Figure 1: Collection of soil water in forest. Picture: Elisabeth Graf Pannatier

Figure 2: Dissolved organic carbon in soil water. Picture: Frank Hagedorn

Figure 3: Tensiometer for the measurement of soil matrix potential. Picture: Oliver Schramm

Figure 4: Soil compaction after passage of a heavy harvesting machine. Picture: Beat Frey

In this research topic, the chemical and the physical properties of water in soils of near-natural ecosystems like forests are investigated. Soil water is essential for plants and soil organisms. It is also important for humans, since ground water originating from forested areas is often used as drinking water. We are interested in studying the reactions of soil water to air pollution, climate change and forest management operations. We provide scientific publications and data for environmental policy makers, forest managers and scientists.

Why soil water is important

Water contained in the pore space of soils, often called soil solution, is essential for the growth and the vitality of plants and soil organisms, since it supplies nutrients to them. Water in forest soils is also important for humans, since groundwater coming from forested catchments is usually of good quality and therefore is often used as drinking water.

However, air pollution leading to acid atmospheric deposition, increased atmospheric nitrogen input or elevated carbon dioxide concentrations can alter the nutrient cycling and the functioning of near-natural ecosystems and, as a consequence, the quality and the quantity of soil water. Climate change like warming or an increased frequency of extreme meteorological events can also affect soil water quality and the quantity of soil water available to plants.

Human activities such as silvicultural practices can modify soil water quality and soil water regime either positively e.g. by a suitable selection of tree species to improve soil quality or negatively e.g. by soil compaction because of the use of heavy harvesting machines resulting in tree regeneration problems.

These anthropogenic influences that affect the cycling of nutrients and water in near-natural ecosystems can threaten important soil functions like storage of water and nutrients or buffering and filtering of atmospheric deposition.

Research objectives

Combining long-term monitoring, field and laboratory experiments and modelling, our research activities aim at:

• a better understanding of carbon and nutrient (N, P, Mg, K, Ca) dynamics  in soils and in particular in the root zone of near-natural ecosystems.
• assessing the reactions of soil water (quality and quantity) in near-natural ecosystems to climate change and to air pollution.
• determining the impact of heavy harvesting machines on the soil water regime and at assessing the compaction sensitivity of different forest soils.
• determining the effects of tree roots on the soil water regime, e.g. by studying how indigenous dominant trees species (e.g. spruce, fir, beech) influence soil water movement and storage with their specific root systems.

These investigations provide important data for environmental policy makers to set up international agreements (e.g. Convention on Long-range Transboundary Air Pollution, Kyoto protocol) or to monitor the effects of environmental measures. They also help forestry professionals to improve the management of forested areas to supply clean drinking water and to protect against floods.

Current projects

Long-term monitoring:

• Soil solution chemistry and soil water availability in long-term monitoring forest plots
  
• Kartierung, Erhebung und Analyse der Böden auf LWF-Flächen

Nitrogen and carbon dynamics in forest soils:

• Swiss Canopy Project: Dissolved organic matter dynamics in a mature deciduous forest under elevated CO2
  
• Alpine treelines in a CO2-rich and warm world
  
• Nitrogen deposition effects on soil organic matter

Site ecology and soil water:

• Der Boden als Standortsfaktor im Schweizer Wald
  

Soil water in the rhizosphere:

• Plant-soil-microbe interactions at different succession stages as key for understanding and process-based modeling of C and N transformations in floodplains
  
• Ecological interactions between higher plants and microorganisms in the acquisition of biolimiting nutrients N, P and K - Soil Solution Part
  

Soil water in metal contaminated soils:

• From Cell to Tree: the soil

Tree root development and soil water

• Wurzelverteilung und Wasserhaushaltseigenschaften im Boden

Soil compaction and soil water:

• Physikalischer Bodenschutz im Wald

Some recent publications (2003-2007)

• Graf Pannatier E., Luster J., Zimmermann S., Blaser P. 2005. Acidification of soil solution in a chestnut forest stand in southern Switzerland: are there signs of recovery? Environmental Science & Technology, 39, 7761-7767.
• Graf Pannatier E. Walthert L., Blaser P. 2004. Solution chemistry in acid forest soils: Are the BC:Al ratios as critical as expected in Switzerland. Journal of Plant Nutrition and Soil Science, 167, 160-168.
• Hagedorn F., Machwitz M. 2007. Controls on dissolved organic matter leaching from forest litter grown under elevated atmospheric CO2. Soil Biology & Biochemistry 39, 1759-1769.
• Hagedorn F., Saurer M., Blaser P. 2004. A 13C tracer study to identify the origin of dissolved organic carbon in forested mineral soils. European Journal of Soil Science 55, 91-100.
• Lüscher P., Thees O., Frutig F., Sciacca S. 2006. Physikalischer Bodenschutz im Wald als Teil der Arbeitsqualität. BGS-Bulletin 2006
• Luster, J., Finlay, R. (eds.). 2007. Handbook of Methods used in Rhizosphere Research, Swiss Federal Research Institute WSL, Birmensdorf, 536 pp.
• Rais D., Nowack B., Schulin R., Luster J. 2006. Sorption of trace metals by standard and micro suction cups in the absence and presence of dissolved organic carbon. Journal of environmental quality 35(1):50-60.
• Waldner P., Schaub M., Graf Pannatier E., Schmitt M., Thimonier A., Walthert L. 2007. Atmospheric Deposition and ozone levels in Swiss forests: Are critical values exceeded? Environmental Monitoring and Assessment 128, 5-17.
• Walthert L., Blaser, P., Lüscher, P. 2003. Langfristige Waldökosystem-Forschung LWF in der Schweiz, Kernprojekt Bodenmatrix: Ergebnisse der ersten Erhebung 1994-1999, Eidgenössische Forschungsanstalt WSL, Birmensdorf.

In press:

• Blaser P., Graf Pannatier E., Walthert L. 2008. The base saturation in acidified Swiss forest soils on calcareous and noncalcareous parent material. A pH-base saturation anomaly. Journal of Plant Nutrition and Soil Science.
• Luster, J., Goerg-Günthardt, M.S., Schulin, R., Nowack, B. Initial soil chemical changes in lysimeters refilled with metal polluted topsoil and acidic and calcareous subsoils. Water, Air and Soil Pollution.

Involved staff

Elisabeth Graf Pannatier (long-term monitoring, water balance)
Frank Hagedorn, (CO2 enrichment experiments, carbon and nitrogen cycle)
Jörg Luster (rhizosphere processes)
Stephan Zimmermann (soil conservation)
Lorenz Walthert (site ecology, soil monitoring)
Peter Lüscher (soil compaction, site ecology)
Stéphane Sciacca (soil compaction)
Daniel Christen (laboratory)
Aloïs Zürcher (laboratory)
Noureddine Hajjar (laboratory)
Oliver Schramm (fieldwork)
Marco Walser (fieldwork)
Roger Köchli (fieldwork)
WSL Central laboratory (chemical analysis)
Adrian Kammer (PhD, nitrogen deposition and soil organic matter)
Benjamin Lange (PhD, root distribution)

Contact

• Elisabeth Graf Pannatier