Dynamic dune restoration: site-specific variability in sediment transport and soil response following notch creation

Coastal sand dunes are dynamic systems that provide critical ecosystem services, yet decades of stabilisation have led to widespread loss of bare sand habitats and associated biodiversity. Restoration efforts increasingly focus on re-establishing dune mobility through interventions such as foredune notch creation, which can enhance inland sand transport. However, the effectiveness of these interventions remains poorly understood, and cross-site comparisons are rare. This study evaluates changes in sediment dynamics and soil characteristics following notch interventions across multiple dune systems in Wales. Sand flux was monitored using sand-rain collectors along intervention and control transects at 50 m, 100 m, and 200 m inland, and soil properties (bulk density, organic matter, calcite, and pH) were measured before and after intervention. Results indicate strong site-specific variability in sediment response. At Aberffraw, sand flux increased by over +200 g m−2 day−1 at 50 m, while Merthyr Mawr showed more localised increases (+30 g m−2 day−1), and minimal changes were observed at Kenfig and Pembrey (<10 g m−2 day−1). Across all sites, a generalised linear mixed model indicated an approximately fivefold increase in sand flux at intervention transects relative to controls. Soil responses were more limited, with modest but statistically detectable changes, including a 29% reduction in organic matter (OR ≈ 0.71) and small increases in calcite content. These findings demonstrate that foredune notching can enhance aeolian sediment transport but resulting soil changes are modest and highly site dependent. The study highlights that intervention effectiveness is governed by interactions among wind regime, sediment supply, and system configuration, emphasising the need for site-specific, process-based approaches to dune restoration.