Study On Land Ecological Security Assessment And Scenario Simulation Based On Landscape Structure Change

Scientific exploration of landscape structure change and its interaction with land ecological security is the scientific basis and important guarantee for promoting ecological protection and high-quality development in the Yellow River Delta.The study selects five phases of land use remote sensing monitoring data from 2000 to 2020,explores the dynamic change process of landscape composition and landscape pattern,analyzes the spatiotemporal differentiation characteristics of land ecological security under the change of landscape structure based on NES model,and uses Geo SOS-FLUS to simulate the landscape structure in 2025,and predicts the spatiotemporal evolution trend of land ecological security under multiple scenarios,On this basis,the corresponding optimization strategy is proposed based on the current conditions and prediction results.Research shows:(1)From 2000 to 2020,the landscape type of the Yellow River Delta was mainly cultivated land,accounting for more than 60% of the total area,forming the base of the landscape of the Yellow River Delta.The fragmentation of landscape pattern in the Yellow River Delta has weakened in the past 20 years,the degree of patch irregularity has gradually decreased,the aggregation and connectivity of the landscape has become higher and higher,and the dominant characteristics of the landscape change track are distinct.The transformation from cultivated land to construction land is the main,and the rate is 22.32%,which is distributed in all counties and districts of the Yellow River Delta,During the study period,accompanied by the mutual conversion of water wetland and construction land,such landscape changes are mainly distributed in Wudi County and Hanting District.(2)From 2000 to 2020,the LES index of the whole region showed a continuous upward trend,from 0.481 to 0.565,which was between the sensitive level(Grade III)and the good level(Grade IV).From the county level,the change process of the LES level in each county is from risk level(Level II)to safety level(Level V).From 2000 to 2015,there are many counties and districts in the sensitive level(Level III).In 2020,except Lijin County,Zouping City and Yangxin County,which are still in the sensitive level(Level III),most counties and districts have reached good level(Level IV),accounting for 73.68% of the total administrative units.The evolution of the spatial pattern of land ecological security from2000 to 2020 has a certain continuity and regularity.On the whole,it has evolved from "low in the north and high in the south" to "high in the east and low in the west".In 2000,the low value area was mainly distributed in the superjacent of the study area;In 2005,most regions changed from risk level(Level II)to sensitivity level(Level III),and the area of good level(Level IV)regions was also expanding,accounting for 13.52% of the total area;In 2010,the area of sensitive(Level III)and good(Level IV)areas continued to expand,accounting for71.86% and 21.49% of the total area.In 2015,the spatial distribution characteristics in the Yellow River Delta were clearly differentiated,and the area of the good grade(Level IV)region changed greatly,mainly distributed in Dongying District,Guangrao County,Boxing County,Changyi City,etc.in the east;In 2020,the level of LES in the western region has been significantly improved,and the spatial differences among counties and districts are gradually narrowing.(3)In 2025,the natural development scenario shows the trend of expansion of cultivated land,wetland to construction land,grassland.Under the cultivated land protection scenario,cultivated and unused land became more,and the change of cultivated land area was higher than the other three scenarios;In the economic development scenario,the construction land constantly encroaches on the cultivated land,grassland and other landscapes,which is not conducive to the construction of regional ecological security pattern;Under the ecological protection scenario,the proportion of ecological land area has increased,the expansion of construction land area has been effectively curbed,and the overall landscape structure has been optimized.The LES index of the whole Yellow River Delta is 0.580,0.618,0.611 and0.629 under the four scenarios.From the perspective of spatial distribution,the land ecological security under the four scenarios shows the characteristics.In addition to the natural development scenario,the security level(Level V)area accounts for the largest proportion in other scenarios.