Dissertations / Theses on the topic 'Foret dense tropicale'

L'etat des forets tropicales est alarmant, leur surface regresse rapidement depuis quelques decennies parallelement, les pays en voie de developpement, en general, et l'afrique centrale, en particulier, ont subi d'importantes mutations politiques, economiques et sociales devant l'acceleration recente de cette tendance, les organismes internationaux ont reagi par le biais d'un concept nouveau, celui du developpement durable la mise en ouvre d'une politique fondee sur ce principe se heurte, toutefois, a une difficulte majeure qui est le manque d'informations scientifiques sur lesquelles fonder la preservation et la mise en valeur de ces ressources. Il ne s'agit pas simplement d'etudier les mecanismes de la deforestation, mais de proposer une approche mettant en evidence les contraintes et processus tant ecologiques que sociaux relatifs a la dynamique observee. C'est dans ce cadre d'investigation que s'insere la problematique de notre travail elle concerne, en particulier, les interactions ville-foret dans la region de pointe-noire (r du congo), zone qui a connu une tres forte urbanisation depuis une cinquantaine d'annees. Deux phenomenes a priori antagonistes peuvent etre observes dans cette region : une progression naturelle de la foret, opposee a des defrichements de plus en plus consequents dans ce contexte, nous avons pu mettre en evidence la dynamique forestiere : celle-ci est a la fois positive (avancee de la foret) et negative (recul de la foret) la premiere releve d'une tendance ancienne a la progression forestiere dans un climax forestier. On distingue deux types deprogression une reconquete forestiere dont la vitesse moyenne annuelle est comprise entre 9 m et 2 m selon les surfaces considerees, et une conquete forestiere dont la vitesse moyenne annuelle est de 2 m a 0 5 metres la seconde dynamique releve de l'action anthropique en effet, elle est la consequence directe de deux mecanismes, qui sont l'urbanisation (croissance demographique et migrations) et le contexte politico-economique (crise caracterisee par un mouvement migratoire vers les campagnes) cette action se traduit par une augmentation des surfaces defrichees au profit de l'agriculture et de l'exploitation du bois comme combustible. Cette action se localise preferentiellement dans un rayon de 50 km autour de pointe- noire et le long des principaux axes de communication. Le bilan global d

Un modele de dynamique forestiere, considere comme un outil d'aide a l'amenagement forestier, peut reposer sur differents niveaux de description du peuplement : arbre, distribution ou peuplement. Une approche est recherchee pour construire un modele a un niveau de description intermediaire entre l'arbre et le peuplement, en s'appuyant sur les donnees du dispositif sylvicole de paracou en guyane francaise. Dans un premier temps la possibilite de construire un modele de trouees est evaluee sous deux angles : d'une part en regardant si la variable d'interaction des modeles de trouees permet d'expliquer les accroissements observes a paracou, d'autre part en testant si le peuplement peut etre decoupe en placettes independantes. Dans les deux cas les resultats n'encouragent pas a la construction d'un modele de trouees. Neanmoins un modele arbre dependant des distances, qui ne tient compte que de la competition pour la lumiere est obtenu ; ce modele permet de reproduire les distributions diametriques et en hauteur ainsi que la repartition spatiale a grande echelle (< 10 m) observees a paracou. Dans un deuxieme temps des methodes pour changer de niveau de description sont etablies, en suivant deux approches : la premiere est une approche methodologique permettant de transposer les equations d'un modele arbre en un modele de distribution en utilisant des techniques issues de la physique (theoreme de liouville, approximation du champs moyen, methode des moments). Cette methodologie est appliquee au modele arbre construit dans la premiere partie. Il en ressort que l'espace joue dans ce modele un role qui ne peut etre neglige. Dans une deuxieme approche un modele qui melange le niveau individuel et le niveau distribution est construit, la transition de la composante distribution a la composante individuelle s'effectuant au diametre de 40 cm. Ce modele met en evidence la variabilite stochastique liee a la demographie des arbres de grande taille.

Orientador: Marcos Silveira Buckeridge
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Doutorado
Biologia Vegetal
Doutora em Biologia Vegetal

Sur la base d'observations effectuées en Côte-d'Ivoire et dont les résultats déjà publiés figurent en annexe, nous abordons ici la régénération naturelle de la forêt au sens large de dynamique cicatricielle ou de reconstitution après destruction partielle, anthropique ou non. Vu la complexité du milieu et des mécanismes, une modélisation ou simplification a été nécessaire. Nous nous sommes limités aux espèces que nous avons qualifiées de structurales, c'est-à-dire aux arbres qui dominent physionomiquement et écologiquement les formations auxquelles ils appartiennent. Ceci exclut notamment les lianes et les espèces véritablement sciaphiles. Dans la lignée de la tradition forestière et conformément aux idées de MANGENOT et de VAN STEENIS, nous distinguons trois groupes stratégiques d'arbres illustrés chacun par un exemple. Le groupe des "forestières sciaphiles" est illustré par Turraeanthus africana, celui des "géantes anémochores" par Khaya ivorensis et celui des "pionnières" par Trema guineensis. La comparaison des caractères vitaux de ces trois espèces avec ceux de dix autres espèces montre le caractère "naturel" de ces groupes, leur validité quant à l'étude de la régénération naturelle. Les caractères les plus marquants de ces groupes se rapportent à l'écophysiologie des graines qui présentent une dormance secondaire chez les pionnières et n'en présentent pas chez les deux autres groupes. Les graines des géantes anémochores se distinguent en effet par leur aptitude à supporter la déshydratation, alors que celles des "forestières" y sont, au contraire, très sensibles. Au chapitre 2, nous introduisons une simplification supplémentaire, en privilégiant une vision de la dynamique forestière marquée par la phase d'ouverture et le rôle de la "composition floristique initiale". Ceci est justifié par le fait que nous ne considérons que des arbres plus ou moins héliophiles et celui que nous considérons uniquement des ouvertures qui n'affectent pas les qualités physico-chimiques du sol (au contraire de leurs qualités biologiques). Cette simplification permet de tirer parti d'une notion classique que nous remettons à l'honneur : celle de "potentiel floristique". Elle permet d'intégrer, dans le schéma explicatif de la régénération naturelle, les conditions stationnelles et historiques. En accord avec d'autres auteurs anciens ou actuels, nous distinguons trois formes principales de potentiel : le potentiel végétatif, le potentiel séminal édaphique et le potentiel extérieur ou advectif. Ces trois formes de potentiel s'expriment quand elles en trouvent la possibilité (existence +survie+ stimulation), selon l'ordre de priorité du premier arrivé, c'est-à-dire : potentiel végétatif puis potentiel séminal édaphique puis potentiel advectif. Leur résistance au choc de l'ouverture croit dans le même ordre. On met enfin et surtout en évidence une concordance entre forme de potentiel et stratégie. Cet ensemble de considérations permet de montrer qu'en fonction de l'intensité des perturbations, de leurs répétitions, la régénération naturelle conduit à des formations dominées par des plantes issues d'un potentiel floristique ou d'un autre, écologiquement bien différents. On aboutit à des changements floristiques et dynamiques profonds. Nous donnons quelques exemples d'évolution de la végétation interprétés selon notre modèle : trouée –persistance – stimulation - expression, le premier à l'échelle de la trouée de chablis, le deuxième à l'échelle du champ sur brûlis, le troisième à l'échelle du paysage. Le modèle permet de montrer qu'il est possible d'orienter la régénération naturelle pour favoriser le développement de formations dominées par des espèces de tel ou tel groupe stratégique. Dans la majorité des cas, il importe surtout d'éviter le développement explosif et quasi irréversible des espèces les plus envahissantes. La lenteur des processus d'évolution vers un hypothétique climax est telle qu'il importe de garder la plus extrême prudence quant à l'aménagement des formations plus ou moins primaires encore existantes et dont le "potentiel" biologique est inestimable
Ecological cycle of three canopy forming species are described from Ivory Coast. They exemplify three different strategies or groups which encompass most of the largest trees. These are the pioneer or belukar strategy of which Trema guineensis is the type, the large wind-born group with khaya ivorensis as an example and shade forest species group with Turraeanthus africana. The seed ecophysiology is what distinguishes those groups at first step. Seeds of Trema exhibit a photoblastic dormancy and are very long lived. Seeds of Khaya can endure high evaporative conditions and the dry seed stay alive for a rather long time, meanwhile Turraenthus seed is very rapidly destroyed by dessication and cannot stay alive without ongoing germination. All the other traits of these species are linked with seed type, mainly: dispersal, growth rate, longevity, height, etc. All this canopy species highly benefit from high light level and need gaps to reach maturity. That is why gaps are so important for their succession, and their reproduction can be described as triggered by the cover opening. Past story and surrounding vegetation determine available species for regeneration. This floristical potential can be divided into three main classes: vegetative potential, seed bank, and dispersal potential. As a rule of thumb, they exhibit the same order of priority in their expression. Each potential has to exist, resist and be stimulated to get in the run till the opening space is saturated back. Identity between strategies and potentials, to say shade species and vegetative potential, pioneer and seed bank, large wind-born species and dispersal potential is demonstrated and used to predict natural regeneration after different degrees of perturbations. Some examples of application are given and some stumbling points are discussed

