Landscape Pattern Analysis And Ecological Vulnerability Assessment Of Longxi-Hongkou Nature Reserve Based On GIS And RS

Longxi-Hongkou National Nature Reserve of Sichuan Province is located in the transition zone from the Chengdu Plain to the northwestern Sichuan Plateau Canyon.It is an ecological barrier in the upper reaches of the Yangtze River.The animal and plant resources in the area are very rich,which plays an important role in maintaining the safety of biodiversity in the surrounding and even the southwest.Due to the impact of geological disasters,especially the strong disturbance of the Wenchuan earthquake in 2008,the vegetation was severely damaged,the forest landscape was significantly degraded,and the ecological functions of the protected area could not be fully utilized.Ecological security and sustainable development.Taking the system coupling theory of geography,landscape ecology and environmental science as interdisciplinary theory as the theoretical basis,the Longxi-Hongkou National Nature Reserve,a typical representative of the southwest mountainous area,was selected as the research area,and the field survey method and literature research were adopted.Method,landscape index method,mathematical model analysis method,spatial analysis method and other research methods,based on geospatial information technology such as RS and GIS,with the remote sensing data in 1998,2008 and 2017 as the main data source,and landscape pattern analysis And ecological vulnerability assessment as the focus,through studying the dynamic evolution of landscape pattern,evaluating its ecological vulnerability based on the landscape pattern,clarifying the succession laws of landscape patterns in natural reserves before and after external disturbance,and revealing the factors and driving mechanisms that affect the change of ecological vulnerability,Propose and demonstrate protection and management measures for regions with different ecological vulnerability levels,with a view to providing scientific and technological reference for the ecological environment governance of similar nature reserves.(1)The landscape pattern of Longkou Hongkou Nature Reserve changes drastically.The overall performance is landscape fragmentation,increased heterogeneity,and complex shapes.The dominant landscapes in the three periods were basically forests represented by broad-leaved forests and coniferous forests.Due to the impact of the Wenchuan earthquake in 2008,secondary geological disasters such as mountain collapses,landslides,and debris flows occurred in large areas and large areas in the study area.With the change of structure and function,the change of regional landscape pattern generally shows that the reciprocal of the fractal dimension decreases,the degree of interference from the outside decreases,the degree of fragmentation and separation increases slightly,the degree of fragmentation of the landscape increases slightly,and the diversity of Shannon The increase in the index and spread indicates that the landscape utilization rate increases,heterogeneity increases,and connectivity decreases.The main reason is the change in the natural environment.Earthquakes and secondary disasters such as landslides and debris flows are key factors in the evolution of landscape patterns.(2)Based on the nature reserves of atypical ecological fragile areas,landscape patterns and ecological fragility are highly coupled,and it is feasible to evaluate ecological fragility using landscape pattern analysis.Using the mathematical model analysis method as the analysis method of ecological vulnerability assessment,through landscape index analysis,it was found that the nature reserve has damaged vegetation,decreased ecosystem function,increased risk of loss of animal and plant habitats,decreased biodiversity,unbalanced ecosystem structure,and environmental resilience Weakened,taking two typical protected animals such as giant panda and Sichuan snub-nosed monkey as examples,analyzed the impact of landscape pattern evolution on habitat;using fractal reciprocal,topographic index,maximum patch index,connectivity,fragmentation,separation,By combining the seven landscape pattern indexes,such as patch density,by constructing the SRP model and using the entropy weight method to determine the weights,the landscape pattern index and the important interference factors that affect vulnerability can be combined to comprehensively and objectively evaluate the ecological vulnerability of the study area Can reveal the trend and driving mechanism of ecological vulnerability in nature reserves.(3)The spatial and temporal differences in landscape types and regional ecological vulnerabilities in Longxi-Hongkou Nature Reserve are obvious.Shrubs,unused land,grasslands,waters and other landscape types have a high degree of vulnerability,and coniferous forests and broad-leaved forests have a low vulnerability.The pressure to prevent major risks of the ecosystem is still severe.Changes in the natural environment are ecologically fragile The basis of the formation of nature,geological disasters have increased the regional ecological vulnerability,the region is basically dominated by Grade I(0<RVI<0.2)and Grade II vulnerable areas(0.2<RVI<0.4),and Grade III vulnerable areas(0.4<RVI <0.6),Grade IV fragile areas(0.6<RVI<0.8),Grade V fragile areas(0.1<RVI<1)account for a small proportion.The areas with high ecological vulnerability are mainly concentrated in the north of the study area,and the areas with low ecological vulnerability are mainly distributed in the south and middle of the study area.As natural factors tend to stabilize,the ecological function will further improve.(4)Aiming at the problem of ecosystem degradation in Longxi-Hongkou Nature Reserve,combining landscape type ecological vulnerability index(CVI)and regional ecological vulnerability index(RVI),and taking Longxi-Hongkou Nature Reserve as an example,Policy recommendations on ecological restoration of different levels of ecologically fragile areas and management of nature reserves are put forward.Slightly(level ?)and mildly(level ?)vulnerable areas focus on natural restoration,and continue to implement key ecological projects such as natural forest protection and returning farmland to forests(grass);moderate(level ?)vulnerable areas to transform some shrubs Forest land or increase the use of planting structure combined with shrubs,shrubs and grasses;focus on the strength(level ?)and severe(level ?)vulnerable areas to explore and promote vegetation construction techniques such as water conservation forests and soil and water conservation forests,and strengthen disasters such as landslides and debris flows.Monitoring.At the same time,three suggestions were put forward to strengthen the protection of animal and plant resources,actively develop community co-management mechanisms,and increase environmental propaganda and education,in order to facilitate the adjustment and optimization of landscape patterns and reduce regional ecological vulnerability.