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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Les zones portuaires peuvent-elles servir de nourriceries alternatives pour les poissons marins côtiers ? : cas des sars en Méditerranée Nord-occidentale / Potential use of ports as alternative nursery habitats by coastal marine fishes : Insights from Diplodus species in the Northwestern Mediterranean

Bouchoucha, Marc 13 December 2017 (has links)
Au cours de leur cycle de vie, la plupart des espèces de poissons marins côtiers passent par des nourriceries littorales dont la qualité influence largement le succès du recrutement et donc le maintien de l’abondance de leurs populations. Or, la construction de ports entrain irrémédiablement une perte de fonction pour les habitats côtiers impactés. Dans ce contexte,l’objectif général de cette thèse était de voir si les zones portuaires peuvent malgré tout servir de nourriceries alternatives pour les poissons marins côtiers. Pour cela, les abondances des juvéniles de quatre espèces de sars, du genre Diplodus, ont d’abord été suivies dans cinq ports méditerranéens. Ceci a permis de montrer que ces espèces côtières peuvent s’installer et grandir avec succès dans les ports. La complexification de la structure 3D de l’habitat augmente sensiblement les abondances de juvéniles. Dans un second temps, la croissance, la condition et les niveaux de contamination desjuvéniles de deux espèces de sars (D. sargus et D. vulgaris) ont été comparés entre différents ports et habitats naturels de la rade de Toulon. Ceci a montré que la croissance et la condition des juvéniles peut être équivalente dans certains ports et dans les zones naturelles adjacentes, avec des niveaux de contamination faibles, même dans les zones les plus polluées. Enfin, la composition multi- élémentaire des otolithes des juvéniles de D. sargus et D. vulgaris a été comparée entre trois ports et deux zones naturelles de la rade de Toulon. Aucun élément chimique lié aux activités portuaires n’aété retrouvé en plus forte concentration dans les otolithes des juvéniles issus des ports. Il n’existe donc pas une signature unique caractéristique de l’ensemble des ports. La composition chimique des otolithes peut néanmoins être utilisée pour étudier la contribution relative des ports aux stocks d’adultes à condition de caractériser la signature de l’ensemble des habitats juvéniles potentiels. L’ensemble des résultats acquis indiquent que les ports peuvent être utilisés comme nourriceries alternatives par plusieurs espèces de poissons marins côtiers. Les projets d’ingénierie écologiquevisant à augmenter la complexité structurale des habitats portuaires sont des pistes intéressantes pour maintenir la biodiversité côtières et les stocks de poissons. / During their life cycle, most of the marine coastal fish species use nursery grounds which quality influence their recruitment and then the conservation of their populations. However, the construction of ports impair irremediably fish nursery function of the coastal areas impacted. The ultimate aim of the PhD research was to assess if ports could provide suitable alternative nursery habitats for coastal fish species. Firstly, abundances of the juveniles of four Diplodus species were surveyed in five marinas located along the French Mediterranean coast. This showed that coastal fishes can successfully settle and grow inside these artificialized coastal areas. Moreover, increasing the complexity of port habitats can considerably enhance their suitability for juveniles, especially at the youngest stages. Secondly, body condition, growth rate and metal contamination in the juveniles of two Diplodus species (D. sargus and D. vulgaris) were compared between different ports and natural areas in the Bay of Toulon. Juvenile growth and condition can be equivalent between fish collected from ports and from adjacent natural areas. Contamination levels in fish were low, even in highly polluted areas. Finally, otolith composition in the juveniles of D. sargus and D. vulgaris was investigated in three ports and two natural areas in the Bay of Toulon. None of the port related had systematically higher concentrations in otoliths from Diplodus juveniles collected in ports. Therefore, otolith microchemistry cannot provide a unique and reliable fingerprint discriminating ports and natural areas. Nevertheless, otolith microchemistry could provide an effective natural tag to determine the contribution of ports to adult stocks provided that a library of all potential juvenile habitat fingerprints is established. All these results confirm that ports can be used as alternative nursery habitats by marine coastal fishes. Ecological engineering projects aiming at increasing structural complexity of port habitats seem promising for biodiversity and fish stock conservation.
92

Macroinvertebrados como bioindicadores em riacho tropical: uma avaliação de impactos por sedimentação, rompimento de barragem e de recuperação após medidas de restauração / Macroinvertebrates as bioindicators in tropical stream: an evaluation of impacts by sedimentation, dam rupture, and recuperation after restoration project application