O presente trabalho teve por objetivo realizar a caracterização silvigênica de um trecho de Floresta Ombrófila Densa Sub Montana em conjunto com o estabelecimento de possíveis relações entre as alterações espaciais do mosaico silvático e os fatores abióticos (solo e topografia). O método utilizado foi o de interceptação de linhas de inventário, com identificação das ecounidades descrito por Torquebiau (1986). Foram dispostas linhas paralelas entre si e distantes 10 m uma da outra. Todos os indivíduos dominantes (mais altos naquele ponto), cujas projeções horizontais das copas interceptaram as linhas, foram amostrados na caracterização silvigênica. Foram tomadas medidas, de no mínimo quatro pontos, da projeção horizontal da copa destes indivíduos até as linhas de inventário, em um sistema de eixos ortogonais (coordenadas x e y). Cada árvore marcada no campo foi classificada, quanto à sua arquitetura, em: árvores do futuro, árvores do presente e árvores do passado (OLDEMAN,1987). As áreas de clareira que interceptaram as linhas também foram amostradas, medidas e mapeadas. O estabelecimento das diversas ecounidades em cada trecho amostrado é feito a partir da união das copas de árvores de mesma categoria. O desenho do mosaico e o cálculo das áreas das ecounidades foram feitos por meio do programa TNTmips, a partir das coordenadas das copas dentro das linhas de inventário. Este trabalho resultou na representação gráfica da cobertura vegetal da área estudada e a sua correlação com os fatores abióticos. Para avaliar o papel dos fatores abióticos na composição espacial do mosaico vegetacional, foram analisadas e combinadas as diversas informações em um Sistema de Informações Geográficas (SIG). Para tal, cada \"classe\" de informação constitui um plano de informação ou um \"layer\" dentro do SIG. De acordo com os resultados pode-se concluir que a caracterização silvigênica indicou que a área estudada representa uma floresta em fase de pré-maturidade por apresentar sinais de perturbações recentes, traduzidas nas altas proporções de ecounidades 1A e em reorganização observadas. Conclui-se ainda quepode ser estabelecida uma relação entre a distribuição das ecounidades e os fatores abióticos estudados.
This study aimed to realize the silvigenic characterization of a Dense Rain Forest in according to the establishment of possible relationships between spatial changing\'s on the silvatic standards and some abiotic factors, such as soil and topography. The method applied was the inventory line interception, identifying the ecounits described by Torquebiau (1986). There were set parallel lines in every 10 meters. All dominant trees (the highest in that point), whose horizontal canopy projections intercepted the inventory line, were sampled in the silvigenic characterization. To measure the canopy projection, there were used at least four points on the inventory line as an orthogonal axis system (X and Y coordinates). Each sampled tree was classified based on its architecture features as: trees of the future, trees of the present or trees of the past (OLDEMAN, 1987). The gap surface crossing inventory lines were also measured and mapped. The ecounit establishment is created by the connection of canopies from the same category (future, present or past). The ecounits design were mapped and its surface measured using the TNTmips software, based on all canopies coordinates over the inventory lines. The study resulted in the graphic representation of vegetation coverage and its correlation with abiotic factors. To evaluate the contribution of the abiotic factors on the vegetation mosaic`s spatial composition, a Geographic Information System (GIS) was settled to combine and analyze all data. Different information classes were overlapped as layers on the GIS environment. According to the results it`s possible to conclude that silvigenic characterization indicates that the studied area represents a pre mature forest, based on recent disturbances sings, confirmed on high rates of ecounits as 1A or reorganization types. It is concluded that the silvigenic mapping represented the architectural behavior of the species related to the soil classification.

Un simulateur de la dynamique forestière, basé sur un modèle d'arbre dépendant des distances, est élaboré, calibré et évalué à partir des données accumulées sur le dispositif sylvicole expérimental de Paracou en Guyane française. Il met en oeuvre des arbres, localisés au sein d'un peuplement et dotés de règles de vie décrites par des sous-modèles de croissance, de mortalité et de recrutement en fonction d'un pas de temps de trois ans.

Le modèle de croissance est dérivé d'un type « potentiel x réducteur » adapté aux spécifités de la forêt dense tropicale humide de Guyane. Il prédit l'accroissement d'un arbre en fonction de son diamètre à l'instant t et de son environnement immédiat décrit par deux indices de compétition : l'un rend compte de la pression subie par l'arbre en début de période de croissance et l'autre de l'évolution de cette pression dans un passé proche. La prise en compte de quinze groupes d'espèces, homogènes du point de vue de la croissance, améliore considérablement son efficacité. Quatre modèles de mortalité prédisent la mort sur pied et la mort par chablis primaire, secondaire ou complexe d'un arbre, et un modèle de recrutement permet de gérer l'apparition de nouveaux individus sur des placeaux de 100m2 en fonction de la place disponible dans le peuplement.

