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Accueil du site → Doctorat → États-Unis → 1992 → The Tana River floodplain forest, Kenya : hydrologic and edaphic factors as determinants of vegetation structure and function

University of California, Davis (1992)

The Tana River floodplain forest, Kenya : hydrologic and edaphic factors as determinants of vegetation structure and function

Njue, Alexander

Titre : The Tana River floodplain forest, Kenya : hydrologic and edaphic factors as determinants of vegetation structure and function.

Auteur : Njue, Alexander

Université de soutenance  : University of California, Davis, USA

Grade : Doctor of Philosophy (PhD) 1992

Résumé
The Tana River floodplain is located in the arid- to semi-arid eastern region of Kenya. A floodplain forest, which can extend up to 1 km on either side of the river channel, occurs as forest patches between Garissa and the Tana delta. The best remaining patches of the floodplain forest are located within the Tana River National Primate Reserve (TRNPR). As home to two endemic and critically endangered subspecies of primates, this floodplain forest is of high conservation importance. This study aims at an objective analysis of the vegetation of the TRNPR and its highly heterogeneous environment, using a stratified random sampling design with six transects and 95 sampling plots. The vegetation of the TRNPR is comprised of 5 distinct species assemblages. Each assemblage includes species that are highly positively associated. Herbaceous species positively associated with particular tree and shrub species are identified, offering a possible means of identifying successional trends using short-term data. The vegetation of the TRNPR can be classified into 6 vegetation types using a numeric classification procedure. Virtually identical vegetation types emerge when different data analysis procedures are used. The most important environmental factors for the ecosystem are identified, on the basis of 15 determined environmental variables. An analysis of the relationships between plant species and environmental factors identifies important environmental factors for the various plant species. Several successional trends may be in operation within the TRNPR. It is suggested that a new vegetation successional pattern may have started in 1988/1989. Soil conditions in abandoned fields are found to be closer to soil conditions in fields under cultivation than to soil conditions in a mature floodplain forest. It is suggested that clearcutting the floodplain forest for cultivation has some detrimental effects on soil conditions which, when coupled with the stressful nature of the floodplain environment, do not favor forest regeneration

Mots Clés : Ecology / Tana River National Primate Reserve, Kenya / Tana River, Kenya / Garissa, Kenya / Forests / Trees / Flowers and plants

Accès au document : Proquest Dissertations & Theses

Page publiée le 22 septembre 2010, mise à jour le 31 décembre 2016