Study on the spatial and temporal evolution of land use in the Yellow River Delta based on optimal analysis grain size

In recent years, the Yellow River Delta wetland experienced significant degradation, posing severe threats to the regional landscape ecological environment. Identifying the optimal analysis grain size to the Yellow River Delta landscape patterns study can provide valuable support for ecological protection and high-quality development in this area. In this study, land use data of the Yellow River Delta in 1980a, 1990a, 2000a, 2010a and 2020a were selected. Landscape index grain size effect analysis and information loss evaluation were comprehensively applied, based on geographic information system software and Fragmentation Analysis, to explore the grain size and landscape pattern change characteristics of Yellow River Delta. The result show that: (1) 150–160 m is the appropriate grain size range for analyzing landscape indices in the Yellow River Delta, and 160 m as the optimal analysis grain size; (2) Over the past 40 years, cultivated land, aquaculture ponds, and construction land expanded, aquaculture ponds increased the most by 1212.98 km 2 , represented a growth rate of 16.24%. Meanwhile, grassland, coastal wetlands, salt pans, forest, and unused land showed a decreasing trend, grassland and salt pans decreased significantly by 991.43 km 2 and 1030.95 km 2 , respectively; (3) At the landscape type level, the LPI (Largest Patch Index) of cultivated land consistently remained above 20, indicating the dominant landscape type in the Yellow River Delta. The LPI of Aquaculture ponds increased by 8.15, gradually strengthening its dominant status. Construction land, inland water, and grassland became more concentrated, while forest landscapes became increasingly fragmented. At the overall landscape level, the SHDI (Shannon Diversity Index), SHEI (Shannon Evenness Index), and DIVISION indices showed a downward trend, indicating a slight increase in the aggregated distribution of various landscape types and a slight improvement in overall landscape connectivity in the Yellow River Delta. These findings provide guidance for ecological protection and land use in the Yellow River Delta.