Le simulateur, programmé en langage SmallTalk-80 selon la technique des systèmes multi-agents, est doté d'une interface conviviale permettant à l'utilisateur : (i) de suivre l'évolution virtuelle dans le temps d'un peuplement et de chacun des individus qui le constituent par le biais de cartes et de graphiques ; (ii) de réaliser à tout moment une gamme très variée d'interventions de manière à tester des scénarios sylvicoles. Les différents essais réalisés montrent que le peuplement que nous avons généré présente un comportement satisfaisant quelle que soit l'intensité des perturbations imposées, mais que sa réactivité est faible au regard d'un modèle matriciel calibré à partir des mêmes données. Nous proposons différentes voies d'amélioration et soulignons l'intérêt que peut présenter ce type de modèle pour la communauté scientifique et, à plus long terme, le gestionnaire forestier.

Une typologie des structures est réalisée à partir d'un échantillon systématique de 3,12 ha et de cinq placeaux de 2 400 à 4 000 m2, représentant les principaux types d'organisation du peuplement. Cette analyse met en évidence des variations des structures spatiales (verticales et horizontales) et des structures floristiques, qui dépendent pour partie de la situation topographique au sein du dispositif, mais également de l'histoire locale du peuplement. L'analyse détaillée des modèles de répartition spatiale des individus et des processus (ponctuels) spatiaux qui permettent d'en rendre compte, montre qu'il convient alors d'envisager, pour les situations exemptes de perturbations majeures depuis longtemps, des mécanismes dynamiques alternatifs à la régénération dans les chablis. Il s'agit de phénomènes de substitution au sens large, qui ne font pas intervenir le potentiel germinatif ; le comblement de trouées de petite dimension, occasionnées par la mort sur pied d'un (ou de quelques) individu(s) de la voûte, est réalisé par les individus prééxistants. Les modalités de la substitution diffèrent en fonction de la situation topographique, en versants ou sur les crêtes. L'ensemble des résultats indique, que seule la prise en compte de l'hétérogénéité spatio-temporelle des mécanismes de renouvellement permettra de concevoir un modèle fiable de la dynamique de fonctionnement des forêts tropicales.

Cette étude est réalisée en forêt dense humide du Cameroun. Elle étudie : i) la capacité d’adaptation des espèces plantées selon deux méthodes dans les dispositifs sylvicoles abandonnés de Mangombé et ii) compare la biodiversité floristique de la forêt de Mangombé à celles de Bidou et Campo moins perturbées. Dans les plantations, les espèces qui se sont adaptées au site et presentant les meilleures performances de croissance diamétrique sont : Gmelina arborea (Verbenaceae), Dipterocarpus alatus (Dipterocarpaceae) et Aucoumea klaineana (Burseraceae). La régénération naturelle en plantation est diversifiée. Les forêts naturelles sont diversifiées comme l’indique l’indice de Shannon, le coefficient de diversité générique et la richesse spécifique qui est élevée à Mangombé (38 familles et 91 espèces), intermédiaire à Bidou (32 familles et 88 espèces) et faibles à Campo (29 familles et 75 espèces). La zoochorie concerne plus de 71% des espèces recensées. L’importance de la flore à affinité forestière consolide la possibilité pour la régénération naturelle de reconstituer à long terme la biodiversité végétale en plantation
This study is carried in rainforest of Cameroon. It presents: i) the adaptability of species, planted with two sylviculturals methods in Mangombe’s plantation and ii) compare the biodiversity of Mangombe’s forest to those of Bidou and Campo less disturbed. The adapted species with few mortality and best diameter increasement are : Gmelina arborea (Verbenaceae), Dipterocarpus alatus (Dipterocarpaceae) and Aucoumea klaineana (Burseraceae). The natural regeneration under canopy in plantation is heterogenic and diversed. The vegetation indices show a high diversity in all the sites : Shannon index, generic diversity and specific richness which is higher in Mangombe (38 families and 91 species), intermediary in Bidou (32 families and 88 species) and lower in Campo (29 families and 75 species). Zoochory concerns more than 71% of the species, and suggests a major role of animals in the regeneration process. The abondance of species familiar to non disturbed natural forest confirms the possibility for the natural regeneration to reconstitute in long term the biodiversity in plantation

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Neste estudo foram avaliadas a eficiência técnica e os custos da aplicação do tratamento silvicultural de desbaste de liberação seletivo, com anelamento e aplicação de herbicida (Tordon, 50% de diluição), em uma Floresta Ombrófila Densa no Estado de Roraima, manejada de acordo com os preceitos de exploração de impac o reduzido e legislação vigente. Para analisar o efeito das características das árvores na desvitalização, foi ajustado o modelo logístico binário, indicando uma menor velocidade de desvitalização para espécies secundárias. Foram aneladas 21,6 arv/ha para favorecer a liberação de 12 arv/ha, em uma relação de 1,8 competidores para cada Árvore Comercial potencial para Colheita Futura (ACCF) liberada. O resultado da aplicação do tratamento silvicultural demonstrou uma boa efetividade da técnica, alcançando 100% de mortalidade das árvores competidoras no período de 12 meses após o anelamento, com 69% das árvores desvitalizadas dentro do período de 6 meses. O custo por hectare atingiu valor total de R$ 77,88/ha, sendo o custo por árvore anelada de R$ 3,59 e o custo por árvore liberada de R$ 5,56. Ao analisar a distribuição dos custos, observou-se que 50% deveu-se ao insumo (no caso específico a aquisição do herbicida), 47% decorreu do custo da mão de obra, 2% deveu-se à aquisição de equipamento de proteção individual e 1% de materiais. O rendimento operacional alcançou 0,76 homem/dia.ha-1, abrangendo as atividades de localização das ACCF, identificação das competidoras, corte de cipós, anelamento e aplicação de herbicida.
This study presents the results of the analysis of technical efficiency and costs of silvicultural treatments carried out in a lowland Amazon rainforest logged under reduced impact logging guidelines. The silvicultural treatments consisted in the postharvest girdling and herbicide treatment (using the product Tordon in 50% solution) of remnant trees competing with future crop trees (FCTs). In order to analyze the effect of girdling on tree mortality, a binary logistic model was utilized. The model indicated a slower mortality process for secondary tree species. On average 21,6 competing trees per hectare were girdled in order to benefit 12 FCTs per hectare (on average 1,8 competitors for every FCT). Results demonstrate the high efficiency of the silvicultural treatments tested: mortality of competitors attained 69% within six months after girdling and 100% within twelve months after girdling. The total cost of girdling amounted to BRL 77,88 per ha, BRL 3,59 per girdled tree and BRL 5,56 per FCT. Of the total cost, 50% arose from production factors, especially herbicide acquisition, while 47% were labor costs. Only 2% of the total costs were generated from work safety equipment and 1% of other materials. The operative productivity attained 0,76 man days per hectare which included the activities competitor identification, climber cutting, girdling and herbicide application.

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.

