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1	Écologie de l’abeille, Apis mellifera unicolor Latreille, dans les écosystèmes forestiers naturels de Ranomafana (Madagascar) et Mare Longue (Réunion) : étude du comportement de butinage et de l’utilisation des ressources florales par approche mélissopalynologique / Ecology of the honeybee, Apis mellifera unicolor Latreille, in the natural forest ecosystems of Ranomafana (Madagascar) and Mare Longue (Réunion) : study of foraging behavior and the use of floral resources by melissopalynological approach Rasoloarijao, Tsiory Mampionona 14 November 2018 (has links) Les écosystèmes forestiers naturels du Sud-Ouest de l’océan Indien (SOOI) sont fortement impactés par la déforestation et font face à de nombreuses invasions biologiques pouvant altérer leur processus, en particulier les interactions de type plantes-pollinisateur. C’est dans ce contexte que s’inscrit cette thèse, décrivant les relations entre un pollinisateur généraliste indigène : Apis mellifera unicolor et la flore de deux écosystèmes de Ranomafana : RA et de Mare Longue : ML. La description palynologique de 135 espèces issues de 52 familles de plantes mellifères de la formation de RA, a fait ressortir les caractères spécifiques des pollens liés à une pollinisation entomophile. Dans un second temps, des suivis phénologiques mensuels de 131 espèces (90% d’indigènes) à RA et 120 espèces (53% d’exotiques) à ML ont permis d’identifier et d’estimer les ressources florales disponibles. Pendant un an, l’analyse mensuelle des miels et pollens collectés a permis de dresser l’inventaire des ressources florales réellement exploitées. Les espèces indigènes ont été significativement plus butinées que les espèces exotiques, malgré une diversité de ressources exotiques supérieures à celles des indigènes (ML). Le comportement de butinage de l’abeille sur le genre Weinmannia a été analysé sur la base de 104 h de vidéo (W. bojeriana et W. rutenbergii à Madagascar, et W. tinctoria à La Réunion). Les fleurs ont été visitées par un cortège de pollinisateurs potentiels : coléoptères, diptères, lépidoptères et autres hyménoptères. A. m. unicolor était le visiteur le plus fréquent à Madagascar. L’ensemble de ces résultats a permis de confirmer le comportement généraliste d’A. m. unicolor, avec toutefois une préférence forte et significative pour les espèces florales indigènes des strates arborées et arbustives et permet d’émettre des hypothèses sur la complexité des interactions entre l’abeille et les écosystèmes du hotspot de biodiversité SOOI. / The natural forest ecosystems of the Southwest Indian Ocean (SOOI) have been strongly impacted by deforestation and face many biological invasions that are alter their balance, particularly plant-pollinator interactions. It is in this context that this thesis is set, describing the relations between an indigenous general pollinator: Apis mellifera unicolor and the flora of two ecosystems of Madagascar (Ranomafana: RA) and Reunion (Mare Longue: ML). The palynological description of 135 species from 52 families of melliferous plants from the RA formation, highlighted the specific criteria of pollens associated with entomophilous pollination. In a second time, monthly phenological monitoring of 131 species (90% native) to RA and 120 species (53% exotic) to ML allowed to identify and estimate the available floral resources. During one year, the monthly analysis of honeys and pollen collected enabled an inventory of the floral resources actually exploited. Native species were significantly more visited than exotic species, despite a diversity of exotic resources superior to that of the natives (ML). The foraging behaviour of the honeybee on the genus Weinmannia was analysed on the basis of 104 hours of video (W. bojeriana and W. rutenbergii in Madagascar, and W. tinctoria in Reunion Island). The flowers were visited by many potential pollinators: Coleoptera, Diptera, Lepidoptera and other Hymenoptera. A. m. unicolor was the most frequent visitor to the two species from Madagascar. The results confirmed the generalist behaviour of A. m. unicolor, with, however, a strong and significant preference for native floral species of tree and shrub strata and makes it possible to speculate on the important place of this bee in the ecosystems of the SOOI biodiversity hotspot. Apis mellifera unicolor Pollen Miel Comportement de butinage Flore indigène Forêt dense humide de moyenne altitude Apis mellifera unicolor Pollen Honey Foraging behaviour Native flora Tropical rainforest
