Study On Landscape Pattern Change And Landscape Restoration Of Jiuzhaigou Scenic Spot After Earthquake

On August 8,2017,a 7.0-magnitude earthquake occurred in Jiuzhaigou,bringing huge property losses and casualties to the local area.Jiuzhaigou scenic spot,as a world-famous natural environment protection area,its ecological environment is also seriously damaged by the earthquake.Vegetation damage,soil erosion and other ecological environmental problems are aggravating.Therefore,the analysis and Research on the landscape pattern change,landscape restoration mode and measures of Jiuzhaigou scenic area is of great significance to the reasonable landscape restoration of the scenic area.In this paper,we obtained the Landsat 8 OLI remote sensing image data and DEM data of the research area in 2016-2019.On the basis of that,by means of GIS and RS technology,the landscape types are divided into five types:forest land,grassland,water,construction land and unused land.Using transfer matrix,landscape pattern index and other analysis methods,the change characteristics of the landscape pattern in the study area after the earthquake are analyzed to grasp the impact of the earthquake on the landscape of the scenic spot and the landscape restoration of scenic spots.Based on the vegetation coverage,this paper analyzes the impact of different slopes,altitudes and soil erosion sensitivities on landscape restoration,and proposes different landscape restoration models.Then,we selects typical disaster points in different models,and studies the landscape restoration measures in combination with their actual natural conditions and damage conditions.The main conclusions are as follows:The landscape pattern of Jiuzhaigou scenic spot changed greatly after the earthquake.From the perspective of landscape area change,water,grassland and other landscape types decrease in large area,and unused land increases.By 2019,although all kinds of landscapes have recovered,there is still large area damage,forest land area decreases by 19.59km~2,and water area decreases by 1.3km~2.From the perspective of landscape type transformation,from 2016 to 2019,the transformation between forest land,grassland and unused land is the most.From the perspective of landscape pattern index changes,after the earthquake,the number of patches in the study area increased,the degree of landscape fragmentation was high,the patch shape changed to irregular,the complexity of landscape structure increased,the overall landscape diversity decreased,and the landscape distribution was relatively scattered.By 2019,with the help of artificial restoration,the landscape damage has improved,but compared with that before the earthquake,the number and density of patches in forest land,grassland,water and construction land are still reduced,and the percentage and shape index of forest land and water body are still reduced.This paper analyzes the influencing factors of landscape restoration from the aspects of vegetation coverage,slope,altitude and soil erosion sensitivity,and finds that from 2016 to 2017,the vegetation coverage of different slope classification,altitude classification and soil erosion sensitivity classification has little change;but from 2017to 2018,the vegetation coverage of different classification has obvious decreases.However,in 2018-2019,with the help of natural and artificial restoration,the vegetation coverage of different grades has increased to a certain extent,and it is found that the slope between 30°and 50°,the altitude between 3000 m and 4000 m,and the low sensitivity area of soil erosion has obvious landscape restoration effect.Thus,the slope is classified into three categories of different slope level according to?30°,30°-50°,?50°.The altitude is classified into three categories of different altitude level according to?3000 m,3000 m-4000 m and?4000m respectively.Based on that,three different landscape restoration modes are proposed,including natural restoration,protective restoration and regulatory restoration.According to different landscape restoration modes and actual damage conditions,different landscape restoration measures are proposed.In the natural restoration area,natural restoration is adopted,and self-restoration is carried out by relying on the self-regulation ability of the environment.In the protective restoration area,protective restoration measures such as pulling protective net are taken to prevent more impact and recurrence of disasters on the environment.In the governance restoration area,the landscape restoration measures of passenger soil spray seeding and ecological bag protection were taken for the collapse damage,the landscape restoration measures of grid protection system and planting bag filling were taken for the landslide damage.In the debris flow damage area,we take different measures for different parts.In catchment area,we take closing hillsides to facilitate afforestation or replanting as measures.In form circulation area,we take hazard prevention as measures.In accumulation area,we take tree planting in micro garden as measures.Through a series of analysis and model measures,the landscape in the study area will be better restored,and this paper will provide theoretical guidance and technical support for the landscape restoration after the earthquake in other similar areas.