Doctorat en sciences agronomiques et ingénierie biologique
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Les forêts tropicales humides sont des écosystèmes très riches en espèces qui disparaissent à une vitesse alarmante. La gestion durable de leurs ressources et en particulier du bois d’œuvre est une solution pour leur préservation. Pour juger du caractère durable d’une exploitation, il faut cependant pouvoir prédire à long terme les effets sur le peuplement des perturbations qu’elle engendre. Un modèle peut permettre de simuler ces effets, mais son développement se heurte à la grande diversité spécifique de ces écosystèmes qui rend impossible l’étude individuelle de toutes les espèces d’arbres. Nous avons cherché à simplifier la composition floristique en regroupant les espèces en fonction de leurs stratégies de réponse à la perturbation. Nous avons d'abord regroupé les espèces en fonction de leur comportement dynamique en croissance, recrutement et mortalité après exploitation. Nous avons utilisé les quinze années de suivi démographique après exploitation enregistrés sur le dispositif expérimental de Paracou pour quantifier les accroissements diamétriques, taux de recrutement et taux de mortalité des espèces les plus abondantes, et comparé deux stratégies de classification. Comme les variables de dynamique sont coûteuses à obtenir, nous avons parallèlement cherché des substituts, faciles à mesurer, à ces variables. Nous avons collecté des traits biologiques et étudié leurs relations avec les variables de dynamique afin d'estimer le degré d'extrapolation du comportement dynamique que permet la connaissance de ces traits. Les traits se substituent efficacement aux variables de croissance mais pas aux variables de recrutement et de mortalité. Ils sont inutilisables pour prédire efficacement la dynamique après perturbation du peuplement. L'utilisation de groupes construits simultanément sur l'ensemble des variables de dynamique constitue le meilleur compromis en termes d’homogénéité de comportement dynamique et de signification écologique des espèces

Un modèle de dynamique forestière, considéré comme un outil d'aide à l'aménagement forestier, peut reposer sur différents niveaux de description du peuplement : arbre, distribution ou peuplement. Une approche est recherchée pour construire un modèle à un niveau de description intermédiaire entre l'arbre et le peuplement, en s'appuyant sur les données du dispositif sylvicole de Paracou en Guyane française. Dans un premier temps la possibilité de construire un modèle de trouées est évaluée sous deux angles : d'une part en regardant si la variable d'interaction des modèles de trouées permet d'expliquer les accroissements observés à Paracou, d'autre part en testant si le peuplement peut être découpé en placettes indépendantes. Dans les deux cas les résultats n'encouragent pas à la construction d'un modèle de trouées. Néanmoins un modèle arbre dépendant des distances, qui ne tient compte que de la compétition pour la lumière est obtenu ; ce modèle permet de reproduire les distributions diamétriques et en hauteur ainsi que la répartition spatiale à grande échelle (< 10 m) observées à Paracou. Dans un deuxième temps des méthodes pour changer de niveau de description sont établies, en suivant deux approches : la première est une approche méthodologique permettant de transposer les équations d'un modèle arbre en un modèle de distribution en utilisant des techniques issues de la physique (théorème de Liouville, approximation du champs moyen, méthode des moments). Cette methodologie est appliquée au modèle arbre construit dans la première partie. Il en ressort que l'espace joue dans ce modèle un rôle qui ne peut etre négligé. Dans une deuxième approche un modèle qui mélange le niveau individuel et le niveau distribution est construit, la transition de la composante distribution à la composante individuelle s'effectuant au diamètre de 40 cm. Ce modèle met en évidence la variabilité stochastique liée à la démographie des arbres de grande taille.

As florestas tropicais exibem elevada biodiversidade e desempenham um importante papel no ciclo global do carbono. Porém, essas florestas têm sido impactadas aceleradamente nos últimos anos. No Brasil, a floresta tropical Atlântica está restrita a aproximadamente 7 % de sua extensão original e seus remanescentes ainda sofrem ameaças. Com isso, informações sobre a dinâmica da vegetação desse bioma são importantes para entender o funcionamento desse ecossistema e servem de subsídio para auxiliar em sua conservação e restauração. No presente estudo, os principais processos que regem a dinâmica de uma floresta (mortalidade, recrutamento e crescimento) foram estimados em duas fisionomias distintas da floresta tropical Atlântica. Além disso, a variação líquida da biomassa acima do solo (BAS) também foi estimada. Para o presente estudo foram utilizadas cinco (5) parcelas permanentes de um (1) hectare inseridas no projeto temático Gradiente Funcional, sendo: quatro (4) na floresta de Terras Baixas e uma (1) na floresta de Restinga. Os inventários foram realizados no momento da implantação das parcelas permanentes (2006) e após dois (2) anos. Os resultados obtidos demonstraram que a Restinga (1635 ind.ha-1) possui maior densidade total de indivíduos vivos com o DAP \'>OU=\'4,8 cm que a Terras Baixas (1221 ind.ha-1). O estoque de biomassa acima do solo (BAS) foi maior na Terras Baixas (212,3 Mg.ha-1) que na Restinga (166,3 Mg.ha-1) (DAP \'>OU=\'4,8 cm). A distribuição dos indivíduos nas classes de diâmetro influenciou essas diferenças estruturais: a Restinga possui maior densidade total de indivíduos na menor classe de diâmetro e a floresta de Terras Baixas possui maior densidade de indivíduos na maior classe. Tal fato também impactou a distribuição do estoque de BAS nas classes de diâmetro: a floresta de Restinga estoca mais biomassa na classe de 10-30 cm e a floresta de Terras Baixas na maior classe de DAP, \'>OU=\'50 cm. A mediana da taxa de incremento diamétrico da comunidade arbórea não diferiu entre os dois tipos de floresta, sendo igual a 1,0 mm.ano-1 na Restinga e 0,8 mm.ano-1 na Terras Baixas (DAP \'>OU=\'4,8 cm). Diferenças na taxa de incremento diamétrico com relação às formas de vida (árvores e palmeiras) foram observadas. A taxa de incremento diamétrico das árvores apresentou relação positiva com o aumento das classes de DAP e o índice de iluminação de copa. O mesmo padrão não foi observado para as palmeiras. A taxa de mortalidade da comunidade arbórea foi semelhante entre os dois tipos de floresta, sendo igual a 2,46 % na Restinga e 2,00 % na Terras Baixas (DAP \'>OU=\'4,8 cm). A taxa de recrutamento também foi semelhante entre as florestas, sendo igual a 1,42 % na Restinga e 1,36 % na floresta de Terras Baixas. A variação líquida da BAS foi maior nas Terras baixas (0,64 Mg.ha-1.ano-1) que na Restinga (0,32 Mg.ha-1.ano-1). Por fim, a floresta tropical Atlântica apresenta maior densidade de indivíduos vivos, menor estoque de BAS, menor taxa de incremento e reposição quando comparada com outras florestas tropicais, possivelmente devido à distribuição da precipitação ao longo do ano
Tropical forests display a biodiversity unmatched by any other vegetation type and play an important role in the global terrestrial carbon cycle. However, tropical forests have been severely impacted in the last years. In Brazil, the tropical Atlantic forest is restricted to approximately 7 % of its original extension and its fragments still remain threatened. Hence, information regarding the vegetation dynamic of this important biome is important to understand the functioning of this ecosystem and support conservation and restoration actions. Here, the principal processes that drive forest dynamics (mortality, recruitment and growth) were estimated for two tropical Atlantic forest types. Additionally, the net aboveground biomass change (AGB) also was estimated. In this study, five one-hectare permanent plots established by the Gradiente Funcional project were adopted: four (4) plots in lowland and one (1) in seasonally flooded Atlantic forest. The forestry inventories were performed in the same time of permanent plot establishment (2006) and after two (2) years (2008). The results showed that the seasonally flooded Atlantic forest has greater total stem density (DBH \'>OU=\'4.8 cm) than lowland Atlantic forest, equal to 1635 ind.ha-1 in seasonally flooded and 1221 ind.ha-1 in lowland forest. The aboveground biomass (AGB) was greater in lowland than in seasonally flooded forest, equal to 166.3 Mg.ha-1 in seasonally flooded and 212.3 Mg.ha-1 in lowland forest (4,8 cm DBH). The distribution of trees among DBH classes influenced these structural differences: the seasonally flooded forest has high stem density at smaller DBH size class while the lowland forest has high stem density at larger DBH size class. In addition, that variation in size structure also impacted the AGB distribution among DBH classes: the seasonally flooded Atlantic forest has more AGB in the 10-30 cm DBH class and the lowland Atlantic forest has more AGB in the large size class ( \'>OU=\'50 cm). The median growth rate of tree community did not differ between the two forest types, equal to 1.0 mm.yr-1 in seasonally flooded and 0.8 mm.yr-1 in lowland forest ( \'>OU=\'4.8 cm DBH). Differences in growth rates regarding the life forms (tree and palm) were observed. Tree growth rates showed positive relationship with crown illumination index and DBH classes. The same tendency was not observed for palm life form. The mortality rate of tree community did not differ between the two forest types, equal to 2.46 % in seasonally flooded and 2.00 % in lowland forest ( \'>OU=\'4.8 cm DBH). The recruitment rate also did not differ between the two forest types, equal to 1.42 % in seasonally flooded and 1.36 % in lowland forest (\'>OU=\'4.8 cm DBH). The lowland Atlantic forest AGB net change (0.64 Mg.ha-1.yr-1) was higher than seasonally flooded Atlantic forest (0.64 Mg.ha-1.yr-1). Finally, the tropical Atlantic forest has higher stem density, lower AGB, lower growth and turnover rates than other tropical forests probably due to rainfall distribution among year

