1. Combating Land Degradation: the Potential of Soil Reconversion
Silvia Tobias1, Franz Conen2, Christine Alewell2
1Swiss Federal Institute for Forest, Snow and Landscape Research WSL
2University of Basel, Dep. Environmental Sciences

2. Outline
Soil sealing: a core reason for land degradation in industrialised countries
Land recycling and soil reconversion: state of the art
Case studies on soil reconversion
Conclusions

3. Current urban development: Dübendorf (CH)
1920
1956
1974
Developing greenfields instead of reusing brownfields!
2003
2008

4. Soil sealing: a core reason for land degradation in industrialised countries
Soil sealing causes:
Impaired water infiltration; stronger surface run-off; reduced water purification capacity due to shortened infiltration paths;
Heat island effect in cities;
Loss of agricultural land (12,000 km2 lost in 21 EU member states between 1990 and 2006!) Gardi et al. 2014
Loss of soil biodiversity; species shift to generalist and ubiquist species; landscape fragmentation;
Loss of recreation area, soil archive.

5. Strategies to limit soil sealing
Targets of future land-take: Germany max. 30 ha/day, Austria max. 25 ha/day until 2050;
Fees for development of fertile agricultural land; Czech Republic, Slovakia;
Promoting permeable surfaces on parking lots, tramways etc.; reduced sewerage fees for landowners infiltrating rainwater on their properties;
Duty to compensate for new soil sealing by de-sealing unused land: city of Dresden.

6. Land recycling: towards circular flow land use management
Avoid development on greenfields;
Contain urban expansion with infill development (urban densification) and brownfield regeneration (“grey” land recycling);
Compensate for new soil sealing with renaturation and de-sealing measures (“green” land recycling).

7. Land recycling in European capitals 2006–2012
Source: EEA, Land recycling in Europe. EEA Report 31: p. 19

8. Examples of green land recycling
Thames Barrier Park, London UK
Emscher Landscape Park, Ruhr Region Germany

9. Research on land recycling and soil reconversion
Research on soils in urban, industrial, traffic, mining, and military areas (SUITMAs):
Anthropogenic soils: modified, restored, constructed by humans for urban parks, greenroofs, urban gardening;
Usually limited potential of ecosystem services.
Guidelines for planners, local authorities, and investors to manage, regenerate and reuse brownfields:
Promoting circular flow land use management to safeguard soil resources
Promoting brownfield regeneration to upgrade urban neighbourhoods

10. Outline
Soil sealing: a core reason for land degradation in industrialised countries
Land recycling and soil reconversion: state of the art
Case studies on soil reconversion
Conclusions

11. Potential ecosystem service performance at Swiss brownfield sites
Source: Duss, A., Brachflächenrückbau in der Schweiz. Master thesis University of Zurich.

12. Results of ecosystem service mapping
644 ha of agricultural land could be restored at sites with high potential for agricultural land use.
This equals the arable land of 32 Swiss farms with in average 20 ha of arable land.
Conflicts arise between developed and agricultural or recreational reuses at brownfield sites in urban areas with good transport connections.
Potential for natural habitats is highest at brownfield sites in mountainous regions.

13. Reconversion of a country road
1995
2003
2012
M. Fries (1995); S. Tobias (2003, 2012)

14. Results from the reconverted road section
Semi-xeric grassland vegetation (Mesobromium erecti) has well established.
Only few red list plant species detected (surrounded by intensive farmland).
Heavily compacted sandy loam with A-horizon < 5cm, followed by C-horizon.
No connection to groundwater aquifer.

15. Restoration of an agricultural soil

16. Comparing restored soil with non-restored reference soil
Restored subsoil consolidated to similar values as reference subsoil. Restored topsoil stayed less compacted than reference topsoil.

17. Conclusions
Soil sealing on greenfields must be restricted severely to maintain multifunctional soils!
Reuse of brownfields helps to contain urban expansion!
Soil reconversion (de-sealing, soil restoration) is technically feasible for agricultural soils, pioneer habitats on virgin soils, and recreation areas!
Soil reconversion enhances quality of life in urban areas and should therefore be considered more in brownfield management!
Research on SUITMAs should include reconverted soils to specify their potentials and limitations of providing ecosystem services!

18. Thank You for Your Attention!