The roots of trees are only sedomly good visible as in this example with an European beech. Photo: Marco Walser

Fig. 2: During the strom Lothar in Dezember 1999 many trees were uprooted and their large root systems exposed. Photo: Marco Walser

AFig. 3: Living fine roots are elastic and turgescent, and the tips are in general colonized with mycorrhizal fungi. Photo: Anika Richter

Fig. 4: Dead fine roots are brittle and hollow, and the branchings and tips are often broken off. Photo: Anika Richter

Fig. 5: Living fine root of a Norway spruce with the tip colonized by hyphae of a mycorrhizal fungus (mycorrhiza). Photo: Ivano Brunner

Fig. 6: Microscopical longitudinal section of a living fine root of an European chestnut. Photo: Ivano Brunner

In that research topic, the roots of trees are investigated in relation to soil properties. Roots take up water and nutrients from the soil, they store carbon compounds, and they provide physical stability. While the fine roots are evident in the uptake of water and nutrients, both fine and coarse roots are relevant in tree stability. Our research delivers an important contribution to the biology and ecology of tree roots, and the results support science as well as extension and teaching. Our aim is the support of the sustainability of forest ecosystems.

Roots - the hidden half

Roots take up water and nutrients from the soil, they store carbon compounds, and they provide physical stabilisation. While the fine roots (roots with a diameter below 2 mm) are evident in the uptake of water and nutrients, both fine and coarse roots (roots with a diameter of 2 mm and above) are relevant in tree stability. Furthermore, fine roots of trees undergo constant replacement in root turnover and provide a large biomass input to the soil containing both carbon and mineral nutrients. Hence fine roots are important in carbon fluxes to soils and in carbon storage in soils, as well as in below-ground recycling of nutrients such as nitrogen, phosphorus, magnesium and calcium. Estimations from temperate forests in Central Europe showed that about 52 t/ha are coarse tree roots and 2.5 t/ha are fine tree roots. Thus, about one third of the forest stands biomass are roots.

Because tree roots are in an intimate contact with their surrounding soil, they somehow reflect the soils chemical and physical properties and conditions. Roots are also able to react to changes in soils with morphological, physiological, and molecular alterations. Therefore, tree roots can be used as indicators.

Research aims

• Development of suitable and reliable methods and tools in order to identify and characterise tree roots.
• Investigation of morphological, physiological, biochemical, and molecular root parameters as reactions to ecological adverse soil conditions such as acidification, eutrophication, high heavy metal contents, drought, elevated temperatures, or compaction.
• Assessment of the contribution of tree roots to the forest soil carbon pools and fluxes, hence to develop and apply methods for improved estimations of root production, mortality, turnover, and decomposition.
• Improvement of physiological, biochemical and molecular methods for the investigation of tree roots of small sample amounts.
• Recording the distribution of tree roots in forest soils, estimation of their impacts on soil functions, e.g. soil stability and soil water properties, and improvement of their services to the sustainability of the forest ecosystems.

Current projects

Soil acidification

Bodenversauerung und Baumwurzelvitalität

Microarray-directed development of biomarkers indicating aluminium stress in trees

Aluminium and heavy metal induced organic acid exudation of forest tree roots

Physiological reactions of chestnut tree roots to acidic soils

Heavy metals

Critical limits and effect based approaches for heavy metals

Root carbon

Fluxes, pools, and turnover of C within the fine root systems of individual trees at a natural forest stand

Influence of above-ground stress on the metabolism of non-structural carbohydrates in poplar roots

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

Root distribution

Wurzelverteilung und Wasserhaushaltseigenschaften im Boden

Soil compaction

Soil regeneration after compaction with the help of roots

International cooperations

COST E38 'Woody Root Processes'

IUFRO Arbeitsgruppe 2.01.13 – Root physiology and symbiosis

Conferences / Workshops

4th International Symposium on Physiological Processes in Roots of Woody Plants, 15.-21. Sept. 2007, Bangor, Wales

Woody Roots and Ecosystem Services, 16.-20. May 2008, Lisbon, Portugal

Special Issues

Plant Biosystems 141 (3), 390-511 (2007): "Recent Advances in Woody Root Research"

Journal of Forest Research 12 (2), 75-160 (2007): "Development and Function of Roots of Forest Trees in Japan"

Recent publications from our Research Unit

• Brunner I, Godbold DL. 2007. Tree roots in a changing world. Journal of Forest Research 12, 78-82.

• Brunner I, Brodbeck S, Walthert L. 2002. Fine root chemistry, starch concentration, and 'vitality' of subalpine conifer forests in relation to soil pH. Forest Ecology and Management 165, 75-84.

• Brunner I, Brodbeck, S, Büchler U, Sperisen C. 2001. Molecular identification of fine roots of trees from the Alps: Reliable and fast DNA extraction and PCR-RFLP analyses of plastid DNA. Molecular Ecology 10, 2079-2087.

• 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).

• Brunner I, Ruf M, Lüscher P, Sperisen C. 2004. Molecular markers reveal extensive intraspecific below-ground overlap of silver fir fine roots. Molecular Ecology 13, 3595-3600.

