樟树人工林株间株内材性变异及其材性预测的研究

樟树人工林株内纤维长度径向变异由髓心向外递增，而后趋于稳定；木材基本密度髓心处稍大，由髓心向外先稍递减而后递增，再趋于稳定；纤维长度和基本密度性状与生长轮年龄关系模型可用来预测其性状值。樟树木材幼龄期约为7－9a，株内细幼龄材基本密度较成熟材小1．0％－9．9％，株内幼龄材与成熟材基本密度差异多不显著；其浸提物含量幼龄材与成熟材之间差异不显著。纤维长度株内变异系数大于株间，木材基本密度均值和浸提物含量二性状则是株间变大于株内变异。生长速度对樟树木材纤维长度、基本密度、浸提物含量等性状影响不显著。     

中国主要人工林树种幼龄材与成熟材及人工林与天然林木材性质比较研究

本文对中国１０种人工林和４种天然林的幼龄材与成熟材及４个树种的人工林木材与天然林木材的构造特征、化学性质、物理性质、力学性质的３３项材性指标差异进行了比较研究。结果表明,在幼龄材与成熟材之间,在统计上表现出差异显著性的为幼龄材比成熟材生长轮宽,管胞列数多,管胞短,直径小,微纤丝角大,密度小,径向干缩小,差异干缩大,流体扩散性高,抗弯强度、抗弯弹性模量、顺纹抗压强度、径面顺纹抗剪强度、径面抗劈力和冲击韧性低等１５项,即４６％的测试项目差异显著;表明在木材加工和用作结构材时应将幼龄材和成熟材视作两个性质不同的总体来考虑,在培育结构材时应研究如何缩短幼年期或改善幼年期材性。在人工林与天然林木材之间,采取人工林幼龄材性质与天然林幼龄材性质相比,人工林成熟材性质与天然林成熟材性质相比,结果表明,多数性质在统计上差异不显著,只有人工林木材比天然林木材胞壁率小、顺纹抗压强度低、差异干缩大、流体扩散性高等４项,即只有１２％的很少数测试项目差异显著;表明有可能通过人工培育的方法培育出与天然林木材性质相近的木材。     

中国主要人工林树种幼龄材与成熟材有人工林与天然林木材性 …

本文对中国１０种人工林和４种天然林的幼龄材与成熟材及４个树种的人工林木材与天然林木材的构造特征，化学性质，物理性质，力学性质的３３项材性指标差异进行了比较研究。结果表明，在幼齿林与成熟材之间，在统计上表现差异显著性的为幼龄材比成熟材生长轮宽，管胞列数多，管胞短，直径小，微纤丝角大，密度小，径向干缩法，差异干缩大，流体扩散性高，抗弯强度，抗弯弹性模量，顺纹抗压强度，径面顺纹抗剪强度，径面抗劈力和冲击     

刺楸木材幼龄期划分的探讨

以安徽琅琊山天然林内的刺楸木材为材料,在研究其解剖特征和物理力学性质变异的基础上,着重探讨刺楸木材幼龄期。结果发现：根据不同材性指标变异模式划分出的幼龄期不相同,以纤维长度和微纤丝角的径向变异规律划分出的幼龄期为１７年,以基本密度和顺纹抗压强度的径向变异规律划分出的幼龄期为１５年;根据同一材性指标不同高度材性变异模式划分的幼龄期也有差异。其总体趋势为：随着树干高度增加,其幼龄期略微变短。     

刺楸木材幼龄期划分的探讨

以安徽琅琊山天然林内的刺楸木材为材料，在研究其解剖特征和物理力学性质变异物基础上，着重探讨刺楸木材幼龄期。结果发现：根据不同材性指标变异模式划分的幼龄期不相同。，以纤维长度和微纤丝角的径向变异规律划分出的幼龄期为１７年，以基本密度和顺纹抗压强度的径向变异规律划分出的幼龄期为１５年；根据同一材性指标不同高度材性变异模式划分的幼龄期也有差异。其总体趋势为：随着树干高度增加，其幼龄期略为变短。     

基于支持向量机(SVM)的班克松人工林成熟材解剖性质的预测

成熟材含量的高低决定木材性质的优劣,合理界定幼龄材与成熟材的分界点,准确预测成熟材材质有利于木材高效加工利用.为了确定人工林班克松的成熟期和预测成熟材解剖性质,采用支持向量机(SVM)界定幼龄材与成熟材的分界点,在此基础上利用幼龄材解剖性质预测成熟材解剖性质.结果表明:人工林班克松幼龄材与成熟材的分界点在树木生长的第18年;成熟期解剖性质明显优于幼龄期,变化较幼龄期平缓;成熟预测误差低、相关性高;预测曲线能够体现解剖性质整体的变化趋势,但对解剖性质测试集突变点及其之后的变化情况表现不足.     

