. These 2 determinisms pose the problem of the Iimiting utllizations of zhl. If the protectionsystem ot these 2 islands is identical (national or intemationallaws) but the management implemented in each of them is different. In Guadeloupe, it's necessary to propose concerted actions between ail actors of zhl for an better integrated
Legendre, Marc. "Potentialités aquacoles des Cichlidae (Sarotherodon melanotheron, Tilapia guineensis) et Claridae (Heterobranchus longifilis) autochtones des lagunes ivoiriennes." Montpellier 2, 1991. http://www.theses.fr/1991MON20295.
Повний текст джерелаDe, Garine-Wichatitsky Michel de. "Ecologie des interactions hôtes/vecteurs : analyse du système tiques/ongulés sauvages et domestiques en zone tropicale." Montpellier 2, 1999. http://www.theses.fr/1999MON20114.
Повний текст джерелаGirard, 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.
Повний текст джерелаHydraulic 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
Messié, Monique. "Contrôle de la dynamique de la biomasse phytoplanctonique dans le Pacifique tropical ouest." Phd thesis, Université Paul Sabatier - Toulouse III, 2006. http://tel.archives-ouvertes.fr/tel-00137145.
Повний текст джерелаGonzalez, Herrera Mailyn Adriana. "Etude de la diversité spécifique et phylogénétique de communautés de plantes ligneuses en forêt tropicale : apport des séquences ADN dans l'identification des espèces et l'étude des communautés." Toulouse 3, 2009. http://thesesups.ups-tlse.fr/682/.
Повний текст джерелаThis dissertation is anchored in the global need for understanding mechanisms underlying plant diversity, as well as the need to develop technical tools that allow one to study diversity. The studies included in this dissertation were conducted at the sites of Nouragues & Paracou in the rainforest in French Guiana. One of the goals was to test the reliability of DNA barcoding as a tool in tropical plant species identification. DNA barcoding performance was tested for seven plastid markers and one nuclear marker over more than 250 angiosperm species. DNA markers correctly delimit species in about 70% of cases. Despite this imperfect success, DNA barcoding was useful to identify juveniles stages, provided an aid to identification at the herbarium, and reveal potential cryptic species. One major goal of this dissertation was to examine ecological mechanisms that drive species assembly beyond the regeneration phase, integrating for this purpose molecular information. This was done by comparing phylogenetic and species diversity patterns of saplings and trees. I found no changes in species or phylogenetic richness across sapling and tree assemblages. However, rare species were favored across these size classes, increasing species evenness at the tree layer. These results, indicates that negative density-dependence is driving species sorting from sapling to tree assemblages. Elucidation of this mechanism highlights the importance of ecological processes beyond the regeneration phase in the maintenance of biodiversity in tropical tree communities
Fernandes, Correa Gilberto. "Les microreliefs "et leur environnement pédologique dans l'ouest du Minas Gerais, région du Plateau Central brésilien." Nancy 1, 1989. http://www.theses.fr/1989NAN10406.
Повний текст джерелаChirat, Guillaume. "Description et modélisation du comportement spatial et alimentaire de troupeaux bovins en libre pâture sur parcours, en zone tropicale sèche." Thesis, Montpellier, SupAgro, 2010. http://www.theses.fr/2010NSAM0005/document.
Повний текст джерелаArid and sub-arid areas, where are located most of the world's cattle, are concerned by a sustainable improvement of their productivity. During the dry season, that can last 9 months, herds range free on territories made of spontaneous plants and crop residues from cultivated areas. From observations of animal activities, intake rates and daily circuits on a sahelo-sudanian territory, we built a herd-oriented model which simulates spatial behavior (circuits) and feed intake (spatialized intake). Our approach consisted in introducing successively the very necessary information that realistically represents animal behaviors. The heuristic rules of herds'choices are a combination of our observations and ethological theories: i.e. factors linked to pastoral resources (cover types, biomass) and other abiotic factors (attraction to watering point and to night park) or to human decisions (breeder's practices). Integration of short-term intake process is based on relationships established between intake rate and available biomass of each cover type in order to emerge daily intakes. Altogether, the implemented equations are within the theoretical frame of the Functional response. The coupling of daily simulated circuits with prevision of intake, allowed calibration of agents Herds decision rules that fit observed behaviors. Although parsimonious, our approach kept the necessary representation of biological phenomena in order to ensure a model transportability to other semi-arid rangeland systems, if parameters are adjusted. Finally, this thesis proposes an original methodology to simulate spatialized feed uptakes by free-ranging cattle in the tropics, with ecological production improvement as a goal
Jabot, Franck. "Marches aléatoires en forêt tropicale : contribution à la théorie de la biodiversité." Toulouse 3, 2009. http://thesesups.ups-tlse.fr/641/.
