Hydrology and Earth System Sciences www.hydrol-earth-syst-sci.net 1027-5606 1607-7938 13 10 2009 10.5194/hess-13-1809-2009 http://www.hydrol-earth-syst-sci.net/13/1809/2009/ http://www.hydrol-earth-syst-sci.net/13/1809/2009/hess-13-1809-2009.html http://www.hydrol-earth-syst-sci.net/13/1809/2009/hess-13-1809-2009.pdf 1809 1821 2009-10-08 Significance of tree roots for preferential infiltration in stagnic soils B. Lange benjamin.lange@wsl.ch P. Lüescher P. F. Germann Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zuercherstrasse 111, 8903 Birmensdorf, Switzerland Soil Science Section, Department of Geography, University of Bern, Hallerstrasse 12, 3012 Bern, Switzerland It is generally recognized that roots have an effect on infiltration. In this study we analysed the relation between root length distributions from Norway spruce (<i>Picea abies</i> (L.) Karst), silver fir (<i>Abies alba</i> Miller), European beech (<i>Fagus sylvatica</i> L.) and preferential infiltration in stagnic soils in the northern Pre-Alps in Switzerland. We conducted irrigation experiments (1 m²) and recorded water content variations with time domain reflectometry (TDR). A rivulet approach was applied to characterise preferential infiltration. Roots were sampled down to a depth of 0.5 to 1 m at the same position where the TDR-probes had been inserted and digitally measured. The basic properties of preferential infiltration, film thickness of mobile water and the contact length between soil and mobile water in the horizontal plane are closely related to root densities. An increase in root density resulted in an increase in contact length, but a decrease in film thickness. We modelled water content waves based on root densities and identified a range of root densities that lead to a maximum volume flux density and infiltration capacity. These findings provide convincing evidence that tree roots in stagnic soils represent the pore system that carries preferential infiltration. Thus, the presence of roots should improve infiltration. Alaoui, A. and Goetz, B.: Dye tracer and infiltration experiments to investigate macropore flow, Geoderma, 144, 279–286, 2008. Alaoui, A. and Helbling, A.: Evaluation of soil compaction using hydrodynamic water content variation: Comparison between compacted and non-compacted soil, Geoderma, 134, 97–108, 2006. Angers, D. A. and Caron, J.: Plant-induced changes in soil structure: Processes and feedbacks, Biogeochemistry, 42, 55–72, 1998. Badoux, A., Witzig, J., Germann, P. F., Kienholz, H., Lüscher, P., Weingartner, R., and Hegg, C.: Investigations on the runoff generation at the profile and plot scales, Swiss Emmental, Hydrol. Process., 20, 377–394, 2006. Beschta, R. L., Pyles, M. R., Skaugset, A. E., and Surfleet, C. G.: Peakflow responses to forest practices in the western cascades of Oregon, USA, J. Hydrol., 233, 102–120, 2000. Beven, K. and Germann, P.: Macropores and water flow in soils, Water Resour. Res., 18, 1311–1325, 1982. Bouma, J.: Influence of soil macroporosity on environmental quality, Adv. Agron., 46, 1–37, 1991. Cheng, J. D., Lin, L. L., and Lu, H. S.: Influences of forests on water flows from headwater watersheds in Taiwan, For. Ecol. Manage., 165, 11–28, 2002. Cognard-Plancq, A.-L., Marc, V., Didon-Lescot, J.-F., and Normand, M.: The role of forest cover on streamflow down sub-Mediterranean mountain watersheds: a modelling approach, J. Hydrol., 254, 229–243, 2001. Demontzey, P.: Etude sur les travaux de reboisement et de gazonnement des montagnes, Imprimerie Nationale, Paris, 1878. Devitt, D. A. and Smith, S. D.: Root channel macropores enhance downward movement of water in a Mojave Desert ecosystem, J. Arid Environ., 50, 99–108, 2002. Di Pietro, L., Ruy, S., and Capowiez, Y.: Predicting preferential water flow in soils by traveling-dispersive waves, J. Hydrol., 278, 64–75, 2003. Ellenberg, H. and Klötzli F.: Waldgesellschaften und Waldstandorte der Schweiz, Mitteilungen EAFV, 48, 587–930, 1972. Engler, A.: Untersuchungen über den Einfluss des Waldes auf den Stand der Gewässer, Mitteilungen der Schweizerischen Zentralanstalt für das forstliche Versuchswesen, XII Band, 1919. FAO-Unesco: Soil map of the world, ISRIC, Wageningen, 1994. Federal Office for the Environment (FOEN): http://www.hydrodaten.admin.ch/d/2179.htm, last access: 16 May, 2008. Flury, M., Flühler, H., Jury, W. A., and Leuenberger, J.: Susceptibility of soils to preferential flow of water: A field study, Water Resour. Res., 30, 1945–1954, 1994. Gärdenäs, A. I., Å imùnek, J., Jarvis, N., and van Genuchten, M. T.: Two-dimensional modelling