An impulsive modelling framework of fire occurrence in a size-structured model of tree-grass interactions for savanna ecosystems

被引:15
作者
Yatat, V. [1 ,2 ,3 ]
Couteron, P. [4 ,5 ]
Tewa, J. J. [1 ,2 ,3 ]
Bowong, S. [2 ,3 ,6 ]
Dumont, Y. [7 ]
机构
[1] Univ Yaounde I, LIRIMA, GRIMCAPE Team, Yaounde, Cameroon
[2] Univ Yaounde I, African Ctr Excellence Informat & Commun Technol, Yaounde, Cameroon
[3] IRD France Nord, IRD, UMI 209, UMMISCO, F-93143 Bondy, France
[4] IRD, UMR AMAP, Montpellier, France
[5] Univ Yaounde I, Higher Teachers Training Coll, Plant Systemat & Ecol Lab, Yaounde, Cameroon
[6] Univ Douala, LIRIMA, GRIMCAPE Team, Douala, Cameroon
[7] CIRAD, UMR AMAP, Montpellier, France
关键词
Savanna; Fire; Asymmetric competition; Impulsive differential equation; Qualitative analysis; Nonstandard finite difference scheme; FINITE-DIFFERENCE SCHEMES; WOODY VEGETATION STRUCTURE; SEMIARID SAVANNA; SPATIAL-ORGANIZATION; AFRICAN SAVANNA; SOIL-WATER; DYNAMICS; COVER; COEXISTENCE; COMPETITION;
D O I
10.1007/s00285-016-1060-y
中图分类号
Q [生物科学];
学科分类号
07 ; 0710 ; 09 ;
摘要
Fires and mean annual rainfall are major factors that regulate woody and grassy biomasses in savanna ecosystems. Within the savanna biome, conditions of long-lasting coexistence of trees and grasses have been often studied using continuous-time modelling of tree-grass competition. In these studies, fire is a time-continuous forcing while the relationship between woody plant size and fire-sensitivity is not systematically considered. In this paper, we propose a new mathematical framework to model tree-grass interactions that takes into account both the impulsive nature of fire occurrence and size-dependent fire sensitivity (via two classes of woody plants). We carry out a qualitative analysis that highlights ecological thresholds and bifurcation parameters that shape the dynamics of the savanna-like systems within the main ecological zones. Through a qualitative analysis, we show that the impulsive modelling of fire occurrences leads to more diverse behaviors including cases of grassland, savanna and forest tristability and a more realistic array of solutions than the analogous time-continuous fire models. Numerical simulations are carried out with respect to the three main ecological contexts (moist, mesic, semi-arid) to illustrate the theoretical results and to support a discussion about the bifurcation parameters and the advantages of the model.
引用
收藏
页码:1425 / 1482
页数:58
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