Повний текст джерелаTropical forests contain a huge diversity of trees, even at small spatial scales. This diversity challenges the idea that, in given environmental conditions, one species should be better suited to this particular environment and progressively exclude all other species. Ecologists have proposed various hypotheses to explain diversity maintenance. One element prevents the test of these hypotheses: the lack of robust methods to link available theories and knowledge on tropical forests to field data, so as to compare different hypotheses. This thesis thus aims at developing more efficient tests of coexistence mechanisms. It is shown that environment filters tree communities at both the regional and local scales. This rejects, for the first time rigorously, the neutrality hypothesis, which aims at explaining species local coexistence in assuming their functional equivalence. This finding stimulates the development of a new dynamical model describing environmental filtering on the basis of species characteristics, such as functional traits. Applications to field data are discussed. Finally, evolutionary relationships among coexisting species contain potentially useful information on their ability to coexist. In this vein, it is shown how to integrate these evolutionary relationships in the test of the neutral theory of biodiversity. The dynamical models studied during this thesis are called, in mathematical terms, random walks. They have been mainly studied here thanks to a statistical technique called Approximate Bayesian Computation, which opens new perspectives for the study of dynamical models in ecology
Nkoue-ndondo, Gustave-Raoul. "Le cycle du carbone en domaine tropical humide : exemple du bassin versant forestier du Nyong au sud Cameroun." Toulouse 3, 2008. http://thesesups.ups-tlse.fr/476/.
Повний текст джерелаSpatial and temporal follow ups of carbon contents and its isotopic signature d13C in the Nyong river basin allow on one hand, at a local scale (small experimental catchment of Mengong), to identify the carbon sources, and on the other hand, at a regional scale (Nyong river basin), to understand the biogeochemical processes which control the carbon transformations and exchanges between the different reservoirs during the transfer from upstream to downstream. In these wet tropical ecosystems, the swampy soils of bottom valley low marshes present in surface a thick organic carbon rich horizon (12 to16 %), with isotopic signatures d13C of -29 ‰ in equilibrium with C3 plants (-32 ‰ to -28 ‰). During the rainy season, the mineralization of organic matter and the leaching of swampy areas are responsible of hight DOC contents (until 38 mg / L) in streamwaters, strong pCO2 and impoverished d13CDIC isotopic signatures (-20 ‰ on average). During the dry season, the shrinkage of the swampy zones facilitates the supply of streams by low DOC content (< 1mg / L) and enriched d13CDIC (d13CDIC until 7 ‰%) grounwaters. The carbon flux into the ocean is estimated to 1. 2*106 t C / year, i. E. 6. 24 t C/km2. Year, of which 80 % of DOC, 8 % of POC and 12 % of DIC. During the transfer from upstream to downstream, a DOC decrease of 33 % is observed in relation with oxidation processes. The resulting strong pCO2 facilitate the CO2 degassing towards the atmosphere, estimated for the Nyong river system at 2. 3* 105 t C / year. This CO2 degassing is accompanied by an isotopic enrichment of about 4 ‰. The weathering of silicate minerals by organic acids leads to a surplus of Ca+Mg (0. 5 < Ca+Mg / HCO3- < 2. 2) with regard to a natural weathering pathway by the carbonic acid (Ca+Mg / HCO3- = 0. 5). .
