Assessment of coastal landscape fragmentation and its driving factors based on optimal scale: A case study of the Yellow River Delta, China

Since the large-scale oil exploration and development in the 1960 s, the Yellow River Delta (YRD) has undergone rapid industrialization and urbanization. Concurrently, the regional landscape ecological structure has experienced significant changes, and the degree of landscape fragmentation has increased. Therefore, a comprehensive assessment of the spatiotemporal dynamics and formation mechanisms of landscape fragmentation is crucial for the protection and restoration of natural ecosystem in the YRD. This study constructs an evaluation index system for landscape fragmentation in the YRD from three perspectives: quantitative characteristics, shape features, and spatial distribution. By combining inflection point analysis, landscape area loss index, and geostatistical models, the optimal spatial scale of landscape fragmentation from 2000 to 2020 is determined. Additionally, the study analyzes the spatiotemporal changes in landscape fragmentation and employs the optimal parameters-based geographical detector (OPGD) model to reveal the formation mechanisms of spatial heterogeneity in landscape fragmentation. The study findings are as follows: (1) The optimal spatial resolution for analyzing landscape fragmentation in the YRD was 80 m, and the extent was 880 m. (2) Between 2000 and 2020, landscape fragmentation in the YRD increased, with the highest level recorded in 2020. Highly fragmented areas, particularly inland regions, expanded remarkably, whereas coastal areas experienced lower fragmentation levels. (3) Distance to rivers and ditch density were the primary factors affecting landscape fragmentation, followed by land-use type and average land gross domestic product. The influence of natural factors was relatively minimal. The interaction between factors had a greater influence on landscape fragmentation compared to individual factors. The distance to rivers and land-use type exhibited the most substantial enhancement effects following interaction with other factors. This study provides valuable insights into the spatiotemporal dynamics and mechanisms of landscape fragmentation in the YRD, providing valuable guidance for the sustainable management and ecological restoration of the region and other similar ecologically sensitive areas.