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The aim of this work was to analyze the floristic composition and horizontal structure of a stretch of the arboreal vegetation in the Biological Reserve of Sooretama. The survey was restricted to a phytosociological sample done on one hundred contiguous portions of 10 x 10 meters. Individuals with PBH ≥ 15 cm were sampled. The forest was segmented in three vertical strata, allowing EIV calculation. A meter and a meter width were used as first center class. A total of 1519 individuals were sampled, distributed in 265 species, 138 genera and 44 families. The Shannon s Index (H ) found was 4,87 nats. In relation to the threatened species, 16 consist in the Red List of Espírito Santo State. The Biological Reserve of Sooretama obtained 57% of similarity with the Natural Reserve of CVRD. The species Rinorea bahiensis (Moric.) Kuntze prevailed in the three strata, with has the largest EIV. The group of the late secondary stood out in all the strata. The stand was considered at advanced successional stage.
O objetivo deste trabalho foi analisar a composição florística e a estrutura fitossociológica de um trecho da vegetação arbórea na Reserva Biológica de Sooretama. O levantamento foi restrito a uma amostragem fitossociológica realizada em 100 parcelas contíguas de 10 x 10 m. Foram amostrados os indivíduos com PAP ≥ 15 cm. A floresta foi segmentada em três estratos verticais, sendo calculado o Valor de Importância Ampliado (VIA). Para a distribuição dos indivíduos por classe de altura, foi utilizado como primeiro centro de classe um metro e amplitude de um metro. Foram amostrados 1519 indivíduos, distribuídos entre 265 espécies, 138 gêneros e 44 famílias. O índice de Shannon (H ) encontrado foi de 4,87 nats. Em relação às espécies ameaçadas, 16 constam na Lista Vermelha do Estado do Espírito Santo. A Reserva Biológica de Sooretama obteve 57,0% de similaridade com a Reserva Natural da Companhia Vale do Rio Doce. A espécie Rinorea bahiensis predominou nos três estratos, possuindo o maior VIA. O grupo das secundárias tardias se destacou em todos os estratos. O estande foi considerado em estádio sucessional avançado.

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Foram avaliadas as alterações na composição florística, fitossociologia e danos em floresta submetida à exploração madeireira de impacto reduzido (EIR) no município de Caracaraí, no estado de Roraima. O experimento consistiu na instalação de nove parcelas permanentes (1 hectare cada), sob o elineamento inteiramente casualizado, com três repetições e três tratamentos (T1 = floresta natural; T2 = floresta submetida a exploração de impacto reduzido + corte de cipós; T3 = floresta submetida a exploração de impacto reduzido + corte de cipós + desbaste por anelagem). Antes da exploração madeireira, foram encontrados 4.724 indíviduos, distribuídos em 42 famílias botânicas, 111 gêneros e 165 espécies, sendo que as famílias botânicas que apresentaram maior número de indivíduos foram: Fabaceae (1.883), Lecythidaceae (609), Sapotaceae (434) e Arecaceae (254). As três espécies com os maiores valores de índice de importância (IVI), em ordem decrescente, foram: Pentaclethra macroloba (52,06%), Eschweilera bracteosa (23,72%) e Pouteria caimito (8,10%). Após a exploração madeireira de impacto reduzido realizada na intensidade média de 3 árvores extraídas por hectare (DAP > 50 cm), correspondente a 18,66 m3/ha e aplicação dos tratamentos silviculturais, não foram encontradas alterações significativas na composição florística, fitossociologia e nas freqüências diamétricas da floresta. A diversidade e equabilidade da floresta também não sofreram alterações significativas (Antes: Shannon = 3,27 e Pielou = 0,64; Após: Shannon = 3,26 e Pielou = 0,64). A exploração madeireira gerou uma média de 41 árvores danificadas/ha e 32 árvores mortas/ha, que correspondem a 15 árvores danificadas por árvore colhida por ha e 12 árvores mortas por árvore colhida por ha. A maior parte dos danos causados à vegetação remanescente resultou da formação de clareiras devido à extração de árvores comerciais da floresta, sendo superior ao impacto causado pela construção de trilhas de arraste. Foram observadas reduções de 5,96% e 18,90% no volume cormecial (DAP > 10 cm) em T2 e T3, respectivamente.
Changes on floristic composition and phytosociological and damage we evaluated in forest subjected to reduced-impact logging (RIL) in the municipality of Caracaraí in the state of Roraima. The experiment consisted in the installation of nine permanent plots (1 ha each), under the completely randomized design with three replications and three treatments (T1 = natural forest; T2 = forest subjected to reduced-impact logging + vine cutting; T3 = forest subjected to reduced-impact logging + cutting vines + girling). Before logging, 4.724 individuals were found, distributed in 42 botanical families, 111 genera and 165 species, and the plant families with the highest number of individuals were Fabaceae (1883), Lecythidaceae (609), Sapotaceae (434) and Arecaceae (254). The three species with the highest values of IVI, in descending order, were: Pentaclethra macroloba (52,06%), Eschweilera bracteosa (23,72%) and Pouteria caimito (8,10%). After the reduced-impact logging (RIL) with 3 trees extracted per hectare (DBH > 50 cm), corresponding to 18,66 m3/ha and application silvicultural treatments, we found no significant changes in floristic composition and phytosociological and diametric frequencies in the forest. The forest diversity and equability did not change significantly (before: Shannon = 3,27 and Pielou = 0,64; After: Shannon = 3,26 and Pielou = 0,64). Logging generated an average of 41 damaged trees / ha and 32 dead trees / ha, equivalent to 15 damaged trees per harvested tree per ha and 12 dead trees per harvested tree per ha. Most damage to remaining vegetation resulted in the formation of gaps due to the commercial extraction of forest trees, higher than the impact caused by construction of skid trails. Reductions of 5.96% and 18.90% in volume cormecial (DBH > 10 cm) in T2 and T3, respectively.

