Partner und Internationale Organisationen
(Englisch)
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A, B, HR, CZ, DK, EE, FIN, F, D, GR, H, IS, IRL, I, LT, NL, N, PL, P, RO, E, S, CH, GB
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Abstract
(Englisch)
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The role of root systems in the CO2 budget of the forests is still largely unknown. One of the reasons is surely the extraordinary effort that has to be undertaken to gather information on size and spread of a whole root system of a tree. In recent years multifaceted modeling approaches have been developed based on existing data to assess the root spread of different tree species (e.g., Adiku et al. 1996; Brown et al. 1997; Lynch 1997). More recently models were developed to estimate root biomass (e.g., Cairns,et al. 1997; Laclau 2002; Vogt et al. 1998). Nevertheless the obtained results still show a wide range in the percentage of root biomass in relation to above ground biomass. This wide range also applies to existing conversion factors that include root biomass into the computation of total biomass.The ROOKEY-project (Roots - the hidden key players) at the Swiss Federal Research Institute WSL aims on investigating root systems of wind thrown trees (European beech and Norway spruce) to compile site dependant correlations among above and below ground biomass. In doing so, the breast height diameter of the stem is used as the main reference. In the first phase of the project, existing data (root-ball dimensions) of 128 European beech and 129 Norway spruce saplings thrown by the 'Lothar' storm-event in the winter of 1999 (Brang 2003) were analyzed. Next, correlations were calculated between the different root-ball parameters (radius, diameter, depth) and the respective breast-height diameter (dbh) of the stem. In order to enable accurate calculations, all above ground parameters of the trees (height of stem and crown, dbh, age and growth rates) were taken into account. In August 2002, a thunderstorm threw a 120-year old European beech in the area of Zürich, Switzerland. The fracture points at the coarse roots around the root ball were rather small, so about 95% of the whole root system was covered in the root ball. The actuality of the event ensured the possibility to expose the coarse roots as well as the fine roots for biomass calculation. Further analyses were based on a 3D grid dividing it into sectors of 30cm. The analysis of the exposed root system of the 120 year-old European beech was finished in December 2003. The resulting data was compared to the existing data of root balls measured on the basis of trees thrown by the 'Lothar'-event of 1999. In addition, root systems of trees aged 03 - 35 years were analyzed in 2004 to close the gap between trees aged 10 and 100 - 120 years. Analyzing the biomass of the root systems of these trees showed that the actual assumption of about 45% of total biomass is by far too high. The average value we calculated about 25% for coarse roots (>3mm). Even if values for fine roots would be added, it would be not more than 30%. Literature: Adiku, S., Braddock, R., Rose, C. (1996): Simulating growth dynamics. Environmental software 11 (1-3), pp. 99-103. Brang, P. (2003): Wurzelballendimensionen von Buchen, Fichten und Tannen. Bericht zur Tagung 'Forstwirtschaft im Ballungsraum' der Sektion Waldbau im Verband der Forstlichen Forschungsanstalten. 11.13. September 2002, Berlin. 103-105. Brown, T., Kulasiri, D., Gaunt, R. (1997): A root-morphology based simulation for plant/soil microbial ecosystem modeling. Ecological Modelling 99, pp. 275-287. Cairns, M.A., Brown, S., Helmer, E.H., Baumgardner, G.A. (1997): Root biomass allocation in the world's upland forests. Oecologia 111 (1), pp. 1-11. Laclau, P. (2002): Root biomass and carbon storage of ponderosa pine in a northwest Patagonia plantation. Forest Ecology and Management 5873, pp. 1-8. Lynch, J., Nielsen, K., Davis, R., Jablokow, A. (1997): SimRoot: Modelling and visualization of root systems. Plant and Soil 188, pp. 139-151. Polomski, J., Kuhn, N. (1998): Wurzelsysteme. Birmensdor, Eidg. Forschungsanstalt für Wald, Schnee und Landschaft. Haupt, Bern. P. 290. Vogt, K., Vogt, D., Bloomfield, J. (1998): Analysis of some direct and indirect methods for estimating root biomass and production of forests at an ecosystem level. Plant and Soil 200, pp. 71-89.
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