Sand dunes; unsung heroes of coastal defence

Visitors to Poldhu Beach might be shocked to discover that much of the sand has disappeared following the storms and high seas at the beginning of January, unveiling a very stony beach and lots of beach litter.  Thanks to Friends of Poldhu, the litter has all been removed, but it will take months, if not years, for the sand to re-appear.  Fortunately, the sand hasn’t gone too far, as any local surfers will be aware, there is now a rather useful sandbar just offshore, creating a tidy right hand break. 

When I first came to the Lizard 20 years ago, it was common for local farmers to quite legally remove sand from the beach.  This ancient right ‘for the betterment of the land’ probably started with a farmhand with a shovel and horse and cart.  By the 1990s, there were regularly fleets of trucks on the foreshore being loaded up by JCB, an unsustainable practice which was fortunately stamped out in 2007.  

Whilst the beach itself has lost much of its sand, the dunes behind the beach have remained remarkably unscathed.  The dunes at Poldhu are designated as a Site of Special Scientific Interest (sssi).  They are an amazing ecosystem, not just rich in wildlife but they also provide an incredibly useful natural defence mechanism against the ravages of storms and high winds. 

The highly specialised marram grass, tolerant of salt, wind and drought, binds the dunes together with a network of tough exploratory roots, allowing the further colonisation of other specialist species until the dunes become more stable.  Windblown sand, which would otherwise be lost from the beach, is trapped amongst the vegetation, and the dunes continue to grow.  Rare and unusual plants such as sea knot grass and sea holly grow amongst the grasses.

The rare ‘sea knot grass’ (Polygonium maritium) growing amongst the dunes

The Poldhu dunes however haven’t always been so healthy.  Until the late 1980s, cars were permitted to park on the beach.  In 1987, the National Trust embarked on a dune stabilisation project.  With cars banned from the beach, with areas temporarily fenced off, marram grass was planted and timber posts were installed to assist with the trapping of sand. 

Over 25 years later, the dunes are healthy, thriving and full of wildlife.  What the recent storms have proven is that they also provide a remarkable natural sea defence, protecting the road, bridge and car park from the ravages of winter storms.

A busy day on the beach (date unknown; any ideas?)

Sand dune restoration project (circa 1987)

  - Justin