anchorage mechanics of deep rooted larch, Larix europea x L. japonica

The anchorage of deep rooted 16-year-old larch trees, Larix europea x japonica, has been studied by combining winching tests with analyses of strain around the base of the trunk and root system and mechanical tests on individual roots. These showed that anchorage is provided by the laterals which em...

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Bibliographic Details
Published in:Journal of experimental botany 1996-10, Vol.47 (303), p.1509-1517
Main Authors: Crook, M.J, Ennos, A.R
Format: Article
Language:English
Subjects:
bending strength
hybrids
Larix
Larix kaempferi
lateral roots
mechanical properties
root systems
roots
simulation
wind damage
wind stress
windthrow
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Summary:The anchorage of deep rooted 16-year-old larch trees, Larix europea x japonica, has been studied by combining winching tests with analyses of strain around the base of the trunk and root system and mechanical tests on individual roots. These showed that anchorage is provided by the laterals which emerge from around the stem base, sinker roots which emerge along their length, and tap roots positioned directly underneath the bole. During anchorage failure the leeward laterals are bent and eventually break close to their base, whilst the windward laterals are pulled out of the ground, with their sinker roots intact. After initially being confined by the soil and bending, the tap root rotates in the soil. Anchorage failure is similar when the soil is dry as when it is wet, but failure occurs closer to the trunk. Strain measurements along the lateral roots revealed that the stresses were highest close to the trunk and that these regions of the roots contribute most to tree stability. The two major components of anchorage were found to be the resistance of leeward laterals to bending and the resistance of tap roots and windward sinkers to uprooting. Bending tests on leeward laterals revealed that they provide around 25% of tree anchorage. Almost 75% of the anchorage strength must, therefore, be provided by the windward sinkers and tap roots. Anchorage strength of roots was positively correlated to their cross-sectional area. The vertical orientation of the sinkers makes the anchorage system of larch more efficient than the plate system formed by Sitka spruce on waterlogged soils and means that no root-soil plate is formed.
ISSN:0022-0957
1460-2431
DOI:10.1093/jxb/47.10.1509