Most coastal dune systems in western Europe are currently in a phase of stabilization (e.g., Provoost et al. 2011). Again, the true reason is not well understood.
Stabilization of these systems may occur because of stabilizing efforts of man over
centuries, reduced anthropogenic pressure, like grazing and wood gathering,
nitrogen input from air pollution, the absence of rabbits due to diseases or climatic
change. Because of stabilization, pioneer stages are becoming rare, causing biodiversity to decrease in many dune systems. Managers try to counteract these
negative effects, for example, by removing vegetation in order to set back vegetation succession, or by restoration of mobile dunes. The question here is whether
stabilization can be reversed in a sustainable way, for example, by restoring natural processes. Or will managers be forced to fight stabilization ‘‘forever’’? What
are the key factors in dune mobility or dune stability? Which can be adapted?
What are the links between nature management and coastal defense? How can the
two benefit from one another? And finally, how can we manage dune landscapes in
a responsible way, that justifies the important geomorphological, ecological, and
other societal values.
7.2 Mobility Versus Stability: The Struggle of Vegetation
Against Sand
Dunes all over the world experience alternating phases of mobility and stability
(e.g., McFadgen 1985, 1994; Arbogast et al. 2002; Tsoar and Blumberg 2002;
Hugenholtz and Wolfe 2005; Clemmensen and Murray 2006; Kutiel 2013). Also,
within a system, mobile and stable phases can coexist (Barbosa and Dominguez
2004; Tsoar 2005; Yizhaq et al. 2007). The state of the system is governed by
climatic parameters and the availability of sand, but on a smaller scale random
processes may interfere.
7.2.1 Driving Forces
Three major driving forces can be recognized (Hesp and Thom 1990): wind
energy, the growing capacity of vegetation, and sand availability (Fig. 7.1).
Human impact (management, nitrogen input, overgrazing) exerts its influence
through its effect on vegetation growth. Transitions from one phase to the other are
driven by changes in climate, sand supply, human impact and other disturbing
factors that might act randomly in space (e.g., rabbit digging). In essence, the
problem of mobility versus stability can be reduced to the struggle of vegetation
against sand: which of the two dominates?
Wind energy and the growth characteristics of vegetation are governed by
climate. For example, increased storminess will increase the available wind energy
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S. M. Arens et al.
Stabilization of these systems may occur because of stabilizing efforts of man over
centuries, reduced anthropogenic pressure, like grazing and wood gathering,
nitrogen input from air pollution, the absence of rabbits due to diseases or climatic
change. Because of stabilization, pioneer stages are becoming rare, causing biodiversity to decrease in many dune systems. Managers try to counteract these
negative effects, for example, by removing vegetation in order to set back vegetation succession, or by restoration of mobile dunes. The question here is whether
stabilization can be reversed in a sustainable way, for example, by restoring natural processes. Or will managers be forced to fight stabilization ‘‘forever’’? What
are the key factors in dune mobility or dune stability? Which can be adapted?
What are the links between nature management and coastal defense? How can the
two benefit from one another? And finally, how can we manage dune landscapes in
a responsible way, that justifies the important geomorphological, ecological, and
other societal values.
7.2 Mobility Versus Stability: The Struggle of Vegetation
Against Sand
Dunes all over the world experience alternating phases of mobility and stability
(e.g., McFadgen 1985, 1994; Arbogast et al. 2002; Tsoar and Blumberg 2002;
Hugenholtz and Wolfe 2005; Clemmensen and Murray 2006; Kutiel 2013). Also,
within a system, mobile and stable phases can coexist (Barbosa and Dominguez
2004; Tsoar 2005; Yizhaq et al. 2007). The state of the system is governed by
climatic parameters and the availability of sand, but on a smaller scale random
processes may interfere.
7.2.1 Driving Forces
Three major driving forces can be recognized (Hesp and Thom 1990): wind
energy, the growing capacity of vegetation, and sand availability (Fig. 7.1).
Human impact (management, nitrogen input, overgrazing) exerts its influence
through its effect on vegetation growth. Transitions from one phase to the other are
driven by changes in climate, sand supply, human impact and other disturbing
factors that might act randomly in space (e.g., rabbit digging). In essence, the
problem of mobility versus stability can be reduced to the struggle of vegetation
against sand: which of the two dominates?
Wind energy and the growth characteristics of vegetation are governed by
climate. For example, increased storminess will increase the available wind energy
108
S. M. Arens et al.