Middle Warta River Valley
Middle Warta River Valley
Key features of the case study
This restoration project was implemented as compensation to loss of ecologically important part of Middle Warta River Valley (Natura2000 site) due to construction of the A2 motorway. Compensation activities aimed for restoration of habitats partly devastated by the earlier hydrotechnical works in the valley of the Warta and in turn to create condition for restoring old ornithological values in this area.
Site description
Particular conditions of the site: size, river type, type of pressures, ecological status, etc.:
The investigated site is located on the Warta river (type 21 – Large lowland river) in its middle course between town of Zagórów and Ląd village. It stretches along ca. 6km of the river and covers area of approximately 420ha. It is a part of large (57104,4 ha) Important Bird Area – Middle Warta River Valley and belongs to Natura2000 network. This IBA is characterized as large site encompassing a wide river valley and being an important breeding site for many species of waterbirds (including ducks, waders and terns) and forest birds (e.g. Middle Spotted Woodpecker) in the country. Since the 70ties of XX century this part of the valley was suffering from deterioration caused by influence of up-stream located reservoir Jeziorsko and by increase of embankments constructing. These factors caused negative changes in water conditions leading to abandonment of agricultural use of land (extensive hay making), secondary succession and in turn disappearing of habitats suitable for birds of the area. Water conditions changes went to both, drying of land in some parts due to too low flow as result Jeziorsko reservoir work regime and cutting off parts of the valley by embankments, and prolonged water stagnation behind the embankments in some parts. The Zagórów – Ląd stretch was one of the most environmentally valuable and at the same time the least deteriorated areas. Therefore, it constituted potentially the area with the largest chance for successful restoration and that’s why it was selected as compensation area for the restoration project. The main pressures in this area can be summarized as: altered hydrological regime due to work regime of Jeziorsko reservoir; construction of long embankments cutting off lateral connectivity between river and its floodplain; construction and malfunctioning of reclamation systems in the valley; changes in land use in the valley.
Measures selection
Motivation/argumentation behind the selection of the measures implemented:
A set of measures aiming for improving lateral connectivity between the main river channel and floodplains was implemented. It should have been leading to reconnect backwaters and wetlands and to create more similar to natural pattern of inundating the river floodplain to improve habitats proper for the desired in the area bird species. In this set following measures were proposed: culverts in the embankments along the river and in embankments of roads located in the floodplain; restoration (by removing sediment and vegetation) of ditches and backwaters in the floodplain; restoration of connection between the main channel and oxbows and backwaters.
Success criteria
Plant communities:
- Presence of species rare from point of view of conservation values
Avifauna:
- Reconstruction of sites important for breeding, migration and overwintering of birds
- Presence and number of species pairs
Ecological response
Intended effects on water restoration and recovery habitats important for nature conservation has not been achieved. This is due for the following reasons:
- a strategy for water management in this part of the valley throughout the existing system of hydraulic structures has not been developed and implemented – it is a task for an urgent execution if the restoration should be successful;
- Despite the existence of IBA, water discharge from Jeziorsko reservoir, operated by Regional Water Management Board in Poznan, does not take into account in any way needs of environmental protection, particularly birdlife and its habitat, that is a subject of protection of this Natura 2000 site. In the current situation it can be expected that within a few years this IBA will finally loss its values and ultimately will be eliminated due to a lack of protection object – it requires immediate resolving.
Therefore, it is difficult to say about fulfilling any of success criteria. Only some minor improvements in number of bird and fish species can be observed, but they don’t have character of general positive changes in ecosystem quality in the area.
Brief description of observed effects of the measures over different types of organisms:
- Phytoplankton
No data found
- Macrophytes and phytobenthos
No data found
- Benthic Invertebrates
No data found
- Fish
4 species from the list of Directive 92/43/EWG were found : Rhodeus sericeus, Misgurnus fossilis, Cobitis taenia, Aspius aspius
- Other biota
Hydromorphological response
Monitoring before and after implementation of the project
Socio-economic aspects
Contact person within the organization
Extra background information
References
Related Measures
- Improve/Create water storage
- Improve water retention
- Increase flood frequency and duration in riparian zones or floodplains
- Link flood reduction with ecological restoration
- Manage aquatic vegetation
- Modify culverts, syphons, piped streams
- Reconnect backwaters and wetlands
- Restore wetlands
- Retain floodwater
