[POS] Biomathematics

[POS-52] Nonlinear stability analysis of patterned vegetation in arid and semi-arid regions

*Guodong Sun¹ (1. Institute of Atmospheric Physics, Chinese Academy of Sciences (China))

Keywords:

A patterned vegetation,Abrupt change,Stability analysis

In arid and semi-arid regions, a patterned vegetation may be vulnerable and unstable. In this study, the stability of two types of patterned vegetation (spots and desert) due to the all physical parameters is explored by employing a mathematical theoretical model in the arid and semi-arid regions. To analyze the nonlinear characters of the stability about the patterned vegetation, an approach of conditional nonlinear optimal perturbation related to the parameter (CNOP-P) is applied. The numerical results show that the two types of patterned vegetation are unstable by the CNOP-P-type parameters perturbation, such as from the spots state to stripes state or a desert state, and from the desert state to spots state. There are different physical mechanisms about the abrupt changes of two types of patterned vegetation. Among all physical processes, the nonlinear transpiration term between vegetation biomass and soil moisture plays an important role in the transform of the spots state, while the nonlinear evaporation terms between vegetation biomass and soil moisture is the key physical process leading to the shift of the desert state. To further explore the role of seven physical parameters in the patterned vegetation shift, the sensitivity analysis (SA) method based on the CNOP-P is applied. It is shown that the sensitive parameters combination is different from parameters combination composed by the ranked higher by single parameter sensitivity. It is suggested that the nonlinear superposition effect of parameters is prominent factor to the shifts of the patterned vegetation.