13 Can We use a Landscape Approach to Assess Natural and Anthropogenic . . .
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13.2 Structure of Intertidalscapes and their Interpretation
According with classical definition of terrestrial landscape, it is a basic structural
unit of the geographic environment (Gudelis 1993), a geosystem which includes a
set of interacting and interdependant entities, forming an integrated whole. If each
landscape is a set of entities (components), it is also a part (component) of a higher
geosystem. Thus, three levels should be considered to understand and interpret the
landscape: the level of landscape, the lower level of landscape components and the
higher level, the level of the higher geosystem. According Dunning et al. (1992)
a landscape is an area of land containing a mosaic of habitat patches, often within
which a particular target habitat patch is embedded in a matrix. Many authors consider the landscape as a level which can be seen directly by an observer situated
from a specific point of view in a vertical and/or horizontal observation. Because the
intertidal zone is a part of the marine environment, we propose to use the term “intertidal seascape” or “intertidalscape”, better suitable than “landscape” for the intertidal
zone. Thus, an intertidalscape is the set of structural components of the ecosystem
or eco-complex between the low-and high-water tidemarks and can be seen by an
observer situated at sea or on land (cliff, dune. . . ). The aims here are to characterize the intertidalscape evolution resulting from the ecological processes which
control spatial structures (patches and mosaics) in response to natural and anthropogenic disturbances. This approach can answer to questions of connectivity between
patches and components of the ecosystems, which correspond with the definition of
the landscape ecology as defined by Wu (2006), discipline in which the ecosystem
complexity is studied through heterogeneity at various spatial scales. Moreover, in a
second step, if dynamics of the ecosystem components are previously well described
and explained, some landscape indicators can be developed and used to assess the
level of disturbance of these ecosystems. We propose here some considerations for
an intertidalscape ecology based on interpretation of the spatial distribution of structural and functional components. For the rocky shores, these components are habitats
(biotope + biocenosis) localized in the rocky matrix and characterized with several
spatial dimensions based on physical, biological and temporal features (periods of
emersion, stochastic events, seasonality. . . ).
The first step of a landscape approach on the intertidal zone will be the identification and the specialization of the habitats. At a higher scale, the identification
of specific associations of some habitats will be able to define an intertidalscape
typology describing the main categories of ecocomplexes based on their geomorphological, physical, biological, but also socio-economical dimensions. Many authors
(see Schoch and Dethier 1996; Little and Kitching 1996) defined different variables
playing a main role in the rocky shores ecology, variables which could be used to elaborate such a typology. The habitat classifications recently developed at the French
national level (“Cahiers d’habitats” Natura 2000; Bensettiti et al. 2004; Rebent,
Guillaumont et al. 2010) and European Community levels (Natura 2000, EUNIS
(http://eunis.eea.europa.eu)) do not consider the level of landscape. To our knowledge, no one approach is being developed to achieve such an intertidal- sea-scape
203
13.2 Structure of Intertidalscapes and their Interpretation
According with classical definition of terrestrial landscape, it is a basic structural
unit of the geographic environment (Gudelis 1993), a geosystem which includes a
set of interacting and interdependant entities, forming an integrated whole. If each
landscape is a set of entities (components), it is also a part (component) of a higher
geosystem. Thus, three levels should be considered to understand and interpret the
landscape: the level of landscape, the lower level of landscape components and the
higher level, the level of the higher geosystem. According Dunning et al. (1992)
a landscape is an area of land containing a mosaic of habitat patches, often within
which a particular target habitat patch is embedded in a matrix. Many authors consider the landscape as a level which can be seen directly by an observer situated
from a specific point of view in a vertical and/or horizontal observation. Because the
intertidal zone is a part of the marine environment, we propose to use the term “intertidal seascape” or “intertidalscape”, better suitable than “landscape” for the intertidal
zone. Thus, an intertidalscape is the set of structural components of the ecosystem
or eco-complex between the low-and high-water tidemarks and can be seen by an
observer situated at sea or on land (cliff, dune. . . ). The aims here are to characterize the intertidalscape evolution resulting from the ecological processes which
control spatial structures (patches and mosaics) in response to natural and anthropogenic disturbances. This approach can answer to questions of connectivity between
patches and components of the ecosystems, which correspond with the definition of
the landscape ecology as defined by Wu (2006), discipline in which the ecosystem
complexity is studied through heterogeneity at various spatial scales. Moreover, in a
second step, if dynamics of the ecosystem components are previously well described
and explained, some landscape indicators can be developed and used to assess the
level of disturbance of these ecosystems. We propose here some considerations for
an intertidalscape ecology based on interpretation of the spatial distribution of structural and functional components. For the rocky shores, these components are habitats
(biotope + biocenosis) localized in the rocky matrix and characterized with several
spatial dimensions based on physical, biological and temporal features (periods of
emersion, stochastic events, seasonality. . . ).
The first step of a landscape approach on the intertidal zone will be the identification and the specialization of the habitats. At a higher scale, the identification
of specific associations of some habitats will be able to define an intertidalscape
typology describing the main categories of ecocomplexes based on their geomorphological, physical, biological, but also socio-economical dimensions. Many authors
(see Schoch and Dethier 1996; Little and Kitching 1996) defined different variables
playing a main role in the rocky shores ecology, variables which could be used to elaborate such a typology. The habitat classifications recently developed at the French
national level (“Cahiers d’habitats” Natura 2000; Bensettiti et al. 2004; Rebent,
Guillaumont et al. 2010) and European Community levels (Natura 2000, EUNIS
(http://eunis.eea.europa.eu)) do not consider the level of landscape. To our knowledge, no one approach is being developed to achieve such an intertidal- sea-scape