| The comprehensive effect of multi-source factors changes the landscape structure and reduces the quality of landscape ecology in large-scale opencast coal mine area,resulting in an ecologically fragile environment.In the study,based on the Landsat remote sensing images of1986,1996,2000,2009,and 2015 in the Pingshuo opencast coal mine area of the Loess plateau in Shanxi Province of China,combined with land use data,the landscape pattern of Pingshuo opencast coal mine area was analyzed from the level of landscape and patch type.The landscape loss index and ecological sensitivity index were selected to analyze the spatial and temporal characteristics of the landscape ecological risk.Considering the impact of landscape ecological quality on ecological resistance,the Minimum Cumulative Resistance model(MCR)was applied to build a landscape ecological network based on the results of landscape ecological risk assessment in 2015,and the complex network method was used to analyze the structure of landscape ecological network.The following conclusions were initially obtained:(1)The main land use types of Pingshuo opencast coal mine area were cultivated land and grassland.During the study period,the area of mining land,grassland,and cultivated land fluctuated the most.The area of forest land and grassland showed a downward trend.The area of urban construction land,rural settlement areas,mining land and industrial land increased.The distribution of cultivated land,forest land,and grassland changed from aggregation to dispersion,and the degree of fragmentation decreased from increase to decrease.Due to the increased interference from human activities,the aggregation of patches has been weakened,the degree of patch type mixing has increased,the degree of irregularity of cultivated land and forest land has increased,and the land shape of cultivated,forest,grass,and transportation land has become more complex.The landscape of industrial and mining land and urban construction land was in a dispersed state,and the form of rural settlement areas tended to be complex,and the connectivity of patches in various landscapes was good.During the study period,the landscape in the study area developed diversified.The patch types in the landscape were evenly distributed in space,and there were no obvious dominant types.(2)There were significant spatial differences in landscape ecological risk in the study area.High-risk areas showed a trend of spreading from southwest to northeast,mainly distributed in peripheral areas of urban construction land and mining land.The rapid expansion of mining land and urban land has increased the fragmentation of the landscape types around the mining land.Low-risk areas were mainly distributed in the west and southeast of the study area,where a large number of forest land and grassland were gathered and distributed.From 1986 to 2015,45% of the areas in the study area had a higher risk level,and 28% of the areas had a lower risk level.Among them,the area of high-risk areas showed an increasing trend,from 1.02% to 16.35%,the average risk rose from 0.46 to 0.50,and the risk value showed a gradually increasing trend.The risk changes in the study area were mainly affected by the scale of mining,urban expansion,grain for green,land reclamation and village relocation.(3)Taking the landscape ecological risk as the resistance factor,using the MCR model to optimize the landscape ecological network to improve its relevance,integrity and stability,and13 potential ecological corridors and 26 ecological nodes have been constructed for specific land protection.Through the complex network method,the landscape ecological network structure was evaluated,the patency of energy flow was improved,the relationship between nodes was strengthened,and the ecological elements of land special protection were determined.The research results provide a scientific basis for the optimization of the landscape pattern and the construction of ecological safety pattern in Pingshuo opencast coal mine area. |
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