1. Effect of stem form factor on wood properties of
sugi (Cryptomeria japonica) plantation trees
- Stem stiffness, anatomical wood properties and knot distribution–
Yoshio KIJIDANI, Shougo HISAZUMI, Kanichi AMAGASAKI,
Satoshi ITO, Ryushi KITAHARA
Division of Forest Science, Faculty of Agriculture
, Miyazaki University, Miyazaki , Japan　

2. Third section in my abstract
The SFF was correlated with the other parameters for 92 sugi trees (p<0.01): suppressed trees of the larger SFF had the smaller crown length ratios (CLR: the ratio of crown length to tree height) and the stiffer stems than dominant trees of smaller SFF. Stem analysis of 9 trees revealed that aging of trees from 5 to 18 years old resulted in an increase of stem slenderness (tree height /ground-line tree diameter) from about 30 to 60. This was associated with a decrease in microfibril angle at S2 layer of latewood tracheid and an increase in tracheid length from cambial age 3 to 16 at 1.2m above ground.
In some rings, Larger SFF decrease microfibril angle at S2 layer of latewood tracheid and increase in basic density at 1.2m above ground.

3. The background of this study
The woods from sugi plantations in Japan
large intra and inter tree variations of wood properties
To promote the use of sugi woods, the variation of wood properties should be controlled by silvicultural practices.
less information for effective silvicutural practices to control the wood properties.
The purpose of this study
To examine the effects of stem form factor (SFF: height to diameter ratio) on stem stiffness, anatomical wood properties and knot distribution in sugi plantation trees.

4. [Results] Stiffer stem Larger SFF
Anatomical properties
Larger SFF
Increase knots amounts / timber volume

5. [Conclusions]
Maintaining appropriately high tree density could produce the woods with higher mechanical properties through the high SFF (height to diameter ratio) and low CLR (the ratio of crown length to tree height)
Pruning may improve the positive effect of the high SFF on mechanical properties by reducing the density of dead knot within the stem.