海南霸王岭国家自然保护区拟石斛的附生特性

拟石斛(Oxystophyllum changjiangense)为海南岛特有的珍稀濒危附生兰科植物。为阐明其附生特性,笔者以分布于海南省霸王岭国家自然保护区的拟石斛为例,在系统调查其资源现状、生境特征及宿主种类的基础上,对其附生宿主的专一性、在宿主上的分布特点及附生个体数量与宿主胸径、树皮特性的相关性等进行分析。结果表明,86.6%的拟石斛个体分布在海拔800~1 000 m且主要附生在山地雨林中水源附近的高大乔木上;附生宿主18种,多见于木兰科、壳斗科、漆树科及梧桐科的植物;附生指数在0.32~0.94之间,其中白花含笑、长柄梭罗和红锥的附生指数接近于1;拟石斛全都分布在宿主的一级分支或二级分支处,二者差异性不显著;附生数量与宿主胸径呈显著性正相关(R=0.397,P0.05),拟石斛对树皮特性选择具有偏好性。     

Effects of resistance of Eremocitrus glauca and Microcitrus australis to viroid infection: replication,accumulation and long‐distance movement of six citrus viroids

In studies to identify genotypes resistant to infection with citrus viroids, Eremocitrus glauca and Microcitrus australis were selected because their evolution in their habitat in Australia and New Guinea may have led to the selection of unusual traits. The movement and accumulation of Citrus exocortis viroid (CEVd), Hop stunt viroid, Citrus bent leaf viroid, Citrus dwarfing viroid, Citrus bark cracking viroid and Citrus viroid V (CVd‐V) in self‐rooted as well as in graft‐ propagated E. glauca and M. australis plants was assessed by northern hybridization, RT‐PCR and by topworking to the sensitive selection 861‐S1 of Etrog citron. In both plant species the inoculated viroids were undetectable unless these plants were grafted to a susceptible Citrus partner, the rough lemon rootstock and/or the topworked Etrog citron, which acted as viroid sources. The results obtained indicate that M. australis and in particular E. glauca are poor viroid hosts in which viroid replication/accumulation does not occur or is extremely inefficient. However, viroid downward and upward movement to grafted Citrus partners in which viroid replication and accumulation occurs efficiently was not impaired. Eremocitrus glauca and M. australis showed differences regarding their properties as viroid hosts, but for both species CEVd seemed to have the lowest affinity among the viroid species tested and CVd‐V the highest. Even though E. glauca and M. australis do not appear to be truly resistant to viroid infection, they are interesting genotypes for further characterization of the mechanisms involved in viroid infection.     

Suppression of Botryosphaeria canker of apple by arbuscular mycorrhizal fungi

Stem brown canker or Botryosphaeria canker disease impairs the growth and kills the shoots, limbs and even trunks of infected apple trees. Apple roots are usually colonized by arbuscular mycorrhizal fungi, which may have a positive influence on plant growth and suppression of diseases. In order to assess the efficacy of AM to suppress the disease severity and plant growth enhancement, nine AMF inoculation treatments (Sclerocystis dussi, Glomus intraradices, G. fasciculatum, G. bagyaraji, G. leptotichum, G. monosporum, Gigaspora margarita, a mixed AM culture and a non-mycorrhizal control treatment) were used in this present study. Two-year-old potted apple plants, maintained under glasshouse conditions, were either pre-inoculated with AMF followed by stem inoculation with Botryosphaeria ribis or simultaneously inoculated with Botryosphaeria ribis and AM. The results indicated that the incidence of canker was less severe in plants inoculated with AMF in comparison to non-mycorrhizal control. Timing of inoculation also had a significant effect on disease development and plant survival. Plants pre-inoculated with mycorrhiza performed better over those inoculated simultaneously with Botryosphaeria ribis and AM fungi. Furthermore, AM inoculation resulted in improved survival and growth of AMF-colonized plants; though, it varied by species of AM fungi utilized.     

