Understanding why some introduced alien plant species become invasive whilst others fail is a fundamental question in ecology, not least because of the considerable ecological and economic damage caused by invasive plants globally. Identifying factors that drive alien plant invasions can inform efforts to predict the nsk of invasion by an introduced plant species. This would allow prevention of introduction of high risk aliens, as well as targeted management of species already introduced that pose the latest threats to the ecolocal integrity of host ecosystems. However, generalisations among the findings of comparative plant invasion studies have been limited by a lack of control of confounding variables such as propagule pressure, time since introduction and phylogeny, a lack of knowledge of introduced species that failed to establish, and inconsistent use of terminology defining the invasion process. This thesis used Amani Botanical Garden (ABG) in the East Usambara Mountains of Tanzania, as a comparative case study system to assess the relative ability of multiple factors to explain invasion success of species introduced to a tropical forest ecosystem.

Thesis (Ph.D.)--Aberdeen University, 2009. / Title from web page (viewed on July 23, 2009). Includes bibliographical references.

Le continent africain a connu une grande période de conflictualité dans les années 1990 ; cettepériode coïncide avec l’essoufflement des politiques purement altruistes des pays occidentauxqui, hésitent de plus en plus à engager leurs troupes dans des conflits qui ne sont pas les leurs.En Afrique, le maintien de la paix est un défi de tous les temps ; l’Union africaine doit réagiraux menaces contre la paix et la sécurité par des réponses collectives fondées et soutenues pardes mécanismes cohérents.D’une résolution des conflits centralisée et contrôlée par le Conseil de sécurité des Nationsunies, s’est progressivement mis en place une alliance entre le système des Nations unies etl’Union africaine ; l’affirmation des interdépendances dans la recherche de la stabilitéimplique la coordination des stratégies et des programmes de sécurité et de défense entre lesdifférents acteurs de la paix sur le continent.Les mécanismes d’action sont repensés et les stratégies bouleversées. Et pour éviter lajuxtaposition des acteurs et l’évitement du chaos, la cohésion et la coordination entre desinstitutions prend son élan.La CEDEAO a prouvé sa capacité à mener une force d’interposition jusqu’au cessez-le-feu etle retour de la paix dans le conflit du Libéria ; elle s’est dotée de mécanismes d’interventionreconnus et structurés qui vont servir de levier à l’UA dans l’élaboration de ses propres outilsde maintien de la paix et de la sécurité sous régionales et régionales.La gestion des conflits va être rénovée avec une vraie architecture de paix et de sécurité del’Union africaine qui, désormais, s’est dotée de mécanismes fonctionnels et de forcesafricaines formées, opérationnelles et surtout interopérables avec les forces des organisationsinternationales.La question de la sécurité et de la stabilité en Afrique et les enjeux de reconstruction qu’ellepose, a nécessité la redéfinition des relations internationales en Afrique subsaharienne.Ces problématiques vont permettre à l’Union africaine d’élaborer et d’instituer la gestion desconflits sur le contient. / The African continent has experienced a long period of conflict in the 1990s, this periodcoincides with the exhaustion of purely altruistic policies of Western countries, increasinglyreluctant to commit troops in conflicts that are not theirs.In Africa, peacekeeping is a challenge of all time, the African Union must respond to threatsagainst peace and security through collective responses based and supported by coherentmechanisms.In a conflict resolution controlled and centralized by the United nations Security Council, hasgradually established an alliance between the UN system and the African Union. Theassertion of the interdependencies in the search for stability involves the coordination ofstrategies and programs of security and defense between the different actors of peace on thecontinent.The mechanisms of action are reconsidered and the strategies changed. And to avoid thejuxtaposition of actors and avoiding chaos, cohesion and coordination among institutions isgaining momentum, its dash.ECOWAS has a proven ability to lead a peacekeeping force until the cease-fire and the returnof peace in the conflict in Liberia. It has mechanisms recognized and structured interventionthat will serve lever to the African Union in developing its own tools for peacekeeping andsecurity sub-regional and regional.Conflict management will be renovated with a real architecture of peace and security of theAfrican Union, which now has functional mechanisms and African forces trained, operationaland especially interoperable with the forces of international organizations.The issue of security and stability in Africa and the challenges of reconstruction it poses,necessitated the redefinition of international relations in sub-Saharan Africa.These issues will enable the African Union to work out for developing and establishingconflict management on the continent.

