一种基于三维激光扫描系统测量树冠体积方法的研究——以油松为例

树冠体积在林业及其他领域得到越来越广泛的应用.该文介绍了三维激光扫描系统的组成、工作原理及工作流程;探讨了应用三维激光扫描系统,通过扫描获取单株树木的三维空间点阵数据,将树冠近似为多个圆台体,求它们的体积之和来计算树冠体积的方法.并在甘肃省小陇山林业局党川林场以油松为例进行了实验,而后对实测数据进行了精度分析,取得了较为满意的结果.研究表明,利用三维激光扫描系统测量树冠体积具有较强的实践意义和应用价值.     

树形管道模型原理

本文简介了树形管道模型的基本理论,并对若干问题进行了讨论。作者认为比管道长L将随分层厚度△Z的增大而增大,Yukihiro等[6]所给出的关系式L_a/L_b=b/a(L_a和L_b分别是△z=a和△z=b时的L值)是有疑问的。     

川西南山地云南松林窗边界木偏冠现象与影响因素

树冠偏倚是树冠外部形态受生物学和非生物学因素综合影响的结果.该文研究了川西南山地阳性树种云南松的偏冠现象及其影响因素.云南松边界木偏冠现象普遍存在,树冠偏倚程度大于0.5的个体达到了95%(偏冠率1)和93%(偏冠率2).自然地理条件下,云南松边界木偏冠方向和方位可能有关,树冠偏向南方的边界木近80%,与地形和光照等非生物环境有关.云南松边界木偏冠程度受云南松自身特征的影响,偏冠率1和胸径、年龄、侧树间距、后树间距存在显著相关关系,和树高、枝下高间关系不显著.云南松偏冠受邻体树木分布影响,偏冠率2和侧树距离有关,和胸径、年龄、树高、枝下高、后树距离无显著相关关系.因此,云南松树冠偏倚程度受多种因素影响,受自身特征、邻体分布和非生物环境的相互作用.      

Variation in Crown and Root Organic Reserves Among Lucerne Genotypes of Different Morphology and Flower Colour

Previous evidence indicates that differences in the concentration of underground organic reserves can drive the survival and growing ability of lucerne under cold and defoliation stresses. In order to provide the selection process with further information on compounds that may influence plant performance under grazing, we assessed variations in cold‐season concentrations of nitrogen and carbon reserves on genotypes that had been identified for morphological features that possibly enhance grazing tolerance. The selected genotypes encompassed distinct morphological patterns (defined as ‘models’) and different taxa within the Medicago sativa complex, as shown by different flower colours. Crown concentrations of reserves were determined on 90 genotypes, whereas root concentrations were measured on a subsample of 15 genotypes. Wide intergenotypic variation was observed for all reserve substances. Comparisons among models and among flower colour classes highlighted the high concentrations of crown carbohydrates and root and crown‐soluble proteins of the model coded as ‘D1’, characterized by prostrate, rhizomatous habit and long dormancy, which largely corresponded to plants with yellow or variegated flowers, typical of ssp. falcata and × varia, respectively. There was a strong ‘flower colour × storage organ’ interaction for sugar concentration, and the results suggested a preferential compartment of sugars in the roots of purple‐flowered genotypes that belonged to the ssp. sativa. A rank correlation analysis indicated a positive relationship between persistence after two years under grazing of half‐sib progenies deriving from 19 genotypes out of the 90 and crown concentrations of carbohydrates of the 19 mother plants.     

Evidence of pAgK84 transfer from Agrobacterium rhizogenes K84 to natural pathogenic Agrobacterium spp. in an Italian peach nursery

Nine Italian peach nurseries, which use Agrobacterium rhizogenes strain K84 to protect plants from crown gall, were monitored for three years with the aim of determining whether transconjugant populations may arise following plasmid exchanges between K84 and autochtonous soil agrobacteria. Six hundred and seventy-eight Agrobacterium isolates were obtained from 120 tumours developed on apricot and peach rootstocks that had been treated in pre-planting with the antagonist. Agrobacteria were characterized for pathogenicity, biovar, opine catabolism and agrocin 84 sensitivity. Colony hybridization was used for screening the isolates harbouring plasmids pTi and/or pAgK84. Analysis of plasmid content and Southern blotting were performed on putative transconjugant agrobacteria found in tumours collected from one nursery where a biological control breakdown was observed. The RFLP analysis of 16S + IGS regions showed that pAgK84 was transferred from the antagonist to virulent and avirulent soil agrobacteria belonging to different ribotypes. Pathogenic transconjugants, inoculated on GF677 rootstocks, were not controlled in vivo by K84 and stably maintained pTi and pAgK84 in the bacterial cells for at least one year. At the end of a biocontrol trial, new transconjugant tumorigenic agrobacteria originated by the transfer of pAgK84 to the pathogen. Virulent and avirulent transconjugants may represent a real threat for biological control by K84 strain since all of them produced agrocin and were insensitive to it. Survival in soil of these populations could make the future application of K84 ineffective.     

联荼冠醚修饰电极测定汞

Several special crown ethers have been used to prepare modified electrodes and their performances are compared. The electrode prepared from bi-dinaphthy1-22-crown-6 shows the best performance characteristics has been studied in detail, which has been appl     

模拟间伐对树冠直径方差发生机制的研究

有些收获表的主林木直径方差为负值，这在理论上是矛盾的。原因之一是在编制收获表的过程中，假定所有主林木的直径相同，没有考虑直径分布。该文在若干假定的前提下，在林木开始竞争时，通过模拟间伐，从理论上探讨树冠直径方差发生机制。     

窄冠杨树品种评选及其类型划分

本文通过对１８个杨树品种无性系在９个试验点的Ｇ×Ｅ互作分析，用８个参数评价生产力，遗传稳定性和生长适应性，并经综合评定，从村冠积比（材积／冠积）方面将１８个品系划分为不同类型，为各试验区评选出了适合栽培的优良品系。     

一年生云南松苗期生长动态规律研究

基于1a生云南松苗高和地径的定株、定期观测数据,采用Logistic方程对其生长过程进行拟合,根据其中参数分析生长动态规律。结果表明:(1)地径生长符合"S"型曲线,呈现"慢-快-慢"节律;苗高生长符合双"S"型曲线,呈现"慢-快-慢-快-慢"节律。(2)根据生长量变化规律,苗高生长过程可分为出苗期、速生期Ⅰ、过渡期、速生期Ⅱ和生长后期;地径生长过程可分为生长前期、速生期和生长后期。(3)苗高两个速生期为23～34d和89～150d,两个速生点时间为第28天和第120天;地径速生期为141～211d,速生点时间为第176天。(4)苗高、地径的累积生长量均在速生期最大,分别占理论上限值的58.37%和57.85%。(5)苗高、地径的生长表现出异速现象,150d之前苗木主要进行高生长、150d之后则以地径生长为主。