A range of options to counter stabilization have been used and again, similar to
restoration actions on foredunes, they range from low-impact and small-scale, to
high-impact and large-scale. In terms of low-impact and small-scale actions, local
disturbance can be promoted by increasing the levels of grazing pressure through
encouraging rabbits, or by the use of domestic stock such as cattle, sheep or horses.
Heavy grazing can, however, result in severe destabilization (Rhind et al., Chap. 8,
this volume) and changes in plant communities (Zunzunegui et al., 2012), but
when used at perceived ‘‘proper’’ intensities, may reactivate the system, as was
found by Grootjans et al. (Chap. 15, this volume, and 2001) and López Rosas et al.
(Chap. 16, this volume)
Elimination of exotic species is also a difficult task. Sometimes they have been
sprayed with herbicides (Hesp and Hilton, Chap. 5, this volume; Hilton et al.
2009), although some invasives, such as marram grass (Ammophila arenaria) are
difficult to eradicate, even with continued application of herbicides and mechanical
removal. In contrast to the above, softer techniques have also proven to be
effective. For instance, in Northwestern USA, marram grass was removed by hand.
This involved painstaking labor, with many volunteer-hours involved. But in the
end, biodiversity increased naturally once the dominant exotic grass was eliminated (Pickart, Chap. 10, this volume). In the Netherlands, remobilization has been
achieved by sod cutting, as well as hand removal of re-sprouting roots for a
number of years (Grootjans et al. 2001). Intensive volunteer work has also been
necessary. Inhibitory woody vegetation has been removed by pruning and felling
(Muñoz-Reinoso et al., Chap. 9, this volume), but also with bulldozers (Kutiel,
Chap. 11, this volume).
Larger scale, more invasive options to reactivate coastal dunes and restore
original vegetation include mechanical disturbances, such as the removal of alien
soils and materials and the creation of new dunes (Hesp and Hilton, Chap. 5, this
volume; van Aarde et al. 1998), and topsoil stripping and deep ploughing (Rhind
et al., Chap. 8, this volume; Graham and Haynes 2004). The latter inverts the soil
profile by burying any surface nutrients and unwanted seeds, while exposing low
fertility subsoil, and inhibits the germination of undesired species (Jones et al.
2010). Another high impact large-scale mobilization action includes beach and
shoreface nourishment in order to counteract shoreline erosion. This strategy has
proven to be very successful in The Netherlands (Arens et al., Chap. 7, this
volume), where the coastline retreat has been reduced and the transfer of sand into
the dunes has increased considerably. A potential drawback of these activities is
the quality of the sand used for nourishment. If the nourished sand differs from the
original sand, e.g., in grain size, carbonate content or mineralogical compounds,
there may be ecological consequences affecting species colonization and growth.
The bottom of the ocean floor, where sediment is removed for beach nourishment,
may also be severely affected after these dredging activities, and some would
argue that this is not a medium- to long-term sustainable action, as coastline retreat
is likely to eventually occur.
Once blowouts are reactivated the dune systems may become destabilized
(Rhind et al., Chap. 8, this volume; Arens et al. 2004). However, maintenance of
20 Coastal Dune Restoration: Trends and Perspectives
331
restoration actions on foredunes, they range from low-impact and small-scale, to
high-impact and large-scale. In terms of low-impact and small-scale actions, local
disturbance can be promoted by increasing the levels of grazing pressure through
encouraging rabbits, or by the use of domestic stock such as cattle, sheep or horses.
Heavy grazing can, however, result in severe destabilization (Rhind et al., Chap. 8,
this volume) and changes in plant communities (Zunzunegui et al., 2012), but
when used at perceived ‘‘proper’’ intensities, may reactivate the system, as was
found by Grootjans et al. (Chap. 15, this volume, and 2001) and López Rosas et al.
(Chap. 16, this volume)
Elimination of exotic species is also a difficult task. Sometimes they have been
sprayed with herbicides (Hesp and Hilton, Chap. 5, this volume; Hilton et al.
2009), although some invasives, such as marram grass (Ammophila arenaria) are
difficult to eradicate, even with continued application of herbicides and mechanical
removal. In contrast to the above, softer techniques have also proven to be
effective. For instance, in Northwestern USA, marram grass was removed by hand.
This involved painstaking labor, with many volunteer-hours involved. But in the
end, biodiversity increased naturally once the dominant exotic grass was eliminated (Pickart, Chap. 10, this volume). In the Netherlands, remobilization has been
achieved by sod cutting, as well as hand removal of re-sprouting roots for a
number of years (Grootjans et al. 2001). Intensive volunteer work has also been
necessary. Inhibitory woody vegetation has been removed by pruning and felling
(Muñoz-Reinoso et al., Chap. 9, this volume), but also with bulldozers (Kutiel,
Chap. 11, this volume).
Larger scale, more invasive options to reactivate coastal dunes and restore
original vegetation include mechanical disturbances, such as the removal of alien
soils and materials and the creation of new dunes (Hesp and Hilton, Chap. 5, this
volume; van Aarde et al. 1998), and topsoil stripping and deep ploughing (Rhind
et al., Chap. 8, this volume; Graham and Haynes 2004). The latter inverts the soil
profile by burying any surface nutrients and unwanted seeds, while exposing low
fertility subsoil, and inhibits the germination of undesired species (Jones et al.
2010). Another high impact large-scale mobilization action includes beach and
shoreface nourishment in order to counteract shoreline erosion. This strategy has
proven to be very successful in The Netherlands (Arens et al., Chap. 7, this
volume), where the coastline retreat has been reduced and the transfer of sand into
the dunes has increased considerably. A potential drawback of these activities is
the quality of the sand used for nourishment. If the nourished sand differs from the
original sand, e.g., in grain size, carbonate content or mineralogical compounds,
there may be ecological consequences affecting species colonization and growth.
The bottom of the ocean floor, where sediment is removed for beach nourishment,
may also be severely affected after these dredging activities, and some would
argue that this is not a medium- to long-term sustainable action, as coastline retreat
is likely to eventually occur.
Once blowouts are reactivated the dune systems may become destabilized
(Rhind et al., Chap. 8, this volume; Arens et al. 2004). However, maintenance of
20 Coastal Dune Restoration: Trends and Perspectives
331