Hydro-ecological relations in the Delta Waters
Hydro-ecological relations in the Delta Waters Hydro-ecological relations in the Delta Waters
As mentioned above aa important question is wh~type of nature w want to &evelop. Do we wwt open easy grassy areas where geese can forage and waders can breed, or vast m?.rshy woods with breeding colonies of rare and threatened birds like the Swonbill Bnd the Bightheron? D? maybe we prelex a mare patchy landscape with grassland vegetation alternating with Shrubs and aoadlmds, inhabitated by threat&& invertebrates, amphihia and reptiles. All these types are possible in large parts of the nw land. %at will be realized depends on t?ie choice how to manage nature. To make such choices the following criteria can be used. Firstly there are the potentialities of the area that may determine the choke. It is good to poiat out several elements of this criterion, like: * The abiotic enviromental onditions, that may differ from place to place. On a salty soil, for instance, it is rather easy to develop a grassland vegetation, but a woodland will nor grow there hefare the soil is desalinated to a depth of several metres. * New plant and animal species will have to ~oloaize the new ateas. ?herefore the proportion of the area, its position to the acraal distribution of the species ~imed at and the presence of suitable migrating zones are very Impe~tant. * Ecosystem& must not only be realisable. They must also be maintainable, especially on the long m. Another important criterion to formulate the goal for ecosystem development is the significence of the nev type of nature for nature conservation. It wfll be clear that the highest priority must be given to species and commities that are threatened on an internatbnal scs%e. A fine1 criterion ia the technical and financial ability to realize the management that is required.
6 SPATIAL VXW If we tmslate the things rienti~ned ab~ve spatially the Eollowfng pattern reeult-s (Fig. 8) . Figure 8 Priorities for futural ecosystem development in the (former) estuaries of the South-West Netherlands. Open circles: salt marshes; hatched circles: former lnarshes and tidal flats to develop as open landscapes; black circles: the same, but to develop as woody landscapes; crosses: agricultural areas that can he set aside for ecosystem development Firstly there is a strong reduction of the salmarsh area. On the one hand the greater part of the remaining salt marshes in the Westerschelde are under great mvironmental pressure and on the other there are hardly any perspectives to develop new marshes in the relatively clean Oosterschelde. This loss can partially he counterbalanced by setting aside parts of some wet agriculture areas in the polders along the Oosterschelde. In those areas, with a lot of saltwater seepage, there are very good conditions to create inland salt marshes and brackish grasslands or even to abandon polderland to tidal influence. Especially the plants and animals of the higher salt marshes can find a habitat here.
- Page 62 and 63: and only l-2% cows frm the aive Sch
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6 SPATIAL VXW<br />
If we tmslate <strong>the</strong> th<strong>in</strong>gs rienti~ned ab~ve spatially <strong>the</strong> Eollowfng<br />
pattern reeult-s (Fig. 8) .<br />
Figure 8 Priorities for futural ecosystem development <strong>in</strong> <strong>the</strong> (former)<br />
estuaries of <strong>the</strong> South-West Ne<strong>the</strong>rlands. Open circles: salt<br />
marshes; hatched circles: former lnarshes and tidal flats to<br />
develop as open landscapes; black circles: <strong>the</strong> same, but to<br />
develop as woody landscapes; crosses: agricultural areas that<br />
can he set aside for ecosystem development<br />
Firstly <strong>the</strong>re is a strong reduction of <strong>the</strong> salmarsh area. On <strong>the</strong> one<br />
hand <strong>the</strong> greater part of <strong>the</strong> rema<strong>in</strong><strong>in</strong>g salt marshes <strong>in</strong> <strong>the</strong><br />
Westerschelde are under great mvironmental pressure and on <strong>the</strong> o<strong>the</strong>r<br />
<strong>the</strong>re are hardly any perspectives to develop new marshes <strong>in</strong> <strong>the</strong><br />
relatively clean Oosterschelde. This loss can partially he<br />
counterbalanced by sett<strong>in</strong>g aside parts of some wet agriculture areas <strong>in</strong><br />
<strong>the</strong> polders along <strong>the</strong> Oosterschelde. In those areas, with a lot of<br />
saltwater seepage, <strong>the</strong>re are very good conditions to create <strong>in</strong>land salt<br />
marshes and brackish grasslands or even to abandon polderland to tidal<br />
<strong>in</strong>fluence. Especially <strong>the</strong> plants and animals of <strong>the</strong> higher salt marshes<br />
can f<strong>in</strong>d a habitat here.