Restoration of key ecosystem functions in river floodplain stretches along the Danube River

Thomas Hein1, Elisabeth Bondar-Kunze1, Andrea Funk1, Martin Kvarda1, Stefan Preiner1, Walter Reckendorfer1, Maren Striebel2, Gabriele Weigelhofer1, Nina Welti3
1 WasserCluster Lunz & BOKU Vienna
2 Carl-von-Ossietzky University Oldenburg & WasserCluster Lunz
3 School of Civil Engineering, The University of Queensland

Invited Talk 12 in Restoration and rehabilitation of ecosystems

17.07.2014, 10:00-10:30, H19

River floodplain systems are of key importance in river systems, as these systems provide a multitude of ecosystem functions and are also appreciated for their high number of ecosystem services. River floodplain systems are known to be of high importance for maintaining high biodiversity and intense nutrient cycling and providing valuable flood water retention zones. Still, these systems are degraded and lost to a high extent, demanding sound ecosystem restoration approaches. For the upper Danube River for example it has been estimated that more than 80% of the original floodplain areas have been lost and the remaining stretches have been affected in various ways. In many cases the basic hydromorphological dynamics have been altered leading to reduced exchange between the main channel and associated floodplains. This reduction might have far-reaching consequences on ecosystem properties. The recovery potential of ecosystem functions by enhancing the exchange conditions is of central interest for planning restoration measures.

In this presentation several restoration approaches leading to increased surface water connectivity between the main channel and floodplain areas are analysed with regard to the effect on fundamental ecosystem properties such as nutrient and carbon dynamics and biodiversity. Management approaches based on controlled and highly managed restoration measures will be compared to ones where mainly riverine dynamics are re-introduced.

We demonstrate that principles of hydromorphological dynamics control habitat availability for indicator groups, potential greenhouse gas emissions and the nutrient status in the water column and sediment compartments and these can be used as proxies to assess environmental changes in floodplain systems. Primary productivity pattern of macrophytes and algae are controlled by these dynamics and effects of restoration measures can affect the balance between macrophyte and algal development. One other result is that changes in hydromorphology as introduced by restoration measures may stimulate nitrogen turnover and can even reduce greenhouse gas emission of nitrous oxide compared to degraded floodplain systems. The results clearly show that increasing hydrological connectivity can impact various ecosystem properties and ecosystem services and these effects have to be considered in a sustainable management approach. Potential long term changes of fundamental ecosystem properties and associated services will be discussed.

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Letzte Änderung 19.06.2014