Content uploaded by David Sebag
Author content
All content in this area was uploaded by David Sebag on Feb 07, 2014
Content may be subject to copyright.
A preview of the PDF is not available
Stone lines and heaps on southwestern Niger plateaus as remains of ancient agricultural land
Abstract and Figures
Les plateaux de la rive occidentale du fleuve Niger sont recouverts de lignes et de tas de pierres sèches alors que ces
surfaces tabulaires sont aujourd'hui dépourvues de toutes cultures. Le sol du plateau est constitué d'un horizon argilo-sableux
visible uniquement dans la zone où ces structures sont présentes. Elles témoigneraient d'un épierrage pour faciliter le travail
agricole du sol. Les matériaux extraits ont été disposés en ligne puis en tas si la quantité de blocs était trop élevée. Ce parcellaire
pourrait être contemporain de l'activité métallurgique située au pied des plateaux et datée de la deuxième moitié du premier
millénaire.
Figures - uploaded by David Sebag
Author content
All figure content in this area was uploaded by David Sebag
Content may be subject to copyright.
Recent global historical cropland modelling grossly underestimates the pre-colonial development of agriculture in the Americas and many parts of sub-Saharan Africa. Such models are usually developed by back casting from recent land cover, combined with environmentally deterministic algorithms. Historical geographers have been slow in responding to a new demand for a global synthesis. In this paper, a preliminary map of African agricultural systems dating to AD 1800 is presented. It forms a component of the project Mapping Global Agriculture and is based on the existing historical literature, observations by early travelers, archaeology and archaeobotany. It should be emphasized that the generated map should be considered preliminary.
Au sud-ouest du Niger dans les environs de Niamey, plusieurs milliers de bas fourneaux à usage unique ont été recensés. Une étude archéologique menée sur une trentaine de structures de bas fourneaux et de leurs scories a révélé la présence de quatre procédés de réduction du fer : trois de type scorie piégée et un de type scorie coulée. Les bas fourneaux à scorie piégée se différencient nettement par la morphologie et le volume de leur cuve. Les bas fourneaux à scorie coulée ont tous la particularité d'évacuer la scorie par de petits orifices creusés dans la cuve. L'écoulement de la scorie à l'extérieur de la cuve se fait soit verticalement soit latéralement. Selon les datations radiocarbone, l'activité métallurgique se développe dès le 2e siècle AD et s'intensifie jusqu'au 14e siècle. Au-delà, elle évolue et perdure jusqu'au milieu du 20e siècle. La production de fer par ces bas fourneaux est relativement faible, elle est principalement destinée au marché local.
Nous présentons un ensemble de connaissances sur les ressources alimentaires des forêts tropicales et leurs utilisations, sous la forme d'un ouvrage en deux volumes qui constitue un prolongement de celui que nous avons publié en anglais dans la série UNESCO-MAB(I). Beaucoup plus qu'une simple traduction des chapitres revus et mis à jour de ce premier ouvrage en anglais, nous avons voulu apporter des éléments récents originaux, constituant 12 nouveaux chapitres; et la révision des textes des auteurs francophones et anglophones a souvent abouti à une version entièrement nouvelle. Faisant ainsi le point sur les connaissances relatives aux stratégies alimentaires et aux adaptations des populations des régions tropicales - adaptations de nature biologique et culturelle -, nous espérons, en mettant ces données à la disposition des responsables des projets de développement, contribuer à une gestion durable et équitable des ressources dans le respect des communautés locales.
Cet article critique la conception classique des droits relatifs à la terre dans les sociétés traditionnelles, l'exemple de référence étant l'Afrique précoloniale. Selon cette conception, il n'y aurait pas eu de véritable droit de propriété mais seulement une sorte d'usufruit, ce droit serait essentiellement collectif, et son titulaire serait la Terre ellemême, en tant que divinité. L'auteur soutient au contraire qu'il existait un véritable droit de propriété en Afrique, mais qu'il ne portait pas sur la même chose qu'en Occident: en Afrique, seule la terre cultivée était susceptible d'appropriation. /// The example of precolonial Africa is used to criticize the classical conception of land rights in traditional societies. Under this conception, there were no real ownership rights but only a sort of usufruct, which was essentially collective, the holder of rights being Earth itself as a divinity. On the contrary, property rights did exist in Africa, but they did not have the same scope as in Europe. In Africa, only cultivated land could be owned.