Chevallier, Pierre. "Complexité hydrologique du petit bassin versant : exemple en savane humide, Booro-Borotou (Côte-d'Ivoire)." Montpellier 2, 1988. http://www.theses.fr/1988MON20221.
Повний текст джерелаArvanitakis, Laurence. "Interaction entre la teigne du chou Plutella xylostella (L.) et ses principaux parasitoïdes en conditions tropicales : approche éthologique, écologique et évolutive." Phd thesis, Université Paul Valéry - Montpellier III, 2013. http://tel.archives-ouvertes.fr/tel-00984578.
Повний текст джерелаUlloa, chacón Juan. "Estimation de la diversité acoustique animale en forêt néotropicale." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS120.
Повний текст джерелаAcoustic signalling is a common behavioural trait among terrestrial animals. The rich sound textures of neotropical forest echo that wildlife is not only abundant, but also diverse and dynamic. This facet of biodiversity can reveal valuable insights of animal communities inhabiting tropical environments, yet remains poorly understood. How to best measure tropical acoustic diversity to address ecological questions? Based on the ecoacoustic framework, we explored the soundscape of neotropical forest, revealing patterns and investigating the ecological underlying processes. First, we tracked the spatiotemporal dynamics of an amazonian soundmark, the song of the bird Lipaugus vociferans, showing activity patterns related to specific habitat features. Then, we investigated amphibian communities with very brief reproduction periods. Coupling acoustic and environmental variables, we shed light on the causes, patterns and consequences of explosive breeding events. Finally, we adapted novel computational tools from the machine learning and pattern recognition disciplines to provide an efficient, objective and replicable analysis of large acoustic datasets. Ecoacoustics, powered with computer algorithms, emerge as a suitable approach to scale-up biodiversity monitoring programs, allowing to better understand and cherish the unique diversity of life sustained by tropical forest
Jaouen, Gaëlle. "Etude des stratégies biomécaniques de croissance des jeunes arbres en peuplement hétérogène tropical humide." Phd thesis, Université Henri Poincaré - Nancy I, 2007. http://tel.archives-ouvertes.fr/tel-00272100.
Повний текст джерелаLemaire, Jérémy. "Mercury contamination in caimans from French Guiana, bioaccumulation and physiological effects." Thesis, La Rochelle, 2021. https://tel.archives-ouvertes.fr/tel-03716076.
Повний текст джерелаMercury (Hg) is a global environmental contaminant that affects ecosystems. It has the particularity to biomagnify through the food web, and to bioaccumulate especially in tissues of top predators. Mercury has been identified to have detrimental effects on human and wildlife. Top predators from tropical ecosystems are particularly affected by Hg contamination due to artisanal small scale gold mining, which uses massive amounts of Hg in the gold extraction process. Crocodilians are top predators of tropical ecosystems and have been identified to accumulate high concentrations of Hg in their tissues. They are potentially good candidates to monitor Hg contamination, as they are long-living animals with low metabolic, and high tissue conversion rates, which favours the bioaccumulation of Hg. Additionally, they have a large repartition over tropical and sub-tropical ecosystems, which make large-scale Hg evaluation possible. My doctoral work focuses on the four caiman species that are present in French Guiana (the Black caiman Melanosuchus niger, the Dwarf caiman Paleosuchus palpebrosus, the Smooth-fronted caiman Paleosuchus trigonatus and the Spectacled caiman Caiman crocodilus). First, I have worked on Hg variation across different tissues obtained by minimally invasive methods, and investigated the influence of morphology and feeding ecology (by using stable isotope method) on Hg contamination in caimans. Second, I have investigated the impact of Hg contamination on physiological mechanisms, and the maternal transfer and its effects on neonates
Mendez, Loriane. "Variabilité du comportement de recherche alimentaire d’un oiseau marin tropical : le fou à pieds rouges (Sula sula)." Thesis, La Rochelle, 2017. http://www.theses.fr/2017LAROS020/document.
