共查询到18条相似文献，搜索用时 203 毫秒
1.
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 相似文献
2.
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 总被引：19，自引：2，他引：19
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。 相似文献
3.
4.
对4个12年生的日本落叶松无性系幼龄材早材单根管胞进行了拉伸实验。结果表明:日本落叶松无性系幼龄材早材单根管胞拉伸弹性模量、拉伸强度和断裂伸长率的均值分别为11.44 GPa、616.59 MPa和6.54%,相应的变异系数为26.97%、26.26%和23.17%。方差分析表明日本落叶松幼龄材早材单根管胞拉伸弹性模量和管胞断裂伸长率在无性系间差异极显著(0.01水平),拉伸强度在无性系间差异不显著;株内早材单根管胞拉伸弹性模量、拉伸强度和管胞断裂伸长率在年轮间差异显著。对日本落叶松无性系幼龄材早材单根管胞拉伸力学性能进行遗传参数估计,单根管胞弹性模量和断裂伸长率的重复力分别是0.79和0.57,属于中度到强度遗传控制,无性系早期选择及材性遗传改良潜力较大。 相似文献
5.
6.
选取杉木、白皮松、日本落叶松三种针叶树材为研究对象,探究并比较位于不同生长轮的单根管胞的形态参数及拉伸力学性能.结果表明,三种针叶树材的管胞长度、宽度、长宽比及拉伸强度、弹性模量、断裂伸长率基本符合随生长轮增加而增大的变化规律;杉木管胞的长度、宽度最大,日本落叶松晚材第9生长轮的管胞具有最佳的拉伸性能.方差分析表明,杉木和白皮松的第3生长轮与其他生长轮的管胞形态具有显著性差异(P<0.05).杉木、日本落叶松的第3生长轮与其他生长轮的管胞拉伸力学性能具有显著性差异(P<0.05),而白皮松各生长轮间的拉伸力学性能没有显著性差异.研究结果为人工林木质纤维的高效利用及建筑用材提供依据. 相似文献
7.
对黄山松天然林与人工林的群落学对比分析表明：黄山松林的植物种类天然林为１９～２９种，人工林仅有９～１７种；天然林下木层和草本层的多样性格数分别为２．８２４２～２．８７６３和１．７９９８～１．８３６６，而人工林分别为１．６０７３～２．０７７５和１．８３６６～１．９３９４。天然林胸径生长量比人工林低０．４７ｃｍ／ａ，树高连年生长量最高峰出现在第２０年，比人工林晚５ａ，材积在第４０年以后增长明显加快（＞０．０１ｍ３／ａ），比人工林迟２０ａ。文中以Ｓｈａｎｎｏｎ－Ｗｉｅｎｅｒ多样性指数及其均匀度、群落系数和相似度系数等指标为判别尺度，揭示了黄山松天然林与人工林之间的群落学差异。 相似文献
8.
七种人工林针叶树材抽出物含量比较 总被引：4，自引：1，他引：3
对７种人工林针叶树材抽出物含量进行了比较研究,结果表明：１）７种木材的热水抽出物含量在９．３９％－２．２４％之间,其中日本落叶松的抽出物含量最高为９．３９％,马尾松含量最低为２．２４％,２）１％ＮａＯＨ抽出物含量在１８．００％－１１．８０％之间,其中长白落叶松的含量最高为１８．００％。杉木含量最低为１１．８０％;３）苯－醇抽出物含量在２．９０％－１．６７％之间,其中杉木的含量最高为２．９０％,云南 相似文献
9.
１６年生火炬松纸浆材性状研究表明：管胞长度径向呈递增稳定的模式，纵向呈递减变化；其长宽比变异类似于管胞长度的变化；管胞长度变化范围为１．４０３～４．４５６ｍｍ，长宽比为４６．７～７０．１，腔径比为０．７１１～０．７８６，壁腔比为０．３８１～０．４９６。基本密度径向由０．３２４ｇ／ｃｍ３递增到０．４２８ｇ／ｃｍ３；纵向递减，其均值变动于０．３１４～０．４０１ｇ／ｃｍ２；株间木材密度均值与管胞长度两性状不相关。纤维素含量由髓心附近３７．０４％递增到树皮附近４３．９１％，木素、多缩戊糖含量分别由２８．７８％、１４．５９％递减到２５．７４％、１２．０５％，其苯醇抽出物含量变化在２．１２％～８．３８％之间。火炬松木材幼龄期约为１０～１３ａ。基于火炬松木材各树龄材性的变化，结合生长量指标，确定其短周期纸浆林适宜采伐树龄约为１２～１３ａ。 相似文献
10.
