Drying Kinetics: Tension Wood In Fagus Sylvatica And Compression Wood In Picea Abies.
Leaning trees produce reaction wood
. With conifers, the reaction is weaker compression wood on the side toward the lean, rarely a serious problem, but be aware of it and leave a larger hinge.
"Trees lean all the time to reach the light, and reaction wood
helps them stand up despite the fact that they're leaning," Snyder said.
Extreme changes of environmental conditions cause the formation of tree-rings that are much wider or narrower compared to neighbour tree-ring width (Schweingruber, 1996) or cause other conspicuous features such as missing rings, reaction wood
, traumatic zones, etc.
Rings that are large on only one side of the tree indicate reaction wood
growth to reinforce the tree's strength against gravity after a hurricane or landslide gave it the old gangster lean.
One example is the Austrian Wood Trading Regulations (OHHU 2006) in which the features taper, knots, reaction wood
, spiral grain, annual ring width, decay, resin pockets, insect attack, cracks, crookedness, annular delamination, and discoloration are defined as relevant grading properties for Norway spruce (Picea abies) and white fir (Abies alba) logs.
The nature of reaction wood
. III: Cell division and cell wall formation in conifer stems // Aust.
An interesting response of trees that have lost their vertical position is the production of reaction wood
. For instance, if a tree has been bent by another tree falling against it or by a boulder rolling down on one side of it, reaction wood
will form along one side of the trunk and bend the trunk back to a vertical position again.
When a coniferous tree leans, reaction wood
is produced on the lower side in association with wider rings that enable the tree to grow upright again (Wardrop, 1964).
Class A/B was of good to medium quality, low in knottiness, no marked reaction wood
, and low in spiral grain.
** Reaction wood
as a proportion of the cross section area of the log;
Limbwood contains a great deal of reaction wood
whose mechanical properties are much different from normal wood.