Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → Allemagne → 2005 → Zur eisenzeitlichen Entwicklung der Kulturlandschaft im Sahel von Burkina Faso : Untersuchungen von archäologischen Holzkohlen

Frankfurt (Main) Universität (2005)

Zur eisenzeitlichen Entwicklung der Kulturlandschaft im Sahel von Burkina Faso : Untersuchungen von archäologischen Holzkohlen

Höhn, Alexa

Titre : Zur eisenzeitlichen Entwicklung der Kulturlandschaft im Sahel von Burkina Faso : Untersuchungen von archäologischen Holzkohlen

Auteur : Höhn, Alexa

Université de soutenance : Frankfurt (Main) Universität, Biowissenschaften,

Grade : Doktorgrade 2005

Résumé
Charcoals from archaeological excavations in the Sahel of Burkina Faso allow reconstruction of the vegetation history of the region in the course of the last 2000 years. Sedentary culture and cultivation of food plants starting around 0 BC/AD, changed the composition of the woody vegetation, especially on the dunes. In comparison with today’s vegetation climatic changes can be detected as well. More than 9000 fragments were analysed. They were retrieved out of seven different archaeological excavations. Six charcoal assemblages come from settlement mounds. At one site a house-complex was excavated. The charcoal assemblages of the settlement mounds showed that the vegetation of the dunes and gallery forests was mainly used to collect firewood. Depending on the location of the site and on different emphases in economy, different taxa are represented in higher proportions, possibly amplified by the anthropogenic selection of available species as firewood. The comparison of the charcoal assemblages reveals changes of the woody vegetation in the course of the Iron Age. In the vicinity of the sites the natural woody vegetation on the dunes, mainly consisting of acacias, was displaced by fields and fallows. The selective support of useful trees, like Vitellaria paradoxa und Faidherbia albida led to their increase. Moreover, fallow species, especially of the Combretaceae, were supported by the practice of field rotation. Rising influence of cattle herding can be seen in the increase of Guiera senegalensis in the late Iron Age samples. The species is promoted by strong grazing in the fallows. The underwood of the gallery forests along the mares und watercourses is cleared more and more in the vicinity of each settlement, since the share of Combretum micranthum diminishes within the stratified charcoal assemblages. During the Iron Age climate and vegetation were of sudano-sahelian character. Especially Vitellaria paradoxa und Detarium microcarpum, which need distinctly higher precipitation than the region receives today, point to moister conditions during the Iron Age. The presence of other taxa, which are found far to the south today, further indicates the sudanian aspect of the woody vegetation of the Iron Age. Taking together anthracological, palynological and carpological results it becomes clear that, against the background of increasingly arid conditions during the late Holocene, the main changes of woody vegetation are anthropogenic. Clearing of fields, agroforestry and cattle herding influenced and changed the vegetation, especially on the dunes. Moreover during the Iron Age, from 0-1500 AD, climate seems to have been comparatively stable. Only afterwards, precipitation diminished in such a manner that during the last 500 years some sudanian taxa vanished from the regional flora, as Vitellaria paradoxa, Detarium microcarpum und Lannea sp. However, the comparison of the iron-age charcoal flora with recent vegetation dynamics and the distribution of species in the 1950s shows that some taxa, like Terminalia sp., might have left the region as late as in the second half of the 20th century.

Présentation

Texte intégral (23,3 Mb)

Page publiée le 12 mars 2006, mise à jour le 2 janvier 2019