Dune Landscape Rejuvenation by Intended Destabilisation in the Amsterdam Water Supply Dunes

In the Dutch coastal dunes, several projects have started in which aeolian activity is stimulated to enhance landscape rejuvenation by increasing aeolian erosion and deposition. The aim of these projects is to reverse vegetation succession and create opportunities for pioneer stages. In 1995, a drinking water extraction canal in the Amsterdam Water Supply Dunes was closed and the original landscape was restored. Since then, the development of the area was left to natural processes. This resulted in large-scale deflation structures and the development of sand drift areas. By means of air photographs, the changes in the landscape were studied. Initially, the sand drift area expanded, up to a maximum of 11 ha in 1999. In the following years, stabilisation of the surface by vegetation became more and more important. After 8 years of undisturbed development, half of the bare surface was still bare, and the active area was still 2.5 times larger than the stabilised area. But bare spots were scattered over the area, and the average size per spot decreased from 10 ha in 1995 to <1 ha in 2003. The percentage of surface covered by pioneer species was large (5 ha in 2003) and might result in increased stabilisation rates in future. Part of the stabilisation could be explained by meteorological conditions during the studied period. Part could be explained because the system is supply limited. Scale might be an important issue in the final success of remobilisation, as indicated by preliminary comparison to larger-scaled projects. Further comparisons are needed. After eight years, it is still too early to say whether large-scale destabilisation measures in the case of artificially fixed coastal dunes result in durable aeolian activity and landscape rejuvenation. However, even if the area will be stabilised within the next years, the landscape has many impulses for new ecological development. For the next decade, we need to continue our monitoring programs; meanwhile, experimentation with methods of reactivation should be conducted.