Study On Dynamic Mechanism Of Striped Vegetation Patterns Under Slope Erosion

Soil erosion is an important ecological process in ecosystems.The dynamic change of vegetation and erosion under long-term interactions is the frontier and hotspot of current research.Aiming at the process of soil erosion and plant growth in the sloped ecosystem,a dynamic model of vegetation-soil-surface water-soil water was constructed,and the dynamic mechanism of the banded vegetation pattern formation as well as the effect of vegetation stripes construction on the reduction of hydraulic erosion were studied.The following results are obtained:(1)On the basis of the vegetation patterns dynamic models of Klausmeier,Rietkerk et al.,Gilad,Saco et al.,a new differential dynamic model of vegetation-soil-surface water-soil water interaction was constructed by modifying the influence of topography on surface water diffusion and soil erosion.The stable equilibrium and Turing bifurcation conditions were calculated based on the model.(2)Under the Turing instability conditions,the vegetation patterns on natural slope were simulated.We quantitatively studied the effects of rainfall,sediment barrier rate by vegetation,slope gradient,vegetation mortality rate,maximum water absorption rate of vegetation on the wavelength,wave numeber,wave velocity,amplitude and vegetation coverage of vegetation patterns.(3)The regular vegetation stripes were constructed by simulating artificial planting,and the growth modes of artificial vegetation stripes on flat slopes and soil ridges were studied.It was found that the vegetation patterns had stability under the change of parameters,and the change of wavelength had a great impact on the patterns.(4)The perturbations of parameters-were used to study the stability of the banded vegetation patterns.It was found that the change of average daily rainfall rate can affect the wavelength of the patterns,but the change of vegetation mortality had little effect on the pattern wavelength.The different way of changing amplitude and frequency of parameters can affect the wavelength of vegetation patterns.When the parameter values change in a relatively gentle way,the pattern wavelength is positively correlated with the average daily rainfall rate.Based on the dynamic model of vegetation-soil-surface water-soil,the investigation in this thesis reveals the dynamic mechanism of the banded vegetation pattern formation on slope,and quantitatively determines the influence of natural and artificial ecosystem parameters on banded vegetation patterns,providing a theoretical basis for using constructing vegetation stripes to control hydraulic erosion on slopes.