Growth and yield prediction models for Acacia mangium grown in the plantations of the central region of Bangladesh

Acacia mangium is a very fast growing species belonging to the family Leguminosae that has been introduced in the plantations in Bangladesh for its faster growth and wide range of adaptability. The present study aimed at development of growth and yield prediction models for the species using simultaneous equation method. Models were selected for the species to estimate stand dominant height, stand diameter, stand basal area per hectare and total volume yield per hectare. Paired t-test, 45-degree line test, percent absolute deviation and biological principle of stand development were used for the validation of chosen models. The results suggest that the models derived were statistically and biologically acceptable and could be satisfactorily used for stands of Acacia mangium of ages 4–7 yrs based on a base age of 6 yr.     

基于时延神经网络的木材干燥模型辨识的研究

木材干燥是一个复杂、多变的过程，传统的系统辨识方法很难建立一个理想的木材干燥模型。利用时延神经网络的特点，本文提出了基于时延神经网络的木材干燥模型辨识方法，并给出了辨识网络和结构。对辨识得到模型的仿真结果表明，利用时延神经网络所建立的模型是可靠且有效的。     

Reactivity of secondary hydroxyl groups in methylβ-d-xylopyranoside toward aβ-o-4-type quinone methide

Methyl-d-xylopyranoside was allowed to react with-O-4-type quinone methide without a catalyst to elucidate the reactivities of secondary hydroxyl groups at the C2, C3, and C4 positions. Benzyl ether-type lignin-carbohydrate complex (LCC) compounds linked at the C2 and C4 positions were predominant, at a ratio of 23. However, the reactivity of the hydroxyl group at the C3 position was quite low. These results strongly suggest that the reactivity of the C2 hydroxyl group in xylan toward quinone methide intermediate is higher than that of the C3 hydroxyl group during biosynthesis of LCCs.     

中国木工机械制造业的国际竞争力探讨

首先阐述了我国木工机械制造业的发展现状,然后运用迈克尔.波特的钻石模型对我国木工机械制造业国际竞争力的影响因素进行了深入分析,最后提出提升我国木工机械制造业国际竞争力的几点建议。     

红松高生长模型的研究(英文)

高生长模型是定量研究树木生长过程的有效途径,本文应用双曲线方程、Logistic方程、三个参数的Richards方程及四个参数的Richards方程对红松的高生长进行了研究。结果表明四个参数的Richards方程在模拟红松高生长时最为合适,且当其参数取不同的数值时,该方程可转化为其它理论方程。在使用四个参数的Richards方程时,可根据立地条件事先给定树高最大值,这样可使模型更符合实际情况。此外,文中还对一种以固定年龄时实际树高为参数值的模型进行了讨论,该模型对于计算给定树木的高生长将更为有效。     

Comparing the model forms estimating generalised diameter-height relationships in Tecomella undulata plantations in hot arid region of India

Four generalised diameter-height equations were developed and compared for pure and even-aged stands of Tecomella undulata in hot arid region of Rajasthan State in India. The data used to fit the equations consisted of 1 540 diameter-height observations collected from the plots laid out in uniformly stocked stands of varying age and density. The performance of four equations was tested by non-linear least squares regression and evaluated using different statistical criteria. Finally, these equations, with the same values of coefficients ob- tained during the fitting phase, were validated by an independent data set consisting of 854 diameter-height observations. Overall, equation （4） （Hui and Gadow function） was found to perform best for both the fitting data set as well as validation data set.     

深圳城市公园植物典型配置模式初探

深圳城市公园生境多样,景观类型丰富,造景水平较高;通过对深圳城市公园植物配置实用模式的调查研究,分析了应用植物种类的选择,总结提炼了18种典型的景观单元配置模式,并提出有利于今后发展的相关工作建议。     

贮木场选址模型的研究

建立了一个贮木场选址的数学模型，这个模型将动态经济评价方法，运输网络和贮木场选址有机地结合起来。     

王朗林区人工缺苞箭竹亚层数量特征及其模型

王朗林区人工缺苞箭竹亚层数量特征及其模型刘兴良，向性明（四川省林业科学研究院成都６１００８１）关键词四川王朗，亚高山暗针叶林，亚建群层，缺苞箭竹，大熊猫，仿真造林缺苞箭竹（Ｆａｒｇｅｓｉａｄｅｎｕｄａｔａ）是四川王朗林区亚高山暗针叶林下亚建群层的主要...     

自然植被净第一性生产力模型及其应用

本文利用中国１２５组天然成熟森林资料及Ｅｆｉｍｏｖａ在ＩＢＰ期间获得的世界各地的２３组森林,草地及荒漠等自然被资料应用及相应的气候资料对目前流行的气候生产力模型;Ｍｉａｍｉ模型,Ｔｏｒｎｔｈｗａｉｔｅ Ｍｅｍｏｒｉａｌ 模型,Ｃｈｉｕｋｇｏ模型,综合模型及北京模型的适用性进行了研究。结果表明：Ｃｈｉｋｕｇｏ模型,北京模型与综合模型都能较好地反应森林净第一性生产力状况,但对于干旱半干旱地区,模型与综