Modelling primary branch frequency and size for five conifer species in Maine,USA

Quantitative models of crown structure have been developed for several conifer species, but these studies have rarely simultaneously fit the models across multiple species. This study used extensive crown structure data for the five primary conifer species in Maine to test for species differences in maximum branch diameter profile, branch density, and relative branch diameter distribution. The species included balsam fir [Abies balsamea (L.) Mill], northern white-cedar [Thuja occidentalis (L.)], eastern hemlock [Tsuga canadensis (L.) Carr.], eastern white pine [Pinus strobus (L.)], and red spruce [Picea rubens (Sarg.)]. After accounting for key covariates, significant species differences were found in all crown structural attributes examined in this study. Profiles for the mean tree indicated that northern white-cedar had the smallest maximum branch diameters throughout the crown and white pine had the largest, except near the base of the crown where the species switched in rank. The density of live branches in a crown had the widest range of variation of the examined crown structural attributes. Red spruce had a significantly higher density of primary branches than the other conifers, particularly in the upper crown. The relative branch diameter distribution indicated that balsam fir had a distribution more skewed towards larger relative branch sizes, while eastern hemlock and red spruce had distributions shifted towards smaller relative branches. This study highlights the range of variability in key crown structural attributes due to inherent species differences, but indicates that models fit across multiple species can perform quite well as the amount of explained variation was relatively high.     

Modeling jack pine branch characteristics in Eastern Canada

A total of 83 trees were sampled in three regions of Eastern Canada in order to model branch characteristics (number of branches per annual shoot, branch insertion angle and diameter) using linear mixed-effects models. Differences in branch characteristics according to branch type (pseudo-whorl at annual shoot apical end (PWA) versus pseudo-whorl between shoot apical ends (PWB)) were also studied. The number of both PWA and PWB branches are proportional to annual shoot length, whereas the number of PWB branches also decreases with tree age. Insertion angle was mainly driven by annual shoot number from apex (branch age). The diameter models showed the most complexity with branch vertical position and tree size (DBH and total height) among the statistically significant variables. Region and plot random effects were minimal compared with tree and annual shoot levels. Tree-level random effects were significant for every model and might be a symptom of genetic control over the number of branches and, to a small extent, branch diameter. Interaction between insertion angle and diameter is relatively strong because all the models using them as independent variables (except for the model of insertion angle for PWB branches) showed better fit statistics. These results lead us to believe that tree-, annual shoot- and branch-level variables should be further explored in order to better understand branch dynamics.     

Response of branch growth and mortality to silvicultural treatments in coastal Douglas-fir plantations: Implications for predicting tree growth

Static models of individual tree crown attributes such as height to crown base and maximum branch diameter profile have been developed for several commercially important species. Dynamic models of individual branch growth and mortality have received less attention, but have generally been developed retrospectively by dissecting felled trees; however, this approach is limited by the lack of historic stand data and the difficulty in determining the exact timing of branch death. This study monitored the development of individual branches on 103 stems located on a variety of silvicultural trials in the Pacific Northwest, USA. The results indicated that branch growth and mortality were significantly influenced by precommercial thinning (PCT), commercial thinning, fertilization, vegetation management, and a foliar disease known as Swiss needle cast [caused by Phaeocryptopus gaeumannii (T. Rohde) Petr.]. Models developed across these datasets accounted for treatment effects through variables such as tree basal area growth and the size of the crown. Insertion of the branch growth and mortality equations into an individual-tree modeling framework, significantly improved short-term predictions of crown recession on an independent series of silvicultural trials, which increased mean accuracy of diameter growth prediction (reduction in mean bias). However, the static height to crown base equation resulted in a lower mean square error for the tree diameter and height growth predictions. Overall, individual branches were found to be highly responsive to changes in stand conditions imposed by silvicultural treatments, and therefore represent an important mechanism explaining tree and stand growth responses.     

高纺锤形苹果树不同枝类生长结果习性研究

为探索苹果枝梢精准化调控技术,以苹果品种烟富3号为研究对象,对其高纺锤形苹果树不同类型侧枝的生长发育、结果效率及果实品质等进行了观察。结果表明,大型侧枝单位长度结果数为1.53个/m,小型侧枝单位长度结果数为8.19个/m。下垂结果枝单位长度结果效率最高,为15.59个/m;倾斜结果枝单位长度结果效率最低,为6.74个/m。不同类型结果枝在果实大小和可溶性固形物含量上无明显差异。另外,侧枝枝龄对花芽类型具有明显影响,枝条的尖削度越大生长越不稳定。枝条生长模式直接影响花芽形成、结果效率和果实品质,精准调控枝梢生长,维持树势和枝势稳定是优质高产的关键。     

试论国有股份公司出资者监督权

从产权角度入手,通过对出资者监督权形成过程的剖析,阐明了确保出资者监督权有效发挥作用的必要条件;介绍了国际上现行的出资者监督权两种设计模式:独立董事和外部监事,并对其优劣进行对比,并论述了建立外部监事制度是较为符合中国国情和目前国资委内部组织结构设置的一种方式。     

Within-crown structural variability of dwarfed mature Abies mariesii in snowy subalpine parkland in central Japan

