Blühende Biodiversität durch die „Neue Traisen“. Fauna, Flora und Habitate der neuen, naturnah geschaffenen Flusslandschaft

The LIFE+ project “Lebensraum im Mündungsabschnitt des Flusses Traisen” (Habitat in the estuary of the Traisen river) is the largest LIFE project dealing with (semi-)aquatic habitats in Austria. The expectations of the project from the point of view of ecological nature conservation were correspondingly high. The project created a large new river section aiming to resemble a natural river ecosystem, with a dynamic riverbed, connected tributaries, and with adjacent floodplains typical of lowland floodplains along the Danube. In addition, a vegetation management for grassland meadows was developed to provide suitable habitats for orchids and thermophilic animals. Our biodiversity monitoring, evaluating the LIFE+ project Traisen by assessing changes of plant, fish, bird, amphibian and dragonfly diversity, highlights the high relevance of such river restoration measures to conservation. Many threatened species (classified as endangered, vulnerable or near-threatened on national Red Lists) of all the assessed groups rapidly colonized the newly created river, its shorelines and small adjacent water bodies, proving the success of the vegetation management. The restoration measures therefore significantly increased the importance of the area as regional biodiversity hotspot for freshwater species and dry meadows with orchids. Currently almost 50 % of the Austrian dragonfly species occur along the new river section at New Traisen. Several highly threatened amphibian and bird species that depend on natural streams furthermore either increased their populations (e.g. the fire-bellied toad, common kingfisher, little ringed plover) or newly colonized the area (e.g. green toad, common sandpiper, bank swallow). This great success underlines the importance of such river restoration projects for mitigating or even reversing the global loss of river ecosystem diversity.