À travers l’analyse des mouvements de population entre les îles Amami et la métropole japonaise, dite « Hondo », ce travail examine les processus de (re)définitions identitaires à l’œuvre chez les habitants de ce petit archipel au Sud-Ouest du Japon, ainsi que les effets de ces mouvements sur les représentations de leur territoire. Les divers types de mobilité repérables chez les gens des îles Amami sont intimement liés à l’histoire de la région. Anciennement intégré au royaume des Ryûkyû, puis sous la domination de la province de Satsuma, l’archipel fut placé sous administration américaine après la Seconde Guerre mondiale, avant d’être rétrocédé au Japon en 1953. Cet arrière-plan historique singulier a eu de multiples conséquences, au premier rang desquelles figure une importante migration interne de personnes originaires d’Amami vers les grands centres urbains de la métropole, en particulier dans la région de Hanshin (Kôbe, Amagasaki, Ôsaka). L’attention portée à l’élaboration de différences « culturelles » entre la métropole japonaise et les habitants des îles Amami met en lumière la volonté de construction d’une nation homogène par les gouvernements successifs depuis Meiji. Cette différenciation a donné lieu à un double processus : d’une part, la marginalisation de la population originaire d’Amami à son arrivée en métropole à partir du début du XXe siècle ; d’autre part, des regroupements d’Amamiens au sein de diverses initiatives culturelles (« amicales des anciens », cours de « chants des îles », médias à destination des « minorités »). Un certain nombre d’« évènements » survenus depuis les années 1990 invitent ensuite à s’interroger sur l’actuelle valorisation de l’« identité amamienne ». L’analyse de trajectoires individuelles permet de faire émerger les multiples raisons d’un mouvement de « retour vers » ou de « départ pour » les îles Amami, ainsi que les effets de ces installations. Ce travail révèle ainsi le dynamisme actuel d’Amami, et, par là, permet de saisir les requalifications de cet archipel et de ses habitants, tout comme sa place actuelle à l’intérieur du Japon. / This work focuses on current processes of identity (re)definition among the inhabitants of the Amami Islands, in the context of strong population movements between this small archipelago of southern Japan and the Japanese metropolis called “Hondo”, as well as on the impact of these movements on their views of their territory. The different types of mobility that can be observed among the people of the Amami Islands are deeply enmeshed in the history of the region. Once part of the Ryûkyû kingdom, then under the domination of Satsuma province, the archipelago was placed under U.S.A. administration after World War II, before its restoration to Japan in 1953. This singular historical background has had multiple consequences, not the least of which is the intense internal migration from Amami towards the big urban centers of the metropolis, in particular in the Hanshin region (Kôbe, Amagasaki, Ôsaka). A focus on the making of “cultural” differences between the Japanese metropolis and the inhabitants of the Amami Islands sheds light on the homogenizing nation-building policies that consecutive governments have set up since Meiji. This differentiation has led to a two-way process: on the one hand, the marginalization of the population hailing from Amami at its arrival in the metropolis, beginning in the early twentieth century; on the other hand, the coming together of Amami islanders within cultural programs (“third age groups”, “island songs” classes, medias destined to “minorities”). Several “events” that have taken place since the 1990s then bring our focus onto the current valorization of the “Amami identity”. An analysis of individual trajectories brings forth the multiple reasons behind movements “back to” or “departing from” the Amami Islands, as well as the effects of these relocations. This work thus renders the dynamics of Amami and, as a result, brings the requalification of this archipelago and it’s inhabitants into focus, and sheds light on its current place within Japan.

As a strategy to conserve tropical rainforests of the East Usambara block of the Eastern Arc Mountains, Tanzania, I developed a set of models that can identify above-average tree species richness areas within the humid forests. I developed the model based on geo-referenced field data and satellite image-based variables from the Amani Nature Reserve, the largest forest sector in the East Usambara. I then verified the model by applying it to the Nilo Forest Reserve. The field data, part of the Tanzanian National Biodiversity Database, were collected by Frontier-Tanzania between 1999 and 2001, through the East Usambara Conservation Area Management Program, Government of Tanzania. The field data used are rapidly collectible by people with varied backgrounds and education. I gathered spectral reflectance values from pixels in the Landsat Enhanced Thematic Mapper (Landsat ETM) image covering the study area that corresponded to the ground sample points. The spectral information from different bands formed the satellite image-based variables in the dataset. The best satellite image logistic regression and discriminant analysis models were based on a single band, raw Landsat ETM mid-infrared band 7 (RB7). In the Amani forest, the RB7-based model resulted in 65.3% overall accuracy in identifying above average tree species locations. When the logistic and discriminant models were applied to Nilo forest sector, the overall accuracy was 62.3%. Of the rapidly collectible field variables, only tree density (number of trees) was selected in the logistic regression and the discriminant analysis models. Logistic and discriminant models using both RB7 and number of trees recorded 76.3% overall accuracy in Amani, and when applied to Nilo, 76.8% accuracy. It is possible to apply and adapt the current set of models to identify above-average tree species richness areas in East Usambara and other forest blocks of the Eastern Arc Mountains. Potentially, managers and researchers can periodically use the model to rapidly assess, monitor, update, and map the tree species rich areas within the forest. The same or similar models could be applied to check their applicability in other humid tropical forest areas. / Ph. D.

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