Fig. 1: Tracks of a heavy forestry vehicle on a skidder trail after repeated vehicle crossings. Photo: Marco Walser (WSL)

Fig. 2: Mapping of various types of tracks (different soil deformation) and of the risk of compaction as a basis for the operational strategy of the forest vehicles. Graph: Peter Lüscher / Stéphane Sciacca (WSL)

Fig. 3: Small experimental plot with wood ash application to study the impacts on soil biology (corresponds to 8t wood ash per ha). Photo: Stephan Zimmermann (WSL)

Soils fulfill various functions. They are habitats of plants, animals, microorganisms and fungi and are consequently an important basic resource for human beings. Soils govern the percolation of water and dissolved substances by acting as a reservoir, a buffer and/or a filter and therefore, they are an important regulator in element cycling. As a consequence of land cultivation and of the emission of harmful substances from various sources, the soil functions are endangered. In the research topic “soil protection” the main threats and their effects on the soil functions and hence on soil fertility are investigated.

Soil functions and soil pressures

In the Swiss legislation on environment protection, soil protection is defined as the maintenance of soil fertility. Referred to the forest this means that the self-preservation of a site-specific forest-biocoenosis with a natural regeneration should be sustainably guaranteed. Root-growth of the trees may only be hindered by natural barriers and the activity of the soil biota has to enable the uninhibited decay of the plant litter under the prevalent site conditions. The main threats which endanger the above defined soil fertiltiy in forests and which are investigated in the research topic soil protection are soil compactions by heavy forest harvesters, soil contaminations with harmful substances, climat change and its influence on soil organic matter as well as alterations of the soil due to land use change.
Current and future research activities include field and laboratory investigations on the impacts of forest-harvesters on soil properties and functions and its regeneration, on the mapping of risk assessment with regard to erosion and landslides, on the assessment of ecological risks (e.g. floodwaters), on the interrelation of soil pore space and distribution of tree roots, on the interrelationship between land use change (e.g. afforestation, litter removal, application of wood ash) and soil chemical properties, and on the investigation of the gas exchange between the soil and the atmosphere depending on the degree of compaction. In addition, extention and maintenance of the data base of soil chemical and physical properties serve as an important tool in order to deduce indicators of soil health, pedotransfer functions and ecological standards for the validation of forest soils.

Recent and current projects

Soil compaction

• Characterization of different compacted wheel tracks by means of microbial properties in a forested site

Wood ash

• Effects of wood ash application on soil chemical properties

Litter removal

• Effects of litter removal on soil chemical properties

Heavy metals

• Heavy metals in Swiss forest soils

• Critical limits and effect based approaches for heavy metals

Root carbon

• Decomposition of litter and fine roots, microbial biomass and activity on LWF-plots

Nitrogen

• Nitrogen deposition effects on soil organic matter

Monitoring

• Soil solution chemistry and soil water availability in long-term monitoring forest plots (LWF)