甲虫体壁薄膜结构反射特性理论研究

对彩色吉丁虫Chrysochroa raja、节日虎甲虫Chrysina chrysagyrea等甲虫体壁多层薄膜结构色的机理进行了理论分析。当薄膜各层光学厚度近似等于可见光波长(380～750 nm)的四分之一时,分析了各膜层厚度、折射率以及入射角对单层薄膜和多层薄膜的反射率影响。计算结果表明甲虫彩虹色由多层膜薄膜的反射干涉而成,其反射谱带宽随着的增大而增大,高低折射率薄膜的光学厚度各自变化但总和保持不变时,薄膜颜色无明显变化,入射角对单层薄膜和多层薄膜的反射率都有一定的影响。这些结论将为进一步认识和研究甲虫的颜色和制备新一代仿生薄膜材料提供理论指导。     

Determining the vulnerability of Mexican pine forests to bark beetles of the genus Dendroctonus Erichson (Coleoptera: Curculionidae: Scolytinae)

Bark beetles of the genus Dendroctonus are natural inhabitants of forests; under particular conditions some species of this genus can cause large-scale tree mortality. However, only in recent decades has priority been given to the comprehensive study of these insects in México. México possesses high ecological diversity in Dendroctonus–Pinus associations. The geographic coexistence of 12 Dendroctonus species suggests greater vulnerability or threat of tree mortality relative to other areas. We use a biogeographic strategy to identify and rank the areas most vulnerable to tree mortality caused by bark beetles in México. We aim to define the areas that might experience high impact by these insects and also to provide a geographic database useful to forest resource management and conservation policies in México. Using collection records of bark beetles and pines, we develop a quantitative estimate of the threat of beetle infestation of forest areas based on factors including pine and beetle species density, host preference and level of mortality caused by beetle species. A quantitative estimate of forest area vulnerability, the Bark Beetle Threat Index (BBTI) was calculated. Despite the vast area of geographic coincidence of Pinus and Dendroctonus in México, the regions of highest bark beetle pressure are restricted to small zones within some mountain systems. The region that has been most affected by this insect group during the past hundred years is the Transverse Volcanic Belt, followed by the Sierra Madre Occidental and Sierra Madre del Sur. Pine diversity is the major determining factor of BBTI at the regional level, while disturbances from extensive logging and ecosystem change are the key factors behind high BBTIs at the local level.     

Changes in the characteristics of potting media with time

Abstract

Growing media for container plants composed of pine bark, peat and sand were evaluated before, during and after five months with ryegrass as the test plant in the greenhouse. Hydraulic conductivity of these materials is very rapid resulting in rapid loss of nutrients, even for the controlled‐release type fertilizers. Channels developed on the perimeter of the growing medium ball adjacent to the container wall resulting in a concentration of plant roots in this zone. Considerable shrinkage or compaction of the media occurred during the five months growth period, especially for peat. Movement of sand was observed for the very porous materials and found to accumulate as a layer lower in the container. All nutrients added were exhausted after 3 months, even for the controlled‐release types of fertilizers.     

黑荆树经营数表编制的研究——Ⅱ经济材出材量表与树皮材积、重量表

黑荆树的树皮和木材分别是提取栲胶、造纸和培养香菇的好原料。福建省漳州市各县已建立了一定规模的原料基地。为正确测定黑荆树的经济材出材量与树皮的材积、重量,笔者调查了133块标准地,砍伐样木333株,继编制了立木材表后,又编制了经济材出材量表与树皮材积、重量表。编表中采用了3个数学模型的选择,所编的数表总体精度均在95％以上。精度高,具有一定的实用价值。     

樟树黄化病对树皮构造特征的影响

通过对樟树正常植株与患黄化病植株的3年生枝条的解剖特征进行比较研究发现,二者树皮构造中,表皮与周皮差异不太显著,但韧皮纤维维管束形态特征及组织比量、筛管比量差异较大,组织比量差异百分率分别为33%和41%,韧皮射线形状也由正常的喇叭状弱化为线形,表明病株的下行输导能力与横向输导能力较正常植株均呈减弱趋势.     

树皮年轮的研究及其意义

在对38科54属96种药用及常见经济树种进行实验研究的基础上,以树皮横切面所见纤维束环带为指标,阐述了树皮年轮的客观存在.并对依据树皮年轮鉴定树龄在林学和生药学等方面的实际应用进行了探讨.     

凹叶厚朴树皮产量预测模型的研究

通过实测61株凹叶厚朴样木胸径、树高和树皮产量,对凹叶厚朴树皮产量预测模型进行研究,采用改进单纯形法建立树皮产量数学模型,并对不同数学模型进行了比较。结果表明,改进单纯形法优化得到的模型y=O．9438643 0．02407896D^2.040018H^0.3646304,y=O.06606968D^2.059642的相关系数最大,分别为O．9623和O．9583,可用于凹叶厚朴树皮产量预测;胸径因子对凹叶厚朴树皮产量预测比树高因子更有效。