relevantly contributed to the elaboration of ecological theories and to a major understanding of the general functioning of ecosystems (e.g., Cowles, 1899; Clements, 1916;
Salisbury, 1922; Olson, 1958; Yarranton and Morrison,
1974).
A characteristic vegetation type including unique species with specific adaptations to the harsh environmental
conditions establishes on coastal dunes (Ranwell, 1972;
Maun, 2009). Such vegetation shows a wide distribution
through different climatic and geographic areas, both at
the species level (particularly those established on the
beach and active dunes) and at the genus level or their
growth forms, so these ecosystems have relatively similar
vegetation worldwide in temperate latitudes (Doing,
1985). Coastal dunes also support a high number of rare
and endemic species (Martínez et al., 1993; Heslenfeld
et al., 2004). Other plants from inland ecosystems, ruderal,
and/or alien species may be also present, mainly associated with the degradation status of the dune. Vegetation
is closely related to the sediment dynamics and geomorphological processes of the dune, and a continuous interaction is maintained between both elements (Ranwell,
1972; Hesp, 2002). On the other hand, the environmental
gradients previously referred determine the establishment
of the different plant species, particularly in the youngest
areas, nearest to the sea, while biological interactions
(mainly positive for the interacting species,
although they may be also negative) play a relevant role
in determining the structure and composition of vegetation, particularly in more stabilized and mature situations
of the dune, toward the inland areas (Lichter, 1998; Maun,
1998). As a result, vegetation becomes ordered in bands
from the strandline and landward, more or less parallel
to the coastline and originating a particular type of landscape composed of a mosaic of habitats, both in dune systems developed on continental coasts, spits, or barrier
islands.
Environmental services and conservation of
coastal dunes
Coastal dune systems are not only relevant from the geomorphological, geological, or ecological point of view.
They also have a recognized historical, archaeological,
scenic, cultural, and socioeconomic interest (Nordstrom
et al., 2000; Heslenfeld et al., 2004; Martínez et al.,
2004; van der Meulen et al., 2004). In addition, they provide us with different direct and indirect benefits and
resources (which are known as environmental services),
acting as zones for livestock grazing, agriculture, sand
exploitation for construction purposes and water extraction, or for human settlement, urban development, tourism, and recreational use (Carter, 1988; van der Meulen
and Salman, 1996; Williams et al., 1997; Kutiel et al.,
1999; Baeyens and Martínez, 2004; Heslenfeld et al.,
2004). Furthermore, coastal dune systems play a relevant
role as natural barriers that preserve other inland natural
areas and human settlements by buffering the effects of
storm waves, tides, and wind and preventing groundwater
salinization by intrusion of sea water, among others
(Carter, 1988; Hesp, 2000; Kidd, 2001; Gómez-Pina
et al., 2002).
Nevertheless, due to an excessive exploitation of the
resources and services they offer, the human demographic
expansion and the relatively recent urban, engineering and
industrial development, many coastal dune systems are
being seriously degraded at present, some of them irreversibly altered and lost (Carter, 1988; Heslenfeld et al.,
2004; Doody, 2012). Only in Europe, it is estimated that
around 25 % of the coastal dune surface has been lost since
1900, while around 55 % of the remaining surface has lost
its natural character, and approximately 85 % of the currently existing dunes are endangered (Heslenfeld et al.,
2004). Among the main damages that coastal dunes suffer
are the net loss or fragmentation of natural habitats, loss of
landscape scenic quality, alteration of soil and aquifers,
water and air pollution, hazards for endangered species,
global biodiversity decline, and increase of the ecosystem
vulnerability. On the other hand, the anthropogenic habitat
degradation and destruction (mainly associated to urban
development and tourism), dune stabilization and eutrophication, expansion of invasive species, and the effects
of global warming and the progressive sea-level rise are
identified as the main current threats to coastal dunes
(Carter, 1988; Kutiel et al., 1999; Nordstrom et al., 2000;
Heslenfeld et al., 2004; Martínez et al., 2004; Doody,
2012; Muñoz-Vallés and Cambrollé, 2013).
Currently, many coastal dunes are being protected
under regional, national, and international initiatives,
devoting a great effort in the conservation, management,
and restoration of such ecosystem from different disciplines and government levels, in pursuit of a sustainable
development that takes into account both the ecosystem
health and the use of their services (Doody, 2012).
Summary
Coastal dunes are Aeolian landforms that form at the interface of terrestrial, oceanic, and atmospheric systems,
mainly associated with dissipative coasts dominated by
marine winds with an ample supply of well-sorted sands
and occurring on ocean, lake, and estuary shorelines. Distributed worldwide, they comprise very diverse climates
and biomes and present a large variety of forms and
dimensions related with sediment supply and wind
regime, where vegetation plays a relevant role. The influence of the sea determines a series of environmental and
biological gradients from the shoreline and landwards.
The harsh environment characterized by the scarcity of
water and nutrients, substrate mobility and sand burial,
incidence of salt spray and sand blasting, high air and soil
temperatures and light intensities in low and medium latitudes, and saltwater flooding in the strandline determines
the establishment of species of singular sand flora and
fauna that are specifically adapted to such stressful
conditions.
