PROJECT DESCRIPTION
BACKGROUND
The project area is located in the Lower Isar Valley in Bavaria, Germany. It covers 699 ha, about 31 km of the river Isar as well as the outstanding alluvial forest and alluvial island system between Loiching and Ettling in the county of Dingolfing-Landau. The river Isar, via the Danube, connects the alpine region with Eastern Europe and therefore plays a very important role in the bio-geographical habitat network, especially for wetland, peatland and dry habitats.
The original character of the alpine and pre-alpine river Isar, however, has changed considerably. Large-scale modifications to the river have been made to meet the demands of flood protection, energy production and the intensification of land use. The ecological function of the river, as well as the alluvial floodplains and the natural dynamics of the alluvial floodplains, have declined significantly. Multiple damming of the riverbed has moreover created migration barriers for a range of species while also preventing the transportation of sediment. Former structures, habitats or species that were characteristic of this area have now disappeared or are highly endangered.
OBJECTIVES
The main aim of the project LIFE Flusserlebnis Isar was to improve the habitats at the Isar valley through restoration measures focused on the river Isar and specific tributaries, and by optimising the habitat conditions in the alluvial areas. It was focused on demonstrating scientific and economic synergies created through close cooperation between water management and nature conservation authorities.
Specific project aims were to:
- Restore the riverbanks of the Isar and its tributaries to improve river dynamics and habitat functions for organisms living in running watercourses;
- Optimise, increase and connect soft- and hardwood alluvial forests with typical alluvial water bodies, especially in areas of restored riverbanks;
- Extend and connect important dry habitats such as alluvial islands;
- Protect seven habitat types listed in Annex I of the Habitat Directive, including two priority ones, and seven species in Annex II of the Habitat Directive as well as to improve their conservation status; and
- Raise awareness among the public and land users of Natura 2000, the LIFE nature project with its valuable habitat types and species, as well as the importance of complex alluvial systems for biodiversity.
RESULTS
The project was completed with success. It has achieved and significantly exceeded its objectives. With the expansion of the project area in one of its most important river sections, the overall project area was also enlarged and the overall impact on aquatic biota and habitats was increased. The large-scale measures implemented contribute significantly to improving the conservation status of targeted habitats and their species and increase coherence in the Natura 2000 network. More specifically, this is the case for the habitats of the river, the riparian forests, and the floodplain waters as well as for the raw and dry sites of the floodplains with their characteristic species inventory.
At the project's core were large-scale construction measures aimed at restoring the river and its bank structures. In the end, the massive earthworks caused considerable additional costs totaling over 1 million euros, which were covered by additional state funding from the Free State of Bavaria, in particular from the Water Management Administration. But it was worth it because the ecological added value is considerable.
The main results of the concrete restoration measures are as follows:
- Creation of structurally rich riverbanks and development of gravel banks and shallow water zones over a length of more than 4,000 m, leading to an improvement in the habitat situation for typical representatives of the barbel region and to a high occurrence of juvenile fish in the restored areas.
- Removal of 5000 m of concrete embankments and creation of near-natural bank and bed structures.
- Revitalisation of an abandoned floodplain oxbow arm over a length of 1.5 km, where the innovative siphon pipe ensures a permanent flow of water.
- Creation of a new, 650 m long side arm with calm shallow water zones like spawning and juvenile fish habitat and new steep natural banks.
- Creation and optimisation of 8 floodplain waters over an area of around 5 ha.
- Creation of 28 small waterbodies in the floodplain as new habitats, especially for amphibian fauna and aquatic insects.
- Development of deciduous and coniferous forests on 55 ha with the long-term goal of achieving a favourable conservation status for habitat types 91E0*, 91F0.
- Creation of deciduous and coniferous forests on 7.3 ha to improve the connectivity of existing habitats; revitalisation of 98 old pollarded willows.
- Creation of dry calcareous grassland on 2.65 ha and lowland hay meadows on 11.27 ha to be developed into the high-quality habitat types 6210 and 6510 in the long term.
- Creation of 58 small biotope structures as suitable habitats for amphibians, insects and reptiles.
- Two large bird nesting aids, 178 nesting boxes and a kingfisher breeding wall installed to create sufficient nesting opportunities for birds of prey, cavity-nesting bird species and bats.
- Securing 33 old biotope trees.
- Purchase of 3.1 ha of agricultural and forestry land for conversion into nutrient-poor open and forest habitats.
The above-mentioned measures have already had a significant positive impact on nature conservation shortly after their implementation. This applies in particular to the rapid response of several fish. Fish population surveys in the main river before and after the implementation of measures showed increase of Sneep (Chondrostoma nasus) about 100 times. The number of catches of the Danube Roach (Rutilus pigus) increased by a factor of 40. A considerable increase was surveyed also in other endangered rheophilic fish species, such as the Danube Whitefin Gudgeon (Romanogobio vladykovi), the Asp (Leuciscus aspius), the European Bitterling (Rhodeus amarus) and the European Bullhead (Cottus gobio). New steep banks were soon utilised by sand martins (Riparia riparia) - they occupy the new river arm with around 200 breeding tubes, which became one of the most important colonies in Bavaria. Several pairs of Little Ringed Plovers (Charadrius dubius) have successfully bred on the newly created gravel banks.
Besides all expected above mentioned ecological effects, visible socio-economic benefits were achieved thanks to the improvement of the accessibility of the Isar river with adjacent Natura 2000 habitats and thus, the increase of the recreational value for local and regional inhabitants. A nature trail of exemplary quality with numerous info boards and intercommunicative stations has been planned and built to raise awareness of public about the river and floodplain habitats and species and their values. Many specialists from German-speaking EU countries were invited to learn about the results of the project at a final project conference. The contracts for the implementation measures benefited the regional construction industry, regional agricultural and forestry enterprises. Regional service companies significantly benefit from the subcontracts, specially from the contracts necessary for the implementation of the large-scale restoration actions.
The project helped implement the Habitats Directive, the Birds Directive and the European Water Framework Directive. It has exemplarily demonstrated conservation scientific and economic synergies created through close cooperation between nature conservation and water management authorities, and all major stakeholders. The proper management of the project sites after the end of the project is secured on a long-term basis by the responsible Water Authority (WWA Landshut), i.e. by the CB itself. The project has substantial demonstration and replication potential. Already in the intermediate stage, it gave the first impulses to continue the restoration of the Isar elsewhere upstream. Inquiries come from several water authorities.
