Analysis On Land Use Transformation And Landscape Fragmentation Of “Ecological-productive-living” In The Yellow River Delta

The Yellow River Delta(YRD)is the youngest growing land and have abundant land reserve resources in China.Since the large-scale agricultural reclamation and the exploitation of oil and gas in the 1950 s and 1960 s,the land use structure has formed into production land dominantly.In the past 20 years,the area of production and living land has been increasing,while the area of ecological land has been decreasing in the study area.The regional land use types have undergone profound transformation,and the landscape pattern has also show a trend of fragmentation.In September 2019,general secretary Xi Jinping convened a meeting in Zhengzhou to make the ecological protection and high-quality development of the YRD a major national strategy.The YRD also entered a new era of “largescale protection,largescale governance and high-quality development”.Therefore,the analysis of the process and characteristics of land use transformation of “ecological-productive-living” and discuss the phenomenon and driving factors of regional landscape fragmentation in the YRD.On the one hand,will enrich the theoretical and practical system for “ecological-productive-living” space;on the other hand,it can also provide a reference for the follow-up land space development,management and optimal allocation.In this study,we used 1998,2008,2018 three periods of Landsat remote sensing imagines combined with object-oriented and visual interpretation to obtain land use data.The method such land use dynamic degree,the land use transformation TUPU and center of gravity transformation were used to analyze the quantitative change of the temporal and spatial characteristics of the transformation process and the transformation maps of the "Sansheng" land from 1998 to 2018.Secondly,from the landscape level and type level select appropriate landscape index and use the methods and models of sensitivity analysis,moving window method and semi coefficient of variation to determine the optimum spatial granularity and extent of landscape fragmentation in the YRD.Finally,spatial autocorrelation index is used to analyze the temporal and spatial variation of landscape fragmentation in the study area and principal component analysis is used to construce landscape fragmentation index in the study area.In addition,geo-detector model is used to distinguish the indicator factors of spatial differentiation of landscape fragmentation.The main research results are as follows:(1)In general,the land structure of “ecological-productive-living” in the study area is dominated by production land,supplemented by ecological land and followed by living land.The areas of production land and living land are increasing,but mainly for the production land.Meanwhile,the area of ecological land is decreasing.From 1998 to 2018,the area of production land in the YRD is increasing,and its distribution scope is gradually expanding to the coastal;the area of ecological land is rapidly decreasing,and the distribution scope is reduced to the estuary of the current channel and the old channel of the Yellow River;the area of domestic land is increasing slightly.The transformation TUPU of land for “ecological-productive-living” was mainly from ecological land to production land.During the study time,the total transformation area of “ecological-productive-living” land was reduced by 561.81 km2,and the transformation process was more complex.The proportion of all transformation types was less than 10%,and no transformation type occupies absolute predominance.(2)The response of landscape index with high sensitivity and extremely high sensitivity to grain size change was analyzed from landscape level and type level.The suitable grain size range was 50 m?140 m at landscape level and 60 m?80 m at patch type level.In order to minimize the information loss of grid data,the optimal spatial granularity of landscape fragmentation analysis is 60 m and the optimal analysis range is 1200 m.(3)There was significant positive correlation among the spatial aggregation effects of spread degree,Shannon diversity,separation degree,patch density and aggregation index in the three periods.Through the analysis of the comprehensive index of landscape fragmentation obtained by using the principal component analysis method,it can be seen that: in 1998,the degree of landscape fragmentation in the south of the Yellow River and the north of the main urban area of Dongying City was relatively high.In 2008,the distribution of region with high degree of landscape fragmentation expanded from the south to the north of the Yellow River,and mainly distributed on both sides of several major rivers.In 2018,the area with high degree of landscape fragmentation was fragmented and dispersed,and the distribution scope was further expanded.(4)According to the calculation of geodetector,the indicator factors of spatial differentiation of landscape fragmentation were distance from coastline,distance from main rivers,microgeomorphic types,channel density,altitude and distance from cities and towns in the study area in1998.In 2008,the main indicator factors were industrial and agricultural output value,channel density,road density,average GDP and population density.In 2018,the main indicator factors were micro-geomorphic types,distance from coastline,distance from towns,soil type and population density.With the change of time,the combination of the main indicator factors is different,from the initial location condition factor and natural environment factor to the location condition factor and socio-economic factor,and finally to the comprehensive effect of local factors,natural environment and socio-economic factor.