Thandy Junio da Silva Pinto 07 February 2018 (has links)
Alterações antrópicas em ecossistemas aquáticos exigem medidas de recuperação dos ambientes degradados, destacando-se projetos de restauração ecológica. Uma das etapas cruciais nesses projetos é a fase de monitoramento, sendo que o uso de macroinvertebrados como bioindicadores apresenta-se como uma importante ferramenta, por eles oferecerem vantagens sobre outros métodos de avaliação. Assim, o objetivo foi verificar os efeitos do assoreamento, antes e depois do rompimento da barragem de um pequeno reservatório em um riacho tropical, sobre a assembleia de macroinvertebrados aquáticos e avaliar a resposta da estrutura da comunidade após a implementação de um projeto de restauração ecológica. A pesquisa foi conduzida no riacho da Campininha, que passou por diversas alterações antrópicas, destacando-se aqui o rompimento de uma barragem e posteriormente a todos esses distúrbios pela implementação de um projeto de restauração ecológica. Foi realizada revisões da literatura para verificação da aplicabilidade da comunidade de macroinvertebrados como bioindicadores de sedimentação e na avaliação de projetos de restauração ecológica. Foram coletados dados pré-existentes antes e após o acidente e realizadas campanhas amostrais dois anos após o início da implantação do projeto de restauração. A comunidade de macroinvertebrados foi avaliada pela aplicação de índices ecológicos estruturais e funcionais alimentares e os resultados analisados por meio de ferramentas de estatística uni e multivariada. A análise da literatura mostrou que a aplicação de índices ecológicos tradicionais, tais como riqueza e diversidade, podem não ser sensíveis o suficiente para indicar impactos relacionados à sedimentação e implementação de projetos de restauração ecológica. Sendo, assim, necessária a utilização de índices que considerem a composição da comunidade, a sensibilidade dos organismos e a utilização de grupos funcionais alimentares e suas relações. Antes do rompimento da barragem a comunidade de macroinvertebrados já apresentava-se empobrecida pelo assoreamento do trecho represado e do canal fluvial. O rompimento da estrutura implicou na perda de importantes grupos e na mudança da composição da comunidade, além da perda de grupos funcionais alimentares, com consequente perda de funções ambientais. Após a implementação do projeto de restauração houve o aparecimento de 20 famílias, no entanto, os índices ecológicos tradicionais não foram capazes de identificar mudanças na comunidade. Métricas de composição e de grupos alimentares apontaram para um processo de recuperação da área. As características do sedimento tiveram um alto poder explicativo da comunidade, mostrando que a recuperação do habitat bentônico é um dos fatores que leva à uma melhor resposta da comunidade, mesmo esse não tendo sido o foco da aplicação do projeto de restauração avaliado. O relativo curto período transcorrido após a implementação do projeto já foi suficiente para indicar melhorias na qualidade ambiental. Tais resultados contrapõe a maioria dos estudos verificados na revisão da literatura. No entanto destaca-se que os mesmos foram conduzidos principalmente em ambientes temperados, indicando que em ambientes tropicais a dinâmica de recuperação é diferente. Assim aponta-se a necessidade da intensificação da implantação de projetos e monitoramento dos mesmos para a criação de um arcabouço teórico para auxiliar gestores e projetistas na sua elaboração. / Anthropic alterations in aquatic ecosystems demand the implementation of recuperation actions, highlighting ecological restoration projects. The monitoring is an important step to these projects, and the macroinvertebrates application as bioindicators is an important tool, because they are advantageous in comparison to another assessment methods. Thus, the goal was verify the effects of silting, and dam rupture in macroinvertebrate community, in a tropical stream, and assess the answer to an ecological restoration project implementation. The research was conducted in the Campininha stream, that was impacted by anthropic alterations, featured a dam rupture and after all this disturbances was implemented an ecological restoration project. A literature review was conducted to verification of the applicability of macroinvertebrates as bioindicators of silting and in ecological restoration projects assessment. Data was collected before and after the dam rupture, and samplings were done two years after the project implementation began. The macroinvertebrates community was assessed by application of structural and functional feeding indexes and the results analyzed by univariate and multivariate statistic. The literature review showed that the traditional indexes application may be not sensible to indicate impacts related to silting and ecological restoration projects implementation, and it is necessary the utilization of indexes that consider the community composition, organisms sensibility and functional feeding groups and your relations. Before the dam rupture, the macroinvertebrate community was already poor by the silting of the lake and fluvial channel. The dam rupture leaded to the loss of important groups and in the change of the macroinvertebrate community composition, also loss of functional feeding groups and consequently environmental functions. After the ecological restoration project implementation were found another 20 families, however, the traditional indexes were not sensible to indicate changes in macroinvertebrates community. Composition and functional feeding groups indexes showed the stream recuperation process. The sediment characteristics had a community high explanative power showing that the benthic habitat recovery is a factor that guide to a better community answer, even this was not the goal of the restoration project application. The relative short time after the project implementation was enough to point a environmental quality recovery, in contrast with the literature review. However the most studies analyzed was conducted in temperate environments, showing that in tropical environments the recovery dynamics is different. Thus, is necessary a intensification of restoration projects implementation and monitoring to a creation of data bases to guide managers and professionals responsible by the projects elaboration in decision make.
93

Biologie et écologie d'une population isolée : exemple d'Eryngium viviparum et perspectives pour sa conservation en France / Biology and ecology of an isolated population : example of Eryngium viviparum and perspectives for its conservation in France