Une analyse de la dynamique forestière et de la croissance des arbres d'une forêt sempervirente des Ghâts occidentaux de l'Inde (dispositif d'étude permanent d'Uppangala) est réalisée, à partir des données de suivis annuels de croissance radiale effectués entre 1990 et 2008 sur plus de 3500 arbres, et de mesures dendrométriques complémentaires (hauteur totale et dimensions de couronne) réalisées ponctuellement. Associée à l'analyse des paramètres démographiques (mortalité et recrutement), l'analyse de la croissance, abordée sous différents aspects (ajustement des croissances radiales moyenne et potentielle, analyse de séries longitudinales de croissance radiale, ajustement d'allométries), permet de caractériser les stratégies de croissance des espèces en fonction de la strate occupée par l'arbre adulte (sous-bois, sous-canopée, canopée, strate émergente). Les cinq espèces principales étudiées présentent des différences significatives aussi bien en termes de démographie que de croissance radiale moyenne et potentielle ; d'allocation préférentielle de la biomasse entre les différentes parties de l'arbre ; de « plasticité » morphologique et de rythmes supra-annuels (et saisonniers) de croissance radiale. D'autre part, les analyses mettent en évidence une forte variabilité intra-spécifique de la croissance radiale, de l'allocation préférentielle de la biomasse entre les différentes parties de l'arbre et des rythmes de croissance. Les résultats obtenus ouvrent des perspectives en modélisation de la dynamique des communautés forestières, pour l'exploration par simulations du rôle des stratégies de croissance dans la coexistence des espèces en peuplement forestier hétérogène.

Dentre as diversas famílias botânicas presentes na Mata Atlântica, as Fabaceae (leguminosas) apresentam grande importância, tanto pela sua abundância e ampla distribuição, como por desempenhar um papel importante no ciclo do nitrogênio (N). Levantamentos realizados em duas fisionomias florestais da Floresta Tropical Atlântica, situadas ao longo de um gradiente altitudinal (Floresta Ombrófila Densa de Terras Baixas e Florestas Ombrófila Densa Montana), mostraram uma maior disponibilidade de N nas Terras Baixas em relação à floresta Montana. Desta forma, o objetivo deste trabalho foi investigar o papel das leguminosas potencialmente fixadoras de N nessas duas fisionomias florestais. Para atingir esse objetivo, foram determinados os conteúdos de N e C, além da composição isotópica do N, nas folhas das leguminosas nodulantes (F+) ou não (F-), e nas folhas de não leguminosas (NF). As coletas foram feitas em uma parcela situada na floresta Montana e em duas parcelas na floresta de Terras Baixas. Analisaram-se 207 amostras foliares e considerando os dois gradientes altitudinais, a média do 15N foi menor nas F+ (0.4±1.2?) em relação a das NF (1.6±1.8?), mas não significativa quando comparada ao valor médio das F- (1.4±1.3?). O valor médio para a concentração de N nas F+ foi mais elevado do que nas NF e F-. Para as concentrações de P não houve diferença entre F+, F- e NF. A concentração de Ca foi mais elevada nas NF do que nas F+, sem diferença significativa em relação às F-. A razão C:N foi maior nas NF ao comparar-se com as F+ e F-, mas sem diferença significativa das NF em relação às F-. O valor médio da razão N:P foi mais elevado nas F+, sem diferir das F-. As Terras Baixas apresentaram maiores valores médios de 15N, P e Ca, e menores razões C:N e N:P. Ao considerar a interação entre altitude e capacidade de nodulação, o valor médio do 15NNF foi significativamente maior nas Terras Baixas, mas sem diferença para plantas F+ entre fisionomias. A concentração de N foi menor nas NF em relação às F+ nas duas altitudes, porém, entre as duas altitudes não houve diferença significativa entre as plantas. Para o PNF, as concentrações foram maiores nas Terras Baixas, mas sem diferença entre altitudes para o valor médio de PF+. O Ca foi mais elevado nas Terras Baixas, tanto para as NF quanto para F+. A razão C:NNF foi menor nas Terras Baixas, não demonstrando diferenças entre fisionomias nas plantas F+. N:P nas NF apresentou valor médio mais elevado nas Terras Baixas, mas sem diferença significativa para N:PF+. Foi possível confirmar que as leguminosas apresentam concentrações distintas de nutrientes em relação a outras espécies, as quais podem interferir na decomposição da matéria orgânica e na dinâmica do ciclo de N dessas fisionomias florestais da Mata Atlântica. Mas, não foi detectado que as leguminosas estavam ativamente fixando nitrogênio atmosférico.
Among several botanical families present in the coastal Atlantic Forest, the Fabaceae family has a significant ecological role not only due its abundance and wide distribution, but as well as for having an important role in the terrestrial nitrogen (N) cycle. Studies conducted by our group have shown that Atlantic tropical forest located in lower altitudes (Terras Baixas) has a more open nitrogen cycle, while, at higher altitudes (Montana Forest) has a more closed nitrogen cycle. Under this scenario the main objective of this project was to investigate the role of Fabaceae on the N and other nutrients cycles in two Atlantic forests, with distinct characteristics of the N cycle. One with an open nitrogen cycle located at 100 m of altitude and another with a closed nitrogen cycle located at 1000 m of altitude. A number of 207 leaf samples was analysed and considering the total sample within the two altitudinal gradients, 15N mean value was lower in F+ (0.4 ± 1.2 ?) relative to the NF (01.06 ± 01.08 ?) but not different when compared to average value of F- (1.4 ± 1.3 ?). The mean value for the concentration of the NF+ showed higher than the F- and NF. P concentrations did not differ between F+, F- and NF. Ca was higher than in NFF+, with no significant difference in relation to F-. C:N ratio was higher in NF when comparing with the F+ and F-, but did not differ to NFF-. Average value of N:P ratio was higher in F+, but did not show difference to F-. The Lowland had higher mean values of 15N, P and Ca, lower C:N and N:P ratios, but no significant difference in the concentration of N compared to Montana. When considering the interaction between altitude and nodulation, the average 15NNF was significantly higher in the Lowland, but no difference for F+ was observed between the sites. F- were not observed in the Lowland. The N concentration was lower in NF compared to F+ in the two altitudes, however, between these parameters and in different altitudes, there was no difference. PNF concentrations were higher in the Lowland, but no difference between altitudes for the average PF+ was observed. Ca was higher in Lowland for both NF and for F+. The C:NNF ratio was lower in the Lowland, showing no differences between the sites in F+ plants. N:P ratio in NF was higher in the Lowland, but there was no significant difference in N:PF+. With the data presented the paradox related to N richness in tropical forests and the absence of fixation in this environment continues. It can be conclude because it was the legumes are not fixing, even when comparing the different physical conditions and nutrient availability. However, it was confirmed that legumes have different concentrations of nutrients in their tissues over other species which may interfere with the decomposition of organic matter and in the N cycle of the ecosystem.

