Hydro-ecological relations in the Delta Waters

wind erasson, desaliuation, aeration, physical and chemical ripening
and decalcification). The time scale of these processed differs from
some manths or years lwind erosion) to tens or hundreds of years
(decalcificetion). In the beg-ing t?e effects of theae individual
processes are quite clear. Wen the new ecosystems grow older it is
getting more and mors difficult to separate them from each other and
from the internal aynamics of the developin& ecosystems theirselves.
Figure 7 (acbording to Drost and Visser. 19111) gives a pod fdea how
the abiotic envixo~meut of different soil types behaves in relation €0
desaUnation. On well percolating soils desalination goes vezy fa&.
Mter some years there is already a rathez large freshwater body in the
soil. Glycophyloue hmbs and grasses can soon caloniee the bare sou
and mrwal shrub and then woodlmd deve,loplaent follows. CLay Layers in
the wail profile stagnate desalination and then this process can take
tens of years. In autumn and Winter the sail is satiuaced fast and most
of ttle rain water will stagmac@ and ran off supetficially. Aere only
the upper soil layers will have E freshwater body and this will
evaporate cempletely in stmmer. In tthis type of habitat halophylous
plant species dominate in the primary vegetation development. !Frees and
shrubs can hardly colonize the vegetation giving it tbe character of
open grassland for a long time.
3.3 Management of water and land
Uatex manasement is especially important on flat shores, where emaller
or larger areas can be inmdated during some time. This is of great
importance for €he suraival and germination oppnrtunitiea 4f certain
plant species. A good exanple how this can influence the fauna is fouad
n Lake Creuelmen. Aere the bird species of scarcely vegetated shell
shores and beaches axe declining (e.g. Kentish Plover, see Fig. 5).
bcaose ef continuing vegetation development. Ffaybe there is a possi-
bility to maintain a larger area of this type of breeding habit& by
raising the waterlevel OS the lake in autumn or winter time during
several weeks. Then a lareer part of the shore is inundated by saline
water, slowing down further vegetation development.