Measures for the conservation of biodiversity: Impact of river restoration on different organism groups

Transcription

1 Measures for the conservation of biodiversity: Impact of river restoration on different organism groups Daniel Hering, Sonja Jähnig, Peter Rolauffs, Armin Lorenz, Christian Feld, Uwe Koenzen, Jochem Kail Hydromorphololgical restoration measures 1

2 Contents Aims of river restoration Effects of river restoration in theory Effects of river restoration in reality The role of catchment land use and local hydromorphology Conclusions Contents Aims of river restoration Effects of river restoration in theory Effects of river restoration in reality The role of catchment land use and local hydromorphology Conclusions 2

3 Aims of restoration measures Aesthetical value, tourism Flood protection Improvement of hydromorphogical status Improvement of ecological status Taxa number of benthic invertebrates Sensitive benthic invertebrate species Fish species number Age structure of fish fauna 3

4 Species number (mayflies, stoneflies, caddisflies, dragonflies, damselflies, mussels, beetles) EPTCBO-Taxa r 2 = 0, impacted Struktur Index not impacted Species number (mayflies, stoneflies, caddisflies, dragonflies, damselflies, mussels, beetles) EPTCBO-Taxa r 2 = 0, impacted Struktur Index not impacted 4

5 Species number (mayflies, stoneflies, caddisflies, dragonflies, damselflies, mussels, beetles) EPTCBO-Taxa r 2 = 0, impacted Struktur Index not impacted Fauna-Index Fauna Index 2,0 1,5 1,0 0,5 0,0-0,5-1,0-1,5-2,0 r 2 = 0,72-2, impacted not impacted Struktur-Index 5

6 Conclusion I Positive relationship between hydromorphological status and ecological status as reflected by the benthic invertebrate fauna Restoration measures will improve hydromorphology Restoration measures will improve ecological status Contents Aims of river restoration Effects of river restoration in theory Effects of river restoration in reality The role of catchment land use and local hydromorphology Conclusions 6

7 Conceptual model Driver Pressure State Impact Increase Decrease Increase/decrease Conceptual model: Organic pollution Driver Pressure State Impact Urbanisation (domestic and industrial wastewater) Organic pollution Oxygen concentration Saprobic Index Increase Decrease Increase/decrease 7

8 Driver Pressure State Impact Conceptual model: hydromorphology Driver Pressure State Impact Dams, reservoirs Agriculture Urbanization Fine sediment intake Riparian veg. removal Wood debris removal Hypolimnic water release Stagnation Sediment traps Straightening Culverts Bank fixation Bed fixation Profile alteration Dams Hydraulic stress # EPTCBO # Trichoptera Mud preferring taxa [%] Litoral preferring taxa [%] Hyporhithral taxa [%] Metarhithral taxa [%] EPT [%] Fauna-Index Rheo-Index Diversity (Shannon-W.) Xylophagous taxa [%] Filterers [%] Phytophagous taxa [%] Grazers [%] ( ) 8

9 Driver Pressure State Impact Fine sediment intake Dams, reservoirs Riparian veg. removal Wood debris removal Hypolimnic water release Wood debris Substrate diversity Agriculture Stagnation Sediment traps Straightening Culverts Current diversity EPT [%] Fauna-Index Urbanization Bank fixation Bed fixation Profile alteration Bed structures Dams Hydraulic stress Gravel Measures: wastewater purification Driver Pressure State Impact Urbanisation (domestic and industrial wastewater) Organic pollution Oxygen concentration Saprobic Index Waste water purification Increase Decrease Increase/decrease 9

10 Measures: wastewater purification Driver Pressure State Impact Urbanisation (domestic and industrial wastewater) Organic pollution Oxygen concentration Saprobic Index Waste water purification Increase Decrease Increase/decrease Measures: wastewater purification Driver Pressure State Impact Urbanisation (domestic and industrial wastewater) Organic pollution Oxygen concentration Saprobic Index Waste water purification Increase Decrease Increase/decrease 10

11 Measures: wastewater purification Driver Pressure State Impact Urbanisation (domestic and industrial wastewater) Organic pollution Oxygen concentration Saprobic Index Waste water purification Increase Decrease Increase/decrease Driver Pressure State Impact Dams, reservoirs Agriculture Urbanization Fine sediment intake Riparian veg. removal Wood debris removal Hypolimnic water release Stagnation Sediment traps Straightening Culverts Bank fixation Bed fixation Profile alteration Dams Hydraulic stress # EPTCBO # Trichoptera Mud preferring taxa [%] Litoral preferring taxa [%] Hyporhithral taxa [%] Metarhithral taxa[%] EPT [%] Fauna-Index Rheo-Index Diversity (Shannon-W.) Xylophagous taxa [%] Filterers [%] Phytophagous taxa [%] Grazers [%] ( ) 11