La gestion durable des forêts tropicales et la conservation de la biodiversité sont des enjeux majeurs, qui ne peuvent être atteints que par une meilleure connaissance du fonctionnement et de la résilience de ces écosystèmes. L'objectif de cette étude, conduite sur le dispositif permanent de Mbaïki (RCA), est d'évaluer l'effet de deux traitements sylvicoles (coupe sélective; coupe sélective + délianage) sur la diversité et la dynamique des peuplements arborescents (dbh ≥ 9,55 cm) en forêt dense semi-caducifoliée. Après s'être assuré que les parcelles sans traitement pouvaient effectivement servir de témoin, nous avons entrepris des études démographiques (mortalité, recrutement, croissance et survie) et des analyses spatiales uni- (relations intraspécifiques) et bi-variées (relations interspécifiques) sur le peuplement global et 37 espèces abondantes. La diversité spécifique des arbres a également été quantifiée. Nos résultats montrent que les deux types de traitement n'influencent significativement ni la diversité spécifique, ni la mortalité au sein du peuplement. L'intensité du recrutement et lacroissance individuelle sont négativement et positivement corrélées, respectivement, à l'intensité de perturbations. L'hétérogénéité environnementale induite par les perturbations (trouées) impacte significativement les patrons de distribution spatiale des espèces arborescentes con- et hétérospécifique, avec des effets espèce- et site-dépendants, sans altérersignificativement la diversité spécifique aux différentes échelles spatiales testées. Globalement, nos résultats montrent la grande résilience des peuplements à l'exploitation extensive
To achieve sustainable management and biodiversity conservation of tropical forests, a better understanding of the functioning and resilience of these ecosystems is still needed. This study aims to evaluate the impact of two silvicultural treatments (selective cutting; selective cutting + liana poisoning) on the diversity and dynamics of ≥ 9.55 cm dbh-tree communities in a semi-deciduous tropical forest. Once verified that unmanaged plots can be used as controls, we implemented demographic studies (mortality, recruitment, growth, survival) and uni- (intraspecific interactions) and bi-variate (interspecific interactions) spatial analyses on the entire tree community and 37 abundant species. We also measured tree species diversity. Our results show that both treatments altered neither species diversity, nor tree mortality. The recruitment rate and radial growth decreased and increased, respectively, with increaseddisturbance intensity. Disturbance-induced environmental heterogeneity (gaps) significantly altered tree spatial patterns, both within and between species, an effect which was often species- and site-dependent but without impacting tree species diversity at any of the spatial scale assessed. Overall, our results demonstrate the high resilience of tree communities to a moderate management intensity

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The Atlantic Forest is considered hotspot for biodiversity conservation, due to its high biological diversity, high endemism and high threat of degradation. This scenario has raised concern about finding information to support recovery projects of degraded areas. This study aimed to evaluate the growth, coverage percentage in the soil and the survival of species of the Atlantic Forest, from the planting seedlings in different treatments, present in a particular area in the recovery process, in the region Vale do Ribeira, located in Sete Barras, Brazil. In 2004, the owner made the removal of vegetation for grazing deployment with brachiaria. In 2009, UFSCar was sought to implement the project of "experimental recovery of degraded areas" where seedlings were planted, divided into spacing of 1.5 x 2 m (dense treatment) and 3 x 2 m (conventional treatment). In this study, from July 2013 was carried out monitoring of the area to assess the growth and survival of planted seedlings as well as the percentage of shading and grasses. Five surveys were conducted (July 2013, October 2013, January 2014, April 2014 and July 2014) to evaluate the survival and growth (height, stem diameter and crown diameter) of the seedlings. 30 months after planting, the 220 individuals initially raised in this study, the survival was 85.2% in the dense treatment and 84.8% in the conventional treatment, so mortality was around 15% for both treatments. The species with the highest average growth in height were Croton floribundus, Cytharexyllum solanaceum, Casearia gossypiosperma, Croton urucurana, Colubrina glandulosa, Lafoensia pacari, Inga marginata e Myrsine guianensis. The species with the highest average growth in stem diameter were Acnistus arborescens, Croton urucurana, Apeiba tibourbou, Croton floribundus, Inga marginata, Campomanesia xanthocarpa, Colubrina glandulosa and Lafoensia pacari. The species with the highest average growth in crown diameter were Croton urucurana, Croton floribundus, Cytharexyllum solanaceum, Acacia polyphyla, Colubrina glandulosa, Inga marginata, Lafoensia pacari and Rhamnidium elaeocarpum. As for the percentage coverage in the soil and grasses, there was significant difference in the dense and conventional treatment compared to witness. It is concluded that the above species are indicated for use in future restoration projects in areas of Rain Forest. Both treatments showed greatest shading (in comparison with witness) at the end of the monitoring period, thereby enabling a reduction of exotic grasses. However, in dense treatment was no shading and greater control of grasses. Thus, it can be concluded that at higher cost of implementation and the similar results, the dense treatment was not recommended thickened in the region.
O bioma Mata Atlântica é considerado um hotspot para conservação da biodiversidade, por apresentar grande diversidade biológica, alto grau de endemismo e elevada ameaça de degradação. Este cenário tem despertado preocupação com relação à busca de informações para subsidiar projetos de recuperação das áreas degradadas. Este trabalho teve como objetivo avaliar o crescimento, porcentagem de cobertura no solo e a sobrevivência de espécies da Mata Atlântica, provenientes do plantio de mudas em diferentes tratamentos, presentes em uma área particular em processo de recuperação, na região Vale do Ribeira, Sete Barras-SP. No ano de 2004, o proprietário fez a supressão da vegetação para implantação de pasto com braquiária. No ano de 2009, a UFSCar foi procurada para implantar o projeto de “Recuperação experimental de áreas degradadas”, onde foram plantadas mudas, distribuídas em espaçamentos de 1,5x 2 m (tratamento adensado) e 3 x 2 m (tratamento convencional). Neste estudo, a partir de julho de 2013 foi realizado o monitoramento da área para avaliar o crescimento e a sobrevivência das mudas plantadas assim como a porcentagem de sombreamento e gramíneas. Foram realizados cinco levantamentos (julho de 2013, outubro de 2013, janeiro de 2014, abril de 2014 e julho de 2014) para avaliar a sobrevivência e o crescimento (altura, diâmetro do colo e diâmetro da copa) das mudas. Após 30 meses do plantio, dos 220 indivíduos levantados inicialmente neste estudo, a sobrevivência foi de 85,2% no tratamento adensado e 84,8% no tratamento convencional, ou seja, a mortalidade ficou em torno de 15% para ambos os tratamentos. As espécies que apresentaram as maiores médias de crescimento em altura foram Croton floribundus, Cytharexyllum solanaceum, Casearia gossypiosperma, Croton urucurana, Colubrina glandulosa, Lafoensia pacari, Inga marginata e Myrsine guianensis. As espécies que apresentaram maior crescimento em diâmetro do colo foram Acnistus arborescens, Croton urucurana, Apeiba tibourbou, Croton floribundus, Inga marginata, Campomanesia xanthocarpa, Colubrina glandulosa e Lafoensia pacari. As espécies que apresentaram maior crescimento em diâmetro da copa foram Croton urucurana, Croton floribundus, Cytharexyllum solanaceum, Acacia polyphyla, Colubrina glandulosa, Inga marginata, Lafoensia pacari e Rhamnidium elaeocarpum. Quanto à porcentagem de cobertura no solo e gramíneas, houve diferença significativa no tratamento adensado e convencional em comparação com testemunho. Conclui-se que as espécies acima são indicadas para serem utilizadas em futuros projetos de restauração em área de Floresta Ombrófila Densa. Ambos os tratamentos apresentaram maior sombreamento (em comparação com testemunho) no final do período de monitoramento, possibilitando assim a diminuição das gramíneas exóticas. No entanto, no tratamento adensado não houve maior sombreamento e controle de gramíneas. Dessa forma, pode-se concluir que pelo maior custo de implantação e pelos resultados similares, o tratamento adensado não seria recomendado na região.

