杨树纸浆材优良无性系选择方法的研究

该文利用主成分分析法、遗传距离聚类分析、选择指数和综合性状评分法 ,对 7年生 2 5个杨树无性系进行优良无性系多性状选择 .通过对上述几种方法的比较认为 :遗传距离聚类分析可把无性系分为在主成分值上各具不同特点的类群 ,从而使具有相似特征的无性系归为一类 ,且在优良类群内可以继续选择 ;主成分分析可以评价各无性系综合性状的优劣 ,并作为无性系选择的参考 ;选择指数是评价生长和材性性状较为理想的方法 ;综合性状评分法 ,从选择结果看与前 3种方法结合起来所选的基本一致 ,而且综合性状评分法是一种较为简便、直观的方法 .4种方法共同应用 ,能够较准确地选出生长迅速和材性优良的无性系 .     

Assessment of molecular detection of Fusarium circinatum in insects and passive spore traps in Pinus radiata plantations

Fusarium circinatum is the causal agent of pitch canker, a destructive disease that threatens natural and planted pine forests around the world. Although pitch canker has caused problems in Spain and Portugal, concerning Europe as a whole, the fungus is not established across the pine distribution area. Its dispersion by wind and/or insect vectors could nevertheless play a role in the colonization of currently uninfected stands. It is therefore crucial to develop monitoring tools for its detection. To this end, we assessed the molecular detection of the pathogen in environmental samples of bark beetles and passive spore traps, collected in two infected Pinus radiata plantations in Basque country, Spain. The spread pattern of F. circinatum was assessed by an experimental design that included insect and spore traps installed at the centre, at the edge and outside the plots. Our results showed that F. circinatum was detected in both types of samples, at almost all collection dates. In both type of samples, positive detections were mainly found at the centre of the plots, a lower proportion at the edge, and very few outside. This suggests that long‐distance dispersion of Fusarium circinatum does not rely on wind spore dispersal neither on insect flight. Our study also shows that molecular methods are a powerful tool to monitor the pathogen in environmental samples.     

快速城市化城市生态基础设施结构特征与调控机制

城市化及其所带来的生态影响成为全球化的重要问题,在发展中国家尤为突出.城市生态基础设施也深受影响,其景观结构和生态功能受到影响.该文目的是通过对城市生态设施景观结构特征与形成机制的分析,研究快速城市化背景下的城市生态基础设施调控方法,为城市生态建设提供理论依据.该文主要分析了以大城市为中心的快速城市化区域生态基础设施的空间破碎化、景观粒度、人工影响与景观不稳定性、系统生态服务功能格局和景观连通性等结构特征,并分析了快速城市化下城市生态基础设施景观结构特征的形成机制.结果显示快速城市化地区基础生态设施表现出高度破碎化、高度人工化和生态不稳定性、低生态服务功能、低景观连通度等特征,并从城市中心向郊区和城市化区域呈梯度差异分布.而区域自然环境资源分布特征、区域管理政策、交通系统和历史文化因素是影响快速城市化地区生态设施结构特征的主要因素.基于这些分析,进一步提出生态系统压力与承载力评估、生态适宜性评价、生态系统生态服务功能估量,以及景观格局与生态过程分析为基础的多尺度综合调控机制.运用景观生态学格局-过程-功能原理,综合研究城市化条件下的城市生态基础设施布局与生态学功能之间的关系及优化调整机制,为城市生态建设与城市规划提供科学理论依据.     

基于ArcGIS环境下DEM流域特征提取及应用

该文详细介绍了ArcGIS9.2中的水文分析工具箱的使用方法,包括从原始DEM数据提取河网的步骤、应注意的问题等。研究区域选取位于北京山区的红门川小流域,采用1∶10000的比例尺、10m分辨率的DEM作为基本的地形数据,应用ESRI公司开发的ArcGIS9.2地理信息系统软件进行流域水文信息特征的提取;并利用SWAT模型运行水文响应单元(HRUs)的生成,共生成了25个子流域和92个HRUs。经分析,得到的研究区域河网特征以及研究区其他常用的流域特征信息,与实际河流水系特征基本吻合,因此应用DEM划分的流域结果是合理的。     