2	Rats invasifs et biodiversité native au sein des forêts denses humides de Nouvelle-Calédonie. : Eléments pour l’amélioration des stratégies de gestion / Invasive rats and native biodiversity in New Caledonian rainforests. : Insights for improvement of management strategies Duron, Quiterie 06 September 2016 (has links) Les rats introduits (Rattus spp.) sont des espèces invasives majeures menaçant la biodiversité sur la plupart des îles de laPlanète. Deux espèces, le rat noir (R. rattus) et le rat du Pacifique (R. exulans) vivent en sympatrie au sein des forêts deNouvelle-Calédonie, où la question de la faisabilité et de l' intérêt de leur contrôle (i.e. limitation locale de leur 'abondance)pour la conservation de la biodiversité native est posée. En raison d'un manque de cadre conceptuel des projets de contrôle,nous avons d'abord réalisé une synthèse et une analyse des opérations de contrôle de rats invasifs dans les milieux naturelsdes îles du monde. Puis, nous avons cherché à caractériser et à comprendre la dynamique des populations de ces deux espècesde rats sympatriques ainsi que leurs interactions avec la biodiversité native en forêt dense humide du massif du Mont Panié.Des opérations de piégeage létal et de capture-marquage-recapture ont montré que les rats noirs étaient plus abondants que lesrats du Pacifique. Les analyses de leur régime alimentaire ont révélé que les deux espèces ont à la fois des proies communeset des proies qui leur sont propres impliquant un renforcement ainsi qu'un élargissement de leurs impacts sur la biodiversiténative. Les rats consomment une grande majorité de fruits et de graines, d'invertébrés et de Squamates mais les oiseaux, quijustifient souvent la mise en place de projets de gestion de rats, ne semblent pas ici être une de leur proie préférentielle. Depotentiels effets positifs des rats sur la dispersion des graines ont également été mis en évidence au travers d'une comparaisondu potentiel germinatif de graines après passage par leur tractus digestif et celui de frugivores natifs. Enfin, nous avons puproposer des stratégies de piégeage létal afin de contrôler efficacement les populations de rats invasifs. Une meilleurecompréhension des impacts des rats en situation de sympatrie ainsi qu' une meilleure connaissance du lien entre densité de ratset intensité des effets sur la biodiversité permettraient d'optimiser les stratégies de contrôle de rats invasifs lorsquel'éradication n'est pas envisageable. / Introduced rats (Rattus spp.) are one of the major invasive species threatening native biodiversity on islands worldwide. Twospecies, the black rat (R. rattus) and the Pacifie rat (R. exulans) are sympatric in New Caledonian rainforests, where questionsasto the feasibility and the utility of their control (i.e. local limitation of their abundance) for the conservation of nativebiodiversity remain unanswered. ln response to the lack of a conceptual framework for control projects, we fi rst conducted areview of invasive rat control operations in island natural areas worldwide. Then we sought to characterize and understand thepopulation dynamics of these two sympa tric rat species and the ir interactions with native biodiversity in the rainforest of MontPanié mountain. Lethaltrapping operations and capture-mark-recapture showed that black rats were more abundant thanPacifie rats. Diet analysis revealed that the two species consume both shared and unshared prey likely resulting in astrengthening and a broadening oftheir impacts on native biodiversity, relative to the impact that each species would haveal one. Rats consume a large quantity of fruits and seeds, invertebrates, and Squamates. However, birds, which often justify theimplementation of rat management projects, do not appear here to be one of the ir preferred prey, either as adults or throughnest predation. A potential positive rat impact on seed dispersal was a Iso highlighted through a comparison of seedgermination after seeds had passed through rat versus native frugivore digestive tracts. Finally, we propose lethal trappingstrategies to efficiently control invasive rat populations. A better understanding ofboth rat impacts in sympatric situations,and the link between rat density and the intensity of their effects on biodiversity would allow optimizing rat control strategieswhen eradication is not feas ible. Espèces invasives Rats introduits Contrôle des prédateurs Prédation Germination Ecologie trophique Ecosystèmes insulaires Forêt dense humide Invasive species Introduced rats Predator control Predation Germination Trophic ecology Island ecosystems Rainforests 577.3 577.8 591.65
3	Methodological investigations on vegetation typology and phytogeography of rain forests of tropical Africa Senterre, Bruno B.M.L. 17 June 2005 (has links) I. An original methodological discussion is proposed on the problem of the typology of tropical rain forest’s plant communities, based on the study of forest types across gradients of continentality and elevation, within Atlantic central Africa. These investigations were based on the statement that the main problems in forest typology are related to the non-zonal or zonal character of the different vegetation types and to non considering the relations and differences between forest strata. II. Field data consisted in phytosociological homogeneous sample plots localized within different recognized phytogeographical entities, in