Повний текст джерелаSeabird foraging behaviour varies through time according to factors that may be related to life cycle stage and/or habitat. However, no study has previously investigated variation in these different factors and how they impact foraging behaviour in a single species simultaneously. The aim of this thesis was to distinguish the fixed part of foraging behaviour from its different degrees of plasticity in a pantropical seabird, the Red-footed booby (Sula sula). Adults and juveniles from different colonies were equipped with GPS tags to track their foraging trips according to several intrinsic (age and breeding stage) and extrinsic factors (physical forcing, primary productivity and competition for resources). Adult foraging behaviour varied significantly within the same colony according to breeding stage. Tracks were shorter during brooding, which is known to be a particularly energy-constraining time period, and longer during incubation and fledging. Multi-year monitoring at one of the colonies revealed flexibility in behaviour under adverse environmental conditions. Longer tracks were observed during breeding seasons with decreased productivity and eddy activity. High plasticity in foraging behaviour according to habitat was observed across the range of the species. The length and range of adult trips varied considerably among colonies, ranging from strictly diurnal to longer trips that included several nights spent at sea. Red-footed boobies did not appear to target particularly productive areas, and intra- and interspecific competition seemed to explain partly the differences observed between colonies. On the other hand, all the individuals showed similar trip structuring and increased searching effort by adopting area-restricted search (ARS) behaviours. The behaviour of juveniles, still fed by their parents after fledging during a long transition period, was described for the first time. Over time, juveniles increased trip ranges, which were considerably lower than that of adults. Associations at sea with other juveniles were frequently identified. This long learning period seems to be an adaptation allowing the gradual acquisition of the skills necessary for the search and capture of prey. While the behavioural plasticity of individuals tends to cushion the effects of unfavourable conditions at the population scale, this flexibility is still limited. In the current context of global change, assessment of behavioural plasticity is necessary in order to better predict the consequences of these changes on populations
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.
Повний текст джерелаMarine 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
Maréchaux, Isabelle. "Individual-based modelling of tropical forests : role of biodiversity and responses to drought." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30244/document.
Повний текст джерелаA great part of uncertainties in our current understanding and projections of the carbon cycle lies in the vegetation compartment. The problem of biodiversity representation in vegetation models has long been an impediment to a detailed understanding of ecosystem processes. The high biodiversity of tropical forests, their disproportionate role in global biogeochemical cycles, together with their vulnerability to direct and indirect anthropogenic perturbations, amplify the relevance of this research challenge. In particular, the predicted increase in drought intensity and frequency in the tropics may impact forest structure and composition, as already observed in natural and artificial experiments. This thesis explores how new advances in modelling and ecophysiology should help improve our understanding of these processes in the future. In the first chapter, I describe an individual-based and spatially-explicit forest growth simulator, TROLL, that integrates recent advances in plant physiology. Processes are linked to species-specific functional traits parameterized for an Amazonian tropical rainforest. This model is used to simulate a forest regeneration, which is validated against observations in French Guiana. Model sensitivity is assessed for a number of key global parameters. Finally, we test the influence of varying the species richness and composition on ecosystem properties. Tropical forest response to drought is not well understood, and this hampers attempts to model these processes. In chapters 2 to 5 I aimed at documenting drought-tolerance and its diversity in an Amazonian forest. A rapid method of determination of a leaf drought tolerance trait, the leaf water potential at turgor loss point (ptlp), was validated and applied to a range of plant species. We established the first community-wide assessment of drought tolerance in an Amazonian forest. These results inform on the drivers and determinants of leaf drought tolerance, across tree species and lianas, tree size, successional stages, light exposition, and seasons. Variability in ptlp among species indicates the potential for a range of species responses to drought within Amazonian forest communities. This is further confirmed by direct monitoring of whole-plant water use on diverse canopy trees during a marked dry season. Finally, I discuss the implications of these results to increase the dialogue between the vegetation modeling community and ecology, to enhance model's predictive ability, and to inform policy choices
Tournebize, Rémi. "Influence des variations spatio-temporelles de l’environnement sur la distribution actuelle de la diversité génétique des populations." Thesis, Montpellier, 2017. http://www.theses.fr/2017MONTT140.
