Jeziorsko reservoir (967)
Poland, Europe
Site overview
KBA status: confirmed
Global KBA criteria: D1a
Year of last assessment: 2010
National site name: Zbiornik Jeziorsko
Central coordinates: Latitude: 51.7833, Longitude: 18.6833
System: freshwater, terrestrial
Elevation (m): 90 to 120
Area of KBA (km2): 99.4167
Protected area coverage (%): 99.08
KBA classification: Global
Legacy site: Yes
Site details
Site description: A storage reservoir (16 km by 3.5 km) in the lowland valley of the unregulated Warta river, between Skêczniew and Warta towns. Meadows and pastures adjoin the reservoir near Proboszczowice and Dzierz¹¿na villages. Its shoreline is formed by natural valley slopes, side dams (which block the mouths of the Teleszyna and Pichna rivers), and also backwater dams, which limit the flooding area when the water-level is at its highest (maximum area is 4,200 ha). The reservoir bottom was not modified before flooding and, when the water-level is low (minimum area 1,700 ha), a varied terrain with scattered small hollows is exposed. The southern part of the reservoir, which floods only during times of high water, is occupied by a mosaic of meadows and willow Salix scrub with groups of partly dead trees. Highest water-levels are reached in April and May, followed by a slow fall.
Rationale for qualifying as KBA: This site qualifies as a Key Biodiversity Area of international significance that meets the thresholds for at least one criterion described in the Global Standard for the Identification of KBAs.
Additional biodiversity: A notable site for breeding and migrating waterbirds; breeding numbers vary from year to year, depending on the water-level. Breeding species of global conservation concern that do not meet IBA criteria: Crex crex (one pair, irregularly).
Habitats
Land use: agriculture (20%) | water management (80%)
| IUCN Habitat | Coverage % | Habitat detail |
|---|---|---|
| Wetlands(Inland) | 95 | |
| Grassland | 5 |
Threats
Summary of threats to biodiversity at KBA: Birds are disturbed by tourism/recreation. Lowering of the water-level too early in the season destroys many nests. The southern part of reservoir is a `silence zone', and is planned as a bird reserve (not yet designated).
| Threat level 1 | Threat level 2 | Threat level 3 | Timing |
|---|---|---|---|
| Agriculture & aquaculture | Annual & perennial non-timber crops | Small-holder farming | Ongoing |
| Agriculture & aquaculture | Marine & freshwater aquaculture | Subsistence/artisinal aquaculture | Ongoing |
| Natural system modifications | Dams & water management/use | Abstraction of surface water (agricultural use) | Ongoing |
| Invasive & other problematic species, genes & diseases | Invasive non-native/alien species/diseases | Unspecified species | Ongoing |
| Pollution | Domestic & urban waste water | Type Unknown/Unrecorded | Ongoing |
| Natural system modifications | Other ecosystem modifications | Ongoing | |
| Residential & commercial development | Tourism & recreation areas | Ongoing | |
| Energy production & mining | Renewable energy | Ongoing | |
| Human intrusions & disturbance | Recreational activities | Ongoing | |
| Climate change & severe weather | Storms & flooding | Ongoing |