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Sand Dune Ecology

East Usambaras

Pitcairn Islands

 

Investigations of sand dune systems have been carried out at two northern Irish sites (Portstewart and Murlough Bay, Dundrum) and have focused on the changes in vegetation and bare sand since the 1940s. These changes have been linked to fluctuating rabbit populations and human disturbance.

Vegetation succession has been investigated in relation to the introduction of exotic species and the dispersal ability of both native and non-native woody plant species. Following the introduction of myxomatosis and the subsequent rabbit population crash, sea buckthorn (Hippophae rhamnoides) has rapidly spread through the dunes to form large monotypic stands. The rate of spread has declined in recent years due to increased grass competition and a reduction in areas of bare sand. Wherever there is an ample supply of propagules, sea buckthorn stands are replaced by a number of shrub and tree species.

The findings are reported in detail in the following two sections:

The impact of sea buckthorn on sand dune ecosystem has been investigated (see Binggeli et al. 1992 for details). The shrub's main impacts are:

  • to alter the soils chemical properties.
  • to facilitate the formation of woodland including a mixture of native and non-native species.
  • to change the composition of mesofauna and ground beetle communities.
 Murlough dunes. Stand of Hippophae rhamnoides being invaded by Acer pseudoplatanus. (34369 bytes)

Murlough dunes. Stand of Acer pseudoplatanus with remains of Hippophae rhamnoides (coarse woody debris in foreground). (30961 bytes)

Murlough dunes. Stand of Hippophae rhamnoides on the spit (pH of sand >8) invaded by Clematis vitalba. (32383 bytes)

Portstewart dunes. Hippophae rhamnoides spreading into species rich dune slack. (37803 bytes)

     
    Copyright 1999 Pierre Binggeli. All rights reserved.