Research On Pattern Dynamics Of The Interaction Between Wind Erosion And Vegetation

In order to solve the deterioration prolem of ecological environment caused by erosion,scholars have introduced nonlinear methods into the field of erosional ecology.Aiming at the issue of the evolution of sand dune vegetation in arid or semi-arid areas,this thesis constructed a dynamic model based on the interactions between wind erosion and vegetation,explored the pattern formation and stability mechanism of the vegetation and sand dunes in wind-eroded areas,and discussed the complex dynamical behaviors of the wind erosion-vegetation system and the impact of system parameters changes on the system behavrios.The main research results are as follows:(1)By analyzing the complex interactions between vegetation and wind erosion,time-and space-continuous and discrete dynamic models were constructed.Through stability and Turing instability analysis,the coexistence states and pattern formation conditions of vegetation and wind erosion were determined.(2)It was found that the wind erosion-vegetation system can generate hot patterns in the Turing area and the Turing-Hopf area by analysis.The occurrence of hot pattern can correspond to the dune landform in natural wind-eroded area.The bifurcation analysis on the spatiotemporally discrete dynamic model showed that the vegetation and wind erosion may exhibit periodic and chaotic dynamic changes.(3)There are three equilibrium points in the wind erosion-vegetation system,revealing the existence of multiple stability for the coexistence of vegetation and eolian sand.The middle equilibrium point is always unstable,and the other two equilibrium points show three stability situations:both are stable equilibrium points,only one equilibrium point is stable,and both are unstable equilibrium points.The existence of multiple stability can exerts influence on the formation of erosion-vegetation patterns.(4)By changing the plant growth rate,the influence of non-uniform growth of plants on the formation of erosion-vegetation patterns was explored.Simultaneously,the destructive effects of extreme conditions on the erosion-vegetation patterns were simulated,and the effects of different temporal evolution scales of the sand dunes on the spatial patterns of the erosion-vegetation system were compared.Based on the wind erosion-vegetation dynamical model,this thesis exploreed the stability mechanism of vegetation and dunes in wind-eroded areas and the nonlinear mechanism of pattern formation,and discussed the influence of multi-stable structures on the formation of erosion-vegetation patterns.By considering the natural ecological processes,the influence of parameter changes on the wind erosion-vegetation system is quantitatively discussed,providing a theoretical basis for predicting the evolution of the ecosystem of vegetation in the wind-eroded area.