红松幼龄材与成熟材力学性质的差异

本文研究了人工林和天然林红松幼龄材与成熟材力学性质的差异.结果显示,成熟材的所有力学性质均高于幼龄材.幼龄材与成熟材的抗弯弹性模量差异在人工林红松中达0.01水平显著,天然林红松也达到0.01水平显著;人工林红松抗弯强度和弦向横纹抗压强度差异达0.05水平显著.抗弯强度、顺纹抗压强度、横切面硬度和弦向横纹抗压强度4项指标的差异达0.05水平显著.     

关于幼龄材问题

就目前市场上速生材居多、幼龄材问题突出以及速生材材性、幼龄材的特点、性质、幼龄材形成的期限、划分幼龄材与成熟材的意义、减少幼龄材的方法以及幼龄材的使用等提出讨论     

人工林马尾松木材性质的变异

本文研究了广西人工林马尾松木材性质的变异及幼龄材与成熟材的差异。结果表明 ,幼龄材与成熟材的分界年龄在 14　 16a ,解剖性质在径向上的变异规律为 :射线比量、树脂道比量、胞壁率、胞腔直径、胞壁厚、管胞长度、管胞宽度和晚材壁腔比是自髓心向外呈递增趋势 ,管胞比量和晚材率为递减趋势 ,早材壁腔比和早材腔径比则近似于一条直线。方差分析结果表明 :树脂道比量、胞壁率、胞壁厚、管胞长度和管胞宽度 ,幼龄材与成熟材差异达显著或极显著水平。 5项木材物理力学性质均为成熟材高于幼龄材 ,且均达差异显著水平。木材性质间的相关分析表明 :木材基本密度与管胞长度、管胞宽度、射线比量、树脂道比量、胞壁率呈显著的正相关关系 ,木材气干密度与抗弯强度、抗弯弹性模量、顺纹抗压强度也呈显著的正相关关系     

天然林五角槭木材材质径向变异规律初探

以天然林五角槭的木材解剖性质为研究对象,分析其株内木材材质径向变异规律,对幼龄材与成熟材进行初步界定。结果表明:细胞壁厚、壁腔比、胞壁率和径、弦向直径幼龄期波动较大,成熟期波动减弱;木纤维长度符合Pan-shinⅠ模型,幼龄材拟合度较好;组织比量符合y=aebx变异模型;幼龄材和成熟材的界定年限为28～33a之间。     

Effects of radial growth rate on selected indices for juvenile and mature wood of the Japanese larch

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.     

Basic density,longitudinal shrinkage and tracheid length of juvenile wood of Picea abies (L.) Karst

Variation in the growth ring width, basic density, longitudinal shrinkage and tracheid length was investigated in the juvenile wood of Norway spruce samples taken from different heights in the stem. Annual height increments were cut from the ten youngest shoots from trees of three different heights. By this method the properties of an individual growth ring could be analysed without taking samples from each ring. Sixteen tree tops of an average stem height of 8, 15 and 25 m were analysed. Basic density was low in the first shoot, highest in the second or third one and decreased gradually thereafter. Longitudinal shrinkage was highest close to the pith and decreased to about 0.2% in the outer rings. Tracheids were only ca. 1 mm long close to the pith and their length increased sharply towards the tenth shoot. The properties of juvenile wood varied with the height in the stem. Longitudinal shrinkage around the pith seemed to increase with increasing height and basic density was highest at 25 m stem height. The applicability of the method for the calculation of basic density and tracheid length in individual growth rings close to the pith is discussed.     