Une analyse de la dynamique forestière et de la croissance des arbres d’une forêt sempervirente des Ghâts occidentaux de l’Inde (dispositif d’étude permanent d’Uppangala) est réalisée, à partir des données de suivis annuels de croissance radiale effectués entre 1990 et 2008 sur plus de 3500 arbres, et de mesures dendrométriques complémentaires (hauteur totale et dimensions de couronne) réalisées ponctuellement. Associée à l’analyse des paramètres démographiques (mortalité et recrutement), l’analyse de la croissance, abordée sous différents aspects (ajustement des croissances radiales moyenne et potentielle, analyse de séries longitudinales de croissance radiale, ajustement d’allométries), permet de caractériser les stratégies de croissance des espèces en fonction de la strate occupée par l’arbre adulte (sous-bois, sous-canopée, canopée, strate émergente). Les cinq espèces principales étudiées présentent des différences significatives aussi bien en termes de démographie que de croissance radiale moyenne et potentielle ; d’allocation préférentielle de la biomasse entre les différentes parties de l’arbre ; de « plasticité » morphologique et de rythmes supra-annuels (et saisonniers) de croissance radiale. D’autre part, les analyses mettent en évidence une forte variabilité intra-spécifique de la croissance radiale, de l’allocation préférentielle de la biomasse entre les différentes parties de l’arbre et des rythmes de croissance. Les résultats obtenus ouvrent des perspectives en modélisation de la dynamique des communautés forestières, pour l’exploration par simulations du rôle des stratégies de croissance dans la coexistence des espèces en peuplement forestier hétérogène

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Muitos estudos têm estimado limites de colheita de produtos florestais não-madeireiros (PFNMs) baseados em dados demográficos das espécies fontes. Heliconia velloziana Emygdio (Zingiberales: Heliconiaceae) é utilizada como flor de corte e no paisagismo, e já foi alvo do extrativismo na comunidade rural na região do estudo (Distrito de Taiaçupeba, Mogi das Cruzes, SP). Nosso objetivo geral foi fornecer bases para a elaboração de planos de manejo sustentável para populações silvestres de Heliconia velloziana, através de: avaliação do conhecimento etnobotânico sobre H. velloziana; análise de sua fenologia reprodutiva em relação as variáveis climáticas; avaliação do rendimento e dos efeitos ecológicos do extrativismo sobre taxas vitais de populações silvestres da espécie alvo em diferentes micro-hábitats. Objetivou-se também verificar o potencial para manejo sustentável da espécie e sugerir um regime de rendimento sustentado específico. Para acessar o conhecimento local sobre H. velloziana, foram realizadas entrevistas informais e semiestruturadas, além de observação participante. Os efeitos ecológicos da colheita experimental sobre taxas vitais e a fenologia reprodutiva foram avaliados através de amostragem aleatória estratificada, em uma área total amostral de 0,12ha (12 parcelas de 10x10m) em seis sítios amostrais abrangendo dois estratos (planície e encosta). Em cada sítio, uma população foi submetida à colheita experimental e outra foi mantida como controle. Os aspectos melhor conhecidos pela comunidade local sobre a espécie alvo foram: nome popular, variação intraespecífica, reprodução clonal, visitantes florais, atrativos florais, floração seqüencial, distribuição e abundância local. A espécie foi considerada útil pelos entrevistados para complementação...
Many studies have estimated harvesting limits for non-timber forest products (NTFPs) based on demographic data of the source species. Heliconia velloziana Emygdio (Zingiberales: Heliconiaceae) is used as a cut flower and gardening, and has already been targeted for extractivism by the rural community of the study region. Our general goal was to provide bases for the elaboration of Heliconia velloziana wild populations sustainable management plans, through: assessing ethnobotanical knowledge about H. velloziana; analyzing its reproductive phenology in relation to climatic variables; assessing the yield and ecological effects of harvesting on vital rates of wild populations of the target species in different micro-habitats. We also aimed to verify sustainable management potential of the species and suggest a specific sustained yield regime. To access local knowledge on H. velloziana, informal and semi-structured interviews were done, besides participant observation. The experimental harvesting ecological effects on vital rates and the reproductive phenology were assessed through stratified random sampling, in a total sampling area of 0,12ha (12 10x10m plots) in six sampling sites enclosing two strata (lowland and hillside). At each site, one population was submitted to experimental harvesting and the other was kept as control. The best known aspects by local community about the target species were: common name, intra-specific variation, clonal growth, flower visitors, floral attractants, sequential flowering, local distribution and abundance. The species was considered useful by the interviewed as familiar income complementation through extractivism, besides other secondary uses. It was identified a rich knowledge about the species` management system, once used, that was considered simple and consisted of two to three... (Complete abstract click electronic access below)

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