An environmental approach to the restoration of badly eroded sand dunes

Published source details Wilcock F.A. & Carter R.W.G. (1977) An environmental approach to the restoration of badly eroded sand dunes. Biological Conservation, 11, 279-291.
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Summary

In 1969 it was apparent that most seaward sand dunes in a 160 ha dune system near the town of Portrush in Co. Antrim (55°12' N, 0°39' W), Northern Ireland, had become severely degraded through excessive human recreational use. A dense network of bare paths, and gullies, hummocks and large blow-outs had developed. Dune grassland communities persisted but with only degenerate marram Ammophila arenaria (the main dune building species) present. In 1969 and 1970 some eroded dunes were closed to the public and a conventional dune restoration programme (brushwood fencing, thatching and marram planting) undertaken. Overall dune recovery did not occur; sand accumulation was poor and planted marram exhibited little growth.

Studies were undertaken in order to identify factors influencing this coastal system. It identified that conventional restoration techniques were unlikely to succeed within a reasonable time as the beach/dune system was essentially stable. Elsewhere, such stabilisation methods had been successful as sand build-up allows marram to establish. Therefore, a new technique was trialed.

In 1973, 10,000m² of badly eroded foredune was smoothed into a more aerodynamic profile using a bulldozer. Marram was planted at 1 m intervals and covered with organic compost mulch (about 1 kg/m²). The extreme seaward dune edge was not planted to allow some instability at the beach/dune interface. At the eastern end of the reprofiled area a dune blow-out was fenced, planted, mulched and thatched; at the western end a similar area was left untouched (as a control). Public access was restricted in these areas. Each site was regularly monitored.

The reprofiling benefited dune recovery and proved very stable despite severe storms in January 1974 and January 1975. In the summer of 1975 the dune surface accreted by 2-3 cm; marram growth was excellent; culms 20-30 cm high at planting were 100-120 cm tall and flowering. Vegetation cover increased from an initial 5-10% to between 60-90%. In 1974 and 1975 a few new species (2 grasses; 13 herbs) appeared (mostly germinating on compost remnants); by spring 1976 these contributed to around 10% ground cover, red fescue Festuca rubra predominating.

In contrast, the conventionally managed area changed little, other than a minor build-up of sand against some fences. The planted marram grew poorly; on slopes (still eroding) plants were degenerate, dead or missing, on flatter areas occasional plants grew. Other than a few creeping thistles Cirsium arvense and dandelions Taraxacum officinale, no new plants colonised. In the third area erosion continued as before, despite public access restrictions.

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