Повний текст джерелаThis project aims at understanding how the structure of the intra-specific genetic diversity in emblematic tropical plant species and in the human species was shaped by the spatiotemporal variation of current and past environments. We developed a genetic inference approach based on the coalescent theory to assess the potential impact of past climatic change onto the evolution of the geographic range and of the neutral and/or adaptive genetic diversity in Amborella trichopoda Baill. in New Caledonia (sister-species of all extant angiosperms, NGS and microsatellite datasets), in Coffea canephora Pierre ex A. Froehn in tropical Africa (Robusta coffee, NGS dataset) and in North-Western European and African (Luhya, Kenya) human populations (NGS dataset 1000 Genomes Project). We found that the climatic fluctuations of the Late Pleistocene influenced the evolution of genetic diversity in these species distributed in temperate and tropical environments. The environmental conditions during the Last Glacial Maximum (LGM, 21.000 years before present) appear as an important factor. The demographic contraction associated with the last global glaciation influenced the divergence between Amborella genetic lineages and contributed to the accumulation of genetic differences between C. canephora lineages. Our results suggest that global glaciation events likely drove idiosyncratic genetic differentiation in tropical rain forests but the intensity of this response varied between species. We also identified multiple events of selection in the genomes of the European human population which were likely triggered by the environmental conditions during the LGM. The associated phenotypic adaptations probably allowed the paleo-populations to maintain their demographic expansion despite the new kinds of selective pressure they faced during the last glacial age in Europe
Majeed, Muhammad Zeeshan. "Emissions of nitrous oxide by tropical soil macrofauna : impact of feeding guilds and licrobial communities involved." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20073/document.
Повний текст джерелаSoils account for about 63% of N2O emissions. Tropical soils are estimated to emit 23% of global N2O emission budget which is much higher than temperate soil N2O emissions. These soils also harbor a huge biodiversity of invertebrates dominated by four types of macrofauna i.e. termites, earthworms, ants and scarabaeid grubs. These macrofaunal groups are considered as soil engineers because they regulate the availability of chemical resources, like mineral nitrogen, for the microorganisms via their specific digestion capabilities and/or by creating and modifying soil habitats. This study is based on the following hypothesis (i) the gut environment or biogenic structures of these soil engineers are considered as hotspots of N2O emission (ii) the N2O emission rates will vary according to their feeding behavior as these macrofauna thrive on diverse substrates with different C:N ratio (iii) the rate of N2O emission in each soil fauna will also depend on the gut density of the bacterial communities involved in the N2O emission (nitrifiers and denitrifiers) and on the mineral nitrogen content within the gut. To assess these different hypotheses in-vitro short-term N2O emission rates were assessed for either live macrofauna (30 species collected from Africa, South America and Europe) or their biogenic materials or both under aerobic incubations. Genes abundance of nitrifiers (AOA and AOB) and denitrifiers (nirK, nirS, nosZ) were quantified by real time quantitative PCR. Soil-feeders and fungus-growing termites and scarabaeid grubs emitted in-vivo N2O while ants did not. Surprisingly, wood- and grass-feeding termites revealed an uptake of N2O. Biogenic structures of earthworms and ants emitted substantial amount of N2O while those of termites did not. The emission difference between macrofauna or their biogenic materials and their control materials was significant for most of the macrofaunal groups studied confirming our first hypothesis. We also confirmed that the feeding behavior (total N content and C:N ratio of food material) is the main factor explaining the observed N2O emission pattern of each macrofaunal group investigated whereas genes abundances, particularly of denitrifiers and gut N mineral content did not appear to be relevant proxies of the N2O emissions rates. A back-on-the-envelope data upscaling suggests that soil macrofauna could contribute from 0.1–11.7% and 0.1–8.8% of the total soil N2O emissions, respectively, for the tropical rainforest and dry savanna ecosystems. This work should contribute to a better estimation of the soil biotic compartment in the different models of greenhouse gas emissions from tropical soils
Schmitt, Boris. "Ressources naturelles et développement dans le monde tropical : les contradictions entre dynamiques écologiques, reproduction sociale et ordre économique international." Phd thesis, Université de Bourgogne, 2013. http://tel.archives-ouvertes.fr/tel-00995156.