独特的大果青杄群落吸引国际保护组织关注

湖北省保康县歇马镇施家沟村三组肖洞坡分布有一个举世独特、绝无仅有的大果青杄群落,其面积约有6hm2,总数约1000～1500株,年龄为1～300年,呈现不同龄级。其中包括132株高30m、胸径40cm以上的大树。近年来,这一群落已引起中外学者和专家的关注,当地被认为很有可能是大果青杄的残遗中心。     

沭阳县颜集虞姬花木合作社建设情况的调研和思考

沐阳县颜集贯勤虞姬花木合作社，实现了农民在市场经济条件下的联合和合作，由过去的松散式产业经营创新发展到目前的利益紧密型产业化经营，提高了农民的组织化程度，改变了农民在市场经济中的弱势地位。给农民带来了实实在在的经济利益，增强了农民抗御市场风险的能力。     

Spirometric performance in Belgian Blue calves: I. Effects on economic losses due to the bovine respiratory disease complex

The aim of this study was to determine whether high spirometric performances in calves are associated with low economic losses due to the bovine respiratory disease complex (BRDC). Five spirometric variables (SV) were measured in 909 double-muscled Belgian Blue calves from 15 to 60 d of age. Afterward, calves were monitored for 6 mo to determine whether they developed BRDC and to determine the costs due to BRDC (i.e., medicine costs and veterinarians' fees, plus estimated financial losses due to mortality in case of death). To analyze the effects of spirometric performances on BRDC cost, a fixed linear model was used for each SV. In addition to SV, each model included the effects of sex, dam's parity, vaccination status, muscular development score, herd-period, and BW. Only herd-period and the maximal ventilation and the vital capacity had significant effects on costs due to BRDC, indicating that these two SV are major physiological determinants of economic losses associated with BRDC. Accordingly, it is assumed that an amelioration of maximal ventilation and vital capacity could result in increased resistance to BRDC in calves.     

Monitoring of atrazine treatment on soil bacterial,fungal and atrazine-degrading communities by quantitative competitive PCR

We report the development of quantitative competitive (QC) PCR assays for quantifying the 16S, 18S ribosomal and atzC genes in nucleic acids directly extracted from soil. QC-PCR assays were standardised, calibrated and evaluated with an experimental study aiming to evaluate the impact of atrazine application on soil microflora. Comparison of QC-PCR 16S and 18S results with those of soil microbial biomass showed that, following atrazine application, the microbial biomass was not affected and that the amount of 16S rDNA gene representing 'bacteria' increased transitorily, while the amount of 18S rDNA gene representing fungi decreased in soil. In addition, comparison of atzC QC-PCR results with those of atrazine mineralisation revealed that, in response to atrazine treatment, the amount of atzC gene increased transitorily in soil pre-treated with atrazine, suggesting that accelerated atrazine biodegradation in soil could be due to a transient increase in the size of the atrazine mineralising community.     

Three-dimensional kinematics of the equine interphalangeal joints: articular impact of asymmetric bearing

The objective of this study was to assess the effects of asymmetric placement of the foot on the three-dimensional motions of the interphalangeal joints. Four isolated forelimbs were used. Trihedrons, made of three axes fitted with reflective markers, were screwed into each phalanx. They allowed to establish a local frame associated with each bone and thus to define the spatial orientation of the phalanges. The limbs were then placed under a power press, and subjected to compression with gradually increasing force (from 500 to 6 000 N). The procedure was performed in neutral position and with the lateral or medial part of the foot raised by a 12 degrees wedge. Flexion, collateromotion (passive abduction/adduction) and axial rotation of the interphalangeal joints were measured using a cardan angle decomposition according to the principle of the "Joint Coordinate System" described by Grood and Suntay. Raising the lateral or medial part of the hoof induced collateromotion (about 5.6 degrees +/- 0.8) and axial rotation (about 6.5 degrees +/- 0.5) of the distal interphalangeal joint. The proximal interphalangeal joint underwent axial rotation (about 4.7 degrees +/- 0.5 at 6 000 N) and slight collateromotion. Both interphalangeal joints underwent collateromotion in the direction of the raised part of the foot (i.e., narrowing of the articular space on the side of the wedge), whereas axial rotation occurred in the direction opposite to the raised part of the foot. These results confirm the functional importance of interphalangeal joint movements outside the sagittal plane. In particular they demonstrate the involvement of the proximal interphalangeal joint in the digital balance. These data are helpful for the identification of biomechanical factors that may predispose to interphalangeal joint injury. Also the data may be of use for the rational decision making with respect to exercise management and corrective shoeing of the lame horse.