time. It is also related to spatial association, whereby there may be alongshore
sequences and stages of development. Therefore, the balances of accumulation
and/or loss may vary in a geospatial arrangement of foredunes that have an array of
differing dimensions in the active beach–dune profile.
There is also the concept of temporal variability. Both Marsh (1864) and Davis
(1956) discuss historical accounts in Europe of coastal dune mobility and stability,
and pose questions about the human role in that dynamic on a century scale. Within a
somewhat longer timeframe, Arbogast et al. (2002) describe evolving natural conditions of foredune growth, stability, mobility, etc., associated with changing lake
levels along Lake Michigan and point to changing sediment supply as the driver for
the sequences of natural mobilization and re-establishment of coastal dunes in the
Great Lakes area and on the oceanic coasts. Thus, there is an inherent temporal
variability in stage of development, and restoration needs to acknowledge that the
foredune feature is probably not definable in absolute terms, but as a geotemporal
stage in the process–sediment response model [see further discussion in Psuty
(2004)]. Indeed, some situations associated with the current sea-level rise scenarios
may cause transfers of sediment in an alongshore context to encourage localized
natural restoration of coastal foredunes (Psuty and Silveira 2010).
3.3.1 Geomorphological Objectives in Foredune Restoration
The geomorphological objective is to define and prescribe the restoration of a
process–sediment response model as the goal for landscape evolution. Importantly,
the model does not have a desired dimensional morphological outcome. It seeks to
achieve maintenance of the processes that are operative at a site and to allow the
vectors of change to occur. In so doing, geomorphological restoration is directed
toward the continuity of the natural change/evolution. There is no final end product
in the natural system; there is continual evolution, as determined by the variable
dimensions of physical processes, the supply of sediment, vegetation colonization
processes, species presence, and the spatial–temporal sequence of landscape
change (van Zoest 1992). Therefore, the goal is to restore the heterogeneity of
features in their geotemporal context. Ehrenfeld (2000) echoes that theme in
stating that restoration ecology should recognize diversity as an outcome and seek
more flexible goals. This is accomplished by allowing the ambient processes to
interact with the natural sediment supply and create the complex of coastal
foredune features. There is a general pattern and sequence that is created by the
sediment budget and there is a more detailed form that is site-specific and nonpredictable. It is not chaos, but it is not totally delimited because the conditions
vary spatially as well as through time. Restoration, in this scenario, applies to the
disencumbering of the ambient processes and the re-establishment of the spatial
mobility of the sediment supply, rather than the creation of a specific ridge of sand.
In the literature, the application of restoration in the context of the coastal
foredune is seen to incorporate several themes and several environmental settings.
36
N. P. Psuty and T. M. Silveira
sequences and stages of development. Therefore, the balances of accumulation
and/or loss may vary in a geospatial arrangement of foredunes that have an array of
differing dimensions in the active beach–dune profile.
There is also the concept of temporal variability. Both Marsh (1864) and Davis
(1956) discuss historical accounts in Europe of coastal dune mobility and stability,
and pose questions about the human role in that dynamic on a century scale. Within a
somewhat longer timeframe, Arbogast et al. (2002) describe evolving natural conditions of foredune growth, stability, mobility, etc., associated with changing lake
levels along Lake Michigan and point to changing sediment supply as the driver for
the sequences of natural mobilization and re-establishment of coastal dunes in the
Great Lakes area and on the oceanic coasts. Thus, there is an inherent temporal
variability in stage of development, and restoration needs to acknowledge that the
foredune feature is probably not definable in absolute terms, but as a geotemporal
stage in the process–sediment response model [see further discussion in Psuty
(2004)]. Indeed, some situations associated with the current sea-level rise scenarios
may cause transfers of sediment in an alongshore context to encourage localized
natural restoration of coastal foredunes (Psuty and Silveira 2010).
3.3.1 Geomorphological Objectives in Foredune Restoration
The geomorphological objective is to define and prescribe the restoration of a
process–sediment response model as the goal for landscape evolution. Importantly,
the model does not have a desired dimensional morphological outcome. It seeks to
achieve maintenance of the processes that are operative at a site and to allow the
vectors of change to occur. In so doing, geomorphological restoration is directed
toward the continuity of the natural change/evolution. There is no final end product
in the natural system; there is continual evolution, as determined by the variable
dimensions of physical processes, the supply of sediment, vegetation colonization
processes, species presence, and the spatial–temporal sequence of landscape
change (van Zoest 1992). Therefore, the goal is to restore the heterogeneity of
features in their geotemporal context. Ehrenfeld (2000) echoes that theme in
stating that restoration ecology should recognize diversity as an outcome and seek
more flexible goals. This is accomplished by allowing the ambient processes to
interact with the natural sediment supply and create the complex of coastal
foredune features. There is a general pattern and sequence that is created by the
sediment budget and there is a more detailed form that is site-specific and nonpredictable. It is not chaos, but it is not totally delimited because the conditions
vary spatially as well as through time. Restoration, in this scenario, applies to the
disencumbering of the ambient processes and the re-establishment of the spatial
mobility of the sediment supply, rather than the creation of a specific ridge of sand.
In the literature, the application of restoration in the context of the coastal
foredune is seen to incorporate several themes and several environmental settings.
36
N. P. Psuty and T. M. Silveira