HYDROLOGICAL SYSTEMS BEYOND A NATURE-RESERVE, THE MAJOR PROBLEM IN WETLAND CONSERVATION OF NAARDERMEER (THE NETHERLANDS)

Ecological relations within a wetland depend on it is hydrology, but t his is determined largely by what happens outside the wetland area. Th ese statements are illustrated with respect to the Naardermeer nature reserve in the Netherlands. Succession and eutrophication have led to a reduction in the variety of vegetation types in the area. Eutrophica tion has been caused by a lowering of the water levels, deposition of guano in bird colonies, pollution of surface water and groundwater, an d atmospheric deposition. The fact that most restoration activities ha ve to be executed outside the wetland demonstrates that the management of the conservation of wetland ecosystems needs to operate on a regio nal scale. The conservation of a wetland depends on water bevels. Howe ver, the qualitative aspects of hydrology are also important. Since la ndscape ecological relations with the surrounding area provide for tra nsport of nutrients, a wetland is not isolated. Changes in hydrology h ave an impact on processes that affect the ecosystems in different way s. These relations ave illustrated from a reserve in the centre of the Netherlands.