Project part-financed by the European Union (European Regional Development Fund)

The Interreg IVB North Sea Region Programme

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Monitoring results

In order to document the vegetation and breeding bird development, several function controls were executed since 1998. The project area represents one of the most valuable breeding sites for birds at the Wurster coast. As expected, salt marsh vegetation developed along the ditches and within the diked-out areas. The salt water influence on the project area was documented by electrical conductivity measurements.

Breeding birds
According to inventories of 2004, Eurasian Skylark (Alauda arvensis), Common Redshank (Tringa totanus) and Northern Lapwing (Vanellus vanellus) represent the dominant breeding bird species on the project area (KÜFOG 2004). Referring to the Red List of Lower Saxony and Bremen, all these species are endangered grassland birds (SÜDBECK & WENDT 2002).
Between 1998 and 2004, the population of Eurasian Skylark and Common Redshank increased significantly on the project area, while the populations of Northern Lapwing (Vanellus vanellus) and Oystercatcher (Haematopus ostralegus) slightly decreased. Behind the background of generally shrinking grassland bird populations in northwestern Germany (NEHLS ET AL. 2001, SÜDBECK & WENDT 2002, SEITZ 2001), it is likely that the increase of population size can be ascribed to the effects of the compensation measure: Extensive grassland use creates a varied, small scale mosaic of vegetation and soil structure offering suitable breeding grounds for wading birds. According to WILMS ET AL. (1997), the project area is assigned as important breeding bird site for the federal state of Lower Saxony.
The stagnating or decreasing development of breeding bird population on the project area between 2001 and 2004 is possibly due to relatively strong dehydration of the project area during spring time. Therefore, the area irrigation depending on the tides is to be improved. Currently, irrigation hardly contributes to soil moisture or to the establishment of shallow water zones on the project area. The ditch water level in the southern part of the project area sank during spring about 30 cm compared to the starting value. After high precipitation or flooding events, water covered areas remain due to the small standing waters and dams created in the northern part of the project area. This enhances the attractiveness of the area as breeding and resting habitat for coastal birds.
According to observations in 2004, a decline of breeding success regarding Common Redshank compared to the situation in 2001 can be stated, while the low breeding success of Northern Lapwing observed in 2001 can be confirmed. For a reliable statement on the breeding success, systematical breeding success controls would be necessary.

First vegetation inventories showed that rare and worth protecting species like Pond water crowfoot (Ranunculus peltatus), Marsh arrowgrass (Triglochin palustris) and Caraway (Carum carvi) are already in place and can be promoted by the compensation measures (KÜVER 2004).
In 2007 (Figure 4), the following positive developments in terms of the development targets were stated:
  • The plant community Puccinellietum maritimae spread on the outer dike areas of the project area and hints at increasing salt influence.
  • According to KÜVER 2004, the flattened ditch banks in the diked-out areas of the project area were settled with patchy salt pioneer vegetation, which presumably developed further to a dense plant community (Plantagini-Limonietum vulgaris) with a high percentage of perennial vegetation and dwarf-shrubs (BIOS 2007).
  • Within the summer polder, water storage led to extensive inundation and salinization of the rich pastureland. Significant is the increasing distribution of the scarcely vegetated small standing waters with Puccinellietum distantis communities in front of the dike.
  • The population size of halophytes remained stable or increased. The core area of distribution is situated in the southwestern part of the outer dike area and spreads to the northern summer polder along ditch and creek banks.
  • According to investigations in 2007, Cirsium arvense is not as dominant in rich pastureland as observed in 2004. Presumably, this development is a result of maintenance mowing practiced in the meantime or/and of increased salt influence.

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Report: Management measures analysis and comparison