We investigated mature dwarf Abies mariesii trees growing in conifer thicket–meadow parklands on a snowy subalpine plateau, where these dwarf trees are buried in the accumulated snow in winter. We focused on structural variation in the needles, shoots, and branchlets within different crown positions (leader crown vs lower crown) of the dwarf trees. In the leader crown, which appears above the snow surface earlier than the lower crown, current-year shoots and branchlets had greater total biomass, and foliage was more closely packed along the stem axis than in the lower crown, whereas current-year shoots in the leader crown had a lower needle mass ratio than in the lower crown. These results suggest that current-year shoots and branchlets in the leader crown have a specific structure that allows them to harvest more light, although construction and maintenance costs would be higher. In contrast, the structural characteristics of current-year shoots and branchlets in the lower crown efficiently concentrate incoming light by avoiding mutual shading within foliage, thus leading to increased biomass of photosynthetic needles within shoot and branchlet biomass. Such within-crown variability at various hierarchical levels from needles to branches in mature, but very dwarf, A. mariesii trees maintains the crown and allows survival within conifer clumps in areas of subalpine parklands that receive heavy snowfall.     

苹果树枝干病害的生物防治研究

从苹果树体上分离得到颉颃菌株AT970 6。室内测定Valsamali等 3种枝干病害的病原抑制作用均为 10 0 %。田间采用AT970 6制剂对腐烂病和枝干轮纹病的防治效果分别为 99 5%和 86 0 %。     

新阶段创新区域农业科研工作路径探析--以广西农业科学院百色分院为例

【目的】探析新阶段创新区域农业科研工作的新路径,为逐步健全和完善国家农业科技创新体系提供参考依据。【方法】以广西农业科学院百色分院（以下简称百色分院）为例,系统总结分析广西发展区域农业科研机构的成功经验及其面临的主要困难及问题,并针对性提出新的发展路径。【结果】自2009年百色分院成立以来,在科技人才队伍建设、农作物新品种引进与选育、农业技术示范与推广、农业科技成果转化等方面均取得新进展;通过科研立项获得的项目经费超过1200万元,发表农业科技论文30余篇;但也存在高层次科技人才缺乏、财政经费紧缺、农业科技成果转化机制不完善等问题。【建议】创新工作理念,引导区域现代农业发展;做好科研定位,发挥区域特色农业优势;抓好示范培训,推进科技成果转化进程;健全管理机制,不断提高科研管理水平;坚持以人为本,着力提升人才支撑能力;加强交流合作,稳步提升科技服务实力。     

‘金叶’复叶槭全光照喷雾嫩枝扦插繁殖技术

为加快‘金叶’复叶槭种苗繁殖,充分利用河南省农业科学院所属的彩叶树种驯化基地的扦插设施,探索‘金叶’复叶槭嫩枝扦插繁殖技术。嫩枝扦插具有生根迅速、成活率高、穗条来源丰富等优点,但扦插设施和基质的选择则是嫩枝扦插成功的关键。利用全光照自动喷雾系统,以纯珍珠岩做基质进行‘金叶’复叶槭嫩枝扦插,以提高其生根率和成活率。扦插结果表明,生根率和成活率均达95%以上,其烂根率几乎为零。因此,以纯珍珠岩做基质通过全光照喷雾嫩枝扦插进行无性繁殖,是实现‘金叶’复叶槭规模化快繁的一种有效途径。     

Effect of joint structure and slope direction on the development of collapsing gully in tuffaceous sandstone area in South China

This study focuses on the collapsing gullies in tuffaceous sandstone area and investigates the slope direction and morphological characteristics of the main and branch gullies. Furthermore, we assess the structural characteristics of the rock joints within this area, including their strike, dip direction and dip angle. The results show that there are 405 collapsing gullies in the study area. The slope directions associated with collapsing gullies and the directions of the main gullies largely fall within the ranges of NE20°-NE90°, SE90°-SE160°, SW240°-SW270°, and NW270°-NW290°. The collapsing gullies include 1103 branch gullies in total, most of which have directions that fall within the ranges of NE20°-NE40°, NE50°-NE70°, NW280°-NW300°, and NW330°-NW350°. The joints in the bedrock are directional and regional, and they can be divided into two main groups. The number of southward dip directions is greater than the number of northward dip directions, and most of the measured dip angles are greater than 60°. The mean dip angle is greatest for joints with measured strike values of NW280°-NW290°, with a value of 85.2°. The development of collapse gullies is affected by both the slope direction and joints. The slope direction determines the direction of the main gullies, with a correlation coefficient of 0.809 (P<0.01). The branch gullies are mainly affected by joints, with a correlation coefficient of 0.876 (P<0.01). The joint structure also influences the degree of development of the collapsing gullies, and the average depth of the gullies that parallel the dominant joint orientation is significantly larger than that of gullies with other directions. Moreover, the average depth of the gullies associated with the dip angle of 85.2° measured relative to the joint strike is 6.89 m, which is significantly greater than that associated with lower dip angles. The dip angles of joints have an important effect on the infiltration of water, and high dip angles accelerate the erosion associated with collapsing gullies.