a region of tropical Africa where these entities are known to be well conserved. A total of 37 such plots were inventoried in the region extending from the littoral forests of Ndoté, Equatorial Guinea, which are wet evergreen forests, to the continental forests of the Dja, Cameroon, known as evergreen seasonal forests. The studied region also included the oriental Atlantic forests of Equatorial Guinea, known as moist evergreen forests or caesalp forests. In various parts of this continentality gradient, some plots were localized within climax non-zonal formations, namely the submontane rain forests. The emphasis was put on the vegetation of the Monte Alén National Park. The sampling methodology was willing to be as "complete ", including all strata, "quantitative ", enumerating all individuals, and "representative ", within each stratum, as possible. These multi-layers plots were realised using nested sub-plots, with a sampling size of 100 individuals for every ligneous stratum recognized (dominant trees, dominated trees and shrubs) and a sampling size of 200m² for the herbaceous and suffrutex stratum. Forest types were defined independently for each stratum and the differences were analysed. A method was proposed for the simultaneous analysis of all floristic data, converting and standardizing the values from ligneous strata, on the one hand, and from understorey strata, on the other hand. III. Ten forest types were described using IndVal and discussed in the general context of the guineo-congolian region, from a syntaxonomic view point (agglomerative classification) and from a phytogeographical view point (divisive classification). Homologies between these two approaches are described. The proposed phytogeographical system is based on an "open " conception of hierarchical classifications, combining advantages of agglomerative and divisive classifications. In concrete terms, the non-zonal criteria, for example the submontane variants, are categorised separately and in analogy with the zonal criteria, related to the usual phytochoria. Analysis of ecological relationships for the 10 communities showed that the main variables related to the floristic variability in our mainland rain forests are elevation, rainfall, hygrometry (estimated using bryophytes cover levels) and distance to the ocean. The two extremes on the vertical microclimatic gradient, dominant trees stratum and herbaceous stratum, give similar typologies, however canonical analysis showed that for the herbaceous layer, non-zonal variables (hygrometry and elevation) were gaining more importance when the influence of the two zonal variables was attenuated. In every case, spatial autocorrelation was less important than the environment in explaining floristic variability but its role increased in the spatial arrangement of understorey species, whose dispersal capacity is generally lower than canopy trees. The phytosociological, phytogeographical and ecological description of forest types is accompanied by a physiognomical description using biological types spectrum, as well as architectural models, leaf sizes, etc. With regard to diversity, we have demonstrated that species richness was higher from upper to lower strata because of the accumulation in lower strata of species from various strata. On the other hand, the proper stratum diversity, i.e. the structural set, decreased from dominant trees to shrubs. The proper diversity of the herb layer showed relatively high figures mainly due to the higher individual density in relation to the existence of microstrata. Within the 37 sample plots, 1,050 taxa have been identified to species or morpho-species levels, for a total of 25,750 individuals. These taxa represent 442 genus among 104 families. The richest forest type is found on the foothills of the Niefang range, on the windward side. This forest type is also characterised by a high number of oligotypic genus and by species belonging to functional types indicators of glacial refuges. These functional types are defined on the basis of the dispersal capacity and on kind of stand needed for effective germination. We formulated the hypothesis that this kind of "foothills refuge ", characterised by his zonal nature, could have been one of the rare refuges for species from mainland rain forests, while montane and fluvial refuges would mainly have preserved species from non-zonal forest types: (sub)montane and riverine. Based on indicator species of submontane forests, a potential distribution map of this forest type has been realised at the Atlantic central African scale. More than 400 submontane forest localities have been mapped. These forests begin at 400m of altitude near the ocean, and progressively at higher altitude for increasing distance to the ocean. Many lowland localities also comprised submontane species, which could indicate the existence of ecological transgressions. These transgressions would allow migratory tracks for submontane species between