of preferential water flow and pesticide transport from a tile-drained field, J. Hydrol., 329, 647–660, 2006. Genenger, M., Zimmermann, S., Hallenbarter, D., Landolt, W., Frossard, E., and Brunner, I.: Fine root growth and element concentrations of Norway spruce as affected by wood ash and liquid fertilisation, Plant Soil, 255, 253–264, 2003. Gerke, H. H.: Preferential flow descriptions for structured soils, J, Plant Nutr. Soil Sci., 169, 382–400, 2006. Germann, P. F. and Beven, K.: Kinematic wave approximation to infiltration into soils with sorbing macropores, Water Resour. Res., 21, 990–996, 1985. Germann, P., Helbling, A., and Vadilonga, T.: Rivulet approach to rates of preferential infiltration, Vadose Zone J., 6, 207–220, 2007. Germann, P. F. and Hensel D.: Poiseuille flow geometry inferred from velocities of wetting fronts in soils, Vadose Zone J., 5, 867–876, 2006. Gish, T. J., Gimenez, D. and Rawls, W. J.: Impact of roots on ground water quality, Plant Soil, 200, 47–54, 1998. Hagedorn, F. and Bundt, M.: The age of preferential flow paths, Geoderma, 108, 119–132, 2002. Hegg, C., Thormann, J.-J., Böll, A., Germann, P., Kienholz, H., Lüscher, P., and Weingartner, R.: Lothar und Wildbäche. Schlussbericht eines Projektes im Rahmen des Programms "Lothar Evaluations- und Grundlagenprojekte", Eidgenössische Forschungsanstalt WSL, Birmensdorf, 2004. Jørgensen, P. R., Hoffmann, M., Kistrup, J. P., Bryde, C., Bossi, R., and Villholth, K. G.: Preferential flow and pesticide transport in a clay-rich till: Field, laboratory, and modeling analysis, Water Resour. Res., 38, 1246, doi:10.1029/2001WR000494, 2002. Kawamoto, K., Mashino, S., Oda, M., and Miyazaki, T.: Moisture structures of laterally expanding fingering flows in sandy soils, Geoderma, 119, 197–217, 2004. KodeÅ¡ová, R., Vignozzi, N., RohoÅ¡ková, M., Hájková, T., Koèárek, M., Pagliai, M., Kozák, J., and Å imùnek, J.: Impact of varying soil structure on transport processes in different diagnostic horizons of three soil types. J. Contam. Hydrol., 104, 107–125, 2009. Kung, K.-J. S.: Preferential flow in a sandy vadose zone: 2. Mechanism and implications, Geoderma, 46, 59–71, 1990. Li, Y. and Ghodrati, M.: Preferential transport of nitrate through soil columns containing root channels, Soil Sci. Soc. Am. J., 58, 653–659, 1994. Mapa, R. B.: Effect of reforestation using \textitTectona grandis on infiltration and soil water retention, For. Ecol. Manage., 77, 119–125, 1995. Materechera, S. A., Kirby, J. M., Alston, A. M., and Dexter, A. R.: Modification of soil aggregation by watering regime and roots growing through beds of large aggregates, Plant Soil, 160, 57–66, 1994. Mitchell, A. R., Ellsworth, T. R., and Meek, B. D.: Effect of root systems on preferential flow in swelling soil, Commun. Soil Sci. Plant Anal., 26, 2655–2666, 1995. Noguchi, S., Tsuboyama, Y., Sidle, R. C., and Hosoda, I.: Spatially distributed morphological characteristics of macropores in forest soils of Hitachi Ohta Experimental Watersheds, Japan, J. For. Res., 2, 207–215, 1997. Perillo, C. A., Gupta, S. C., Nater, E. A., and Moncrief, J. F.: Prevalence and initiation of preferential flow paths in a sandy loam with argillic horizon, Geoderma, 89, 307–331, 1999. Polomski, J. and Kuhn, N.: Wurzelsysteme, Haupt, Bern, Stuttgart, Wien, 1998. Roth, K., Schulin, R., Flühler, H., and Attinger, W.: Calibration of time domain reflectometry for water content measurements using a composite dielectric approach, Water Resour. Res., 26, 2267–2274, 1990. Soil survey division staff: Soil survey manual, Soil Conservation Service, U.S. Department of Agriculture, Handbook 18, 1993. Tremblay, Y., Rousseau, A. N., Plamondon, A. P., Lévesque, D., and Jutras, S.: Rainfall peak flow response to clearcutting 50% of three small watersheds in a boreal forest, Montmorency Forest, Québec, J. Hydrol., 352, 67–76, 2008. Wang, Z., Wu, Q. J., Wu, L., Ritsema, C. J., Dekker, L. W., and Feyen, J.: Effects of soil water repellency on infiltration rate and flow instability, J. Hydrol., 231–232, 265–276, 2000. Weiler, M. and Naef, F.: An experimental tracer study of the role of macropores in infiltration in grassland soils, Hydrol. Process., 17, 477–493, 2003. Withington, J. M., Reich, P. B., Oleksyn, J., and Eissenstat, D. M.: Comparisons of structure and life span in roots and leaves among temperate trees, Ecol. Monogr., 76, 381–397, 2006. Zimmermann, S., Luster, J., Blaser, P., Walthert, L. and Lüscher, P.: Waldböden der Schweiz. Band 3. Region Mittelland und Voralpen, Eidgenössische Forschungsanstalt WSL, Birmensdorf, Hep Verlag, Bern, 2006.