Rascle, Pauline 30 November 2018 (has links)
L'isolement géographique est une menace élevée pour le maintien des populations sur le long terme. Il est donc primordial de comprendre selon quel degré la viabilité des populations est affectée par leur isolement, notamment en vue de définir des priorités en terme de conservation. Eryngium viviparum J.Gay (Apiaceae) est une des espèces végétales les plus menacées d'Europe avec une distribution ibéro-armoricaine très fragmentée. En France, son statut de conservation est devenu particulièrement critique avec la disparition de la presque totalité de ses populations au cours des années 1980, à l'exception d'une seule, suite à la destruction de son habitat par les activités humaines. Cette unique population fait depuis plusieurs années l'objet d'une conservation et d'une gestion attentives au sein d'une réserve protégée. Malgré ces actions, l'isolement de cette population soulève des interrogations quant à sa viabilité sur le long terme. Dans ce cadre, et à travers une approche multidisciplinaire, la thèse propose un renforcement des connaissances sur les caractéristiques écologiques et biologiques d'E. viviparum, et plus particulièrement concernant sa dernière population française. Elle s'articule selon trois axes principaux : (1) L'étude de l'amplitude écologique de l'espèce, puis la caractérisation de ses préférences écologiques à fine échelle au sein de la dernière population française (2) L'évaluation de la viabilité de la population isolée d'après ses paramètres démographiques, son niveau de diversité génétique et son degré de différenciation avec d'autres populations. (3) L'expérimentation des modalités de réintroduction en France. Les résultats apportés par ce travail contribueront à définir les prochaines priorités en matière de gestion et de conservation pour assurer le maintien d'E. viviparum sur le long terme en France. Le cas d' E. viviparum fournit un bon modèle d'étude pour évaluer l'effet de l'isolement sur la dynamique d'une population isolée et pour appliquer une conservation adaptée à cette problématique. / The geographical isolation is an important threat for the long term preservation of populations. It is crucial to understand how the viability of populations is affected in such context, in particular to define conservation priorities. Eryngium viviparum J.Gay (Apiaceae) is one of the most endangered plant in Europe, with a fragmented distribution between the NW of the Iberian peninsula and Brittany. ln France, the species is maintained only on a single locality, after the destruction of its habitat by human activities during 1980s. Despite a conservation program and an attentive management within a protected area, the strong isolation experimented by this population bring up questions about its long-term viability. In this context, through a multidisciplinary approach, this thesis aims to improve the biological and ecological knowledge of E. viviparum, and more particularly within its last French population. This thesis is organized according three main axes : (1) The study of large-scale E. viviparum ecological amplitude, and the characterization of its fine scale ecological preferences within the last french population. (2) The viability evaluation of the isolated population according to its demographic modalities, and to its genetic structure in comparison with Iberian populations. (3) The experiment of its reintroduction modalities in France.The results of this study will contribute to define the long-term conservation priorities of E. viviparum in France. Finally, the case of E. viviparum is a good model to study the effect of the isolation on an isolated population dynamic, and to apply adapted conservation for species in a similar context.
94

Suivi des impacts d’un arasement de barrage sur la végétation riveraine par télédétection à très haute résolution spatiale et temporelle / Monitoring dam removal impacts on riparian vegetation unsing very high spatial and temporal resolution remote sensing

Laslier, Marianne 26 September 2018 (has links)
Les cours d’eau font l’objet de prescriptions législatives encourageant leur restauration, et l’arasement de barrages est une des solutions utilisées actuellement en France pour y parvenir. La végétation riparienne participe à l’intégrité et à la stabilité des systèmes fluviaux, Elle est donc une composante majeure à évaluer dans le cadre des actions de restauration .Les objectifs de la thèse sont d'analyser la dynamique de colonisation des berges exondées à court terme dans le contexte de l’arasement des barrages de la Sélune (Normandie) et de développer des indicateurs de suivi à long terme des zones ripariennes. Dans un premier temps, une analyse des dynamiques de colonisation aux échelles intra et interannuelles réalisée à l’aide d’images drone et de relevés terrain a révélé la pertinence de l’utilisation d’images drones pour cartographier la végétation, ainsi que des dynamiques successionnelles rapides, avec un potentiel de restauration passive et de stabilisation des sédiments. Dans un second temps, l’analyse de nuages de points LiDAR en trois dimensions acquis en hiver et en été a montré la complémentarité des deux dates d’acquisition pour cartographier des indicateurs de statut des ripisylves à large échelle tels que les essences principales, l’ombrage ou la densité de strates herbacées et arbustives. Ces résultats permettent de discuter les dimensions méthodologiques et opérationnelles de l’utilisation des approches par télédétection pour le suivi des ripisylves. / Rivers are the object of legislation encouraging their restoration, and dam removal operations represent one of the solution to achieve it in France. Riparian vegetation plays a fundamental role in stabilizing and maintaining fluvial systems, being at the interface between terrestrial and aquatic environments. It is therefore a very important component which has to be evaluated in river restoration operations. One of the consequences of dam removal on riparian vegetation is the colonization of the dewatered sediments in the reservoir. The objective of the thesis are to define short term colonization dynamics of vegetation in context of dam removal (Sélune River, Normandy), and to develop long term indicators for the monitoring of riparian vegetation. First, an analysis of intra and interannual colonization dynamics revealed the potential of using drone images to map riparian vegetation, and fast successional dynamics with high passive restoration and sediment stabilization potential. Secondly, the analysis of 3D point clouds extracted from LiDAR data acquired in winter and summer highlighted the complementarity of the two acquisition dates to map indicators of riparian status at large scale, such as main riparian species, shading or density of herbaceous and shrubby strata. These results make it possible to discuss the methodological and operational dimensions of the use of remote sensing approaches for the monitoring of riparian vegetation
95

Retenční kapacita říční nivy a alternativní protipovodňová opatření v povodí řeky Berounky. / Retention capacity of flood plain and alternative flood protection in the Berounka River catchment.