isolated mountain ranges, not only during glacial periods, through heights at the northern and southern borders of the congo basin, but also contemporarily through the lowland riverine forest network, in the centre of this basin. Finally, a special attention has been attributed to littoral forests and to some cases of choroecological transgressions, coupled to the ecological equalization phenomenon. plant diversity foothills refuge glacial refuge environmental stability conservation rarefaction curves individuals-area curves species-area curves compensations écologiques Guinée Equatoriale Monte Alén Monts de Cristal Réserve de Ndoté rainforest transgression Monte Alén Cristal mountains strate forestière sous-bois ensemble structural groupe écologique modèles architecturaux guilde types fonctionnels synusie genres monotypiques genres paucispecifiques diversité végétale courbes aire-espèces courbes individus-espèces courbes de raréfaction courbes aire-constance aire minimale morpho-espèces pléistocène constancy-area curves minimal area structural ensemble understorey ecological group synusia oligotypic genus Réserve de Biosphère du Dja Cameroun Quaternaire glaciation refuge glaciaire refuge de pied de massifs montagneux stabilité environnementale conservation transgression forestière phytosociology plant community phytogeography open classification non-zonal nested plots forest types IndVal morphospecies pleistocene littoral forest rain forest afromontane submontane altitudinal belt glaciation Quaternary Equatorial Guinea ecological equalization continentality continentalité étage d’altitude forêt littorale forêt dense humide afromontagnard submontagnard IndVal types forestiers phytosociologie phytogéographie classification ouverte azonal relevés emboîtés multistrates monotypic genus architectural model guild plant functional type Ndoté Reserve Cameroon Dja Biosphere Reserve forest stratum forest layer understory
4	Recherches méthodologiques pour la typologie de la végétation et la phytogéographie des forêts denses d'Afrique tropicale Senterre, Bruno 17 June 2005 (has links) I. An original methodological discussion is proposed on the problem of the typology of tropical rain forest’s plant communities, based on the study of forest types across gradients of continentality and elevation, within Atlantic central Africa. These investigations were based on the statement that the main problems in forest typology are related to the non-zonal or zonal character of the different vegetation types and to non considering the relations and differences between forest strata.<p><p>II. Field data consisted in phytosociological homogeneous sample plots localized within different recognized phytogeographical entities, in a region of tropical Africa where these entities are known to be well conserved. A total of 37 such plots were inventoried in the region extending from the littoral forests of Ndoté, Equatorial Guinea, which are wet evergreen forests, to the continental forests of the Dja, Cameroon, known as evergreen seasonal forests. The studied region also included the oriental Atlantic forests of Equatorial Guinea, known as moist evergreen forests or caesalp forests. In various parts of this continentality gradient, some plots were localized within climax non-zonal formations, namely the submontane rain forests. The emphasis was put on the vegetation of the Monte Alén National Park.<p><p>The sampling methodology was willing to be as "complete ", including all strata, "quantitative ", enumerating all individuals, and "representative ", within each stratum, as possible. These multi-layers plots were realised using nested sub-plots, with a sampling size of 100 individuals for every ligneous stratum recognized (dominant trees, dominated trees and shrubs) and a sampling size of 200m² for the herbaceous and suffrutex stratum.<p><p>Forest types were defined independently for each stratum and the differences were analysed. A method was proposed for the simultaneous analysis of all floristic data, converting and standardizing the values from ligneous strata, on the one hand, and from understorey strata, on the other hand.<p><p>III. Ten forest types were described using IndVal and discussed in the general context of the guineo-congolian region, from a syntaxonomic view point (agglomerative classification) and from a phytogeographical view point (divisive classification). Homologies between these two approaches are described. The proposed phytogeographical system is based on an "open " conception of hierarchical classifications, combining advantages of agglomerative and divisive classifications. In concrete terms, the non-zonal criteria, for example the submontane variants, are categorised separately and in analogy with the zonal criteria, related to the usual phytochoria.