© 2001 Heron Publishing—Victoria, Canada
Topology, scaling relations and Leonardo's rule in root systems from African tree species
Armin L. Oppelt (1), Winfried Kurth (2) and Douglas L. Godbold (3)
1. Georg-August-Universität Göttingen, Institut für Forstbotanik, Büsgenweg 2, D-37077 Göttingen, Germany / 2. Georg-August-Universität Göttingen, Institut für Forstliche Biometrie und Informatik, Büsgenweg 4, D-37077 Göttingen, Germany / 3. School of Agricultural and Forest Sciences, University of Wales, Bangor, Bangor Gwynedd LL57 2UW, U.K. / Received January 4, 2000
Summary
Aspects of root architecture, including topology, link length, diameter and scaling relations, were analyzed in excavated
coarse root systems of three field-grown fruit tree species (Strychnos cocculoides Bak., Strychnos spinosa Lam. and Vangueria infausta Burch) and the fruit-bearing shrub Grewia flava DC. We investigated the root systems using semi-automatic digitizing and computer-based 3-D reconstruction techniques. Topological
analysis was carried out to investigate branching patterns as basic determinants of root architecture. New topological indices
were developed and revealed significant differences among the species. The different architectural strategies can be explained
in terms of cost–benefit relations and efficiency in soil resource exploration and exploitation. In addition, some well-known
hypotheses about geometry and scaling, most of them previously unverified by empirical observations on root systems, were
tested. For practical applications, the main emphasis is on the relationship between proximal root diameter, an easily determined
parameter, and several parameters describing the size of the whole root system. We also tested the “pipe stem” theory, essentially
dating back to Leonardo da Vinci, which underlies many models and which we found conformed to our measurement data with reasonable
accuracy. A physiological consequence of the “constant cross-sectional area rule” may be a certain homogeneity of hydraulic
architecture throughout root systems.
Keywords:
architecture, branching pattern, cross-section area, Grewia flava, root diameter, root length, Strychnos cocculoides, Strychnos spinosa, Vangueria infausta.
