369 
To do so an extensive relation study has to 
be made of the succession in different 
locations. To analyse the relations between 
the changes of any one site with its spa 
tial characteristics the use of a Geograp 
hic Information System will be indispensab 
le. The most important factors to examine 
are: 
* distance to sea (salt spray, windvelo- 
city) * age of the landscape (soil proper 
ties) * groundwaterlevel (xero-, hygrosere 
succession) * vegetation in surrounding 
sites * human an animal interference 
In the study area a further rise of the 
groundwatertable is expected in the next 10 
to 20 years. Probably groundwater will 
influence the succession in the dune 
slacks. Without human interference this 
will stimulate the growth of the woody 
species. Dense and tall shrub and woodland 
will increase even more. Loss of the youn 
ger succession stages has to be feared. 
Réintroduction of livestock and activation 
of blowouts may be used as managment tools 
to restore the characteristics of the youn 
ger dunes. 
6 CONCLUSIONS 
The the time interval between the sets of 
photographs fit in with the rates of chan 
ges in the structure of vegetation. 
Aerial photographes give sufficient infor 
mation in landscape transitions and can be 
very useful to develope an adequate dune 
management. In dune areas landscape succes 
sion is a relatively fast process. A dune 
manager should harmonize his way of acting 
to this process. 
Analysis and classification has to be done 
in a systematic way. The great advantage of 
using a determination key is that: 
* interpretation is done systematically 
* all photos are handled in the same way 
* and all maps get the same legend. 
For the case study area the conclusion is 
that: 
Diversity in vegetation structure increa 
sed. Moss/herb/grass vegetations were rep 
laced by shrub and woody vegetations. The 
landscape changed by this bush encroachment 
and became more and more fixated. . If the 
succession in the Haasvelderduinen conti 
nues loss of the open moss and grass vege 
tation , younger succession stages and 
geomorphological processes has to be fea 
red. 
To prevent this loss and to restore dune 
forming processes, (belonging to the grey 
dune area) succession has to be retarded. 
Cattle and sheep grazing and the activation 
of blowouts maybe used as managment tools 
to reintroduce the characteristics of the 
younger dunes. 
ACKNOWLEDGEMENTS 
The author is very grateful to dr. G Bae- 
yens, ing. J.Duyve dr. P. Ketner and ir. A. 
Ehrenburg for their assistance in this 
research. 
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