Indicateurs anthropogènes de la végétation et des sols de quelques savanes de l’Afrique de l’Ouest

Pomel, Simon; Pomel-Rigaud, Françoise; Schulz, E

doi:10.4000/books.pub.10088

Cited by 10 publications

(3 citation statements)

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“…Either it is a tool to clear land for new fields -few areas where fallow -either shifting cultivation is still practised or it is used for cleaning or sanitary purposes [63][64][65][66]. The Sahel is a savanna region and climatically it is influenced by tropical summer rains (monsoon) with a gradient from about 800 to 150/ 200 mm/y and with a rainy season of 3-5 months.…”

Section: The Sahel and Its Savannasmentioning

confidence: 99%

Vegetation Dynamics. Natural versus Cultural and the Regeneration Potential. The Example of Sahara-Sahel

Schulz¹,

Adamou²,

Ibrahim³

et al. 2020

Plant Communities and Their Environment

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There is a principal and controversial debate on the so-called 'Greening-Regreening' of the Sahel. There still is the old philosophy of an expanding/shrinking ecosystem Sahara versus Sahel. In some concepts, it is presented as annual. Another concept is based on a general degradation of the Sahelian savannas-in some cases with a decline to a lower state of ecological equilibrium after a short period of resilience. Anyhow, there are also signs of still ongoing regeneration processes of vegetation and soil. The main problem, however, lies in the principal lack of terrestrial observation and in the confusion of terms. This mostly concern on vegetation units and their dynamics. The goal of this article is to explain the general nature of the Sahara and the Sahel based on maps and graphs. We try to analyse the dynamics of boundaries during the last 200 years. The main results are the tripartite nature of the Sahara, divided into semidesert, desert and Saharan savanna with relatively stable boundaries. A reconstruction of the vegetation for the last 200 years confirmed the position of these borderlines even under different states of the plant cover. It also revealed the nature of Sahelian savannas as cultural landscapes-in higher diversity and density. It is also possible that the North Sahelian savannas had been for long times under the dynamics of elephant landscapes. A high-resolution sediment and pollen record from the Middle Sahel of Niger evidenced the high diversity and resilience up to the severe drought of the 1970s. It was a definite stroke from which these savannas never reached again their former diversity despite a slide recovery named 'Regreening'. The various projects for regeneration or conservation in Sahara or Sahel differ in two types of projects. The one is the installation of Nature Reserves/National Parks with special reserves for emblematic animals as keystone organisms and an auto-regeneration of vegetation and soil. The other type consists of pasture rotation projects such as in the Malian Gourma or in the Central Air Mts. The first initiative resulted in the decade-long protection against the severe degradations, which were typical for the surrounding regions. The rotation system was based on timewise open wells and of observed pasture status. It was conceived together with the local populations and has been respected until the invasion of northern cattle keepers during the peak of drought in 1984. After severe quarrels, the system collapsed and the savannas degraded heavily. A comparable project worked in the central Air Mts. for 5 years. Remarkable results have been, but the Vegetation-Natural and Cultivated Vegetation in a Changing World 2 rebellion of the 1990s, put a sudden end on it. The general insecurity of the last decades caused by civil war and/or various terrrorist groups led to a re-evaluation of a great number of regeneration initiatives including the pharaonic 'Great Green Wall' , a continent wide forest belt. However, smaller projects on the village level may better develop as ...

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Section: The Sahel and Its Savannasmentioning

confidence: 99%

Vegetation Dynamics. Natural versus Cultural and the Regeneration Potential. The Example of Sahara-Sahel

Schulz¹,

Adamou²,

Ibrahim³

et al. 2020

Plant Communities and Their Environment

Self Cite

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“…Pour qui circule entre Sahel et Soudan, du Sénégal au Tchad et du Mali à la Côte d'Ivoire ou au Bénin, la savane est un paysage ordinaire qui frappe à la fois par une certaine homogénéité d'ensemble et une grande diversité des faciès et qui résiste souvent à toute tentative de schématisation trop simplificatrice. Il a aussi été souligné par Pomel et al (1994) la relative déconnexion entre la zonalité climatique assez simple qui caractérise l'Afrique de l'Ouest et ses grands domaines biogéographiques (figure 1), d'une part, et la grande variété des paysages végétaux eux-mêmes qui montrent, audelà de leurs seules composantes floristiques, une multitude de particularités aux échelles locales et régionales, d'autre part. Ainsi, dans le contexte structurant des zones bioclimatiques sahélienne et soudanienne, avec leurs contraintes biophysiques et leurs spécificités floristiques, ce sont bien les sociétés humaines, avec leurs pratiques et leurs caractéristiques socioéconomiques, techniques ou culturelles qui façonnent, de façon continue, les paysages et déterminent leur singularité.…”

Section: Un Paysage « Ordinairement » Construitunclassified

“…15 À l'échelle continentale de l'Afrique et à celle du temps très long du Quaternaire, l'histoire des feux est documentée à travers les carottages marins profonds (Bird et Cali, 1998 ;Dupont et Schefuß, 2018 Pomel et al (1994), les feux seraient un facteur essentiel dans la « construction anthropogène » du Sahel, en tant que zone de végétation au cours de l'Holocène.…”

Section: Un Facteur Capital : Le Feuunclassified

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Ballouche¹

2019

paysage

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Comparative Regional Geography in India and West Africa: Soils, Landforms and Economic Theory in Agricultural Development Strategies

Gunnell¹

1997

The Geographical Journal

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Indicateurs anthropogènes de la végétation et des sols de quelques savanes de l’Afrique de l’Ouest

Cited by 10 publications

References 14 publications

Vegetation Dynamics. Natural versus Cultural and the Regeneration Potential. The Example of Sahara-Sahel

Vegetation Dynamics. Natural versus Cultural and the Regeneration Potential. The Example of Sahara-Sahel

Ordinaires, dégradés ou patrimoniaux ?

Comparative Regional Geography in India and West Africa: Soils, Landforms and Economic Theory in Agricultural Development Strategies

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