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1.
The relationships between bending properties, compressive strength, tracheid length, microfibril angle, and ring characteristics
of 20-year-old Taiwania (Taiwania cryptomerioides Hay.) trees were examined. The trees came from different thinning and pruning treatments, but the practices showed no significant
effect on the investigated properties. The results showed that based on comparison with the literature, plantation-grown immature
Taiwania have noticeably lower average strength properties than mature trees of the same species. Wood density and bending
and compressive strengths were not related to either tracheid length or microfibril angle in young Taiwania. There were positive
relationships between bending strength and compressive strength. The wood density, ring width, earlywood width, earlywood
density, and latewood percentage were the most important predictors of strength by simple linear regressions. The wood density
and ring width/earlywood width may be considered as indicators for assessing the bending strength, while wood density and
latewood percentage were the best predictors of compressive strength by multiple linear regressions. 相似文献
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Cheng-Jung Lin Song-Yung Wang Te-Hsin Yang Ming-Jer Tsai 《Journal of Wood Science》2006,52(4):337-341
Taiwania (Taiwania cryptomerioides Hay) is an important timber species in Taiwan. Growth in generally improved trees under intense silvicultural practice is
so rapid that rotations or the practice of thinning trees may be as short as 20–30 years. Thus, the wood properties of young
plantation trees need to be characterized to effectively use this resource. The effects of different thinning and pruning
methods on the compressive strength parallel to grain of young Taiwania trees were explored. Average compressive strengths
with various thinning treatments revealed the trend of no thinning > medium thinning > heavy thinning and in the pruning treatments
showed the trend of medium pruning > no pruning > heavy pruning. However, most results showed no statistically significant
differences among thinning and pruning treatments. 相似文献
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This study investigated the effects of various thinning and pruning methods on the knots (number and size) and lumber recovery from Taiwania (Taiwania cryptomerioides Hay.) plantation trees. The results showed that heavy thinning caused more knots and larger-diameter knots than medium or no thinning; moreover, pruning caused fewer numbers of knots and smaller-diameter knots than no pruning. Better-quality Taiwania trees occurred with the no-thinning/no-pruning treatments, as shown by analyzing the knots, although the results also showed that the healing process seemed to have produced not completely clear wood during the 9 years after the pruning treatment. The thinning intensity slightly enhanced the lumber recovery of logs. Pruning did not affect lumber recovery from taiwania trees and logs. Thinning increased the lumber recovery per tree due to an increase in the diameter at breast height. 相似文献
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台湾杉、秃杉引种栽培试验及生长效果分析 总被引：3，自引：0，他引：3
通过在福建省闽清美菰林场引进台湾杉与秃杉进行育苗和造林试验,结果表明:相同或不同海拔营造台湾杉与秃杉纯林,其两种树种间或不同海拔之间的林分主要指标的生长量差异不显著。试验还表明台湾杉与秃杉是福建省高海拔山地造林较为优良的用材树种,速生期长,可以扩大造林范围。 相似文献
6.
Effects of radial growth rate on selected indices for juvenile and mature wood of the Japanese larch 总被引：1，自引：0，他引：1
To examine the differences between juvenile and mature wood, 12 aged sample trees from two areas of Nagano Prefecture were harvested; and the radial development of tracheid length, the ring density, and the relation of the radial growth rate (observed by ring width) with some selected indices of ring structure were investigated. The results proved that the radial variation of tracheid length with ring number can be described by a logarithmic formula, and both plantations reached the demarcation of juvenile and mature wood at age 18. With the segmented regression method, we also analyzed radial variation of mean density and found that the demarcation of juvenile and mature wood was at age 15 for sample trees from Saku and at age 21 for those from Yabuhara. By using the results of estimates from juvenile and mature wood based on ring density, we found that high growth rates resulted when producing lower-density wood during the juvenile period, but these rates did not occur during the mature period. The basic reason for this phenomenon is the variation in patterns of earlywood and latewood in juvenile and mature wood, respectively. This result advised us that when managing plantations of Japanese larch it is necessary to take different measurements at different growth periods. 相似文献
7.
Song-Yung Wang Cheng-Jung Lin Chih-Ming Chiu Jin-Hau Chen Te-Hsin Yung 《Journal of Wood Science》2005,51(1):1-6
The effects of different thinning and pruning methods on the bending strength and dynamic modulus of elasticity (DMOE) of young Taiwania (Taiwania cryptomerioides Hay) were investigated. The average DMOE, modulus of elasticity (MOE), and modulus of rupture (MOR) in the thinning treatments showed the following trend: no thinning > medium thinning > heavy thinning. This indicates that thinning reduces average bending properties. The average DMOE, MOE, and MOR in the pruning treatments showed the following trend: medium pruning > no pruning > heavy pruning. According to this tendency, better average qualities of lumber and specimens were from wood subjected to no-thinning and medium-pruning treatments according to an ultrasonic wave technique and static bending tests. However, most results showed no statistically significant differences among thinning, pruning, and thinning and pruning treatments. The average values of DMOE, MOE, and MOR of visually graded construction-grade lumber were significantly greater than those of below-grade lumber. Moreover, there were very significant positive relationships between density, ultrasonic velocity, DMOE, MOE, and MOR, although the determination coefficients were small. 相似文献
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安溪秃杉引种造林试验初报 总被引：2，自引：1，他引：1
通过对秃杉引种造林试验研究表明,秃杉具有良好的适应性、速生性和抗逆性,对幼林观测表明,其造林成活率、树高、胸径长势良好,年平均树高生长量达0.8 m、胸径生长量达1.2 cm;与福建柏、杉木生长量比较,秃杉树高提高了12%~21%、胸径提高了13%~29.8%,具有明显的增益优势,适宜作为南方用材林进一步引种栽培和推广示范。 相似文献
9.