Pergl, Michal January 2017 (has links)
This thesis deals with the retention capacity of Berounka during the hydrological extremes. Flood prevention and flood condition are main subjects of this thesis. Two selected river areas of Berounka are analysed by the passive retention volume and by the transformation of the flood wave. The first area is situated on the lower course of Berounka near the Černošice, and this area is significantly anthropogenically influenced. The second area which has nature character is located on the middle course of Berounka near Křivoklát. This thesis contains an evaluation of the hydromorphological state of flow in both areas. The results of passive retention indicate negligible influence of the flood situations. 1D hydraulic model HEC-RAS displays the transformation of the flood wave. The results of the transformation are flow velocity and depths of the river valley in 100-year-old and 20-year-old flows. The transformation of the flood wave in the first area is on the minimum level and did not reach its potential retention capability. The culmination flow in the second area is reduced because of a geomorphological shape of the river. Moreover, the near natural flood protection precautions are proposed in this thesis. Mean flow velocity in 100-year floods could be reduced by 1 - 1,6 m.s-1 by forestation of...
96

Experimental biodiversity enrichment in an oil-palm plantation

Gérard, Anne 15 November 2016 (has links)
Die großflächige Umwandlung von tropischen Wäldern hat zu dramatischen Verlusten von Biodiversität und assoziierten Ökosystemdienstleistungen und –funktionen geführt. Indonesien ist ein besonders schwerwiegendes Beispiel für den Verlust von Waldflächen und Biodiversität. Landumnutzungen, in starkem Maße durch den Anbau von Ölpalmen vorangetrieben, stellen eine erhebliche Bedrohung für die außergewöhnlich hohe Biodiversität des Landes dar. Landwirtschaftssysteme, wie Agroforstsysteme, können hingegen genutzt werden, um die Biodiversität und Ökosystemfunktionen in von Ölpalmen dominierten Landschaften zu erhöhen. In Regionen, in denen Ölpalmplantagen bereits die Landschaft dominieren, kann diese Erhöhung nur durch systematische Renaturierung erfolgen. Die zugrunde liegenden ökologischen und soziökonomischen Prozesse und damit verbundene Beschränkungen und Kompromisse von Renaturierungsmaßnahmen in von Ölpalmen dominierten Landschaften sind jedoch weitgehend unbekannt. Um diese Wissenslücke zu schließen, habe ich mit Kollegen aus Deutschland und Indonesien ein Langzeitexperiment zur Erhöhung der Biodiversität aufgebaut. Wir haben experimentell Bäume in Form von „Inseln“ in eine konventionelle Ölpalmplantage gepflanzt und hierbei systematisch die Flächengröße, das Diversitätslevel und die Artzusammensetzung variiert. Wir haben hierfür sechs multifunktionale heimische Baumarten ausgewählt. Auf der Fläche der Bauminseln haben wir einen Teil der Ölpalmen gefällt, um die Lichtverfügbarkeit für die gepflanzten Bäume durch eine reduzierte Ölpalmdichte zu erhöhen. In dieser Doktorarbeit stelle ich den Aufbau des Experiments vor und gebe einen breiten Einblick in anfängliche Auswirkungen des Experiments, indem ich ökologische Aspekte in Betracht ziehe, sowie Veränderungen hinsichtlich des Ernteertrags. Da die Zeit kurz nach der Pflanzung ein Nadelöhr für die Langzeitetablierung der Bäume darstellt, ist sie sehr kritisch, um die erwünschten Renaturierungserfolge in der Zukunft zu erzielen. Des Weiteren kann die Anfangszeit auch aus der Sicht der Landwirte eine entscheidende Hürde darstellen, da der Nutzen der Bauminseln erst lange Zeit nach ihrer Pflanzung entsteht. Zuerst beschreibe ich Umweltvariablen und biotische Charakteristika der den experimentellen Flächen assoziierten Vegetation, Invertebraten und Vögel vor der Errichtung des Experiments, sowie anfängliche Auswirkungen des Experiments auf die Fauna. Ein Jahr nach der Errichtung des Experiments hatten die Baumpflanzungen einen insgesamt positiven Effekt auf die Artengemeinschaften von Vögeln und Invertebraten in der Plantage. Die Größe der Bauminseln wirkte sich lediglich auf die Diversität und Abundanz von Invertebraten positiv aus, die somit auf kleinskalige Veränderungen reagierten. Ausgehend von diesen Ergebnissen erwarte ich einen weiteren Anstieg der Biodiversität und Ökosystemfunktionen in der Zukunft. Danach berichte ich über den Anwuchserfolg der Bäume und ermittle die wichtigsten Determinanten für den Wuchs und das Überleben der Bäume. Insgesamt sind die Bäume gut angewachsen, jedoch gab es große Unterschiede zwischen den Baumarten hinsichtlich relativer Höhenwachstums-, Dickenwachstums- sowie Überlebensraten. Arten mit hohen Wachstumsraten wiesen vorwiegend auch hohe Überlebensraten auf. Auf Versuchsflächenebene hatten Standortbedingungen, Flächengröße und Diversitätslevel der gepflanzten Bäume lediglich einen geringen Einfluss auf das mittlere Baumwachstum und die Überlebensrate. Auf Individuenebene habe ich signifikante Nachbarschaftseffekte festgestellt. Hohe benachbarte Bäume und die Distanz zu verbleibenden Ölpalmen begünstigten die Entwicklung der Bäume. Noch ist es zu früh zu entscheiden, welche der Baumarten sich generell am besten eignen, um Renaturierungsziele zu erreichen. Unterschiede in der anfänglichen Entwicklung liefern jedoch wichtige Informationen für eine zukünftige Bewertung der Arten. Zuletzt präsentiere ich Auswirkungen des Experiments auf den Ölpalmertrag. Nach zwei Jahren waren die Erträge pro Ölpalmindividuum erhöht, sowohl auf als auch direkt neben den Versuchsflächen. Die geschätzten Ertragsänderungen für die verschiedenen Flächengrößen unter Einbezug von Ernteverlusten durch gefällte Ölpalmen sowie Effekte auf benachbarte Ölpalmen deuten darauf hin, dass die erhöhten Ernteerträge insbesondere in großen Bauminseln mindestens das Fällen von Ölpalmen kompensiert haben. Diese Ergebnisse, die in der frühen Phase der Bauminseletablierung erzielt wurden, sind vielversprechend für die Erarbeitung nachhaltiger Managementoptionen für Ölpalmplantagen, die ökologische und ökonomische Funktionen in Einklang bringen. Die anfänglichen Auswirkungen waren stärker und insbesondere aus ökonomischer Perspektive profitabler als ich erwartet habe. Die Nachbarschaftseffekte und die Auswirkungen der experimentell veränderten Variablen waren bislang jedoch überwiegend schwach. Ich erwarte, dass diese Auswirkungen mit der Zeit stärker ausgeprägt sein werden. Durch Erkenntnisse, die aus zukünftigen Langzeitbeobachtungen des Experiments, das ich in dieser Doktorarbeit vorstelle, gewonnen werden, können Wissenslücken geschlossen werden. Somit kann die Ausarbeitung von Managementrichlinien für von Ölpalmen dominierten Landschaften ermöglicht werden, die sowohl ökologisch verbessert als auch ökonomisch lohnenswert sind. Diese Doktorarbeit stellt einen wesentlichen Beitrag zur generellen Beurteilung des Experiments dar, wodurch darüber hinaus auch neue Erkenntnisse für die Renaturierungswissenschaft gewonnen werden können.
97

