Morphological dynamics and vegetation interactions in coastal dunes: UAV-based insights from Pingtan Island, China

Abstract

The interactions between vegetation and morphology on coastal dunes are essential for understanding and managing biogeomorphological processes. While these interactions have been studied at dune field or transect scales over weekly, annual, and decadal timescales, the coupling of individual dunes across several types at seasonal scales remains poorly understood. We selected nine coastal dunes of three types along Tannan Bay on Pingtan Island, China. Seasonal investigations combining unmanned aerial vehicle-based LiDAR monitoring and vegetation surveys were conducted to evaluate vegetation and dune morphology dynamics and analyze their interactions. The results revealed that (1) sediment accumulation increased from the beach to the windward slope but decreased near the dune crest and leeward slope. This accumulation was significant in winter and was controlled by spatiotemporal vegetation dynamics, typhoons, and topographic variations. (2) Coastal dune morphology influenced vegetation distribution, with vegetation on incipient foredunes and nebkhas concentrated on windward slopes and in interdunal areas. Blowouts are primarily found near the inlet and depositional zones. (3) Vegetation and dune elevation were significantly correlated along the across-shore gradient. Results indicate that a 1 % increase in coverage leads to a rise in dune elevation of 0.029–0.067 m, most pronounced in spring and weakest in summer. Additionally, vegetation cover was significantly associated with erosion–deposition in most dunes. Our findings demonstrate the impact of vegetation on dune morphological dynamics and their responses. These results enhance our understanding of eco-geomorphic feedback in coastal dune evolution, facilitating more effective coastal management and restoration.