A drastic drying-out of the fen was successful only in the early 20th century, using machines to dig channels. Secondary meadows formed in place of fen, and the most of the lakes disappeared. A large part of the area was ploughed, afforested, and peat mines were opened. In the 1950s, the communist regime organised new drainage activities. A lot of students were driven to the Hanság to dig out new and deep channels, and kill the vipers (Viper rakosiensis, which is now strictly protected!). The regime wanted to demonstrate the victory of humans over nature. However, it soon turned out that agriculture and forestry were not suited for this area — the peat soil degraded quickly and the alien hybrid poplar plantations and crop plants could not grow well because the soil is too wet in the spring, and too dry in the summer. Hay making is the most successful use of land here. Unfortunately, in the last decade, the number of farm animals has decreased drastically in Hungary which has decreased demand for hay, making it no longer worthwhile to mow the meadows. Alien and invasive plant species (Solidago gigantea) are spreading in the abandoned meadows.

In spite of the drainage, and a lot of human disturbance, the Hanság has retained relatively large part of its natural values. Patches of the natural vegetation survived in the wet meadows and forests, and the aquatic communities partly survived in the drainage channels. The peat layer is 50-100 cm thick in an extended area yet. Hanság became a protected natural area in 1976, and since 1994 it has been a part of the Fertö-Hanság National Park. The most serious deficiency of the protected area is the very small percentage of remaining wetlands, so the National Park Authority decided to restore the Hanság’s wetland areas.

Restoration actions

Restoration of the whole former fen would be the most effective approach from a nature conservation point of view, but the present human activity and demand makes it impossible. Technical possibilities, safety and economical criteria were considered when choosing the areas to be restored. In the spring of 2001, 600 ha of a secondary meadow was reconstructed and rewetted from the river Rábca and a drainage channel. The restoration area consists of three units which are connected but which can be flooded independently. Most of the trees were cut down, but some remain on higher ground. Dikes were built around the planned wetland pools, and water was transported through sluices to the area. The water quality is not the best, but not very bad, and regular hydrochemical monitoring has begun. Water depth in the inundated area is between 10-80 cm and some artificial islands were formed to provide nesting habitat for birds. In certain places native plant and fish species were reintroduced. Gravel roads and a lookout stand were built on the dikes to provide the necessary transport for maintaining, controlling, scientific monitoring and future public demonstration. The project was completely financed by the Hungarian State and Dutch Kingdom.

The botanical monitoring started before inundation with habitat mapping of the area. Coenological relevés were made after inundation along 11x100 m long permanent transects — 56 plant species were detected in the secondary meadow, and 21 of them could survive after inundation. In the first vegetation period after inundation, a marshy habitat developed, dominated mainly by Phalaroides arundinacea, Polygonum amphybium, Glyceria maxima, Typha latifolia, Carex acutiformis, and Carex riparia. The effect of water depth was clearly indicated by the development of vegetation types.

After the flooding, many water birds returned to the area. The habitat developed in the first year is suitable for different bird species than habitat of later years. For example, avocet (Recurvirostra avosetta) and black winged stilt (Himantopus himantopus) appeared in the first summer in areas of sparse vegetation, but later on these areas will be covered by close vegetation, so these birds will presumably disappear. The most characteristic breeding species in the first year were the little grebe (Trachybaptus ruficollis) and coot (Fulica atra). Other characteristic breeding species were mallard (Anas platyrynchos), garganey (Anas querquedula), common pochard (Aythya ferina), great-crested grebe (Podiceps cristatus), and red-necked grebe (Podiceps griseigena). Three pairs of strictly protected avocets, 7 pairs of strictly protected black winged silt, and 25 pairs of common tern (Sterna hirundo) built nests on the artificial islands. The area is also an important feeding ground for migrating birds — near many duck species we also continuously observed many great white egrets (Casmerodius albus), grey and purple herons (Ardea cinerea, A. purpurea), spoonbills (Platalea leucorodia) and a pair of feeding white tailed eagles (Haliaetus albicilla).

The monitoring of invertebrate species has started as well.

If we see ecological restoration as a process of repairing the composition, structure, function and dynamics of pre-existing indigenous ecosystems, this Hanság restoration action is not perfect. Inundation by surface water usually is not suitable for full restoration of a fen or a bog. Extended hydrogeological research is necessary to reveal where rewetting by good quality groundwater is possible. We plan to do this work.

The results of the first year biodiversity assessment show that the vegetation of the inundated area consists of common marsh species, but these species were abundant before the drainage of Hanság as well. The new wetland area increased the landscape-level habitat diversity, and provided important nesting and feeding areas for several protected bird species.