A century of landscape-level changes in the Bow watershed, Alberta, Canada, and implications for flood management

Taggart-Hodge, Tanya 09 December 2016 (has links)
This study used a comparison of one hundred and forty-eight historical (1888-1913) and current (2008-2014) oblique photographs from thirty-two stations to identify land cover changes that have occurred in portions of the Bow and Elbow valleys as well as surrounding Kananaskis Country region. Implications of these changes for flooding and flood management were explored. Forest cover was found to have drastically increased over the past century, particularly in the Bow valley, as did areas of direct human development. In the same time period, grasslands increased in the Elbow valley but decreased in the Bow, while regenerating areas decreased uniformly throughout both valleys. An analysis of pre (2008)-and-post (2014) flood conditions demonstrated no change in coniferous forest cover in both valleys over the 6-year period, but uncovered a decline of 20% in the Elbow and 3% in the Bow in the broadleaf/mixedwood category. The Elbow’s channel zone was larger in 2014 compared to 2008, whereas the extent of the Bow’s channel zone remained constant. However, both the Bow and Elbow’s bare exposed bars increased substantially, most likely as a result of the 2013 flood. The major source of water flows that contributed to the 2013 flood event originated in high elevation rock and scree areas, which, unlike floodplains, are elements of the watershed that cannot be manipulated over time. It is now recognized that forest cover should act as a buffer to floods. Nevertheless, the 2013 flood event occurred despite the massive buffering effect of a huge increase in older forest stands across the study area. The final discussion includes recommendations for improving flood management in the area. / Graduate / 0329, 0768, 0478 / tanya.taggarthodge@gmail.com
98

La patrimonialisation des grands sites : évolution des doctrines et transformation des espaces : exemple des promontoires littoraux emblématiques bretons / The making heritage of "grands sites" : evolution of doctrines and transformation of lands : example of the symbolic Britanny littoral headlands

