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University of Sheffield (1991)

Vegetation studies in the Algerian Sahara

Benhouhou, Salima S.

Titre : Vegetation studies in the Algerian Sahara.

Auteur : Benhouhou, Salima S.

Université de soutenance : University of Sheffield

Grade  : Doctor of Philosophy (Ph.D.) : 1991

The present study consists of an ecological investigation in the Béni-Abbès/Ougarta area of the North West Sahara. Phytosociological units are described, the main ecological factors highlighted and additional ecological observations made, particularly in relation to dynamic aspect of the vegetation.The extraction of ecological factors was achieved using direct and indirect gradient analyses. The latter is part of an integrated approach where floristic variation obtained with the DECORANA program, using detrended correspondence analysis, is related to the environmental data set recorded by a trend surface analysis with the MINITAB package. Floristic variation is then summarised along the most important factors retained with a technique of seriation applying SERIATE. In the direct gradient analysis, canonical correspondence analysis was applied with the CANOCO program. Classification identified seven main vegetation types in the area. Ordination analyses extracted a strong grazing factor operation in all five habitats. The expression of the grazing factor was different in each one. The supporting studies confirmed the primary importance of rainfall, topography, soil and grazing in this arid environment. They also started to elucidate dynamic aspects of the ecosystem and identified fruitful areas for further research. The impact of sedentarization and the use of vehicles has had a marked effect on the vegetation which has decreased over the last forty years.

Annonce : EThOS (UK)

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