Повний текст джерелаLe, Thi Huong. "Impact of land use change and agricultural practices on aquatic microbial diversity and functioning in a tropical system." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1203/document.
Повний текст джерелаLand use (LU) change towards non-sustainable agricultural practices enhances soil degradation, erosion, and the loss of soil microbial diversity. However, the impacts of LU change on in-stream microbial community structure remain poorly understood, particularly in tropical ecosystems. Through controlled experiments and in situ investigations, I assessed how different LU and agricultural practices, via hydrological processes, affect the quantity and quality of stream dissolved organic matter and associated microbial community structure. The results of this work show the importance of considering both past and present LU along with hydrological processes when assessing stream microbial diversity and metabolic capacities. While the experiments in controlled conditions (micro- and mesocosms) allowed disentangling the relative importance of direct overland flow and soil community on stream bacterial structure, the in situ approach gave an integrated view of these processes at the basin scale. This emphasizes the need to use sustainable LU management practices if we wish to mitigate off-site impacts on downstream aquatic systems
Couic, Ewan. "Interactions microorganismes - mercure - composante du sol : des outils pour l'évaluation de la qualité de la restauration écologique des sites miniers aurifères en Guyane française." Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC1150/document.
Повний текст джерелаFor more than 150 years, gold mining in French Guiana has disrupted the landscape by causing massive deforestation of mining concessions. The consequences are multiple, both for the environment and human health. Indeed, for decades the use of mercury in the extraction process has led to pollution of aquatic systems, contaminating the food chain. In order to ensure that gold mining is carried out in a sustainable development perspective, the Mining Code has imposed an obligation since 1998 to rehabilitate the sites operated. Several revegetation methods using different plant species have been adopted to accelerate ecological succession. However, quality control of ecological restoration is difficult to implement and it is necessary to have reliable and inexpensive bio-geo-indication tools to estimate the recovery of the functionalities of anthropized ecosystems and assess the risk of mobility of toxic metallic elements.In this context, the objectives of this thesis work were to evaluate the quality of ecological restoration of mining sites in French Guiana through a characterization of microbial activities, the functioning of biogeochemical cycles of major elements (C,N,P) and the dynamics of mercury. The originality of this work lies in the evaluation over time and space of the interactions between vegetation cover - physico-chemical properties of the soil - microbial activities - mercury speciation after revegetation and making it a diagnostic tool for the success of this restoration. To this end, several sampling campaigns were carried out in French Guiana on a panel of rehabilitated mining sites, with different types of vegetation cover. Soil samples were taken from replanted sites with fabaceous species (A. mangium and C. racemosa), and from non-restored sites. We then evaluated the main functionalities of the microbial communities of these sites through the use of several soil quality bio-markers. In order to estimate the fate of mercury, measurements of total mercury as well as operational and environmental specimens were carried out. This thesis work revealed a positive effect of revegetation on the density and activities of soil microbial communities. Sites restored with fabaceous species have thus shown microbial biomass, macro-element mineralization rates (C,N,P), and catabolic diversity significantly higher than sites that have not been restored. The associations of fabaceous plants show more conclusive results than the use of monoculture in terms of microbial functionalities. While the activities of aerobic microorganisms have been impacted by the return of vegetation, our results confirm that restoration influences the activities of anaerobic microbial communities. Indeed, work on iron-reducing (IRB) and sulfate-reducing (SRB) bacterial communities shows varying activities between revegetation modalities. These differences are related to the physical and chemical properties of the soil and the nature and density of the vegetation cover. BFR communities are more active on rehabilitated sites while SRB communities are more active on poorly restored sites. These differences in activities have consequences on mercury mobility and methylation. Our work also shows that while mercury in re-vegetated sites is associated with stable phases of the soil, including iron oxides, in non-restored sites it is in soluble forms that can potentially be mobilized in the water network, bioavailable and assimilated by organisms in the food chain.In conclusion, the interdisciplinary approach proposed in this work made it possible to identify certain fundamental microbial ecological processes that impact the recovery of the functionalities of degraded mining ecosystems. This work provides an original, applied and promising tool for assessing the quality of ecological restoration that may be of interest to decision-makers responsible for the rehabilitation of mining sites in French Guiana
Sabajo, Clifton. "Changements dans l’utilisation des terres et de la couverture terrestre en Asie du sud-est : les effets de la transformation sur les paramètres de la surface en Indonésie." Thesis, Paris, AgroParisTech, 2018. http://www.theses.fr/2018AGPT0005.
