CARACTERISATION DES LIGNEUX SAHELIENS LE LONG DU FLEUVE LOGONE A BONGOR, TCHAD

In recent decades, Africa has experienced one of the strong variations in rainfall observed globally. The woody vegetation found along the banks of the Logon River on the outskirts of the town of Bongor is undergoing major changes due to climatic disturbance and human pressure. This study made it possible to characterize the floristic composition and the structure of this Sahelian plant formation. The experimental plan is a complete block of 6 treatments represented by the different village. In each village 5 plots were delimited and identified using stakes, i.e. total of 30 plots. The specific richness of the bank was evaluated through the floristic and dendrometric surveys and it shows 36 species divided into 20 families and 27 genera and dominated by Combretaceae and Caesalpiniaceae 11.11% each. The Nahaina (302 individuals/ha) and Sekie (299 individuals/ha) villages have a very high density compared to the Tchingofo (207 individuals/ha) and Zigui (223 individuals/ha) villages. The most represented phytogeographical types are the pantropical species in all the different growing environments 54% and the least represented are the cosmopolitan types 1%. This study presents all the species as accidental, the highest proportions of which are as follows: Balanites aegyptiaca (12.82%), Acacia hockii (11.83%) and Hyphaene thebaica (9.73%), Piliostigmareticulatum (9.53%) and Ziziphusmauritiana (8.28%).