Etudes des facteurs influant la dynamique du paysage dans le département de Ouallam (Niger)

Headnote

ABSTRACT: In Niger in general and particularly in the department of Ouallam located in the Northern part of the area of Tillabéri, the natural resources undergo since decades a thinning down without precedent under the influence of several factors. The aim had by this work is to characterize the factors responsible for this environmental pollution on a local scale. To this end, an investigation of perception coupled to observations into the ground was carried out into the aspects relating to the causes of the degradation of the grounds. The analysis of the causes of landscape degradation was categorized in climatic, physical and anthropic factors. The results raise that with a standardized index of pluviometry (ISP) varying from -2,54 to 2,24, precipitations constitute the principal climatic factor influencing environmental dynamics. In the physical plan, the units of the relief evolve in basins slopes where the degradation of the plates is reflected on the other components. The factors anthropic causing the dynamics of the local ecosystems are: extension and the overexploitation of the grounds, cut of wood, the clearing, overgrazing, exploitation of the fodder and the residues of the cultures. The surveyed people affirmed the regression of the vegetation and the progression of the naked grounds, respectively to 94,91 % and 38,43 % of the guarantors. According to the population, the progressive degradation of the environment is caused mainly by the anthropic exploitation and bad pluviometry, respectively 93,38 % and 66,91 % of the appreciations made by the guarantors.

KEYWORDS: Analyze, Causes, Changements, Ecosystemes, Niger west.

RESUME: Au Niger en général et particulierement dans le département de Ouallam situé dans la partie Nord de la région de Tillabéri, les ressources naturelles subissent depuis des décennies un amenuisement sans précédent sous l'influence de plusieurs facteurs. Le présent travail est entrepris afin de caractériser les facteurs responsables de la dynamique de l'environnement a l'échelle locale. A cet effet, une enquete de perception couplée a des observations de terrain a été réalisée sur les causes de la dégradation des terres. L'analyse de ces dernieres a été ainsi catégorisée en facteurs climatiques, physiques et anthropiques. Les résultats obtenus relevent qu'avec un indice standardisé de la pluviométrie (ISP) variant de -2,54 a 2,24, les précipitations constituent le principal facteur climatique influençant...