La forte variation du regime des pluies au Sahel est reconnue par tous. La phenologie de la strate herbacee dominee par des plantes annuelles suit ce cycle annuel en faisant alterner une courte saison de croissance et une longue saison morte. Le Gourma situe dans la bande sahelienne au Mali est une zone pastorale soumise a cette variabilite temporelle des ressources pastorales (eau et fourrage) liee au regime de la mousson Ouest africaine, et aux fortes variations interannuelles de la pluviosite. Cette etude a pour objectif d’evaluer la sensibilite de la production de la strate herbacee aux variations de la distribution intra-saisonniere des pluies au Sahel a travers le cas du site pastoral d’Agoufou. Les simulations ont ete effectuees avec le modele STEP (Sahelian Transpiration Evaporation and Production model). Les analyses reposent sur de simples permutations des pluies journalieres enregistrees sur le site en 2010, realisees de facon aleatoire sans modifier le total saisonnier ni les cumuls journaliers. Les resultats montrent que la relation entre le cumul des pluies saisonnieres et les phytomasses herbacees mesurees en fin de saison masque des chutes de production intra-saisonniere liees aux stress hydriques, notamment au cours de la periode de croissance rapide qui affectent la production saisonniere. Le modele pourrait servir dans un systeme integre d’alertes precoces pour anticiper les penuries de fourrage frequentes dans cette region.Mots cles : Production primaire, strate herbacee, variation pluviometrique, stress hydrique, modele STEP. English Title: Sensitivity of herbaceous vegetation production to the variability of rainfall distribution in the Sahel (Agoufou, Mali): a modeling approachThe strong spatial and temporal variability of rainfall patterns in the Sahel is accepted by everybody. The phenology of the herbaceous layer dominated by annual plants follows this rhythm by alternating a short growing period with a long dormancy period. The Gourma region located in the Sahelian belt in Mali is a pastoral area subject to this temporal variability of resources (water and forage) linked to the rains regime. This study aims to assess the sensitivity of the herbaceous vegetation production to the variation of the intra-seasonal rainfall distribution in the Sahel through the case of the Agoufou rangeland site. The simulations were performed with the STEP model (Sahelian Transpiration Evaporation and Production model). The analyses were based on simple changes of rainfall height recorded on the site in 2010, carried out randomly without changing the seasonal total or the daily totals. The results show that the relationship between rainfall totals and the fall of the herbaceous mass conceal intra-seasonal production related to water stress especially during the period of so-called main growth can affect the seasonal production. The model could be used in an integrated early warning system to anticipate frequent forage shortages in this region.Keywords: Primary production, herbaceous layer, rainfall variation, water deficit, STEP model.
Sensibilité de la production herbacée aux aléas de la distribution des pluies au Sahel (Agoufou, Mali): une approche par modélisation
M. Diawara,P. Hiernaux,S. Sissoko,É. Mougin,A. Ba,Nogmana Soumaguel,Hawa Salif Diakité
Published 2020 in International Journal of Biological and Chemical Sciences
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2020
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International Journal of Biological and Chemical Sciences
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2020-08-17
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