Ecological security analysis using the landscape pattern of typical watershed in earthquake-affected areas:a case study of the Longxi River Basin
The frequent geological disasters in the mountainous areas of southwestern China cause crucial damage to regional landscape patterns,threatening regional ecological security.Exploring the spatial and temporal changes in landscape patterns in disturbed areas and conducting a quantitative analysis of ecological security can provide a theoretical basis for maintaining the ecological security of river basins.This study focused on the Longxi River Basin as the study area,targeting the worst-hit area of the Wenchuan earthquake.Utilizing phase 4 remote sensing image data and on-site investigation spanning from 2005 to 2015,the minimum cumulative resistance model was employed to identify the ecological source,construct the resistance surface,and classify the ecological security level based on resistance values.The landscape safety pattern was then constructed,and the mechanisms driving changes in landscape pattern was explored.The results showed the following:(1)From 2005 to 2015,the intensity of the influence of bare land,gullies,and geological disasters on Category 6 threatened landscapes within the watershed evolved.The influence of bare land on water area continued to increase,whereas the influence on the other five types of landscape decreased.Gullies exhibited exerted opposing influence on cultivated land,forest land,and irrigation compared with that on construction land,traffic land,and water area.Moreover,geological disasters had almost no effect on the water area and the other five types.(2)The overall ecological security of the basin exhibited a dynamic trend,initially experiencing a sharp decline from 71.01 before the earthquake to 28.60 one year after the earthquake.However,seven years post-earthquake,a notable recovery was observed,with the ecological security increasing from 56.77％recorded before the earthquake.(3)The watershed safety was classified into four levels based on the resistance values,progressing from large to small into low-safety areas(59.44％),low-medium safety areas(20.86％),high-medium safety areas(11.73％),and high-safety areas(7.99％).This shift signified an enhancement in the overall safety of the basin,particularly in the upstream,southwest,and southeast of the basin characterized by steep slopes and unstable surfaces.In conclusion,the changes in landscape patterns may have a large impact on the ecological security of the study area.The results of the ecological security analysis can provide a reference for ecological restoration and sustainable development of the watershed.
geological hazardLongxi River Basinlandscape patternlandscape ecological securityMCR model
NETL
NSTL
万方数据
