PROJECT DESCRIPTION
BACKGROUND
The Zwin is the largest and most significant tidal salt marsh site in Belgium, with a surface area of nearly 180 ha on Belgian territory 125 ha of tidal saltwater lagoon, gullies and salt marshes and 55 ha of sand dunes and tidal sandy beach and a further 27 ha in The Netherlands. The RAMSAR convention has defined the site as a wetland of international importance for waterfowl. Along with the nature reserve of the Bay van Heist and the Ijser Geul (estuary of the Yzer), the Zwin is one of the three wildlife stepping stones along the Belgian coast, connecting major sites in The Netherlands, UK and the north of France. To the southeast of the area can be found a polder that was restored as a tidal ecosystem under the ZTAR LIFE project. This project was following up the projectZENO, which focused on a wide restoration plan, creating a complex of around 665 ha of coastal ecosystems. A lagoon was created by sand extraction in the western part of the project's site in the 1950s. Here, small islands have for decades offered a safe breeding ground for numerous birds. As sand deposits begin to connect these islands to the mainland, they become accessible to terrestrial predators and opportunities for safe breeding diminish. This situation has also led to the loss of the habitat, Mudflats and sandflats not covered by seawater at low tide (intertidal habitats). Furthermore, the overgrowth of willows and reeds, the development of fresh and brackish ponds and the accumulation of litter have led to the disappearance of the natterjack toad (Bufo calamita).
OBJECTIVES
The Flemish regional nature and forest agency, which took over the management of the Zwin in August 2006, planned to restore the rich biodiversity of this internationally important Natura 2000 site by carrying out large-scale restoration of the ecological dynamics in the Zwin area. In this way, it would be helping to implement the Birds and Habitats Directives. Specific aims of the project were to:
Restore the habitats of Humid duneslacks and aquatic biotope for the natterjack toad by excavating six depressions in the contact-zones between fresh groundwater and brackish water; Restore salt marsh with colonising Salicornia and other annuals on mud and sand to create developed salt meadows (Glauco-Puccinellietalia maritimae) over 8 ha by cutting off Elymus athericus sods; Restore opportunities for nesting, foraging and resting for coastal bird species, safeguarded from terrestrial predators by restoring the tidal lagoon (9 ha) with its bird islands (3 ha); Repel the encroachment of the salt marshes and dunes with high grasses, in order to restore intertidal habitat types (Livestock grazing would be introduced on 80 ha of salt meadows and 9 ha of dune habitats); and Improve the supply of salt seawater in the tidal flood plain by enlarging the tidal inlet, while raising public awareness and support for its measures through several communication actions.
RESULTS
The ZTAR project completed all the foreseen actions:
The restoration of the western salty lagoon with nesting islands; The restoration/rejuvenation of an area of silted-up and grass-dominated schorre by removing the top soil; The installation of fences for the restoration of the traditional grazing of the salty grasslands (schorre); The digging and restoration of ponds for the natterjack toad; The deepening and enlarging of the main gully of the Zwin estuary (access to the sea and channel for the tidal movements of water) in order to restore the tidal dynamic in the whole area; and The enlarging of the Zwin area by removing the international dyke, allowing the tidal system on an additional 120 hectares of former agricultural land. To publicise these achievements, the project created an exhibition, produced films and held an international conference. The first monitoring results showed that a mosaic of mud flats and plots of vegetation linked to salty soils are starting to form and will soon develop into a foraging area for many birds. Areas that are now being managed by grazing are also developing a diverse vegetation cover in line with the target habitats while those areas where grazing is not occurring are continuing to degrade. Thanks to the restoration of a complex of nesting islets in the western salty lagoon, isolated from the surrounding land and thus protected from terrestrial predators (mainly foxes), the nesting populations of birds have increased in number of species and nesting pairs. Also, the newly dug or restored areas are developing into valuable aquatic sites and natterjack toads have been reintroduced in line with the Flemish action plan for the species. The enlargement and deepening of the Zwin gully has immediately improved the water dynamic in the whole Zwin area. The rising tide enters the area more easily and faster and therefore the most remote parts to the west of the area are better flooded. Moreover, cross-border management of the Zwin has also improved. Further information on the project can be found in the project's layman report and After-LIFE Conservation Plan (see "Read more" section).
