Biological Response to Mechanical Stimulation
You can't make a plant grow by pulling on it.
-- Chinese sayingThigmomorphogenesis: The response of plant growth and development to mechanical stimulation, by MJ Jaffe, 1973
Plant Biomechanics: An Engineering Approach to Plant Form and Function, by KJ Niklas, 1992
Design in Nature: Learning from Trees, by C Mattheck, 1998
Thigmomorphogenesis: a complex plant response to mechano-stimulation, by EW Chehab et al, 2008
E and G increase from pith to bark.
E increases with height.
G decreases with height.
-- "Micro Mechanical Measurement of Wood
Substructure Properties" by David Kretschmann
Growth Characteristics
density, MC, knots, checks, shakes, splits, slope of grain, reaction wood, decay
checks, shakes, splits - separation of wood fibers
checks are seasoning defects
shakes occur in growing tree
Knots
living limb → tight/sound/intergrown knots
dead limb → loose/dead/encased knots (transition from tight to loose)slope of grain around limb
Reaction Wood
leaning trees, cracks, contact
compression wood in softwoods (30-40% higher density)
tension wood in hardwoods (5-10% higher density)darker, more latewood, 10X longitudinal shrinkage
