Spatial-Temporal Evolution and Pattern Characteristics of Green Infrastructure in the Pisha Sandstone Area of the Middle Reaches of the Yellow River Basin, China

The arsenic sandstone region constitutes one of the most severe soil erosion hotspots in the middle reaches of the Yellow River, China, where the soil and water conservation capacity is continuously deteriorating and landscape fragmentation is intensifying. Green infrastructure (GI), as a network system of green spaces, can effectively mitigate soil erosion and optimize regional landscape patterns. Based on land-use change data from 2003 to 2023, this study integrated Morphological Spatial Pattern Analysis (MSPA), landscape index method, and Minimum Cumulative Resistance (MCR) model to identify and analyze GI in the pisha sandstone region. The results revealed that: 1) The characteristics of land use type conversion exhibited distinct phased differences between 2003 and 2023. Prior to 2013, farmland was the primary outflow type, accompanied by a reduction in unused land and an expansion of forest land, water bodies, impervious surface, and grassland. After 2013, grassland became the dominant outflow type, with a decrease in water bodies and an increase in farmland, forest land, impervious surface, and unused land. 2) From 2003 to 2023, the total area of GI in the study region showed a trend of initial increase followed by decrease, maintaining a proportion between 84.66% and 87.70%. Spatially, it presented a pattern of aggregation in the northwest and sparseness in the southeast. 3) During the study period, the number of ecological source sites decreased from 20 to 14, the number of general ecological corridors reduced from 152 to 75, and the number of important ecological corridors declined from 38 to 16. 4) The network closure index (α index) decreased from 0.54 to 0.13, the line-point ratio (β index) dropped from 1.90 to 1.14, and the network connectivity index (γ index) fell from 0.70 to 0.44. The GI network structure exhibited a fragmented pattern characterized by local concentration and overall sparseness. This study focuses on the spatiotemporal evolution and pattern characteristics of GI in the special landform of pisha sandstone, providing a theoretical basis for territorial spatial planning, soil erosion control, and human habitat improvement in this region. It also offers new insights for research on ecological security and human habitat quality in special landform areas globally.