Variation in density of Picea sitchensis in relation to within-tree trends in tracheid diameter and wall thickness

The influences of cambial age and ring width on density of Sitkaspruce (Picea sitchensis (Bong.) Carr) were analysed in relationto within-tree trends in tracheid diameter and cell wall thickness.Discs were sampled at breast height from a total of 24 trees,from seven stands at three contrasting sites in Wales, and atbreast height, 30 per cent and 60 per cent total tree heightfrom one of the stands. Across the juvenile wood, ring density decreased with ring numberfrom the pith while radial tracheid diameter increased. Theseoverall trends were considered to be inherent to tree growth,presumably associated with cambial ageing, since they occurredin all trees on all sites. In juvenile wood, density also variedwith site growth rate (as indicated by ring width) at similarcambial age, wider rings being associated with more rapidrateof change in tracheid diameter with ring number and with decreasein tracheid wall thickness. Consequently, on a site having treeswith high growth rate density decreased more rapidly acrossthe juvenile wood, down to a lower minimum value, than on siteswith a slower growth rate. In mature wood, the decrease in densitywith increase in ring width was associated with differencesin both tracheid diameter and wall thickness. Density was slightly(though not significantly) higher at breast height than in comparablerings at 30 per cent total height, associated with significantlythicker tracheid walls at breast height. Changes in radial tracheid diameter (with ring number, or withring width) were associated with greater differences in theearlywood than towards the latewood end of each growth ring,while variations in wall thickness with ring width were associatedwith rate of increase in wall thickness towards the latewoodend. This may account for some previously conflicting reportson influence of silvicultural management on density, for densityis likely to vary with influence of environment on the seasonalcycle of cambial activity. The extent of the juvenile wood as delimited by the inner coreof wide growth rings does not necessarily correspond to theregion of varying tracheid dimensions in Sitka spruce.     

幼龄材范围的确定及树木生长速率对幼龄材生长量的影响

本文以杉木、日本落叶松的人上林和天然林木材为对象，选择ｙ＝ａ＋ｂｌｎｘ回归模式。利用其管胞特征因子随年轮数的变化，研究划分幼龄材年轮界限的最适因子，并就生长速率对幼龄材生长量的影响进入了探讨。结果表明：杉木和日本落叶松的人工林及天然林木的管胞特征值在径向水平上的变化均遵循ｙ＝ａ＋ｂｌｎｘ模式，尤其管胞长度与年轮数回归的相关系数Ｒ均达０．９８以上；管胞长度与管胞宽度及纤丝用相比，遗传率最大，随年轮数变化的模式最稳定，是划分幼龄材界限的最佳因子，由此得出杉木人工林幼龄材界限年轮为２０－２２（距髓心距离为１２．９－１３．２ｃｍ）、天然林为１６－１８（４．１－４．５ｃｍ），日本落叶松人工林为１９－２３（８．７－１０．５ｃｍ）、天然林为２３－２４（２．９－３．１ｃｍ）；幼龄材生长量与树木生长速率成正比。     

Control of tracheid cross-sectional dimensions in Norway spruce and Scots pine wood raw material

Abstract

Wood properties, including tracheid cross-sectional dimensions, show a large degree of variation. To improve the properties of products made from wood, different methods to control variation have been developed. This study aims to determine the theoretical efficiency of three control strategies: the fractionation of pulped tracheids into earlywood and latewood, the separation of juvenile and mature wood, and sorting of logs according to tree size. The efficiency of each method was studied by first constructing virtual trees from measured tracheid cross-sectional dimensions, then simulating the efficiency of above-mentioned methods. The tracheid dimension data include Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.). The simulations show that separation into earlywood and latewood classes has the highest theoretical efficiency and yields the lowest variances in raw material. Classification into juvenile and mature wood groups is the second most efficient method, and the sorting of logs according to the size class of the tree is the least efficient method. It was also concluded that the variation in cell-wall thickness and radial diameter mainly originates from differences between earlywood and latewood, whereas the variation in tangential diameter mainly originates from differences between mature and juvenile wood.     