• Brunner I, Zimmermann S, Zingg A, Blaser P. 2004. Wood-ash recycling affects forest soil and tree fine-root chemistry and reverses soil acidification. Plant and Soil 267, 61-71.

• Finér L, Helmisaari H-S, Lõhmus K, Majdi H, Brunner I, Børja I, Eldhuset TD, Godbold DL, Grebenc T, Konopka B, Kraigher H, Möttönen M-R, Ohashi M, Oleksyn J, Ostonen I, Uri V, Vanguelova E. 2007. Variation in fine root biomass of three European tree species: Beech (Fagus sylvatica L.), Norway spruce (Picea abies Karst.) and Scots pine (Pinus sylvestris L.). Plant Biosystems 141, 394-405.

• Genenger M, Jäggi M, Siegwolf R, Chalot M, Frossard E, Brunner I. 2003. Rapid 15N uptake and metabolism in fine roots of Norway spruce. Trees 17, 144-152.
  
• Genenger M, Zimmermann S, Frossard E, Brunner I. 2003. The effects of fertiliser or wood ash on nitrate reductase activity in Norway spruce fine roots. Forest Ecology and Management 175, 413-423.

• Genenger M, Zimmermann S, Hallenbarter D, Landolt W, Frossard E, Brunner I. 2003. Fine root growth and element concentrations of Norway spruce as affected by wood ash and liquid fertilisation. Plant and Soil 255, 253-264.

• Godbold DL, Brunner I. 2007. The platform of European root science, COST action E38: an introduction and overview. Plant Biosystems 141, 390-393.

• Heim A, Brunner I, Frey B, Frossard E, Luster J. 2001. Root exudation, organic acids, and element distribution in roots of Norway spruce seedlings treated with aluminum in hydroponics. Journal of Plant Nutrition and Soil Science 164, 519-526.

• Heim A, Brunner I, Frossard E, Luster J. 2003. Aluminum effects on Picea abies at low solution concentrations. Soil Science Society of America Journal 67, 895-898.

• Hirano Y, Brunner I. 2006. Quantitative determination of callose in tree roots. Journal of Plant Physiology 163, 1333-1336.

• Hirano Y, Graf Pannatier E, Zimmermann S, Brunner I. 2004. Induction of callose in roots of Norway spruce seedlings after short-term exposure to Al. Tree Physiology 24, 1270-1283.

• Hirano Y, Mizoguchi T, Brunner I. 2007. Root parameters of forest trees as sensitive indicators of acidifying pollutants: a review of Japanese research. Journal of Forest Research 12, 134-142.

• Hirano Y, Walthert L, Brunner I. 2006. Callose in root apices of European chestnut seedlings; a physiological indicator of aluminium stress. Tree Physiology 26, 431-440.

• Ostonen I, Püttsepp U, Biel C, Alberton O, Bakker MR, Lõhmus K, Majdi H, Metcalfe D, Olsthoorn A, Pronk A, Vanguelova E, Weih M, Brunner I. 2007. Specific root length as indicator of environmental change. Plant Biosystems 141, 426-442.

• Qin R, Hirano Y, Brunner I. 2007. Exudation of organic acid anions from poplar roots after exposure to Al, Cu and Zn. Tree Physiology 27, 313-320.

• 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.

• Richter AK, Walthert L, Frossard E, Brunner I. 2007. Does low soil base saturation affect the vitality of fine roots of European beech? Plant and Soil 298, 69-79.

• Ruf M, Brunner I. 2003. Vitality of tree fine roots: reevaluation of the tetrazolium test. Tree Physiology 23, 257-263.

• Vanguelova E, Hirano Y, Eldhuset TD, Sas-Paszt L, Bakker MR, Püttsepp U, Brunner I, Lõhmus K, Godbold DL. 2007. Tree fine root Ca/Al molar ratio – Indicator of Al and acidity stress. Plant Biosystems 141, 460–480.
  

Publications on mycorrhizas

• Brunner I. 2001. Ectomycorrhizas: their role in forest ecosystems under the impact of acidifying pollutants. Perspectives in Plant Ecology, Evolution and Systematics 10, 13-27.

• Brunner I, Brodbeck S. 2001. Response of mycorrhizal Norway spruce seedlings to various nitrogen loads and sources. Environmental Pollution 114, 223-233.

• Sell J, Kayser A, Schulin R, Brunner I. 2005. Contribution of ectomycorrhizal fungi to cadmium uptake of poplars and willows from heavily polluted soil. Plant and Soil 277, 245-253.
  

Involved staff

Ivano Brunner, project leader

Beat Frey, project leader

Christoph Sperisen, project leader

Peter Lüscher, project leader

Daniela Steiner, lab technician

Roger Köchli, field technician

Anika Richter, PhD

Tina Endrulat, PhD

Nadine Grisel, PhD

Nicole Regier, PhD

Benjamin Lange, PhD

Contact

• Ivano Brunner