Tanoak (Notholithocarpus densiflorus) Coarse Root Morphology: Prediction Models for Volume and Biomass of Individual Roots

Brandon H. Namm^*, John-Pascal Berrill

Department of Forestry and Wildland Resources, Humboldt State University, Arcata, USA.

DOI: 10.4236/ojf.2016.61001                

Abstract

Descriptions of tree root morphology inform design of belowground biomass and carbon inventories and sampling for research. We studied root morphology of tanoak (Notholithocarpus densiflorus), an important component in mixed evergreen forests of California and Oregon, USA. Tanoak re-sprouts from belowground lignotubers after disturbances, and stores an unknown amount of carbon in coarse roots underground. We sought to ascribe explanatory nomenclature to roots’ morphological features and to identify models describing tanoak root morphology. Twelve tanoak root systems were excavated, dissected, and measured. Roots tapered according to their circumference and location. Larger roots closer to the lignotuber (located at the base of the tree stem) tapered more rapidly per unit of length. Tanoak roots forked frequently. Root cross-sectional area was preserved after forking events (i.e., the sum of cross-sectional areas for smaller roots on one side of the fork correlated with the adjoining large root). Occurrence and quantity of root branches (small roots branching laterally from larger roots) was dependent upon length of the source root segment. Our models of tanoak root morphology are designed to be organized together to estimate biomass of any segment or collection of lateral roots (e.g., roots lost/missed during excavation, or in lieu of destructive sampling), given root diameter at a known distance from the lignotuber. The taper model gives distal- and proximal-end diameters for calculation of volume for segments of root tapering between forks. Frequency of forking and branching can also be predicted. Summing the predicted mass of each lateral root segment, branch, and forked segment would produce an estimate of mass for a contiguous network of lateral roots.