长岭岗林场日本落叶松幼龄材木材密度测定 总被引：1，自引：0，他引：1
对生长于湖北长岭岗林场陡坡地及平缓地两种立地条件的。12年生日本落叶松林的木材密度进行了测定，通过差异显著性分析，结果为：两种立地条件下日本落叶松幼龄材的基本密度、气干密度和全干密度，在α=0.05水平下差异均不显著，其木材的基本密度为0.443g／cm^3，变异系数为2．22％；气干密度为0．537g／cm^3，变异系数为1．71％；全干密度为0．502g／cm^3，变异系数为1．79％。 相似文献
11.
The annual ring width, density and shrinkage variation from pith to bark in Chinese fir (Cunninghamia lanceolata) and Boka sugi (Cryptomeria japonicd) were studied and compared. The results show that the ring width decreased sharply from pith to bark for Chinese fir. However, the ring width variation pattern for Boka sugi followed a different way, i.e., the ring width decreased to the fifth ring, increased to the tenth ring, decreased again to the fifteenth, and then increased to the twentieth, where it became constant. The large variations of Boka sugi appeared to show the maintenance of fast growth for many years. The annual ring mean density of Chinese fir increased gradually from pith to bark. However, the density changes for Boka sugi indicated the opposite trend, i.e., the mean density decreased gradually from pith to bark. The former showed a pattern as the same as a pine and a larch, and the latter was often found in a cedar and a cypress. The longitudinal shrinkage in juvenile wood was much hig 相似文献
12.
本文就中条山油松株内幼龄材与成熟材材性差异的比较研究,讨论对幼龄期划分的依据。根据木材解剖特征、物理力学性质的径向变异规律,确定其幼龄期为14年。随着树干高度的增加,油松木材幼龄期逐渐缩短、株内幼龄材范围及所占断面上的比例变小。株内幼龄材与成熟材材性差异显著。幼龄材管胞长度短、直径小,胞壁薄,微纤丝角度大,生长轮较宽,晚材率低,浸提物含量高,基本密度较大。幼龄材的力学强度远远小于成熟材。 相似文献
13.
《Scandinavian Journal of Forest Research》2012,27(1-4):68-74
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. 相似文献
14.
15.
M. K. Seth 《Wood Science and Technology》1981,15(4):275-286
Summary Radial pattern of variation in the first-formed earlywood tracheid length in blue pine shows that it increases outwards from the pith at first rapidly up to the 10th ring, then more slowly up to about the 40th ring and thereafter it remains more or less constant. It is correlated significantly and positively with both age and distance from the pith up to 40 years. In the mature wood zone i.e. after 40 years, tracheid length is not affected by either age or distance from the pith. The mean tracheid length of mature wood is significantly and positively correlated with the mean tracheid length of juvenile wood and also with the tracheid length of each of the juvenile wood rings. Based on the results of this study some guidelines for sampling are proposed. Trees with greater than 51 cm d.b.h. or above 40 years of age can be compared by sampling only four outermost consecutive mature wood annual rings; and those with less than 51 cm d.b.h. or below 40 years of age can be compared by sampling any of the juvenile wood rings.A part of Ph. D. thesis submitted to Himachal Pradesh University, Simla-171 005 (India), under the supervision of Dr. K. K. Jain, Associate Professor. The author is thankful to Dr. Jain for constant encouragement and to the University Grants Commission (India) for financial assistance 相似文献
16.
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
17.
对火炬松（ＰｉｎｕｓｔａｅｄａＬ．）速生材５个高度木材的基本密度、年轮宽度、生长率、晚材率和管胞弦壁纤丝角进行系统测量、统计和分析，结果表明，木材基本密度随树干高度的增加而降低．但各高度之间的差异不显著；生长率从髓心向外，南北方向都是随年轮数的增加而减小，在高度上是随树干高度的增加而增大．但其差异性均不显著．晚材率与木材基本密度呈线性正相关，与纤丝角呈线性负相关；木材基本密度与纤丝角呈负相关；纤丝角与生长率呈正相关．其相关显著性均随树干高度的增加而减弱．这些规律，为火炬松速生材的有效利用和林木生长调控提供了理论依据． 相似文献