Modelling Fires as Pulses in Tree/Grass Interactions: Study of Long-term Impact in Forest-Savanna Dynamical Systems


  • Alexis Tchuinte Tamen* University of Yaoundé I
  • Yves Dumont CIRAD - Umr AMAP
  • Samuel Bowong University of Douala
  • Jean-Jules Tewa University of Yaoundé I
  • Pierre Couteron IRD - Umr AMAP



It is usually admitted that fires play an important role in tree-grass interactions in savanna ecosystems. In this talk, we present a model of tree-grass dynamics using impulsive differential equations, considering fires as discrete events [1]. This framework allows us to carry out a comprehensive qualitative mathematical analysis that revealed more possible outcomes than the analogous continuous model [2].В  We investigated local and global properties of the equilibria and show that various states may co-exist. Though fire periodicity may drive the system to different and abrupt shifts between vegetation, we also show that direct shading of grasses by trees, through a facilitation/competition parameter, is an influential process too, leading to bifurcations. Finally, using a suitable numerical approach [3], we carried out numerical simulations related to three main climatic zones, observable in Central Africa, to illustrate our theoretical results.

Author Biographies

Alexis Tchuinte Tamen*, University of Yaoundé I

Phd student, Laboratory of Applied Mathematics

Yves Dumont, CIRAD - Umr AMAP

Samuel Bowong, University of Douala

Jean-Jules Tewa, University of Yaoundé I

Pierre Couteron, IRD - Umr AMAP






Conference Contributions (Pretoria)