Speaker : Pei-Yu Kuo Plantation Density and Thinning Effect on the Length of Tracheid and Maturing Age of Japanese- cedar Grown in Taiwan

I ntroduction Japanese-cedar is one of the important resources in Taiwan. Large percentage of plantation Even-aged Low economic value Plantation density Thinning intensity Anatomy of the wood

Material and Method – site location

Material and Method – data of the site Site Original numbers （ 1968 ） Light thinning treatment （ 1990 ） Intensity of thinning treatments （ 2001 ） Average Basel Area (cm 2 ) A trees / ha （ Type A ） 550 trees / ha Heavy thinning (40%) A2Medium thinning (25%) A3Light thinning (10%) B trees / ha （ Type B ） 750 trees / ha Medium thinning (25%) B2 Light thinning (10%) B3No thinning477.23

Result and Discussion 1 The anatomy from pith to bark and their relationship

Result and Discussion Ring number from pith (years) length of tracheid (mm) The growing curve of trachied is a log curve

Result and Discussion The MFA decreased rapidly at first and then remained constant. Ring number from pith (years)

Result and Discussion The degree of MFA and the length of tracheid have contrary trend.

Result and Discussion Second thinning First thinning Plantation density 33 rd to 36 th 23 rd to 32 nd 1 st to 22 nd We not only discuss the average data, but also separate those data into three sections and discuss the effect of each treatment.

Result and Discussion Tracheid length Average1st – 22nd23rd – 32nd33rd – 36th A ± ± ± ± 0.11 A ± ± ± ± 0.16 A ± ± ± ± 0.12 B ± ± ± ± 0.07 B ± ± ± ± 0.13 B ± ± ± ± 0.04

Result and Discussion 2 Three methods to distinguish the maturing age

Result and Discussion Ring number from pith (years) length of tracheid (mm) Method 1 : the elongation ratio of log curve is less than 1%

Result and Discussion Ring number from pith (years) length of tracheid (mm) Method 2 : Reducing the numbers of sample

Result and Discussion Ring number from pith (years) Aaccumulated width of annual ring (mm) Method 3 : the elongation ratio of log curve is less than 3%

Result and Discussion AB Method 1 a （ year ） Method 2 a （ year ） Method 3 a （ year ） Tracheid length (mm) Mature a Wood 3.00 ± ± ± ± ± ±0.14 Juvenile b Wood 2.24 ± ± ± ± ± ±0.59 Microfibril Mature a Wood ± ± ± ± ± ±1.20 Juvenile b Wood ± ± ± ± ± ±6.85

The length of tracheid decreases with the increasing MFA. It shows negative linear regression (R 2 =0.71) when the length of tracheid is versus the angle of MFA. The average lengths of high plantation density or one to twenty years grown tracheid have significant longer lengths than low plantation density tracheid. But, there is no significant difference in thinning treatment. Conclusions The anatomy from pith to bark and their relationship The effect of planation density and thinning

Using the three mentioned methods to determine the age of maturity, we can conclude that it is 19 years old. Morerover, there is no significant difference between the results of these methods above to judge the age. No matter in the length of tracheid or the angle of MFA, mature wood has significant longer tracheid length and smaller MFA than juvenile wood. Conclusions Three methods to distinguish the maturing age

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