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The role of disturbances in mangrove wood formation and forest structure: Effect of large sedimentation events

Disturbance can take various forms and are characteristic of any ecosystem including mangroves. When maintained within certain allowable limits, disturbances permits maintenance of a given stable state which is equivalent to resilience hence the ecological status is not compromised. Disturbances may disrupt the natural balance of processes within such ecosystems including changes in sediment budgets and salinity and tidal regimes. As such, it may trigger a series of responses in tree establishment and development. While such responses may be displayed in loss of stability of a forest and may culminate in irreversible degradation of the system, disturbances could also result in improved performance of physiological processes and consequently tree growth. It may equally lead to the development of adaptive mechanisms to counteract the resultant otherwise stressful effects. Sediment accretion is one of the important natural processes within the mangrove environment particularly in the face of relative sea level rise. In each case, sediment fluxes are gradual and while the trees thrive from the benefits of terrestrial sediment, the system ensures balance in elevation for possible sea level rise scenario. However, abrupt and/or rapid sediment input leading to partial burial of the trees may be detrimental to the trees development in the short term and the entire ecosystem in the long run. But how are ecophysiological processes affected before the mangroves trees die from partial sediment burial? What is the threshold below which normal tree functioning is ensured.The main objective of this study was to understand the impacts of disturbance on mangrove trees, as individuals and as an assemblage. Specifically the study targeted large sedimentation on selected ecophysiological processes (phenology, water transport), root development and general physiognomy and hence its impact on wood formation in mangroves. A survey was also done on the extent of wood exploitation and other human activities, in order to obtain background information on the environmental management in the area and hence to help create an integrated picture of the evolving mangrove ecosystem in the human-nature context.Main question: What is the significance of sedimentation in shaping the ecological status of mangrove forests? / Doctorat en Sciences / Author's maiden name: Judith Auma OKELLO / Due to a technical Di-Fusion bug it was not possible to input the correct date of the defense. The correct date is Thursday 30 June 2016. / info:eu-repo/semantics/nonPublished

Identiferoai:union.ndltd.org:ulb.ac.be/oai:dipot.ulb.ac.be:2013/232475
Date30 June 2016
CreatorsOchieng, Judith Auma
ContributorsKoedam, Nico, Dahdouh-Guebas, Farid, Kairo, James G., Beeckman, Hans, Triest, Ludwig, De Cannière, Charles, Kervyn, Matthieu, Drouet, Thomas, Vermaat, Jan, Lens, Frederic
PublisherUniversite Libre de Bruxelles, Vrije Universiteit Brussels, Université libre de Bruxelles, Faculté des Sciences – Sciences biologiques, Bruxelles
Source SetsUniversité libre de Bruxelles
LanguageEnglish
Detected LanguageEnglish
Typeinfo:eu-repo/semantics/doctoralThesis, info:ulb-repo/semantics/doctoralThesis, info:ulb-repo/semantics/openurl/vlink-dissertation
FormatNo full-text files

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