Growth and wood quality of sugi (Cryptomeria japonica) planted in Akita prefecture (II). Juvenile/mature wood determination of aged trees

Variations of certain anatomical and mechanical indices within tree stems of aged sugi (Cryptomeria japonica) trees planted in Akita prefecture were studied. The determination of the juvenile/mature wood boundary was also discussed, and the effects of wood structure on mechanical properties were investigated. On the basis of radial and vertical variation of the anatomical and mechanical indices, modulus of elasticity (MOE)/ shear modulus (G) was chosen as the index for determining the juvenile/mature wood boundary. The increase rates of MOE/G at the points of 1%, 2%, and 3% were discussed. It was found that for aged trees, all three points were thought to be effective for dividing juvenile and mature wood. However, for younger trees, the point of 2% was recommended, which was mostly consistent with the result obtained by the increase rate of 1% for tracheid length (TL). Among mechanical properties, the MOE showed more significant juvenile/mature wood differences than did modulus of rupture (MOR) and . By correlation analysis, it was suggested that microfibril angle largely contributed to the indices of MOE and G, and specific gravity largely contributed to the indices of MOR and .Part of this report was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, March 2003     

Differences in wood properties between juvenile wood and mature wood in 10 species grown in China

 This study examined the intrinsic differences in various wood properties between juvenile wood and mature wood in 10 major reforestation species in China. Comparisons between juvenile wood and mature wood were made in both plantation- and naturally-grown trees. Considerable differences in most wood properties were found both between plantation-grown juvenile wood and mature wood, and between naturally-grown juvenile wood and mature wood. This suggests that wood properties of plantation-grown trees, to a large extent, depends on their juvenile wood contents, and can thus be manipulated effectively through rotation age. In general, the longer the rotation age, the lower the juvenile wood content, and the stronger the mechanical properties of the plantation-grown woods. However, the differences between juvenile wood and mature wood vary with wood properties and species. In general, juvenile wood and mature wood have less difference in chemical composition than in anatomical and physico-mechanical properties. Compared to the softwoods studied, the hardwoods appear to have less difference between juvenile wood and mature wood. Received 25 June 1999     

Variation Within Trees of Wood Anatomical Properties in Chinese-Fir Plantation and Their Relationship Modeling Equations

A comprehensive analysis on the variation pattern of early- and latewood tracheid morphological parameters along tree (Cunninghamia lanceolata Hook.) height, including length and width, wall thickness, tissue proportion, cell wall percentage, width of growth rings, and on the relationship among them are conducted. The results indicate an initially rapid and then gentle increase of tracheid length and width, thickness of the radial wall and tangential wall of tracheid, area percentage of tracheid from pith to outward, while S2 microfibril angle (Mfa) of tracheid, and rays percentage gradually decrease and then tend to be stable. The variation of all anatomical parameters but earlywood cell wall thickness shows no significance along tree height. The radial variation pattern of width of growth rings is characterized with initially slight decrease followed immediately by a rapid and then much more gentle increase from pith to outward. The delimitation age between juvenile and mature wood is 14-16 years. Com     

马尾松人工林管胞长度的株间和株内变异

林木株间变异和株内变异是木材的两个主要变异来源,由于木材性状具有较强的遗传性以及育林措施对木材的可塑性,人们可以培育出材质优异的木材,然而因变异的存在,在如何充分利用木材时却遇到了许多困难。林学家的一个主要目的就是在充分掌握木材变异规律的基础上,采用有效方法提高材质的均匀性。     

Douglas-fir wood quality studies part I: Effects of age and stimulated growth on wood density and anatomy

Douglas-fir trees about 21 years old and growing on a poor site were thinned and fertilized causing accelerated growth. The characteristics of the wood across the 30-year age span were studied for 7 trees from the treated plot. Four trees of nearly uniform ring growth were also studied for some characteristics. Radial and tangential tracheid diameters, tracheid length and percent latewood were correlated quite well with log of age, coefficients ranged from 0.76 to 0.88 on pooled data. All tracheid dimensions when correlated with log of age gave high coefficients on a within-tree basis. The strongest relationship in all age-related factors was between 0 and 12 to 14 years. Specific gravity increased with age in all trees to about 16 to 18 years, then leveled off.Fertilization and thinning caused immediate production of lower density wood with somewhat lower percent latewood, a slight decrease in tracheid diameter tangentially but slightly greater radially, and a small decrease in tracheid length. The effects were mainly in the first 3 to 4 years after treatment, then there was recovery to normal wood density and cell dimensions. Wood from the trees of uniform growth showed no significant change over the same time period in percent latewood, specific gravity, and tracheid length.The research was financed by funds from State of Washington Initiative 171, Institute of Forest Products and the College of Forest Resources, University of Washington, Seattle.