Analysis on landscape pattern dynamics and driving force in Yongding River Basin from 1980 to 2020

In order to study the dynamic change law of landscape pattern in the basin with the cascade flow characteristics of plateau-mountain-plain-coastal ecological elements, 7 Landsat remote sensing images of Yongding River Basin from 1980 to 2020 were taken as the main data source, and the evolution characteristics of landscape pattern in Yongding River Basin in recent 40 years were analyzed by comprehensively using the methods of landscape area dynamic analysis, landscape pattern index and mathematical statistics, and its driving factors were revealed. The results showed that: 1) From 1980 to 2020, Yongding River Basin was dominated by cultivated, forest and grass land, accounting for about 90%. The area of cultivated land and grassland had decreased by 1376.38 and 463.42 km² respectively in the recent 40 years, the area of construction land and forest land had increased, and the dynamic degree of comprehensive land use had changed the most from 2015 to 2020. 2) At the type level, the fragmentation degree of construction land patches had decreased significantly, while the changes of other land types were not obvious. At the landscape level, Shannon Diversity Index (SHDI) and Shannon Evenness Index (SHEI) had increased from 1.29 to 1.35 and 0.67 to 0.75, respectively; the overall landscape structure tended to be complex, the heterogeneity had increased, the degree of agglomeration had decreased, and the landscape fragmentation had been intensified. 3) The change of watershed landscape pattern was affected by socio-economic factors, natural factors and policy factors, in which socio-economic development was the main driving force, and economic development and the change of urban and rural population structure were the main driving factors of landscape pattern change.