Latest revision as of 08:59, 17 December 2015

Middle Warta River Valley

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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

No data found

Monitoring before and after implementation of the project

Brief description of available records and data ownership:

Before:

• Ornithological monitoring
• Plant communities monitoring

After implementation:

• Ornithological monitoring
• Plant communities monitoring

Data ownership: General Directorate of National Roads and Motorways

Socio-economic aspects

Brief description of socio-economic conditions in the site of the project and how the implementation of the project affects other ecosystem goods and services (e.g. recreation, water purification, flood protection, forestry, etc):

• Ecosystem goods and services:

No data found

• Conflicts and synergies:

No data found

Contact person within the organization

Not available (the project seems not have any sustaining after year 2009)

Extra background information

References

• Winiecki A., Krupa A., (2006) Concept of water circulation restoration in the central part of the Konin Valley between Zagórów and Ląd [in Polish]

• Winiecki A., Stachnowicz W., Mielczarek S., (2009):Environmental monitoring of habitats devastated by the earlier hydrotechnical works in the valley of the Warta and of the newly created conditions for restoration of old ornithological values in the municipalities of Ląd and Zagorów,(Year I - 2009) [in Polish]

• http://obszary.natura2000.org.pl

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

Related Pressures

• Hydrological regime modification
• Artificial barriers downstream from the site
• Alteration of instream habitat
• Embankments, levees or dikes
• Impoundment
• Alteration of riparian vegetation
• Channelisation / cross section alteration