Juvenile wood properties are studied in a ring-porous tropical hardwood – teak (Tectona grandis L. F), to assess the utilisation potential of short rotation timber. Compared to mature wood, it is characterised by wide
rings, short fibres, small diameter, low vessel percentage, high cell wall, wide microfibrillar angle and relatively low or
almost similar mechanical properties. While the average modulus of elasticity and modulus of rupture in juvenile wood are
85% and 82% respectively of the mature wood value, the longitudinal compression strength is similar. With relatively small
fibrillar angle of 15° and the scope for genetic selection of individual trees, teak juvenile wood has potential for desired
dimensional stability. The segmented regression models and visual interpretation of radial patterns of variation in anatomical
properties reveal that juvenility in plantation grown teak extends up to 15, 20–25 years depending on the property, growth
rate and individual tree and plantation site. The fitted regression models, to explain the age-related variations in juvenile
wood properties range from simple, linear to exponential, reciprocal and quadratic equations. Fibre length, microfibrillar
angle, vessel diameter/percentage and ring width appear to be the best anatomical indicators of age demarcation between juvenile
and mature wood, although maturation age often varies among the properties. The projected figures for proportion of juvenile
wood in plantation grown teak at breast height are 80–100% and 25% at ages 20 and 60 years respectively.
Received 3 November 1998 相似文献
10.
在全面系统收集秃杉人工林资料的基础上，采用SPSS软件整理、分析、辨别、筛选秃杉人工林的年龄与优势平均胸径、优势平均高的有效数据，用于秃杉人工林立地指数回归分析--导向曲线数学模型的建立和按照编制秃杉人工林立地指数的有关要求进行相关数据的整理、分析、计算，依据其整理、分析、计算，再对其结果进行秃杉人工林立地指数的编制。 相似文献
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Taiwania (Taiwania cryptomerioides Hayata), native to Taiwan, is one of the most economically important tree species grown there. In this article we summarize
the current results of phytochemistry and bioactivity of Taiwania extracts, including antifungal, antitermite, antibacterial,
and antimite activities as well as cytotoxicity against three tumor cells. The resources of Taiwania are also addressed.
Received: January 23, 2002 / Accepted: March 8, 2002
Acknowledgment The authors thank the National Science Council of R.O.C. for financial support (NSC-90-2313-B-002-344).
Correspondence to:S.-T. Chang 相似文献
13.
通过对台湾杉和秃杉两种珍稀树种的引种栽培,就台湾杉和秃杉两种珍稀树种从种子(球果)到幼苗的整个发展过程,以及种子和苗木的生产技术做了细致的探索性研究,并就培育出的幼苗进行观察、记载和绘制成图;经定植3 a后评价引种成败。研究结果可为杉科台湾杉属的系统发育和亲缘关系方面的研究提供理论基础;也可为用材林造林、园林绿化树种提供参考和对这两种珍稀树种继续引种栽培提供实践依据。 相似文献
14.
秃杉引种耐荫性的初步研究 总被引：2，自引：1，他引：2
在江苏南京、江宁、句容等地对引种秃杉的耐荫性初步研究表明,秃杉幼龄阶段具有较强的耐荫性。苗期可以适应200～300勒克司的微弱光照,幼树枝叶在500～1000勒克司弱光照下的树冠内,仍能正常生长。适度遮荫可以提高裸根苗移植成活率,避免或减少日灼造成的生理病害,并促进苗木生长。利用这一重要生物学特性对于在纬度偏北、海拔低、光照强的江苏引种区选择合理的秃杉引种栽培模式,保障引种顺利进行,扩大和保存繁衍秃杉珍稀树种资源具有重要实践意义。 相似文献
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采用不同肥料种类和施肥剂量对秃杉人工林进行施肥对比试验。观测胸径、树高和蓄积生长量,分析不同肥料种类和施肥剂量对秃杉人工幼龄林高、粗和蓄积生长量的效应。试验结果表明,合理的施肥措施对秃杉人工林生长有明显促进作用,与对照相比,年高生长增加34%,粗生长增加26%,蓄积生长增加35%。 相似文献
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秃杉人工林的培育技术 总被引：1，自引：4，他引：1
云南省于20世纪80年代初开始大面积营造秃杉人工林。通过多年的试验研究和造林实践，已形成了一套完备而实用的秃杉人工林培育技术。据此从采种、育苗、林地选择、定植栽培及抚育管理等方面系统而详尽地介绍了秃杉人工林的此套成熟培育技术。 相似文献
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秃杉种源—家系联合试验表明,秃杉发芽、物候、苗期及幼林生长等11个性状中,真叶全现、一年生幼树抽高、一年生幼树全高种源间差异显著,发芽率、发芽势差异不显著;造林11年生时,种源间、家系/种源间生长性状差异显著,在遗传方差中,种源方差分量所占比例较大,种源效应最明显。选择秃杉优良种源有贵州交、贵州格、贵州昂、贵州丹、云南滕冲种源,优良种源平均单株材积遗传增益为29.68%,实际增益为34.60%。利用种源发芽、物候、苗期及幼林生长、11年生生长性状等11个性状,采用主成分分析方法,将秃杉区划为3个种源区,第1个种源区为湖北利川种源,第2个种源区包括云南昌宁、云南滕冲种源,第3个种源区包括云南龙陵、贵州丹、贵州格、贵州昂、贵州交种源,其中第3个种源区种源在广东生长表现良好,适宜在广东适生区域引种推广。 相似文献