DUNES
201
Salisbury, 1922; Olson, 1958; Yarranton and Morrison,
1974).
A characteristic vegetation type including unique species with specific adaptations to the harsh environmental
conditions establishes on coastal dunes (Ranwell, 1972;
Maun, 2009). Such vegetation shows a wide distribution
through different climatic and geographic areas, both at
the species level (particularly those established on the
beach and active dunes) and at the genus level or their
growth forms, so these ecosystems have relatively similar
vegetation worldwide in temperate latitudes (Doing,
1985). Coastal dunes also support a high number of rare
and endemic species (Martínez et al., 1993; Heslenfeld
et al., 2004). Other plants from inland ecosystems, ruderal,
and/or alien species may be also present, mainly associated with the degradation status of the dune. Vegetation
is closely related to the sediment dynamics and geomorphological processes of the dune, and a continuous interaction is maintained between both elements (Ranwell,
1972; Hesp, 2002). On the other hand, the environmental
gradients previously referred determine the establishment
of the different plant species, particularly in the youngest
areas, nearest to the sea, while biological interactions
(mainly positive for the interacting species,
although they may be also negative) play a relevant role
in determining the structure and composition of vegetation, particularly in more stabilized and mature situations
of the dune, toward the inland areas (Lichter, 1998; Maun,
1998). As a result, vegetation becomes ordered in bands
from the strandline and landward, more or less parallel
to the coastline and originating a particular type of landscape composed of a mosaic of habitats, both in dune systems developed on continental coasts, spits, or barrier
islands.
Environmental services and conservation of
coastal dunes
Coastal dune systems are not only relevant from the geomorphological, geological, or ecological point of view.
They also have a recognized historical, archaeological,
scenic, cultural, and socioeconomic interest (Nordstrom
et al., 2000; Heslenfeld et al., 2004; Martínez et al.,
2004; van der Meulen et al., 2004). In addition, they provide us with different direct and indirect benefits and
resources (which are known as environmental services),
acting as zones for livestock grazing, agriculture, sand
exploitation for construction purposes and water extraction, or for human settlement, urban development, tourism, and recreational use (Carter, 1988; van der Meulen
and Salman, 1996; Williams et al., 1997; Kutiel et al.,
1999; Baeyens and Martínez, 2004; Heslenfeld et al.,
2004). Furthermore, coastal dune systems play a relevant
role as natural barriers that preserve other inland natural
areas and human settlements by buffering the effects of
storm waves, tides, and wind and preventing groundwater
salinization by intrusion of sea water, among others
(Carter, 1988; Hesp, 2000; Kidd, 2001; Gómez-Pina
et al., 2002).
Nevertheless, due to an excessive exploitation of the
resources and services they offer, the human demographic
expansion and the relatively recent urban, engineering and
industrial development, many coastal dune systems are
being seriously degraded at present, some of them irreversibly altered and lost (Carter, 1988; Heslenfeld et al.,
2004; Doody, 2012). Only in Europe, it is estimated that
around 25 % of the coastal dune surface has been lost since
1900, while around 55 % of the remaining surface has lost
its natural character, and approximately 85 % of the currently existing dunes are endangered (Heslenfeld et al.,
2004). Among the main damages that coastal dunes suffer
are the net loss or fragmentation of natural habitats, loss of
landscape scenic quality, alteration of soil and aquifers,
water and air pollution, hazards for endangered species,
global biodiversity decline, and increase of the ecosystem
vulnerability. On the other hand, the anthropogenic habitat
degradation and destruction (mainly associated to urban
development and tourism), dune stabilization and eutrophication, expansion of invasive species, and the effects
of global warming and the progressive sea-level rise are
identified as the main current threats to coastal dunes
(Carter, 1988; Kutiel et al., 1999; Nordstrom et al., 2000;
Heslenfeld et al., 2004; Martínez et al., 2004; Doody,
2012; Muñoz-Vallés and Cambrollé, 2013).
Currently, many coastal dunes are being protected
under regional, national, and international initiatives,
devoting a great effort in the conservation, management,
and restoration of such ecosystem from different disciplines and government levels, in pursuit of a sustainable
development that takes into account both the ecosystem
health and the use of their services (Doody, 2012).
Summary
Coastal dunes are Aeolian landforms that form at the interface of terrestrial, oceanic, and atmospheric systems,
mainly associated with dissipative coasts dominated by
marine winds with an ample supply of well-sorted sands
and occurring on ocean, lake, and estuary shorelines. Distributed worldwide, they comprise very diverse climates
and biomes and present a large variety of forms and
dimensions related with sediment supply and wind
regime, where vegetation plays a relevant role. The influence of the sea determines a series of environmental and
biological gradients from the shoreline and landwards.
The harsh environment characterized by the scarcity of
water and nutrients, substrate mobility and sand burial,
incidence of salt spray and sand blasting, high air and soil
temperatures and light intensities in low and medium latitudes, and saltwater flooding in the strandline determines
the establishment of species of singular sand flora and
fauna that are specifically adapted to such stressful
conditions.
DUNES
201