Повний текст джерелаOver the last decades, Indonesia has experienced dramatic land transformations with an expansion of oil palm plantations at the expense of tropical forests. Indonesia is currently one of the regions with the highest transformation rate of the land surface worldwide related to the expansion of oil palm plantations and other cash crops replacing forests on large scales. As vegetation is a modifier of the climate near the ground these large-scale land transformations have major impacts on surface biophysical variables such as land surface temperature (LST), albedo, vegetation indices (e.g. the normalized difference vegetation index, NDVI), on the surface energy balance and energy partitioning.Despite the large historic land transformation in Indonesia toward oil palm and other cash crops and governmental plans for future expansion, this is the first study so far to quantify the impacts of land transformation on biophysical variables in Indonesia. To assess such changes at regional scale remote sensing data are needed.As a key driver for many ecological functions, LST is directly affected by land cover changes.We analyze LST from the thermal band of a Landsat image and produce a high-resolution surface temperature map (30 m) for the lowlands of the Jambi province in Sumatra (Indonesia), a region which experienced large land transformation towards oil palm and other cash crops over the past decades. The comparison of LST, albedo, NDVI, and evapotranspiration (ET) between seven different land cover types (forest, urban areas, clear cut land, young and mature oil palm plantations, acacia and rubber plantations) shows that forests have lower surface temperatures than the other land cover types, indicating a local warming effect after forest conversion. LST differences were up to 10.1 ± 2.6 ºC (mean ± SD) between forest and clear-cut land. The differences in surface temperatures are explained by an evaporative cooling effect, which offsets an albedo warming effect.Young and mature oil palm plantations differenced in their biophysical. To study the development of surface biophysical variables during the 20 – 25 years rotation cycle of oil palm plantations, we used three Landsat images from the Jambi province in Sumatra/Indonesia covering a chronosequence of oil palm plantations.Our results show that differences between oil palm plantations in different stages of the oil palm rotation cycle are reflected in differences in the surface energy balance, energy partitioning and biophysical variables. During the oil palm plantation lifecycle the surface temperature differences to forest gradually decrease and approach zero around the mature oil palm plantation stage of 10 years. Concurrently, NDVI increases and the albedo decreases approaching typical values of forests. The surface energy balance and energy partitioning show a development patterns related to biophysical variables and the age of the oil palm plantations. Newly established and young plantations (< 5 years) have less net radiation available than mature oil palm plantations, yet have higher surface temperatures than mature oil palm plantations. The changes in biophysical variables, energy balance and energy partitioning during the oil palm rotation cycle can be explained by the previously identified evaporative cooling effect in which the albedo warming effect is offset. A main determinant in this mechanism is the vegetation cover during the different phases in the oil palm rotation cycle. NDVI as a proxy for vegetation cover showed a consistent inverse relation with the LST of different aged oil palm plantations, a trend that is also observed for different land use types in this study. (Last and final summary in the thesis)
Quinard, Aurélie. "Diversité génétique individuelle, différenciation morphologique et comportementale entres les sexes, patterns d'appariement et paramètres démographiques chez une espèce d'oiseau tropicale et monogame, la tourterelle à queue carrée, Zenaida Aurita." Phd thesis, Université de Bourgogne, 2013. http://tel.archives-ouvertes.fr/tel-00995585.
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