Backdunes

Backdunes are a coastal dune feature located landward of the foredune line on sandy coastlines. They form a secondary dune complex that runs behind the primary dune barrier and often extends toward inland vegetation zones. Backdune formation occurs as wind-blown sand from the beach is trapped by surface features and vegetation, gradually accumulating to create a distinct dune belt. Over time, plant colonization and soil development stabilize the sand, reducing mobility and supporting different microhabitats than the foredunes.

The structure and composition of backdunes vary but commonly include scattered grasses, shrubs, and other vegetation that trap windblown sand and promote soil formation. They may host communities adapted to drier, wind-exposed conditions and can influence local hydrology by affecting infiltration and saltwater intrusion. Ecologically, backdunes contribute to biodiversity, provide shelter for wildlife, and serve as buffers against inland erosion and storm surge by absorbing energy and slowing sand transport.

Disturbance and management play major roles in backdune dynamics. Human activities such as development, trampling, and recreation can degrade vegetation and trigger sand movement, while restoration efforts—replanting vegetation, installing sand fences, and restricting access—aim to stabilize dunes. Restoration can alter natural sediment pathways and dune mobility if not carefully planned.

Threats include invasive species, sea-level rise, extreme storms, and ongoing coastal development. Backdunes are found in many temperate and subtropical coastlines worldwide and are often considered an integral part of broader dune systems used for protection, habitat, and landscape resilience.