We analysed pollen and charcoal in a lake-sediment core from Laguna Zoncho, a small mid-elevation lake in southernmost Costa Rica. The record provides evidence of 3000 years of human occupation, forest clearance, agriculture and fires in the area. Laguna Zoncho is located 2 km from the Las Cruces Biological Station, and results are relevant to understanding the likely extent of prehistoric disturbance within the premon tane rain forests of this biological reserve. Pollen grains ofZea mays in the basal sediments of the Zoncho core constitute the oldest botanical evidence of maize cultivation in southern Costa Rica. The presence of maize pollen in almost every sample analysed indicates nearly continuous occupation of the lake basin for 3000 years. Charcoal abundances and percentages of pollen grains and spores of forest and disturbance taxa fluctuate strongly downcore, reflecting variable intensities of past human impact. Forest clearance and burning by indigenous people were most marked between 3240 and 460 cal. yr BP. Sediments deposited subsequently indicate forest regeneration and few, if any, fires. However, indigenous cultivation of maize continued on a small scale until European settlement in the twentieth century.
In the West African semiarid belt of the Sahel, for the second half of the XXth century, lasting droughts (1970s–1980s) and one of the World's highest population growths have resulted in major land cover and hydrological changes that can be quantified using aerial photographs. This paper aims to provide one of the longest combined observations of land cover and hydrological changes for semiarid areas using a time series of normalised mosaics of aerial photographs dating back from 1950, field inquiries, and updated groundwater data. The 500 km2 study area in southwest Niger was chosen (i) for its rural environment representative of the rain-fed agriculture belt of the Sahel and (ii) to encompass the main hydrological study sites investigated in this region over the past two decades (Hapex-Sahel and AMMA experiments, 1990–2000s). Results have significant implications for future freshwater availability and food security in the Sahel.
Works of conservation of water and grounds and sorghum output in the Northern Center of Burkina FasoFace to the degradation of their vital spaces, the populations of Burkina Faso in general, area of Dem in particular became aware of the need for damming up the plague. They have, only or with the support of techniques of the State, the projects and ONG, undertaken work of conservation of water and grounds as well as the agroforestery. After more than two decades of practices, the agrarian landscape of the area of Dem still presents non made-up sectors; those arranged are it by various techniques: stony cords, cords of Andropogon gayanus, mulching, zaï. During the crop year 2002, measurements were taken on the growth and the output of the sorghum according to installations carried out. All the fields were selected on bottom glacis. The results obtained make it possible to affirm that the techniques of conservation of water and the grounds practised in the area of Dem are beneficial for the cultures and leaving for the populations. Indeed, the outputs are better with the practice of the zaï (1,730 t/ha), because this technique combines fertilization of the ground by contribution of compost or manure and conservation of moisture for one longer period after each rain. Even the mulching which, among the various techniques applied, gives the results low (0,77 t/ha), offers outputs six times higher than those of the pieces without installation (0,12 t/ha) on bottom glacis. The positive impact of the techniques of conservation of water and the grounds on the output of the sorghum shows the possibility to increase in the agricultural production, for little that the populations are sensitised and that these techniques are improved for a broad diffusion near the peasants exploiting the same types of grounds and under the same climate.
Bulletin de la Société Préhistorique Française
- M Ould Khattar
- D Grebenart
- R Vernet
OULD KHATTAR, M.; GREBENART, D.; VERNET,
R. (1994) -Les parcellaires préhistoriques du Tagant
(Mauritanie), Bulletin de la Société Préhistorique
Française, 91: 6, p. 457-458.