Effect of growth stress and interlocked grain on splitting of seven different hybrid clones ofEucalyptus grandis×Eucalyptus urophyllawood

Abstract

Trees with high levels of growth stress begin to show log end splits (LES) immediately after harvesting, usually reaching its maximum end split in a week, and these tensions also create splits during lumber manufacturing. Interlocked grain is another characteristic that impacts the properties of eucalyptus wood. The aim of this study was to evaluate the effect of growth stress and interlocked grain patterns on log end splitting of seven different hybrid clones of Eucalyptus grandis × Eucalyptus urophylla planted in Brazil. The growth stress indicator (GSI) was measured in standing trees before harvesting. Splits were measured on logs in three different stages, and interlocked grain from wood blocks was obtained across the center of the cross-section. The results showed that LES occurred as soon as the trees were harvested; however, for better selection of clones, LES should be evaluated after a week of harvesting. There were statistically significant correlations for GSI with LES. Clones that presented higher values of interlocked grain tended to develop lower values of GSI and LES. Using GSI and interlocked grain measurements, it was possible to select the most indicated eucalyptus clones for lumber production.

Maturation Stress and Wood Properties of Poplar (Populus × euramericana cv. ‘Zhonglin46’) Tension Wood

“…Our results support the hypothesis that gravitropism (ability to restore upright growth) in poplar trees is synergistically affected by increased tensile growth stress and promotion of secondary growth on the upper side of the inclined stem [44]. The mean values for the RLMS (−0.16%-0.00%) here are similar to those found in other studies on Populus × euramericana [15] and Eucalyptus grandis-urophylla [45]. The RLMS were significantly different between peripheral positions, which is interpreted as an adaptation enabling them to re-orient the stem to vertical growth [44].…”

“…Growth stress affects timber production, causing problems such as radial splitting at the log edges and bowed/twisted sawn planks [15,16]. Some reaction wood can cause serious defects, leading to economic losses in the lumber industry [3].…”

Use of Eucalyptus grandis clones treated with a water repellent to improve the dimensional stability of utility poles

“…These stresses are generated during the growth and maturation of cells in the youngest rings of the tree, which tend to expand laterally and contract longitudinally, while there is resistance in older tissues. This leads to a high degree of stress by having tension on the surface of the trunk and compression in the center (Richter 2015, França et al 2020. While the tree is standing, the stresses are balanced across the trunk; when dislodged, the tissues under tension tend to contract longitudinally (periphery of the trunk) and those under compression (center of the trunk) tend to expand longitudinally (Oliveira et al 2010).…”