兴安落叶松立木材积和树皮材积可加性模型研建

【目的】确保立木材积和树皮材积预测的一致性并提高预测精度。【方法】以大兴安岭兴安落叶松为研究对象,分别采用控制法和分解法研建了可加性模型系统。利用SAS统计软件模型模块proc model中的NSUR法进行拟合及参数估计。拟合结果采用确定系数(R2)和均方根误差(RMSE)进行评价;检验结果则通过确定系数(R2)、均方根误差(RMSE)、平均相对误差(MRE)、平均误差绝对值(MAB)和相对误差绝对值(MPB)进行评价。【结果】从模型的整体评价结果来看,两种方法的拟合和检验效果均很好,基于分解法构建的模型略优于基于控制法构建的模型;不同径阶的检验表明,对于中等径阶的树木(20≤D<36 cm),基于控制法的模型相对较好,而对于小径阶(5≤D<20 cm)和大径阶的树木(D≤36 cm),基于分解法的带皮、去皮、树皮材积模型的预测精度要比基于控制法的各立木材积模型要稍好。【结论】总的来说,两种可加性模型系统均能很好地预测单木带皮材积、去皮材积和树皮材积,并确保得到满足一致性的预测结果,在具体应用时可根据实际情况选择适合的可加性材积模型系统。     

降香黄檀树皮率、心材率及木材密度研究

对降香黄檀（Dalbergia odorifera）的树皮率、心材率,木材密度进行了研究。结果表明：降香黄檀树皮体积百分率及质量百分率平均值分别为20．14％、13．77％;心材百分率平均值为30．53％,心材形成的年龄为9～15a;生材密度平均值为1．064g／cm^3;基本密度平均值为0．715g／cm^3;生材含水率平均值为49．21％。降香黄檀树皮体积百分率及质量百分率均随着树高的增加而增加;生材密度及心材率随着树高的增加而减少;基本密度随着树高增加,呈大-小-大-小的趋势变化;生材含水率随着树高的增加,呈小-大-小-大的趋势变化。     

板栗树皮电阻值与枝干病害的关系

利用万用电表对板栗枝干病害的病情程度与树皮电阻值的关系进行了研究。结果表明：在不同的植株间,树皮电阻值随着病情的加重而增加;在同一植株上,树皮电阻值随着树体的高度增加而增大;在树干基部、主枝和梢头三个部位中,电阻值差异比较显著．诙研究为今后板栗乃至其他林木枝干病害研究提供了一种简便易行的新方法。     

白僵菌对小蠹虫的致病力及持续控制作用的研究

在室内利用不同浓度的球孢白僵菌Z28菌悬液对小蠹的幼虫和成虫进行了感染,随浓度增加幼虫和成虫死亡率均随之增加.在相同条件下,白僵菌侵染幼虫能力高于成虫,侵染致死时间幼虫也短于成虫.在室外使用涂刷和注菌2种方式对小蠹虫进行了防治.浓度为0.1亿孢子/mL和1亿孢子/mL利用注菌方式防治小蠹效果明显高于涂刷;但当浓度达到10亿孢子/mL时,2种接菌方式之间无显著差异.经过连续3年监测发现,未防治区有虫株树和虫口密度相对比较稳定,虫口密度居高不下.化防区有虫株数和虫口密度波动性大,与化防区相比白僵菌防治区表现出持续有效控制的优势,但2年后控效基本消失.     

Heartwood, sapwood and bark content of teak trees grown in Karnataka, India

We evaluated heartwood, sapwood and bark content in teak trees. A total of 27 sample plots were laid out in teak plantations raised by State Forest Department in Karnataka covering different age groups...     

马尾松树皮胶粘剂的研究——树皮成分及制胶配方的探讨初报

本文分析了马尾松树皮的主要化学成分,并探讨了用全树皮制胶的配方与工艺。试验结果表明,马尾松全树皮胶加入35％的增强树脂,可以制造室外型胶合板,其胶合强度达到了国家GB 1349—78或GB 9846.4—88的标准要求。     

苎麻茎皮cDNA文库的构建

以生长中期的苎麻茎皮为材料,提取总RNA,经纯化mRNA后,合成双链cDNA。双链cDNA加上EcoRI-SmaI接头后,用限制酶NotI酶切并除去小于400bp的短链cDNA,长的cDNA片段连接到EcoRI-NotI酶切载体pAP3neo上,获得滴度为2.6×104的苎麻cDNA文库,插入片段大部分分布在500bp～1500bp之间。该文库的建立为苎麻表皮功能性新基因的发现奠定了基础。     

RAINFALL INTERCEPTION BY GRASS

Forestry and forest industry in the Republic of South Africa are compared first with other primary and secondary industries in the country with regard to capital invested, value of output, number of employees, salaries and wages paid out, and export earnings.

Secondly, South Africa is compared with other countries with regard to forest area, growth and timber output, and per caput consumption of forest products.     

Soil testing of horticultural substrates (ii) Desirable nitrogen values for the 1: 1.5 water extract

Abstract

The initial nitrogen desirable value (DV) to give maximum dry weight and maximum growth rate for various growing periods has been estimated for the 1: 1.5 water extraction procedure by regressing dry weight and net growth rate against soil test values using a quadratic function. The DV for dry weight and growth rate has been estimated for chrysanthemum and verbena (2 trials each) and for dry weight for tomato (1 trial) in a number of substrates.

The DV for maximum dry weight of chrysanthemum, grown for 48 days under winter conditions, were: Peat 151–211 ppm and greater, Bark 140‐168 ppm and Peat and Sawdust and Sand (PSS) 135–162 ppm. Under summer conditions and grown for 35 days, the DV were as follows: Peat 134 — 172 ppm, Peat and Pumice (PP) 142 ‐170 ppm, Bark 168–202 ppm and PSS 152–172 ppm.

The DV for maximum dry weight of verbena grown for 42 days under spring conditions were as follows: Peat 57 ppm, Bark 41 ppm and PSS 48–52 ppm and greater. Under summer conditions and grown for 38 days, the DV for verbena were: Peat 77–90 ppm, PP 70–85 ppm, Bark 67–73 PPm and greater, and PSS 72 ppm.

For the chrysanthemum and verbena trials, the DV for maximum growth rate over various periods were generally in the range of DV found for maximum dry weight. However, the values did tend to increase later in the life of the crop.

The DV for maximum dry weight of tomato were as follows: Peat 260–290 ppm, PP 211–240 ppm, Bark 220–254 ppm, PSS 186–236 ppm and Sawdust and Sand 190–220 ppm. This trial, in contrast to the others, was not conducted in conditions free from leaching and this may have given a higher DV.     

Effects of amending Container growing media with Dolomitic limestone on the growth of Photlnia ‘Fraseri’

Abstract

The results of three years of experimentation on the effect of the addition of dolomitic lime to pine bark‐sand media shows that Photinia ‘Fraseri’ responds positively to lime additions. This response was not due to pH changes, since for two of the three years only a small change was observed in pH and lime requirement values. It is more likely that the increased growth is due to an improved magnesium environment. Not only was the magnesium content of the foliage increased with lime addition, but the K:Mg ratio was decreased to a level where potassium‐magnesium antagonism was not important.