CHAPTER 20
Quantifying Landscape / Ecological Succession in a Coastal Dune
System Using Sequential Aerial Photography and GIS
S. Shanmugam and M. Barnsley
ABSTRACT: This chapter presents an attempt to measure the path of habitat and
vegetation succession in a coastal dune system (Kenfig NNR, south Wales) using
remote sensing and GIS. The loss of slack habitats associated with the continuing
stabilization of this dune system is a major cause for concern. These habitats support a
range of plant species, including the rare fen orchid, Liparis loeselii, as well as other
hydrophytes. A decrease in their areal extent implies a reduction in biodiversity. To
quantify the overall rate and spatial dimension of these changes, a series of aerial
photographs dating from 1962 to 1994 were digitised and analysed in an image
processing system. The resultant maps, transferred to a vector-based GIS, were used to
derive a transition matrix for the dune system over this period of time. The results
indicate that there has been a marked reduction in the total area of bare sand (19.6% of
the dune system in 1962, but only 1.48% in 1994) and a decline in both the areal
extent and the number of dune slacks. Over the same period of time, there has been an
increase in Salix repens dominated habitats, at the expense of pioneer species. Analysis
of the habitat maps, together with hydrological data, within the GIS suggests that even
the dry slacks have the potential for further greening and to support invasive species.
In terms of habitat management, however, there is still scope to restore many of the
slacks to their original state. It is estimated that at least 24% of the area occupied by
partially and moderately vegetated slacks could be rehabilitated.
Introduction
The coastlines of the world, over 440,000 km in length, represent both a dynamic
natural environment and an important context in which a diverse range of human
247
D.R. Green and S.D. King (eds.), Coastal and Marine Geo-Information Systems, 247–260.
© 2003 Kluwer Academic Publishers. Printed in the Netherlands.
Quantifying Landscape / Ecological Succession in a Coastal Dune
System Using Sequential Aerial Photography and GIS
S. Shanmugam and M. Barnsley
ABSTRACT: This chapter presents an attempt to measure the path of habitat and
vegetation succession in a coastal dune system (Kenfig NNR, south Wales) using
remote sensing and GIS. The loss of slack habitats associated with the continuing
stabilization of this dune system is a major cause for concern. These habitats support a
range of plant species, including the rare fen orchid, Liparis loeselii, as well as other
hydrophytes. A decrease in their areal extent implies a reduction in biodiversity. To
quantify the overall rate and spatial dimension of these changes, a series of aerial
photographs dating from 1962 to 1994 were digitised and analysed in an image
processing system. The resultant maps, transferred to a vector-based GIS, were used to
derive a transition matrix for the dune system over this period of time. The results
indicate that there has been a marked reduction in the total area of bare sand (19.6% of
the dune system in 1962, but only 1.48% in 1994) and a decline in both the areal
extent and the number of dune slacks. Over the same period of time, there has been an
increase in Salix repens dominated habitats, at the expense of pioneer species. Analysis
of the habitat maps, together with hydrological data, within the GIS suggests that even
the dry slacks have the potential for further greening and to support invasive species.
In terms of habitat management, however, there is still scope to restore many of the
slacks to their original state. It is estimated that at least 24% of the area occupied by
partially and moderately vegetated slacks could be rehabilitated.
Introduction
The coastlines of the world, over 440,000 km in length, represent both a dynamic
natural environment and an important context in which a diverse range of human
247
D.R. Green and S.D. King (eds.), Coastal and Marine Geo-Information Systems, 247–260.
© 2003 Kluwer Academic Publishers. Printed in the Netherlands.