Tuesday, 27 March 2012

The loss of UK sand dunes

Guest blog by Dr Laurence Jones, based at CEH's Bangor site.

Sand dunes are one of the UK’s most threatened habitats and are high in biodiversity, with many rare and interesting species such as natterjack toad and orchids. As with any coastal habitat, they are primarily long, linear features and so are particularly susceptible to pressures from the land on the one side, and from the sea on the other.

Work that CEH scientists and others did for the UK National Ecosystem Assessment (2011) collated the trends in UK dune area since the 1900s (Figure 1 below).

Estimated UK sand dune area over time
Figure 1: UK sand dune area, 1900, projected to 2060
Conversion to agriculture, and expansion of housing (Figure 2 below), tourism or leisure developments such as golf courses have been the main reasons for loss of dunes in the past. These losses are still continuing, but at a slower rate.

Habitat loss on the Sefton coast, north-west England
Figure 2: Habitat loss on the Sefton coast, north-west England, loss
to urbanisation, forestry and golf courses. Red line shows seaward
limit of urban extent in 1945. Note the subsequent development at Aindale
and Formby. Golf courses and afforestation of dunes pre-date 1945.

All coastlines around the UK are now experiencing sea-level rise which is already affecting many systems, causing a steepening of beach profiles which indicates a loss of sediment and will result in coastal erosion. A study in Wales has shown many dune systems are forecast to lose around 50m of coastline to sea level rise in the next 80 years.

The picture is more complicated however, and depends partly on the amount of sand supply to the beach and dune. Some dune systems are actively accreting (i.e. getting bigger) because they have adequate sand supply, despite sea level rise.

Sand dunes provide many useful functions for society, and one of these is sea defence. They form part of the natural sea defences along the Sefton coast in north-west England, north east England, the Severn estuary, the North Norfolk coast and in North Wales. Loss of dune area reduces this sea defence function, and means more costly (and ugly) hard engineering needs to be put in place instead.

As well as loss of area, many sand dunes are suffering from a deterioration in quality, and are in declining or unfavourable condition for conservation. This is due to a wide range of factors, including under-grazing or sometimes over-grazing, nitrogen deposition and climate change.

Sand dunes
Sand dunes, high in biodiversity and important sea defences,
are one of the UK's most threatened habitats.

However, despite these undesirable changes, coasts and dunes are still a very important resource for tourism in the UK and provide considerable value to society as a whole.

Added on 29 March 2012:

Declining habitat quality means that restoration has an important role to play, and CEH has conducted scientific monitoring of a dune restoration project in North Wales at Talacre Warren which looked at burying nutrient-rich surface layers under 1 metre of bare sand. 

Additional information

Dr Laurence Jones is a plant ecologist based at the Centre for Ecology & Hydrology's Bangor site.

More details on CEH's Coastal Research.

UK National Ecosystem Assessment, Technical Reports, Chapter 11: Coastal Margins.

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