PASTORAL VALUES AND INTER-DECENNIAL PRODUCTIVITIES OF THE GOULBI N'KABA VALLEY IN NIGER

Objective : This study is conducted on the Goulbi N'Kaba Valley in Niger. The objective of this study is to determine the pastoral value and productivity of this area. Methodology : The methodological approach is focused on the sites of pastoral discharge sites and on two (2) transects (GB-GT and KH-DK), approximately 6.5 km long, running through the adjacent terraces (fields), the corridors of passage and the sylvo-pastoral zone (ZSP) of the valley. Phytosociological surveys based on abundance (number) and dominance (recovery) of species, and the harvest of phytomass were regularly made in plots of 2500 m². The quadratic points aligned method and the integral biomass harvest method were applied. Forage and pastoral values, productivities and load capacities were appreciated. Results : Forage values (legumes, graminoids, phorbes) of pastoral discharge sites in 2004 (16 ; 22 ; 51) are higher than those in 2014 (8 ; 10 ; 29). This trend is maintained at the level of adjacent terraces (with 24, 22, 63 in 2004 against 17 ; 12 ; 40 in 2014) and corridors of passage (with 22 ; 21 ; 60 in 2004 against 15 ; 15 ; 11 in 2014). Pastoral values (2004 and 2014) move in the same direction as forage values (2004 and 2014). The productivity of species under crown is greater than that of species outside crowns. The productivities of 2004 are higher than those of 2014 on pastoral discharge sites and corridors of passage. Nevertheless those of 2014 (1398.6 ± 444.5 kg MS / ha) are higher than those of 2004 (1127.8 ± 608.4 kg MS / ha) on the adjacent terraces of the Goulbi N’Kaba valley. The carrying capacity follows the same trend as productivity in the Goulbi N'Kaba valley, but with much smaller values. Conclusion : Pasture and pastoral values and productivities revealed the deterioration of rangelands of pastoral discharge sites, adjacent terraces and passage corridors in the Goulbi N'Kaba valley from 2004 to 2014.