Vegetation of dune slacks

A very different vegetation develops from that of dry dunes, where the sand is within reach of the dune system's fresh water table. This can happen either because of a blowout (see picture opposite) or where the water table rises towards an existing surface. Under these conditions dune slacks develop, which are often characterised by a marked annual fluctuation in water level. Water levels in slacks normally reach a peak in early spring, when many are flooded for periods of several months. They then fall sharply through the summer, reaching up to 2 m below ground level before starting to rise again in autumn (Ranwell 1972a).

Caption: Eroding dune at Braunton Burrows. Note the developing wet dune slack to the right of the picture.

A summary description of the communities in dunes slacks can be found in relation to a typical sand dune succession.

References

Ranwell, D.S. 1972a. Ecology of Salt Marshes and Sand Dunes. Chapman and Hall, London, 258 pp.