Sahelian rangelands provide most of the fodder grazed by livestock, first source of income of rural population. However grazing, together with droughts, is commonly accused to degrade vegetation, leading to desertification. Yet, monitoring rangeland sites in Mali, Niger and Senegal over several decades, including under AMMA-CATCH, confirmed the large sensitivity of the herbaceous production and species composition to rainfall vagaries. By comparing sites under contrasted grazing pressure, it revealed strong resilience to grazing unlike other arid ecosystems. Remote sensing found overall regreening since early 1980's (Dardel et al 2014) while livestock population increased steadily.
The main reason of resilience could be that the herbaceous vegetation is almost exclusively composed of short cycle annuals fitting the monomodal distribution of monsoon rainfall (Hiernaux Le Houérou, 2006). Herbaceous growth monitoring every 2 weeks indicated that at least 80% of the herbaceous production was achieved in 3 weeks (Hiernaux et al. 2015). This is very short time for livestock grazing year round to impact growth all the more than they are mobile and grazing behavior optimizes feed quality selection (Assouma et al. 2018 ). Moreover, grazing in the dry season limits livestock intake to a third, at most, of the herbaceous mass at the onset of the dry season (Diawara et al. 2018). Indeed livestock by trampling are transferring straws to litter and litter to the soil organic matter. Moreover livestock are returning to soil about half of the organic matter intake as feces, and larger fractions of minerals through feces and urine excretions (Hiernaux et al. 2014). Finally the impact of grazing and trampling on the transient soil seed stock is multidirectional depending on plant species but globally minor. The resilience only holds as far as the livestock system is pastoral and seasonally mobile adjusting grazing pressure to fodder availability. The settling and intensification based on feed inputs could question the resilience.
Assouma MH et al 2018. Livestock Science J.
Dardel C et al 2014. Rem. Sens. of Envir. 140: 350 364
Diawara MO et al 2018. Cah. Agric. 27: 15010.
Hiernaux P et al 2014. Afr. cont. 249 : 21 35.
Hiernaux P et al 2015. In Sultan B et al. IRD ed.: 171- 192
Hiernaux P Le Houérou HN 2006. Sèch. 17: 51-71
| Type : | : | oral |
| Langue du texte intégral | : | anglais |
| Commentaire | : | To fit with the 2000 character limit we summarized the references. The full references are as follows: Assouma M H, Lecomte P, Hiernaux P, Ickowicz A, Corniaux C, Decruyenaere V, Diarra A R, Vayssières J, 2018. How to better accont for livestock diversity and fodder seasonality in assessing the fodder intake of livesetock grazing semi-arid sub-Saharan Africa rangelands. Livestock Science J. (accepted). Dardel C., Kergoat L., Mougin E., Hiernaux P., Grippa M, Tucker C.J., 2014. Re-greening Sahel: 30 years of remote sensing data and field observations (Mali, Niger). Remote Sensing of Envir., 140: 350-364 Diawara MO, Hiernaux P, Mougin E, Grippa M, Delon C, Diakité HS, 2018. Effets de la pâture sur la dynamique de la végétation herbacée au Sahel (Gourma, Mali) : une approche par modélisation. Cah. Agric. 27: 15010. Hiernaux P., Diawara M.O. et F. Gangneron, 2014. Quelle accessibilité aux ressources pastorales du Sahel ? L'élevage face aux variations climatiques et aux évolutions des sociétés sahéliennes, Afrique contemporaine, n° 249, p. 21-35. Hiernaux P., Diawara M.O., Kergoat L., Mougin E., 2015. La contrainte fourragère des élevages pastoraux et agro-pastoraux du Sahel. Adaptations et perspectives. In Sultan B., Lalou R., Sanni M.A., Oumarou A., Soumaré M.A. (eds) Les sociétés rurales face aux changements climatiques et environnementaux en Afrique de l'Ouest. IRD editions, Marseille: 171- 192 Hiernaux P. and H.N. Le Houérou, 2006. Les parcours du Sahel. Sècheresse, 17(1-2) : 51-71 |
| Thématiques | : | Articulation avec les politiques de développement |
| Mots-Clés | : | Resilience ; livestock grazing ; pastoral ; sahel ; desertification |
| PDF version | : |  PDF version |