Le Fur, Yann 06 May 2013 (has links)
Cette thèse s’inscrit dans une perspective compréhensive des processus de patrimonialisation de grands sites naturels bretons, de leur découverte à leur réhabilitation, ici la pointe du Raz, le cap Fréhel et la côte sauvage de Quiberon. Ces promontoires littoraux, objets inventés au 19e siècle, sont devenus au fil du temps des supports d’oeuvres littéraires et picturales, d’introspection et de fascination exercée par la puissance des éléments marins. Ces lieux ont accueilli depuis les années 1950 des fréquentations touristiques de plus en plus importantes, ayant provoqué des phénomènes de mise à nu des sols, que l’administration de l’Environnement a jugé menaçants pour leur intégrité. Il y a une trentaine d’années, elle a donc décliné une politique de réhabilitation dont la matérialisation principale fut la conduite d’‘Opérations Grands Sites’. De quelle manière ces projets de réhabilitation sont-ils menés et selon quelles doctrines ? Comment prennent-ils en compte les différents usages et valeurs attribuées à ces patrimoines ? Cette thèse analyse les aménagements, désaménagements et réaménagements de ces sites, l’imbrication de la montée de la doctrine écologique et des jeux d’acteurs qui s’y développent, et, interroge leur incidence sur le patrimoine et les modalités de son appropriation, ce que nous appelons le processus de patrimonialisation. La première partie retrace la patrimonialisation des grands sites naturels emblématiques de France, leur invention (chapitre 1), les politiques publiques mises en place en vue de leur protection (chapitre 2 et 3), et se focalise sur nos terrains d’étude (chapitre 4). La seconde partie montre les évolutions du cadre doctrinal, organisationnel et normatif de l’action publique, favorisant la protection de l’environnement et l’aménagement touristique. Elle montre le renouvellement des principes d’action publique (chapitre 5) et les transformations des espaces induites par les doctrines et les jeux d’acteurs (chapitre 6 et 7). Enfin, la troisième partie aborde les effets de ces réhabilitations sur le patrimoine et le processus de patrimonialisation contemporains (chapitre 8 et 9) et propose une réflexion sur la dimension normative des opérations de réhabilitation : nous démontrons qu’elles sont constitutives du processus de patrimonialisation. / This work analyzes in a comprehensive perspective the heritage making of the Brittanygreat sites, namely the point of Raz, the cape of Fréhel and the wild coast of Quiberon. These coastal headlands, objects invented in 19th century, became over time supports of literary and pictorial works, of introspection and fascination exercised by the power of the marine elements. Since the 1950s, aincrease of tourist attendances has led to the degradation of their ecosystems, that the administration of the Environment considered that’s a threat for their integrity. Thirty years ago, this administration introduced a policy of rehabilitation the main realization of which was the conduct of « Opérations Grands Sites ». How are these projects of rehabilitation led and according to which doctrines? How dothey take into account the various uses and the values attributed to these heritages? This thesis analyzes the land planning, dis-planning and re-planning of these sites, the rise of the ecological doctrine and stakeholders' interactions and questions their incidence about the heritage and the modalities of its appropriation, that we call the process of heritage making. The first part redraws the heritage making of the big symbolic natural sites of France, their invention (chapter 1), the public policies creation with the purpose of their protection (chapter 2 and3), and a more precisely a focus on our study fields (chapter 4). The second part shows the evolutionsof the doctrinal, organizational and normative dimension of the public action, favoring the environmental protection and the tourist development. It shows the renewal of the principles of publicaction (chapter 5) and the transformations of the spaces, which it led from stakeholders' interactions in presence (chapter 6 and 7). Finally, the third part approaches the effects of these rehabilitations on contemporary heritage and process of heritage making (chapter 8 and 9) and proposes a reflection on the normative dimension of the operations of rehabilitation. We make the demonstration that they area part of the process of heritage making.
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Alternativas para restauração florestal de pastagens / Alternatives of Forest Restoration of Pastures