Publications

• Blaser, P.; Zimmermann, S.; Luster, J.; Shotyk, W. 2000. Critical examination of trace element enrichments and depletions in soils: As, Cr, Cu, Ni, Pb, and Zn in Swiss forest soils. - Sci. Total Environ. 249: 257-280.
• Blaser, P.; Zimmermann, S.; Luster, J.; Walthert, L.; Lüscher, P. 2005. Waldböden der Schweiz. Band 2. Region Alpen und Alpensüdseite. - Birmensdorf, Eidg. Forschungsanstalt WSL, Bern, Hep Verlag. 920 pp.
• Brunner I, Luster J, Günthardt-Goerg MS, Frey B. 2007. Heavy metal accumulation and phytostabilisation potential of tree fine roots in a contaminated soil. Environmental Pollution (in press).
• Ernst G., Frey B. 2007. The effect of feeding behaviour on Hg accumulation in the ecophysiologically different earthworms Lumbricus terrestris and Octolaseon cyaneum: a microcosm experiment. Soil Biology and Biochemistry 39: 386-390.
• Frey B., Hagedorn F., Giudici F. 2006. Girdling of a sweet chestnut forest: Carbon allocation to roots drives soil respiration but has little effect on microbial biomass. Forest, Ecology and Management 225: 271-277.
• Frey B., Stemmer M., Widmer F., Luster J., Sperisen C. 2006. Microbial characterization of a heavy metal-contaminated soil in a model forest ecosystem. Soil Biology and Biochemistry 38: 1745-1756.
• Hartmann M., Frey B., Kölliker R., Widmer F. 2005. Semi-automated genetic analyses of soil microbial communities: comparison of T-RFLP and RISA based on descriptive and discriminative statistical spproaches. Journal of Microbiological Methods 61: 349-360.
• Heim A., Frey B. 2001. Mikrobielle Aktiviäten in nährstoffarmen Waldböden entlang eines Höhentransektes in den Schweizer Voralpen. Mitteilungen Deutsche Bodenkundliche Gesellschaft 96: 337-338.
• Heim A., Frey B. 2004. Predicting litter decomposition rates for Swiss forests. Biogeochemistry 70: 301-315.
• Lazzaro A., Hartmann M., Blaser P., Widmer F., Schulin R., Frey B. 2006. Bacterial community structure and activity in different Cd-treated forest soils. FEMS Microbiology Ecology 58: 278-292.
• Lazzaro A., Schulin R., Widmer F., Frey B. 2006. Changes in lead availability affect bacterial community structure but not basal respiration. Science of Total Environment 371: 110-124.
• Lüscher P., Thees O. und Frutig F. 2005. Physikalischer Bodenschutz im Wald ist kein Luxus. Zürcher Wald 6/2005.
• Lüscher P., Thees O., Frutig F. und S. Sciacca. 2006. Physikalischer Bodenschutz im Wald als Teil der Arbeitsqualität. BGS-Bulletin 2006.
• Luster, J.; Zimmermann, S.; Frey, B.; Brunner, I.: Lüscher, P.; Walthert, L.; Blaser, P. 2006. Schwermetalle in Schweizer Waldböden. Wald und Holz 4/06: 35-36.
• Luster, J.; Zimmermann, S.; Zwicky, C.N.; Lienemann, P.; Blaser, P. 2006. Heavy metals in Swiss forest soils: modification of lithogenic and anthropogenic contents by pedogenetic processes and implications for ecological risk assessment. In: Frossard, E.; Blum, W.E.H.; Warkentin, B. (Eds.). Function of soils for human societies and the environment. Geological Society, London, Special Publications 266: 63-78.
• Luster, J.; Zimmermann, S.; Lüscher, P.; Walthert, L.; Zwicky, C.; Lienemann, P.; Blaser, P. 2006. Tiefenverteilung von Chrom, Nickel, Kupfer, Zink und Blei in Schweizer Waldböden und Implikationen für die Mobilität dieser Schwermetalle. - Bull. Bodenkd. Ges. Schweiz 29: 31-34.
• Novak B., Rais D., Frey B., Menon M., Schulin R., Günthardt-Goerg M., Luster J. 2006. Influence of heavy metal contamination on soil parameters in a lysimeter experiment designed to evaluate phytostabilization by afforestation. For. Snow Landsc. Res. 80: 201–211.
• Richter, A., Frossard, E., Brunner I. 2007. Polyphenols in the woody roots of Norway spruce and European beech reduce TTC. Tree Physiology 27, 155-160.
• Rigling D., Günthardt-Goerg M., Blauenstein H., Frey B. 2006. Absorption of heavy metals into Armillaria rhizomorphs from contaminated soils. For. Snow Landsc. Res. 80: 213–220.
• Walthert, L.; Zimmermann, S.; Blaser, P.; Luster, J.; Lüscher, P. 2004. Waldböden der Schweiz. Band 1. Grundlagen und Region Jura. - Birmensdorf, Eidg. Forschungsanstalt WSL, Bern, Hep Verlag. 768 pp.
• Zimmermann S., Frey B. 2002. Soil respiration and microbial properties in an acid forest soil: the effects of wood ash. Soil Biology and Biochemistry 34: 1727-1737.
• Zimmermann, S.; Blaser, P.; Luster, J.; Waltert, L; Lüscher, P. 2006. Waldböden der Schweiz. Band 3. Region Mittelland und Voralpen. - Birmensdorf, Eidg. Forschungsanstalt WSL, Bern, Hep Verlag., 847 pp.

Involved Staff

Stephan Zimmermann (inorganic contaminants, gas exchange, database)
Peter Lüscher (soil physics)
Beat Frey (soil biology)
Lorenz Walthert (site characteristics, database)
Frank Hagedorn (soil carbon)
Elisabeth Graf-Pannatier (soil solution)
Benjamin Lange (PhD student)
Stéphane Sciacca (soil physics)
Marco Walser (pedothek, fieldwork, laboratory)
Roger Köchli (fieldwork, pedothek, laboratory)
Alois Zürcher (laboratory)
Daniel Christen (laboratory)
Central analytical laboratory WSL (chemical analysis)

Contact

• Stephan Zimmermann