| The change of landscape pattern affects the regional ecological environment and plays an important role in improving the ecological environment and ecological restoration.The decrease of river water,insufficient vegetation coverage,riverbed desertification and human land contradiction in Yongding River Basin have a profound impact on the change of landscape pattern.Based on this,it is of great significance to study the landscape pattern change and driving force in Yongding River Basin.In order to reveal the characteristics of landscape pattern change and its driving factors in Yongding River Basin,seven Landsat remote sensing images of Yongding River Basin in 1980,1995,2000,2005,2010,2015 and 2020 were used as the main data source,combined with GIS and Fragstats 4.2 and other software to quantitatively describe the dynamic change characteristics of landscape pattern in Yongding River Basin and 18 River corridors within 2 km in recent 40 years,select socio-economic factors and natural environmental factors,analyzed the driving force of landscape change in Yongding River Basin in recent 40 years by using principal component analysis method,and identified the location of high fragmentation of river corridors at this stage.The main results are as follows:(1)The land use in Yongding River Basin has always been dominated by agricultural,forest and grass land,accounting for an average of 91.12%.The dynamic degree of comprehensive land use was the largest from 2015 to 2020,accounting for 0.46%.The land use types of the corridors of the main tributaries of Sanggan River and Yanghe River were mainly agriculture,forestry and grassland,accounting for an average of 85.78%.The peak value of comprehensive utilization dynamics was concentrated in 2010～2020,with the maximum of 2.23%;The main stream corridor of Yanghe River was mainly agricultural land,accounting for an average of 60.15%.The dynamic degree of land use was the largest from 1980 to 1995,which was 0.62%;The corridors of the main and tributaries of Yongding River were dominated by agriculture,forestry and grassland only in the first section of Yongding River,accounting for an average of 82.64%.Other river sections are dominated by agriculture and construction land,accounting for an average of 74.70%.The dynamic degree of comprehensive utilization was the maximum from 2010 to 2020,accounting for 2.53%;(2)The overall landscape fragmentation of Yongding River Basin increased,the LPI decreased from 7.17%to 6.67%,the CONTAG decreased from 60.47%to 55.86%,the IJI increased from 57.90%to 66.33%,the SHDI increased from 1.29 to 1.35,and the SHEI increased from 0.67 to 0.75.The landscape heterogeneity increased,the landscape structure tends to be complex,and the degree of ductility and agglomeration decreased.The landscape fragmentation of the main tributaries of Sanggan River increased in Huihe River and Yuanzi River sections,decreased in Hunhe River section,increased first and then decreased in Sanggan River section(Ⅰ),and the inflection point was 2015,and decreased first and then increased in other river sections,and the inflection point was 2010;The landscape fragmentation of Yanghe trunk and tributaries first decreased and then increased in Dongyang River,Yanghe River and Qingshui River,and the inflection point was 2010,while that of Xiyang River and Nanyang River decreased first,then increased and then decreased,and the inflection points were 2010 and 2015 respectively;The landscape fragmentation of the main and tributaries of Yongding River first decreased and then increased,and the inflection point was 2010;(3)Principal component analysis shows that the main influencing factors of landscape pattern change were per capita GDP,GDP,tertiary industry,secondary industry and primary industry.Among them,GDP growth was mainly affected by industry,social consumer goods trading,import and export trade and tourism output value.Social and economic development was the main driving force of landscape pattern change;(4)Based on the standardization of grid data of 18 River corridors in Yongding River Basin in 2020,the grid data with standard deviation greater than 1.5 was extracted for visualization,and the high fragmentation location was identified.It is identified that the high fragmentation locations of Sanggan River and its tributaries,Yanghe River and its tributaries,Yongding River and Yongding New River are mainly concentrated in large villages and towns.In conclution,the main land use types in Yongding River Basin were agriculture,forest and grassland.In recent years,the comprehensive land use dynamics and landscape fragmentation have increased,and socio-economic development was the main driving force of landscape pattern change.Most of the high fragmentation locations of river corridors were large villages and towns.The analysis of landscape pattern change characteristics and driving forces in Yongding River Basin can provide a theoretical basis for regional ecological environment improvement and ecological restoration. |
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