Horizon 1 1 17 ACLN : Articles dans des revues avec comité de lecture non répertoriées par l'AERES Biomath art. no 1404212 [18 ] SAVANE BOISEE FEU DE BROUSSE FONCTIONNEMENT DE L'ECOSYSTEME DYNAMIQUE DE VEGETATION MODELISATION ANALYSE QUALITATIVE ZONE TROPICALE AFRIQUE SUBSAHARIENNE 2014 fdi:010075322 ENG Biomath 1314-684X 10.11145/j.biomath.2014.04.212 https://www.documentation.ird.fr/hor/fdi:010075322 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/divers19-03/010075322.pdf 3 Horizon (IRD) Several continuous-time tree-grass competition models have been developed to study conditions of long-lasting coexistence of trees and grass in savanna ecosystems according to environmental parameters such as climate or fire regime. In those models, fire intensity is a fixed parameter while the relationship between woody plant size and fire-sensitivity is not systematically considered. In this paper, we propose a mathematical model for the tree-grass interaction that takes into account both fire intensity and size-dependent sensitivity. The fire intensity is modeled by an increasing function of grass biomass and fire return time is a function of climate. We carry out a qualitative analysis that highlights ecological thresholds that summarize the dynamics of the system. Finally, we develop a non-standard numerical scheme and present some simulations to illustrate our analytical results. 082VEGET01 ; 020MATH01