Succession des communautés végétales des jachères protégées en zone sahélienne: cas de Banizoumbou (Niger)

Abstract

Objective: The importance of disturbance (duration or intensity) seems decisive in determining the state of vegetation and successional dynamics. The purpose of this study is to study and examine variations in the floristic richness, diversity and production of protected fallow land in Banizoumbou. Methodology and Results: The phyto-sociological surveys were carried out according to the sigmatist method of Braun-Blanquet (1932). Sampling was carried out on the basis of land use types, so fallows and fields were inventoried following 6 transect, 1000 square meter equidistant plots of 500 m were set. A total of 33 surveys were carried out, including 18 in the fallows and 15 in the fields. Our findings show that diversity depends on the successional stage even within the same type of land use. Analysis of the indices shows that in addition to fallow land, fields are also important sources of biodiversity. Thus, Shannon's diversity index increases according to the fallow and field age, but this increase is much higher in the fallows in than the fields. The results reveal also that average density of the study area is 260 individuals per hectare, of which Guiera senegalensis represents more than 70%. The mean height, mean diameter, average density and highest average cover were observed at fallow land. Conclusion and Application of results: The present study showed that variation in plant diversity is a function of age at both field and fallow land. Thus diversity evolves more rapidly at fallow land.