(2) Fragmentation and organism migration—most of the manipulated dunes were
isolated within the vegetated area. Only those dunes that were adjacent to the
mobile or semi-stabilized dunes showed a slight establishment of psammophilic animals, mainly rodents. Our 4 years of observations demonstrated that
rodents, which are marked, either do not show up at the next captured year
(probably predated) or can be found at the same dune where they were previously captured or at the closest dune. Therefore, the spatial continuity of the
mobile dunes is crucial for organism migration and establishment.
(3) Removal of perennial plant method—dunes in which the vegetation was
clipped and uprooted showed a rapid regeneration of perennial plants (similar
to the findings in the Netherlands—Arens et al., Chap. 7) compared with the
dunes where the vegetation was removed by a bulldozer. Dwarf shrubs, such
as Artemisia monosperma, which dominates the dunes, have long roots
(at least 3 m) (Martínez et al. 1998; Zhenghu et al. 2004) with rejuvenate buds
to cope with water limitations and sand burial or exposure. Hence, the
remaining roots left under the surface after the plant removal allowed the plant
re-growth throughout the covering layer of the sand. Therefore, the method of
vegetation removal should ensure complete uprooting.
Similar to our results, Arens and Gleen (2006) conducted a large-scale destabilization of dunes in Netherlands by vegetation removal. The main measure was
soil mobility. After 8 years of observation they did not succeed in remobilizing the
dunes to the extent they expected owing to limitations of sand supply and rapid
regeneration of the vegetation under humid conditions.
11.5 Conclusions
Coastal sand dunes are threatened worldwide because about two-thirds of the
world’s population live along the coast. Therefore, the conservation of this landscape is crucial and very challenging. In areas where the wind velocity is too low
to cause significant movement of the dunes (as in Israel), and where the impact of
humans has largely been removed, a stabilization process is taking place. However, some of these areas have maintained the mobile dunes’ biodiversity as they
co-evolved under traditional human interference, which ensured the existence of
mobile dunes together with their characteristic ecosystems. Moreover, because
these sand dunes have been fragmented, leaving ‘‘islands of mobile sand’’,
psammophilic plants and animals have evolved independently from the original,
spatially continuous population to form new subspecies and species that are
considered endemic. In Israel, the majority of endemic plants and animals are
found within the Mediterranean coastal dunes. Conservation policies in Israel that
included non-active management in nature reserves, including in Nizzanim, were
common until very recently.
182
P. Bar (Kutiel)
isolated within the vegetated area. Only those dunes that were adjacent to the
mobile or semi-stabilized dunes showed a slight establishment of psammophilic animals, mainly rodents. Our 4 years of observations demonstrated that
rodents, which are marked, either do not show up at the next captured year
(probably predated) or can be found at the same dune where they were previously captured or at the closest dune. Therefore, the spatial continuity of the
mobile dunes is crucial for organism migration and establishment.
(3) Removal of perennial plant method—dunes in which the vegetation was
clipped and uprooted showed a rapid regeneration of perennial plants (similar
to the findings in the Netherlands—Arens et al., Chap. 7) compared with the
dunes where the vegetation was removed by a bulldozer. Dwarf shrubs, such
as Artemisia monosperma, which dominates the dunes, have long roots
(at least 3 m) (Martínez et al. 1998; Zhenghu et al. 2004) with rejuvenate buds
to cope with water limitations and sand burial or exposure. Hence, the
remaining roots left under the surface after the plant removal allowed the plant
re-growth throughout the covering layer of the sand. Therefore, the method of
vegetation removal should ensure complete uprooting.
Similar to our results, Arens and Gleen (2006) conducted a large-scale destabilization of dunes in Netherlands by vegetation removal. The main measure was
soil mobility. After 8 years of observation they did not succeed in remobilizing the
dunes to the extent they expected owing to limitations of sand supply and rapid
regeneration of the vegetation under humid conditions.
11.5 Conclusions
Coastal sand dunes are threatened worldwide because about two-thirds of the
world’s population live along the coast. Therefore, the conservation of this landscape is crucial and very challenging. In areas where the wind velocity is too low
to cause significant movement of the dunes (as in Israel), and where the impact of
humans has largely been removed, a stabilization process is taking place. However, some of these areas have maintained the mobile dunes’ biodiversity as they
co-evolved under traditional human interference, which ensured the existence of
mobile dunes together with their characteristic ecosystems. Moreover, because
these sand dunes have been fragmented, leaving ‘‘islands of mobile sand’’,
psammophilic plants and animals have evolved independently from the original,
spatially continuous population to form new subspecies and species that are
considered endemic. In Israel, the majority of endemic plants and animals are
found within the Mediterranean coastal dunes. Conservation policies in Israel that
included non-active management in nature reserves, including in Nizzanim, were
common until very recently.
182
P. Bar (Kutiel)