Riverscape Lower Inn - An ecological perspective for riverscape management in the floodplains of the Lower Inn

PROJECT DESCRIPTION

BACKGROUND

The project is located at the border between Germany and Austria in the SACs Salzach und Unterer Inn (DE7744371), Unterer Inn (AT3105000) and "Auwlder am unteren Inn" (AT3119000) as well as in the SPAs Salzach und Inn (DE7744471) and "Unterer Inn" (AT3105000). The site comprises a heavily altered river-floodplain system with several specific attributes that give it a high conservation value but also pose challenges for its management:

The area is one of the most important breeding, resting, and wintering areasin Central Europe, with over 130 proven breeding bird species;

The Inn river provides habitat for several protected fish species;

Key fluvial habitats for the rheophilic fish fauna are largely missing;

Two hydropower plants pose a barrier for fish and other aquatic organisms;

Habitats and species once typical for (dry) barren sand- and gravel habitats are limited to secondary habitat-sites such as the flood protection dykes;

Riparian forests (91E0*) are over-aged due to missing rejuvenation, many stocks are dominated by allochthonous trees and shrubsand;

Many small aquatic waters have disappeared over the past few decades due to siltation and terrestrialisation having an adverse impact on amphibian and other fauna and flora of temporary water bodies; and

Human uses such as recreation, fishing, and hunting may disturb the breeding birds.

OBJECTIVES

The LIFE Riverscape Lower Inn project aims to improve site-specific habitats and their connectivity in one of the largest coherent river-floodplain systems of the River Inn. The complex framework conditions call for a systemic, large-scale approach to secure the ecological value of the site over the long term. The project has thus been designed as part of a comprehensive management strategy for the River Inn, its floodplains and the dam system. The measures also complement previously realised projects in the impoundments of the hydropower plants Ering and Egglfing as well as previous LIFE projects. Additional to the objectives listed in the FFH and Bird Directives, the project will help to meet the requirements of the Ramsar Convention and the Water Framework Directive. Measures will help achieve good ecological potential and good ecological status as specified in the River Management Plans. Specifically, the project aims to:

Improve habitat conditions and conservation status for breeding, resting and wintering bird species including Alcedo atthis, Nycticorax nycticorax, and all species of waders and waterfowl;

Improve habitat conditions and conservation status for the endangered rheophilic fish guild, including Hucho hucho, Romanogobio uranoscopus, R. vladykovi, and L.souffia agassizi;

Improve habitat conditions and conservation status for the typical wetland fauna and flora including 91E0*, amphibians and insects;

Improve habitat conditions and conservation status of dryland species and habitats, to benefit particularly the habitat types 6510, 6210/6210* and Lanius collurio;

These main goals can be broken down into the following specific feasible objectives:

Create of high-quality fluvial habitats such as shallow banks, gravel bars, riffles and steep erosional banks;

Carry out de-sedimentation measures to create high-quality habitats such as oxbows, shallow banks and mud flats;

Create high-quality habitats in the mouth of tributaries;

Create natural, unfortified river banks;

Connect fluvial habitats to allow rheophilic fish access to upstream section, tributaries, and large floodplain areas;

Interlink highly productive floodplain habitats;

Implement a vegetation management to foster vegetation types of European importance; and

Implement a visitor management

The project aims at a hydromorphological/connectivity impact remediated in more than 83 waterbodies followed by natural recovery.

RESULTS

Expected results:

Creation of two large bypass rivers and the interlinking of different river sections;

- Migration of more than 40 fish species through the bypass rivers including nine FFH-Annex II species; - Unhindered migration within the River Inn between Passau (rkm 0; mouth of the Danube) and Rosenheim HPP (rkm 185.5) and into the Danube; - Unhindered migration into the Salzach River, the main tributary of the Inn, and one of the largest rivers in Austria. Thereby more than 140 km of the Salzach will be accessible to the fish including more than 60 km of free flowing habitat downstream; and - Unhindered migration into the tributaries Mhlheimer Ache, Enknach and Stampfbach, thereby making accessible valuable spawning and nursery grounds;

Creation of new fluvial habitats through the construction of two large bypass rivers with a total length of around 9 km (around 14 ha)

- Increase of functional gravel bars (spawning, breeding, nurseries) by 4.2 ha; - Spawning of several lithophilous fish species including Hucho hucho; - Breeding grounds for Actitis hypoleucos and Charadrius dubius; and - Habitat type 91E0: 1.2 ha along the banks of the bypass system;

River bank restoration (9 km)

- Support of 9 fish species listed in the standard data form including Hucho hucho - Alcedo atthis: 0.4 to 0.7 breeding pairs per kilometre, i.e. 4 to 7 new breeding pairs; and - Create 18 ha potential area for the habitat types 3220, 3240, and 91E0*;

De-sedimentation measures (around 20 ha)

- Support three fish species listed in the SDF; - Support 56 bird species of the SDF (waders and waterfowl); and - Create macrophyte-dominated waters to foster diving ducks and the habitat types 3220, 3240, and habitat type 91E0* on the banks;

Islands, backwaters and ponds

- Provide nurseries for larvae drifting from the spawning grounds in the bypass channel as well as resting, breeding, and feeding grounds for water fowl; and - Small ponds will provide habitats for amphibians and aquatic invertebrates;

Tributaries - Provide flood refuges and spawning areas for river fish;

- Create potential area for the habitat types 3220, 3240, and 91E0* on the banks;

Meadow management

- Foster habitat types 6510 and 6210/6210* and significantly enhance their conservation status and their area by around 100 ha; and - Double the population of Lanius collurio;

Forest management

- Improve conservation status of 91E0* in areas purchased in the LIFE project Lower Inn with riparian Woodland