Modelling fires as pulses in tree/grass interactions: study of long-term impact in forest-savanna dynamical systems
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]. 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. (Texte intégral)
| Main Authors: | , , , , |
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| Format: | article biblioteca |
| Language: | eng |
| Subjects: | U10 - Informatique, mathématiques et statistiques, K01 - Foresterie - Considérations générales, F40 - Écologie végétale, savane, forêt tropicale, incendie de forêt, herbage, arbre d'ombrage, compétition biologique, dynamique des populations, modèle mathématique, méthode statistique, http://aims.fao.org/aos/agrovoc/c_6825, http://aims.fao.org/aos/agrovoc/c_24904, http://aims.fao.org/aos/agrovoc/c_3045, http://aims.fao.org/aos/agrovoc/c_3366, http://aims.fao.org/aos/agrovoc/c_25548, http://aims.fao.org/aos/agrovoc/c_917, http://aims.fao.org/aos/agrovoc/c_6111, http://aims.fao.org/aos/agrovoc/c_24199, http://aims.fao.org/aos/agrovoc/c_7377, http://aims.fao.org/aos/agrovoc/c_1432, |
| Online Access: | http://agritrop.cirad.fr/577590/ http://agritrop.cirad.fr/577590/1/475-2808-1-PB.pdf |
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