Structure and functions ofPinus sylvestris var.sylvestriformis plantation ecosystem

Changbai pine (Pinus sylvestris var.Sylvestriformis) is an endemic and important tree species in Changbai Mountain. There were only 63 plant species in Changbai pine plantation, where hemicryptophyte was dominant(39.68%). Simpson diversity index was 0.87, Shannon-Wiener diversity index was 2.96, and evenness index was 0.82. Community structure were divided into three layers: tree layer, shrub layer and herb layer. The total biomass and net production were 111.982 t/hm² and 8942.80 kg/(hm² a) respectively. The total biomass for tree, shrub and herb layers were 106.150, 2.230, 2.264 t/hm², accounting for 94.79%, 1.99%, and 2.02%, respectively, and net production for those were 7465, 223, and 1182 kg/(hm² a), accounting for 83.47%, 2.49%, and 13.22% of the total respectively. The nutrient content in various organs is in the order of needle> branch> root> bark> trunk, For the assimilated organ, the nutrient content is in the order of N> K> Ca> P> Mg, and that in absorption organ is in the order of Ca> N> K> P> Mg. For the whole plantation ecosystem, nutrient content is in the order of soil> litter> herb layer> shrub layer> tree layer. Nutrient storage and its accumulation rate in tree layer take up 88.79% and 76.43% of the total, respectively. The project is funded by the Opened Research Station of Changbai Mountain Forest Ecosystems, Chinese Academy of Sciences Responsible Editor: Chai Ruihai     

谈房屋结构设计中应引起注意的几个问题

本通过设计及施工的实践，着重阐述了结构设计中应该注意的问题。     

碧峰峡森林土壤性状研究

碧峰峡不仅是旅游景点,还是多学科研究的天然“实验室”,地处雅安亚热带区,原始森林植被保护完好,土壤垂直分布明显,地质现象复杂,也是大熊猫、金丝猴出没之地。经研究结果：土壤呈酸性,自然肥力高．经相关分析结果：土壤有机质含量和ＣＥＣ等有关理化特性的相关性,较物理性粘粒与ＣＥＣ间更加显著。     

竹片覆面胶合板的初步研究

本文研究了以竹片为外层材料、多层杨木单板为芯层材料的复合胶合板的结构和力学性能，分析了板坯结构形式、纵向纵片厚度、单板层数及板坯压缩率与产品机械强度之间的关系。初步研究结果表明，板坯结构形式对产品的静载荷抗弯曲性能影响显著；在试验范围内，纵向竹片厚度为３．５－５．０ｍｍ、板坯压缩率在２３％左右时，竹片覆盖面杨木胶合板的综合力学性能比较理想。     

秦岭山地云杉林结构特征与更新动态的研究

云杉 (ＰｉｃｅａａｓｐｅｒａｔａＭａｓｔ.)林是秦岭林区高中山地带的顶极群落类型之一 ,由于其蓄积量高、材质优良 ,亦为秦岭林区开发利用最早的森林类型 (张仰渠 ,1 988)。陕西省云杉天然林面积日渐稀少 ,且资源分散 ,因此恢复云杉林在高山地带特有的防护作用 ,是秦岭林区一个重要的研究课题。本文根据对该林区天然云杉林、择伐更新林及皆伐迹地更新林的调查对比分析 ,研究了云杉林的结构特征及其更新动态 ,以期为探索该区云杉林的恢复途径及扩大这一树种资源提供科学依据。1　研究区概况及方法1 1　研究区概况　该研究在陕西省宝鸡市…     

四川盆地丘陵区主要森林群落结构特征研究

本文对四川盆地丘陵区主要森林群落--人工柏木纯林、次生栎柏混交林和桤柏混交林的群落结构特征进行了研究.结果表明：在群落的物种组成、生活型、层片结构以及Shannon-Wiener多样性指数、Pielou均匀度指数和Simpson生态优势度指数表征的群落综合特征上,次生混交林与人工林具有很大差异.人工柏木纯林物种数量少,乔、灌、草层的物种多样性和均匀度较低,生态优势度较高;次生栎柏混交林和桤柏混交林物种数量较多,乔、灌、草层有较高的物种多样性和均匀度,较低的生态优势度.     

Cytotoxic alkoxylated xanthones from the resin of Garcinia hanburyi

Three new xanthones, garcinolic acid (1), 10α-ethoxy-9,10-dihydromorellic acid (2), and 10α-ethoxy-9,10-dihydrogambogenic acid (3), along with six known compounds were isolated from the resin of Garcinia hanburyi. These compounds were tested for their cytotoxicities against A549, HCT116, SK-BR-3 and HepG2, and showed high inhibitory effects on the cell lines.     

Molecular Markers in Population Genetics of Forest Trees

Rapid progress is being made in many areas of forest population genetics owing to the newly available molecular techniques and the fast growth of genomic and sequence data. This paper reviews the currently available genetic markers and their applications in studies on gene diversity, population structure and differentiation, gene flow, introgression, phylogeny and gene evolution. Various marker-based population analyses have highlighted the evolutionary history of many tree species. However, up to now, genetic markers have not fulfilled the expectations for studies on the adaptive variation and the effects of natural selection on forest tree populations. Studies based on integrated and extensive genome sampling, especially the coding regions of the genome, in combination with adaptive traits can potentially improve this situation. This would provide us with a comprehensive knowledge of the evolutionary mechanisms shaping the population changes, both adaptive and neutral.     

南京大厂绿化隔离带规划探索

依据南京大厂环境监测结果即各种污染物在平面、立面的空间分布特征进行绿化隔离带的布局与结构规划探索,包括绿化隔离带的功能分区、主次林网结构设置、交错林带及林间网眼的要素控制、植物选择等建议。     

Lignin fragments rich in detached side-chain structures found in water-soluble LCC

The content of the glyceraldehyde-2-aryl ether-type structure in water-soluble lignin–carbohydrate complex (LCC) fractions, which were obtained from Japanese cedar and birch residual wood meal after milled wood lignin isolation, was determined by ozonation. Quite high amounts of the glyceraldehyde-2-aryl ether-type structure were found in water-soluble LCC fractions of both species; about 3–5 times higher than those of other fractions. This result, as well as the high content of the β-1 structure in these fractions shown in our previous reports, suggest that lignin in these fractions has the characteristics of endwise-type lignin, because the glyceraldehyde-2-aryl ether-type structure and β-1 structure are typical characteristics of this type of lignin fraction. These results are in good agreement with the generally accepted hypothesis that the glyceraldehyde-2-aryl ether-type structure and β-1 structure are generated at the same time by a radical coupling reaction. The results also indicated that these two structures are present in close proximity in the lignin.