12 Conceptual model: restoration measures Effects of a selected restoration measure: Decrease of coarse sediment deficit downstream of weirs Driver Pressure State Impact Fine sediment intake # EPTCBO # Trichoptera Dams, reservoirs Riparian veg. removal Wood debris removal Hypolimnic water release Stagnation Sediment traps Straightening Culverts Bank fixation Bed fixation Profile alteration Dams Hydraulic stress Mud pref. taxa [%] Hyporhithral [%] Metarhithral [%] EPT [%] Fauna-Index Rheo-Index 12

13 Driver Pressure State Impact Fine sediment intake # EPTCBO # Trichoptera Dams, reservoirs Riparian veg. removal Wood debris removal Hypolimnic water release Substrate diversity Mud pref. taxa [%] Stagnation Sediment traps Straightening Culverts Sediment transport Current diversity Hyporhithral [%] Metarhithral [%] Bank fixation Bed fixation Profile alteration Bed structures Sheer stress EPT [%] Fauna-Index Dams Hydraulic stress Water depth Floodplain structures Rheo-Index Conclusion II Positive relationship between hydromorphological status and ecological status as reflected by the benthic invertebrate fauna Restoration measures will improve hydromorphology Restoration measures will improve ecological status Hydromorphological restoration affects the biota through complex cause-effect-chains 13

14 Contents Aims of river restoration Effects of river restoration in theory Effects of river restoration in reality The role of catchment land use and local hydromorphology Conclusions Example: re-braiding of mountain rivers 7 measures (active and passive restoration) Lahn, Eder, Orke, Nims, Bröl 14

15 Some typical pictures of restored streams 15

16 Positive effects on floodplain vegetation 200 * Number of species i l lti l 8 7 * Number of vegetation assemblages i l lti l 16

17 20 * Positive effects on riparian ground beetles Number of species i l lti l 100 * Percentage of riparian species 0 i l lti l No effects on benthic invertebrates Number of genera i l lti l Number of species i l lti l 17

18 Restoration of a lowland river (Schwalm) TIM online LUA NRW Effects on benthic invertebrates Hydromorphological quality Number of genera Number of species Ecological quality Moderate Moderate 18

19 Conclusions III Positive relationship between hydromorphological status and ecological status as reflected by the benthic invertebrate fauna Restoration measures will improve hydromorphology Restoration measures will improve ecological status Hydromorphological restoration affects the biota through complex cause-effect-chains Hydromorphological restoration does not guarantee effects on the biota Contents Aims of river restoration Effects of river restoration in theory Effects of river restoration in reality The role of catchment land use and local hydromorphology Conclusions 19

20 Case study Schwalm Catchment [km 2 ] Case study Schwalm Catchment [km 2 ] Hydrom. quality Ergebnisbericht Niers, Schwalm und nördliche sonstige Maaszuflüsse; 20

21 Case study Schwalm Catchment [km 2 ] Hydrom. quality Ecological quality benthic inverts Moderate Moderate Moderate Moderate Case study Schwalm Effects of the catchment No source populations of sensitive species Input of fine sediment High quality habitats covered with sand Catchment area counteracts the effects of local restoration 21

22 Case study Waldbach PS4 PS5 PS3 PS2 PS1 PS3 Case study Waldbach PS5 PS4 PS3 PS2 PS1 PS1 PS2 PS3 PS4 PS5 Hydrom. quality Ecological quality benthic inverts 22

23 Effects of local restoration measures Catchment Restored section Wood debris Gravel Side arms Riparian vegetation Conclusion IV Positive relationship between hydromorphological status and ecological status as reflected by the benthic invertebrate fauna Restoration measures will improve hydromorphology Restoration measures will improve ecological status Hydromorphological restoration affects the biota through complex cause-effect-chains Hydromorphological restoration does not guarantee effects on the biota Catchment-based effects may counteract or support the effects of local restoration measures 23

24 Contents Aims of river restoration Effects of river restoration in theory Effects of river restoration in reality The role of catchment land use and local hydromorphology Conclusions Conclusion V Local restoration measures may improve the ecological status as measured by the benthic invertebrate fauna If source populations of sensitive species are present in the catchment In small streams If high quality habitats (gravel, wood) are restored Restoration measures will require long time periods to improve the ecological status as measured by benthic invertebrates In catchments lacking source populations In large rivers If the restored section is short compared to river size 24

25 Conclusion VI Floodplain species and communities may react much faster to restoration than aquatic communities, thus being suited as early indicators. Background thesis 6 Multiple interactions between rivers and floodplains require compatible approaches of the WFD and Habitat Directives. Background thesis 7 Acknowledgements Report to the German Federal Environment Agency: Ökologische Fließgewässerrenaturierung Erfahrungen zur Durchführung und Erfolgskontrolle von Renaturierungsmaßnahmen zur Verbesserung des ökologischen Zustands (Ecological river restoration experiences and with river restoration measures and their success) 25