However, one comprising target is the re-establishment of the natural dynamic.
Thus, national and regional authorities should give space to natural dynamics and
free movement of dunes in coastal areas as much as possible.
The dynamic nature of dunes (Figs. 3 and 4) was, and sometimes still is,
considered as a challenge. Through history, human settlements near coastal dunes
were threatened by the moving sands. There are many examples of villages which
even disappeared underneath the sands. Examples of lost villages are Sier on the
wadden isle of Ameland, Berkheide near The Hague, a town called Onze Lieve
Vrouwe op Zee on Duiveland, Kenfig in Wales and Shoyna in Russia (Williams and
Davies 2001; Stulp 2011; Raffaele and Bruno 2019). As we have seen before, people
tried to decrease the dynamics of the sand by fixing the dunes through the plantation
of either Marram grass (and other sand-binding grasses) and pine trees. However, by
reducing the natural dynamics, the functioning of the ecosystem is affected. Vegetation succession and encroachment of shrubs and trees are accelerated, whereas
invasive species may enter and degrade the system. Species such as Japanese rose
(Rosa rugosa) in temperate coastal regions of Europe or Sour fig (Carpobrotus
edulis) in many warm coastal regions worldwide are often concentrated in areas with
limited natural dynamics. At the Baltic and North Sea coasts, the Japanese rose is
often removed mechanically because the species richness is lower in plots where this
species occurs (Isermann 2008; Novoa et al. 2013).
In the past, at North and Baltic Sea coasts, rabbits were—at a large scale—able to
keep the dune landscape open, through grazing and the digging of holes, but there
populations have been decimated by (sometimes deliberately introduced) viruses,
like VHS and Myxomatosis. Nowadays, intensive management is often necessary to
maintain an open dune landscape. One common practice is the introduction of large
grazers into the dunes, but their effect is often insufficient. Cattle and horses are often
not able to keep up with the encroachment of woody plants. In some cases, they even
increase encroachment by concentrating nutrients and compacting the soil,
preventing aeolian processes resetting the system. Meanwhile, nitrogen deposits
from heavy industries, often located near harbours, increase the rate of encroachment. One specific victim of human influence in the dune system is the Northern
wheatear (Oenanthe oenanthe), a passerine bird that nests in abandoned rabbit holes
in dune grasslands. As the vegetation closes, the small ground orientated bird loses
habitat and nesting opportunities. Moreover, heavy metal industries and nearby
marine transports are causing an increased deposition of toxins in dune areas. Dioxin
levels in the eggs of the Norther wheatears in the Dutch dune system are that high
that a large amount of the embryos die before hatching (Van Oosten 2015).
Sand dunes of shorelines are natural defence systems against forces of the sea.
However, in many regions the dynamic of coastal dunes is part of the controversy
between nature and coastal protection. For example, dunes in the Wadden Sea area
to a great extent are artificially stabilized by plantations of Ammophila arenaria or
Ammocalamogrostis x baltica, also in areas where the sedimentation rate is positive.
In contrary to natural unvegetated and vegetated dunes such plantations are speciespoor, and normally do not offer space for rare, endemic or threatened species. Fences
are used across all dune areas in Europe to control the stream of visitors, with the
Coastal Habitats, Shallow Seas and Inland Saline Steppes: Ecology,. . .
299
Thus, national and regional authorities should give space to natural dynamics and
free movement of dunes in coastal areas as much as possible.
The dynamic nature of dunes (Figs. 3 and 4) was, and sometimes still is,
considered as a challenge. Through history, human settlements near coastal dunes
were threatened by the moving sands. There are many examples of villages which
even disappeared underneath the sands. Examples of lost villages are Sier on the
wadden isle of Ameland, Berkheide near The Hague, a town called Onze Lieve
Vrouwe op Zee on Duiveland, Kenfig in Wales and Shoyna in Russia (Williams and
Davies 2001; Stulp 2011; Raffaele and Bruno 2019). As we have seen before, people
tried to decrease the dynamics of the sand by fixing the dunes through the plantation
of either Marram grass (and other sand-binding grasses) and pine trees. However, by
reducing the natural dynamics, the functioning of the ecosystem is affected. Vegetation succession and encroachment of shrubs and trees are accelerated, whereas
invasive species may enter and degrade the system. Species such as Japanese rose
(Rosa rugosa) in temperate coastal regions of Europe or Sour fig (Carpobrotus
edulis) in many warm coastal regions worldwide are often concentrated in areas with
limited natural dynamics. At the Baltic and North Sea coasts, the Japanese rose is
often removed mechanically because the species richness is lower in plots where this
species occurs (Isermann 2008; Novoa et al. 2013).
In the past, at North and Baltic Sea coasts, rabbits were—at a large scale—able to
keep the dune landscape open, through grazing and the digging of holes, but there
populations have been decimated by (sometimes deliberately introduced) viruses,
like VHS and Myxomatosis. Nowadays, intensive management is often necessary to
maintain an open dune landscape. One common practice is the introduction of large
grazers into the dunes, but their effect is often insufficient. Cattle and horses are often
not able to keep up with the encroachment of woody plants. In some cases, they even
increase encroachment by concentrating nutrients and compacting the soil,
preventing aeolian processes resetting the system. Meanwhile, nitrogen deposits
from heavy industries, often located near harbours, increase the rate of encroachment. One specific victim of human influence in the dune system is the Northern
wheatear (Oenanthe oenanthe), a passerine bird that nests in abandoned rabbit holes
in dune grasslands. As the vegetation closes, the small ground orientated bird loses
habitat and nesting opportunities. Moreover, heavy metal industries and nearby
marine transports are causing an increased deposition of toxins in dune areas. Dioxin
levels in the eggs of the Norther wheatears in the Dutch dune system are that high
that a large amount of the embryos die before hatching (Van Oosten 2015).
Sand dunes of shorelines are natural defence systems against forces of the sea.
However, in many regions the dynamic of coastal dunes is part of the controversy
between nature and coastal protection. For example, dunes in the Wadden Sea area
to a great extent are artificially stabilized by plantations of Ammophila arenaria or
Ammocalamogrostis x baltica, also in areas where the sedimentation rate is positive.
In contrary to natural unvegetated and vegetated dunes such plantations are speciespoor, and normally do not offer space for rare, endemic or threatened species. Fences
are used across all dune areas in Europe to control the stream of visitors, with the
Coastal Habitats, Shallow Seas and Inland Saline Steppes: Ecology,. . .
299