Mônico, Allan Camatta 06 June 2019 (has links)
As áreas degradadas têm crescido no mundo e no Brasil, necessitando de métodos de restauração ecológica eficientes e com baixo custo que permitam a rápida reconstrução das florestas tropicais. A pecuária é a atividade agrícola de maior impacto na geração de áreas degradadas e o Brasil detém atualmente o maior rebanho bovino do mundo. As pastagens, em sua maioria, são degradadas e possuem baixo nível tecnológico, resultando em baixas produtividades para o setor. Por isso objetivo do estudo foi testar diferentes estratégias de restauração na estruturação de comunidades florestais tropicais em pastagens abandonadas vizinhas a fragmentos de Mata Atlântica (Floresta Estacional Semidecidual-FES). Para isso foram instalados 12 tratamentos repetidos quatro vezes, com parcelas de 600 m2 (12x50m), totalizando 2,88 ha no Instituto de Zootecnia de São Paulo, em Sertãozinho, SP. O Instituto foi escolhido por estar estrategicamente localizado em uma região altamente fragmentada e ter histórico de uso intensivo do solo, realidade de boa parte das pastagens do Brasil. A tese foi estruturada em três partes principais. A primeira comparou as comunidades resultantes dos tratamentos com sucessão secundária e condução da regeneração com diferentes níveis de manejo para controle das gramíneas e fertilização do solo. Previamente foram avaliados os solos, que se apresentaram férteis e compactados, e os bancos de sementes, que demonstraram alta dominância de arbustos e gramíneas e distribuição heterogênea de espécies arbóreas. A avaliação da regeneração demonstrou que o melhor tratamento foi o que recebeu aplicação de herbicida e fertilização, e o pior foi o Controle que parece estar com a sucessão estagnada ou muito lenta. Quanto maior e mais intenso o manejo da regeneração, maiores foram os resultados obtidos para a densidade de indivíduos, altura e área de copa das comunidades, contudo nenhum tratamento alcançou estruturar um dossel florestal em 32 meses de monitoramento. No segundo estudo foram comparados o tratamento com o melhor manejo da regeneração com 32 meses, com outros dois que receberam plantios de apenas duas espécies pioneiras de recobrimento, com e sem fertilização da regeneração, sobre áreas que estavam com a regeneração sendo manejada. Em apenas 20 meses os plantios criaram uma estrutura florestal com maior cobertura e registraram maior densidade de indivíduos e diversidade de espécies de estágios finais da sucessão. Não houve resposta da fertilização do solo na regeneração sob os plantios. O terceiro capítulo da tese testou a semeadura de mamona (Ricinus communis L.) para construção de dosséis transitórios, enriquecidos ou não com espécies secundárias iniciais, entre linhas de plantios de espécies de recobrimento. Esses dosséis tinham como objetivo controlar as gramíneas e favorecer a sobrevivência e crescimento dos indivíduos plantados. Os resultados demonstraram um controle efetivo das gramíneas e redução na mortalidade de espécies secundárias iniciais sob as copas dos dosséis de mamona. Ao final da tese os 12 tratamentos são comparados quanto à eficiência ecológica e custos, concluindo que quanto mais intensivos os manejos adotados, aumentando a previsibilidade das comunidades formadas e o sucesso da restauração, maiores os custos diretos. De forma adicional foram apresentados mais dois itens com aprendizagens obtidas com o desenvolvimento da tese. Esse estudo foi importante por apresentar diversas estratégias de restauração para pastagens próximas a remanescentes florestais em contexto de matriz fragmentada e solos que tiveram uso intensivo, apresentando alta representatividade na faixa de FES que se estende pela região central do Brasil. Os resultados obtidos podem auxiliar pequenos e grandes proprietários rurais, tomadores de decisão, formuladores de políticas públicas e todos os envolvidos na cadeia de restauração ecológica em relação a como se estruturar com eficiência ecológica e custos mais reduzidos comunidades florestais biodiversas e sustentáveis em pastagens abandonadas. / The extension of degraded areas has grown in Brazil and in the world, raising the need for efficient and low-cost ecological restoration methods that allow the rapid reconstruction of tropical forests. Livestock farming is the agricultural activity of greatest impact generating degraded areas and Brazil currently has the largest cattle herd in the world. Most pastures are degraded and have a low level of technification, resulting in low productivity for the sector. Therefore, the objective of this study was to test different restoration strategies for the structuring of tropical forest communities in abandoned pastures adjacent to fragments of Atlantic Forest (Semideciduous Seasonal Forest - SSF). We deployed 12 treatments and four repetitions, in plots of 600 m2 (12x50m), 2.88 ha total at the São Paulo Zootechny Institute, in Sertãozinho, SP, Brazil. The Institute was chosen because it is strategically located in a highly fragmented region and has a history of intensive land use, which is the reality of most of Brazil\'s pastureland. The thesis was structured in three main parts. The first one compared communities resulting from secondary succession to communities resulting from assisted natural regeneration after the application of different management intensities of grass control and soil fertilization. The soils were evaluated previously and found them to be fertile and compacted, and the seedbanks showed high dominance of shrubs and grasses with a heterogeneous distribution of tree species. Natural regeneration evaluation revealed that the best treatment was the application of herbicide plus fertilization, and the worst was the control treatment, that lead to a stagnated secondary succession or to very slowly changes. The higher and more intense the management of natural regeneration, the greater the results obtained regarding density, height and crown area. However, no treatment managed to structure a forest canopy within 32 months. In the second study, the treatment with the best results at the age 32 months was compared with two other treatments in areas were regeneration was being managed; both received plantations of two pioneer species, one was fertilized and the other was not. In only 20 months, the plantations created a forest structure with greater canopy cover, higher density and diversity of species common to the final stages of succession. Soil fertilization had no influence over natural regeneration under the plantations. The third chapter of the thesis tested the sowing of castor bean (Ricinus communis L.) between planting lines of fast-growing wide-canopy native species aiming the construction of transient canopies, enriched or not by the plantation of early-secondary seedlings. These canopies should control grasses and favor the survival and growth of planted individuals growing underneath. The results demonstrated an effective control of grasses and a reduction in the mortality of early-secondary species under the canopy; although more studies are needed to improve the technique. At the end of the thesis, the 12 treatments were compared in terms of ecological efficiency and costs, concluding that the more intensive the management adopted, increasing the predictability of the resulting communities and restoration success, the greater the direct costs. In addition, two other items were presented as lessons learned during the development of the thesis. This study was important because it presented several restoration strategies for pastures close to remnant forests in a fragmented matrix on intensively used soils, highly representative of SSF, that extends through the central region of Brazil. The results obtained can help small and large landowners, decision makers, policymakers and all of those involved in the ecological restoration value chain regarding how to structure ecologically and cost-effectively sustainable and biodiverse forest communities over abandoned pastures.
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Comportamento silvicultural de espécies nativas usadas no enriquecimento artificial de florestas alteradas na Amazônia, visando potencializar a exploração econômica da Reserva Legal / Silvicultural behavior of native species used in artificial enrichment of altered forests in Amazon aiming to enhance the economic exploitation of Legal Reserve

