Far-from-equilibrium travelling pulses in sloped semi-arid environments driven by autotoxicity effects

TL;DR

This paper extends a model of semi-arid environments to include autotoxicity, analyzing travelling pulse solutions through numerical and analytical methods, and highlighting autotoxicity's role in vegetation patterns.

Contribution

It introduces an extended model with autotoxicity effects and rigorously proves the existence of travelling pulses using geometric singular perturbation theory.

Findings

Travelling pulses are confirmed both numerically and analytically.

Autotoxicity significantly influences vegetation pattern formation.

Good agreement between analytical solutions and numerical simulations.

Abstract

In this work, an extension of the 1D Klausmeier model that accounts for the toxicity compounds is considered and the occurrence of travelling stripes is investigated. Numerical simulations are firstly conducted to capture the qualitative behaviours of the pulse-type solutions and, then, geometric singular perturbation theory is used to prove the existence of such travelling pulses by constructing the corresponding homoclinic orbits in the associated 4-dimensional system. A scaling analysis on the investigated model is performed to identify the asymptotic scaling regime in which travelling pulses can be constructed. Biological observations are extracted from the analytical results and the role of autotoxicity in travelling patterns is emphasized. Finally, the analytically constructed solutions are compared with the numerical ones, leading to a good agreement that confirms the validity of the conducted analysis. Numerical investigations are also carried out in order to gain additional information on vegetation dynamics.