Keywords

Belowground, Biomass, Carbon, Root Taper, Tree Root Architecture

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Bingham, I. J., Baddeley, J. A., & Watson, C. A. (2001). Development and Evaluation of Technique for the Rapid Measurement of Cereal Root Systems. HGCA Project No. 257, London: Home Grown Cereals Authority.
[2]	Böhm, W. (1979). Methods of Studying Root Systems. Berlin: Springer. http://dx.doi.org/10.1007/978-3-642-67282-8
[3]	Coutts, M. P. (1983). Development of Structural Root Systems in Sitka Spruce. Journal of Forestry, 56, 1-16. http://dx.doi.org/10.1093/forestry/56.1.1
[4]	Coutts, M. P., Nielsen, C. C. N., & Nicoll, B. C. (1999). The Development of Symmetry, Rigidity and Anchorage in Structural Root System of Conifers. Plant and Soil, 217, 1-15. http://dx.doi.org/10.1023/A:1004578032481
[5]	Danjon, F., & Reubens, B. (2008). Assessing and Analyzing 3D Architecture of Woody Root Systems, a Review of Methods and Applications in Tree and Soil Stability, Resource Acquisition and Allocation. Plant and Soil, 303, 1-34. http://dx.doi.org/10.1007/s11104-007-9470-7
[6]	Danjon, F., Caplan, J., Fortin, M., & Meredieu, C. (2013). Descendant Root Volume Varies as a Function of Root Type: Estimation of Root Biomass Lost During Uprooting in Pinus pinaster. Frontiers in Plant Science, 4, 402. http://dx.doi.org/10.3389/fpls.2013.00402
[7]	Danjon, F., Fourcaud, T., & Bert, D. (2005). Root Architecture and Wind-Firmness of Mature Pinus pinaster. New Phytologist, 168, 387-400. http://dx.doi.org/10.1111/j.1469-8137.2005.01497.x
[8]	Drexhage, M., Chauviere, M., Colin, F., & Nielsen, C. C. N. (1999). Development of Structural Root Architecture and Allometry of Quercus petraea. Canadian Journal of Forest Research, 29, 600-608. http://dx.doi.org/10.1139/x99-027
[9]	Fitter, A. H., Stickland, T. R., Harvey, M. L., & Wilson, G. W. (1991). Architectural Analysis of Plant Root Systems: 2. Influence of Nutrient Supply on Architecture in Contrasting Plant Species. New Phytologist, 118, 375-382. http://dx.doi.org/10.1111/j.1469-8137.1991.tb00019.x
[10]	Kalliokoski, T., Nygren, P., & Sievanen, R. (2008). Coarse Root Architecture of Three Boreal Tree Species Growing in Mixed Stands. Silva Fennica, 42, 189-210. http://dx.doi.org/10.14214/sf.252
[11]	Kalliokoski, T., Sievanen, R., & Nygren, P. (2010). Tree Roots as Self-Similar Branching Structures: Axis Differentiation and Segment Tapering in Coarse Roots of Three Boreal Forest Tree Species. Trees-Structure and Function, 24, 219-236. http://dx.doi.org/10.1007/s00468-009-0393-1
[12]	Lavigne, M. B., & Krasowski, M. (2007). Estimating Coarse Root Biomass of Balsam Fir. Canadian Journal of Forest Research, 37, 991-998. http://dx.doi.org/10.1139/X06-311
[13]	Le Goff, N., & Ottorini, J.-M. (2001). Root Biomass and Biomass Increment in Beech (Fagus sylvatica L.) Stand in North-East France. Annals of Forest Science, 58, 1-13. http://dx.doi.org/10.1051/forest:2001104
[14]	Littell, R. C., Milliken, G. A., Stroup, W. W., Wolfinger, R. D., & Schabenberger, O. (2006). SAS for Mixed Models (2nd ed.). Cary, NC: SAS Institute Inc.
[15]	Mao, Z., Saint-André, L., Bourrier, F., Stokes, A., & Cordonnier, T. (2015). Modelling and Predicting the Spatial Distribution of Tree Root Density in Heterogeneous Forest Ecosystems. Annals of Botany, 116, 261-277. http://dx.doi.org/10.1093/aob/mcv092
[16]	Nicoll, B. C., & Ray, D. (1996). Adaptive Growth of Sitka Spruce Root Systems in Response to Wind Action and Site Conditions. Tree Physiology, 16, 891-898. http://dx.doi.org/10.1093/treephys/16.11-12.891
[17]	Nielsen, C. C. N., & Hanson, J. K. (2006). Root CSA-Root Biomass Prediction Models in Six Tree Species and Improvement of Models by Inclusion of Root Architectural Parameters. Plant and Soil, 280, 339-356. http://dx.doi.org/10.1007/s11104-005-3503-x
[18]	Noordwijk, M., Spek, L. Y., & de Willigen, P. (1994). Proximal Root Diameter as a Predictor of Total Root Size for Fractal Branching Models. Plant and Soil, 164, 107-117. http://dx.doi.org/10.1007/BF00010116
[19]	Nygren, P., Lu, M., & Ozier-Lafontaine, H. (2009). Effects of Turnover and Internal Variability of Tree Root Systems on Modeling Coarse Root Architecture: Comparing Simulations for Young Populus deltoides with Field Data. Canadian Journal of Forest Research, 39, 97-108. http://dx.doi.org/10.1139/X08-158
[20]	Oppelt, A. L., Kurth, W., & Godbold, D. L. (2001). Topology, Scaling Relations and Leonardo’s Rule in Root System from African Tree Species. Tree Physiology, 21, 117-128. http://dx.doi.org/10.1093/treephys/21.2-3.117
[21]	R Development Core Team (2003). R: A Language and Environment for Statistical Computing. Vienna: R Foundation for Statistical Computing.
[22]	Richardson, A. D., & Dohna, H. Z. (2003). Predicting Root Biomass from Branching Patterns of Douglas-Fir Root Systems. Oikos, 100, 96-104. http://dx.doi.org/10.1034/j.1600-0706.2003.12081.x
[23]	Santantonio, D., Hermann, R. K., & Overton, W. S. (1977). Root Biomass Studies in Forest Ecosystems. Pedobiologia, 17, 1-31.
[24]	SAS Institute Inc. (2004). SAS/STAT 9.1 User’s Guide (Vol. 1-7). Cary, NC: SAS Institute Inc.
[25]	Soethe, N., Lehmann, J., & Engels, C. (2007). Root Tapering between Branching Points Should Be Included in Fractal Root System Analysis. Ecological Modelling, 207, 363-366. http://dx.doi.org/10.1016/j.ecolmodel.2007.05.007
[26]	Stokes, A., & Mattheck, C. (1996). Variation of Wood Strength in Tree Roots. Journal of Experimental Botany, 298, 693-699. http://dx.doi.org/10.1093/jxb/47.5.693
[27]	Tappeiner, J. C., McDonald, P. M., & Roy, D. F. (1990). Lithocarpus densiflorus (Hook. and Arn.) Rehd. In R. M. Burns, & B. H. Honkala (Tech. Coords.), Silvics of North America: Volume 2. Hardwoods (pp. 827-842). United States Department of Agricultural Handbook 654, Washington DC: SRS Publication.
[28]	Thome, D. M., Zabel, C. J., & Diller, L. V. (1999). Forest Stand Characteristics and Reproduction of Northern Spotted Owls in Managed North-Coastal California Forests. Journal of Wildlife Management, 63, 44-59. http://dx.doi.org/10.2307/3802486
[29]	Vercambre, G., Pages, L., & Habib, R. (2003). Architectural Analysis and Synthesis of Plum Tree Root Systems in an Orchard Using a Quantitative Modeling Approach. Plant and Soil, 25, 1-11. http://dx.doi.org/10.1023/A:1022961513239
[30]	Zanetti, C., Vennetier, M., Mériaux, P., & Provansal, M. (2015). Plasticity of Tree Root System Structure in Contrasting Soil Materials and Environmental Conditions. Plant and Soil, 387, 21-35. http://dx.doi.org/10.1007/s11104-014-2253-z