English summary
Wetlands: challenges and innovation in succession management
Objectives
The wetlands of Wieden and Weerribben belong to the most important wetland ecosystems in Western Europe. In order to maintain all rare habitats in the course of succession from open water to wet forest continuous management efforts are needed. In order to enlarge and to secure the biodiversity for the future, management tools are needed that are complementary tot the regular management. The main tools in this project to enhance biodiversity are the creation of more open water, especially in areas with a good water quality, the recovery of floating trembling bogs and the improvement of the reed beds by removing the top soil. These measures will improve the habitats and the conditions for the plants and animals that depends on these ecosystems. Another important focus of attention will be the recovery of natural gradients between open water and the surrounding vegetations.
The project will stimulate the area and quality of the following habitats: oligo-mesotrophic water with benthic vegetation of Chara spp. (3140), natural eutrophic lakes with Magnopotamion or Hydrocharition vegetation (3150), calcareous fens with Cladium mariscus and species of the Caricion davallianae (7210),, transition mires and quaking bogs (7140), Molinia meadows on calcareous, peaty or clayey-silt-laden soils (6410), wet heath with Erica tetralix (4010), hydrophilous tall herb fringe communities (6430) and bog woodland (91D0).
Apart from improvement of the habitats the project will also benefit several species mentioned in the Habitat and Bird Directive. Special attention will be given to the Bittern (Botaurus stellaris), the Black tern (Clidonias niger), the Fen orchid (Liparis loeselii) and the endemic subspecies of the butterfly Large copper (Lyceana dispar). To the other species that will benefit from the improvement of these habitats belong the dragonfly Leucorhinia pectoralis, and the fishes Rhodeus sericeus, Misgurnus fosilis and Cottus gobio.
A relevant part of this application forms the monitoring of the effects of more fluctuations in water level to the most relevant habitats in these wetlands. We are very happy that there is support in the region to realise more natural fluctuations in the water level in the whole wetland area. Nowadays there is almost no fluctuation, whereas higher levels in winter and lower in summer support a better water quality, and improves succession from open water onwards. However, before realising increasing fluctuation a pilot in a representative area of the wetland is needed. This pilot will be performed in a part with the already mentioned habitats and species.
The complete wetland area of Wieden en Weerribben is about 9000 ha. The direct effects of the interventions will affect about 123 ha but the integral effects will be visible in a much larger area, estimated to be about 1200 ha. The influence on this area of about 1200 ha will be mainly due to the improvement of the water support, enabling to prevent lowering of the internal water levels. The high costs of this application pro hectare are much lower when we take this much larger area into account!
Actions and means involved
The main actions are: 1) realising new open water; 2) recovery of buffered reed beds by removing the acidified top soil; 3) removing the trees from wet and young forest in order to recreate reed beds with Sphagnum, as well as to enable good conditions for quivering bogs and trembling bogs. Special attention will be focused on the improvement of the habitat for the Bittern, mainly by attention for improving gradients between water and reed beds as well as by removing the top soil of dried up reed beds. Apart form the measures in the field there will be much attention for informing the public. Since the project can be very interesting for other managers of wetlands we will organise a workshop for European partners, especially for those with LIFE-projects.
Expected results
Enlarged size and quality of the relevant habitats and increased population size of many rare species of these wetlands in a substantial part of the wetlands of Wieden and Weerribben. Due to the measures we will be able to maintain the variation in habitats of these complex ecosystems.
