Dynamics, threats and management of dunes

UNDER CONSTRUCTION

==Processes and mechanisms driving natural dynamics & ecosystem development==

During the last thirty years, almost 75% of Mediterranean coastal dunes have been damaged or destroyed, principally by tourism consequences (Géhu, 1985; Salman & Strating, 1992; in Van Der Meulen & Salman, 1993). There are different kinds of destruction causes. First, the natural vents which are erosion by storms or/and sea level rise, overwash, and sea flooding events. The vulnerability of coastal dunes to flooding depends on the characteristics of the dune system itself: height, width, conservation status etc. It also depends on the intensity and impact of the event (e.g. sea level rise, storm intensity). The taller dunes are more resistant to flooding but possibly more susceptible to erosion while the shorter dunes might be more vulnerable to flooding. In the next century, climate change will lead to a rise of mean sea‐level, a likely increase of storms intensity and frequency and a more contrasted distribution of wetness between winter and summer (GIECC 2001, 2007, in Vinchon et al., 2008). These changes will modify the coastal erosion and sea‐flooding hazards. Dune dynamics are driven by naturally occurring disturbances, which can be both common and recurrent. However when these disturbances increase in intensity or frequency or are removed there can be substantial alterations in community dynamics (Psuty and Martinez, 2004). Dunes are thought to be fragile because only a slight disruption (either natural or human induced) may lead to change and long‐term progressive alteration (Carter, 1988) and their natural diversity might be compromised easily.