| Summary: | 碩士 === 國立臺灣大學 === 森林學研究所 === 91 === This research focused on the effects of four plantation densities（1.2 m×1.2 m, 1 m×3 m, 2 m×2 m and 3 m×3 m）of Taiwania（Taiwania cryptomerioides Hay.）on the eight characteristic values of tree rings and percentage of latewood by using RESISTOGRAPH○R and Soft X-ray micro-densitometer methods successively.
The result of this study shown that the lower plantation density was, the greater ring width and earlywood width were. Latewood width, earlywood density and maximum density were the highest when plantation density was the lowest. Plantation density had no significant effect on ring density. Both latewood density and minimum density were the greatest in the 2 m×2 m group while those were the lowest in the 1 m×3 m group. Similarly, plantation density had also no significant effect on percentage of latewood.
Comparing the density profiles obtained from above methods, the highest correlation coefficient was only r＝0.79（r2＝0.62）. The relationship between two methods shown the earlywood-related characteristic values (ring width, earlywood width, ring density, earlywood density, and minimum density) had the higher relationship and the correlation coefficients were greater than 0.5; however, except percentage of latewood, the latewood-related characteristic values (latewood width, latewood density, and maximum density) had the lower relationship, and the correlation coefficients were lower than 0.5. It shows that RESISTOGRAPH○R method had higher accuracy on the result of experiments on earlywood than those of latewood.
The abnormally rising of resistance profile by RESISTOGRAPH○R in sapwood occurred in either drilling from pith or from bark. The situation made it difficult to analyze the resistance profile of sapwood. The resistance profile by RESISTOGRAPH○R did not always show the real wood density especially in latewood. RESISTOGRAPH○R may be suitable for detecting and testing the decay space of rotten woods, however, it still needs to be further studied to apply on dendrochronology.
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