Annals of Botany

Anchorage failure is prevented by a rigid central part of the root system

Storms can cause catastrophic damage to European forests. Surmising that anchorage is partly determined by root architecture, Dorval et al. computed the mechanical characteristics of the main components of root systems from 3D digitising data of 48 undamaged, leaning or heavily toppled Pinus pinaster trees from stands damaged by a storm 3 years previously.

Scheme of the nine mechanical compartments and the spatial limits.
Scheme of the nine mechanical compartments and the spatial limits. Segments were coloured according to their compartment: (1) stump in grey, (2) taproot in black, (3) zone of rapid taper (ZRT) of horizontal shallow roots in dark blue, (4) horizontal shallow roots beyond the ZRT in light blue, (5) sinker roots branching from the ZRT in red, (6) sinker roots beyond the ZRT in magenta, (7) intermediate-depth horizontal roots in yellow, (8) deep roots in green, (9) oblique roots in dark grey. The mean percentage with respect to the stem volume in straight trees is indicated for each compartment.

The results show that it was mainly the flexural stiffness of the large main taproot at the central part of the root system that secured anchorage, preventing leaning and stump displacement. The distal section of the taproot and attached deep roots contributed to strong anchorage support and toppled trees were shown to have a lower relative root biomass – stump excluded – than straight trees. A variety of architectural root designs can provide good anchorage for trees, depending partly on available soil depth.

Root Biology Issue This paper is part of the Root Biology Special Issue.

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