<p><p>Analysis of ecological relationships for the 10 communities showed that the main variables related to the floristic variability in our mainland rain forests are elevation, rainfall, hygrometry (estimated using bryophytes cover levels) and distance to the ocean. The two extremes on the vertical microclimatic gradient, dominant trees stratum and herbaceous stratum, give similar typologies, however canonical analysis showed that for the herbaceous layer, non-zonal variables (hygrometry and elevation) were gaining more importance when the influence of the two zonal variables was attenuated. In every case, spatial autocorrelation was less important than the environment in explaining floristic variability but its role increased in the spatial arrangement of understorey species, whose dispersal capacity is generally lower than canopy trees. The phytosociological, phytogeographical and ecological description of forest types is accompanied by a physiognomical description using biological types spectrum, as well as architectural models, leaf sizes, etc.<p><p>With regard to diversity, we have demonstrated that species richness was higher from upper to lower strata because of the accumulation in lower strata of species from various strata. On the other hand, the proper stratum diversity, i.e. the structural set, decreased from dominant trees to shrubs. The proper diversity of the herb layer showed relatively high figures mainly due to the higher individual density in relation to the existence of microstrata. Within the 37 sample plots, 1,050 taxa have been identified to species or morpho-species levels, for a total of 25,750 individuals. These taxa represent 442 genus among 104 families. The richest forest type is found on the foothills of the Niefang range, on the windward side. This forest type is also characterised by a high number of oligotypic genus and by species belonging to functional types indicators of glacial refuges. These functional types are defined on the basis of the dispersal capacity and on kind of stand needed for effective germination. We formulated the hypothesis that this kind of "foothills refuge ", characterised by his zonal nature, could have been one of the rare refuges for species from mainland rain forests, while montane and fluvial refuges would mainly have preserved species from non-zonal forest types: (sub)montane and riverine.<p><p>Based on indicator species of submontane forests, a potential distribution map of this forest type has been realised at the Atlantic central African scale. More than 400 submontane forest localities have been mapped. These forests begin at 400m of altitude near the ocean, and progressively at higher altitude for increasing distance to the ocean. Many lowland localities also comprised submontane species, which could indicate the existence of ecological transgressions. These transgressions would allow migratory tracks for submontane species between isolated mountain ranges, not only during glacial periods, through heights at the northern and southern borders of the congo basin, but also contemporarily through the lowland riverine forest network, in the centre of this basin. Finally, a special attention has been attributed to littoral forests and to some cases of choroecological transgressions, coupled to the ecological equalization phenomenon.<p> / Doctorat en sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished Sciences exactes et naturelles Agronomie générale Phytogeography -- Africa, Sub-Saharan Forest surveys -- Africa, Sub-Saharan Phytogéographie -- Afrique noire Inventaires forestiers -- Afrique noire submontane afromontane rain forest littoral forest pleistocene morphospecies IndVal forest types nested plots non-zonal open classification phytogeography plant community phytosociology transgression forestière conservation stabilité environnementale refuge de pied de massifs montagneux refuge glaciaire glaciation Quaternaire Cameroun Réserve de Biosphère du Dja oligotypic genus synusia ecological group understorey structural ensemble minimal area constancy-area curves pléistocène morpho-espèces aire minimale courbes aire-constance courbes de raréfaction courbes individus-espèces courbes aire-espèces diversité végétale genres paucispecifiques genres monotypiques synusie types fonctionnels guilde modèles architecturaux groupe écologique ensemble structural sous-bois strate forestière Cristal mountains Monte Alén rainforest transgression Réserve de Ndoté Monts de Cristal Guinée Equatoriale compensations écologiques species-area curves individuals-area curves rarefaction curves environmental stability glacial refuge foothills refuge plant diversity altitudinal belt Quaternary Equatorial Guinea ecological equalization continentality continentalité étage d’altitude forêt littorale forêt dense humide afromontagnard submontagnard types forestiers phytosociologie phytogéographie classification ouverte azonal relevés emboîtés multistrates monotypic genus architectural model guild plant functional type Ndoté Reserve Cameroon Dja Biosphere Reserve forest stratum forest layer understory

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