Erdmann, Andreia Alves 09 March 2015 (has links)
O Brasil é hoje um dos maiores produtores de madeira nativa do mundo. A demanda por este produto é cada vez maior perante a diminuição da oferta e supervalorização das madeiras de crescimento lento, tornando a silvicultura de espécies nativas um desafio, pois não existem estudos suficientes relacionados à produção de mudas, estabelecimento, crescimento e manejo florestal dessas espécies madeireiras. Neste contexto, este trabalho teve como objetivo avaliar a influência do microssítio na sobrevivência e crescimento de espécies nativas madeireiras utilizadas no enriquecimento artificial de florestas remanescentes na Amazônia (Pará), definidas como Reserva Legal (RL) da propriedade, mas que sofreram exploração madeireira recente, visando recompor e potencializar a exploração econômica dessas áreas. As espécies objeto desse trabalho, que foram usadas no enriquecimento artificial da RL, são: Carapa guianensis, Cedrela fissilis, Cordia goeldiana, Handroanthus serratifolius e Hymenaea courbaril. Essas espécies foram plantadas em abril de 2012 e avaliadas aos 9 e 19 meses após o plantio. Com o objetivo de identificar o momento que essas espécies são mais susceptíveis e que condições do microssítio influenciaram a mortalidade, foram caracterizadas as árvores circundantes à cada muda plantada, a taxa de herbivoria da muda, a possível competição com trepadeiras e plântulas, as aberturas no dossel sobre a muda e a luz difusa incidente. Para testar o efeito da espécie e do tempo na mortalidade das mudas, foi ajustado um modelo linear generalizado misto de análise de variância. Para testar a independência entre a sobrevivência e as variáveis ordinais do microssítio, foram construídas tabelas de contingência bidimensionais e aplicados os correspondentes testes de qui-quadrado. As análises demonstraram que a Carapa guianensis foi a espécie com maior mortalidade nos primeiros meses pós-plantio. Além disso, a mortalidade das espécies foi independente dos fatores luz difusa, árvores circundantes às mudas, trepadeiras e plântulas. Entretanto, a mortalidade de Carapa guianensis, Cedrela fissilis, Cordia goeldiana e Hymenaea courbaril foi explicada pelo vigor das mudas na fase inicial; a mortalidade de Cordia goeldiana foi explicada pela herbivoria; Carapa guianensis e Handroanthus serratifolius tiveram a mortalidade influenciada pela abertura no dossel. Afim de identificar os fatores do microssítio limitantes no crescimento das espécies, foram caracterizadas a herbivoria das mudas, a competição com trepadeiras, a competição com plântulas e luz difusa incidente. Para análise estatística, foram considerados modelos lineares de efeitos mistos para a altura, considerando as variáveis do microssítio. A herbivoria não interferiu no crescimento das espécies avaliadas. A luz direta na muda e a luz difusa alta foram significativas para o crescimento das espécies. Cordia goeldiana, Handroanthus serratifolius e Hymenaea courbaril tiveram crescimento máximo com a variável luz direta. As espécies avaliadas tiveram maior crescimento em locais com mais trepadeiras, provavelmente a maior incidência de luz tenha possibilitado o crescimento das trepadeiras e das espécies plantadas. As interações muita trepadeira x luz difusa alta e muita trepadeira x luz direta tiveram efeito negativo no crescimento de Hymenaea courbaril. O crescimento de Cordia goeldiana foi afetado negativamente pelo número de plântulas circundantes. / Brazil is one of the largest producers of native timber in the world. The demand for this product is increasing towards the supply is decreasing and overvaluation of the slowgrowing wood, turning out native species forestry a challenge because there are not enough studies related to the production of seedlings, establishment, growth and forestry management of these species. In this context, this study aimed to evaluate the influence of micro-sites on survival and growth of native timber species used in artificial enrichment of forest remnants in Amazon (Pará), defined as Legal Reserve (LR) of the property, even though suffered recent logging, aiming to restore the economic potential of these areas. The species used in this study are Carapa guianensis, Cedrela fissilis, Cordia goeldiana, Handroanthus serratifolius and Hymenaea courbaril. These species were planted in April 2012 and evaluated at 9 and 19 months after planting. In order to identify the right moment that those species are more susceptible and which micro-site conditions influenced the mortality, the surrounding trees to each planted seedling were characterized, the rate of herbivory of the seedling, possible competition with vines and other seedlings, openings in the canopy over the seedling and diffuse incident light. To test the effect of species and time in the mortality of seedlings, a generalized linear mixed model analysis of variance was adjusted. To test the independence between survival and the ordinal variables from the micro-site, two-dimensional contingency tables were constructed and applied chi-square tests. Analysis showed that Carapa guianenses was the specie with the greatest mortality in the first months after planting. In addition, the mortality of the species was independent from the factors: diffused light, surrounding trees to seedlings, vines and seedlings of other species. However, the mortality of species Carapa guianensis, Cedrela fissilis, Cordia goeldiana and Hymenaea courbaril was explained by the vigor of the seedlings in the initial phase; the mortality of Cordia goeldiana was explained by herbivory; and Carapa guianensis, Handroanthus serratifolius have mortality influenced by canopy opening. In order to identify the micro-site limiting factors in the growth of the species, herbivory of seedlings, competition with vines, competition with seedlings and diffuse incident light were characterized. Statistical analysis included linear mixed models for height, considering the micro-site variables. Herbivory did not affect the growth of the species assessed. The direct light over the seedling and high diffuse light were significant for the growth of the species. Cordia goeldiana, Handroanthus serratifolius and Hymenaea courbaril had maximum growth with the variable direct light. The species evaluated had higher growth in places with more vines, probably the largest incidence of light enabled the growth of vine and the species planted. Interactions high level of vine x high diffuse light and high level of vine x direct light had a negative effect on the growth of Hymenaea courbaril. The growth of Cordia goeldiana was negatively affected by the number of surrounding plants.

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