海口市行道树的树种选择

海口市地处热带北缘,属海洋性热带季风气候,全年日照时间较长,冬无严寒、夏无酷暑,终年无霜,春暖回升快,年平均气温238℃,年平均降雨量1691．7毫米。优越的自然条件,有利植物生长发育,大多数植物移栽易成活,是城市绿化的有利因素。但也存在常风大、台风多和降雨时空分布不均,旱季和雨季明显等问题,对城市绿化不利。全市现已绿化的道路120条,共有行道树约6．8万株。主要树种是：椰子树、黄甚榕、细叶榕。高山榕、红花羊蹄甲、樟树、印度紫檀、盆架树、洋蒲桃、非洲换、秋枫、木麻黄、白千层等。在城市园林部门的努力下,目前海…     

富宁县城镇绿化树种选择与配置探讨

本文主要就目前富宁县城市行道树的现状以及城市行道树选择的原则,在对富宁县行道树现状进行全面调查进行分析的基础上,针对目前富宁县城区道路行道树存在的问题,提出了改变富宁县目前街道树绿化品种单一、无层次感、不稳定的现状,并提出行道树配置的措施,特别是老城区行道树上的改造方面,为丰富城市行道树种提出建议。     

浅析园林绿化树种的选择和配置

随着经济的快速发展,人们对城市环境的要求越来越高。生态城市的建设,能够为市民提供舒适的居住环境,从而发挥最佳的社会效益、经济效益与生态效益。本文主要分析了影响树种选择的因素和原则,以及绿化规划的建议。     

浅谈天津市行道树的应用现状与选用分析

行道树是城市园林绿化的骨干树种,美化了城市景观,促进了城市生态环境的改善。对天津市现有行道树的选择与应用进行了分析,找出了天津市行道树栽植和管理方面存在的主要问题,提出了改变天津市行道树种应用现状的对策。     

沈阳市建成区行道树的结构与功能研究

城市森林不仅可以减少城市中的裸露地面 ,更是大气污染的天然净化器。它可以促使大气中Ｏ2和ＣＯ2 的平衡 ,降低多种有害气体浓度 ,吸附空气中的灰尘[3] 。沈阳市是一个重工业城市 ,由于历史和现实的原因 ,以工矿企业污染物排放为主要污染源的大气污染日益严重。因此 ,城市森林的建设对于减轻城市大气污染至关重要。行道树是城市森林的重要组成部分 ,是连接城市分段隔离绿地的纽带 ,同时又为野生动物提供了栖息地及迁移通道 ,被认为是城市自然恢复的重要手段 ,其功能越来越受到人们的重视[8] 。怎样合理配置行道树的结构 ,发挥其最大生态效…     

柳州市行道树资源调查与结构特征分析

该研究通过对柳州市区主要道路园林绿化全面踏勘,在四城区中筛选出68条道路行道树进行现场调查和综合评价。结果表明:(1)柳州市行道树共有28种,隶属于17科21属,常绿树种与落叶树种比例及乡土树种与外来树种比例合理。(2)柳州市行道树中小叶榕和黄葛榕在各城区应用频度较高,树种组成结构相对单一。(3)季相树种在各城区应用频度不均衡,部分城区春季景观营造效果显著,而夏秋冬季相景观效果不显著。(4)绿化达标率和林荫路推广率离国家生态园林城市还有较大差距,物种丰富度和多样性指数有待提高。建议加大乡土树种的应用与推广,提高各城区物种丰富度及季相树种的应用,营造城市道路特色季相景观。该研究成果提出了发展乡土树种、丰富树种多样性及季相景观营造的技术建议,对柳州市行道树树种规划和建设提供了科学依据。     

上海城市绿化利用树种资源的现状与发展对策

在对上海城市园林植物群落进行树种调查的基础上,统计了常用城市绿化树种资源数量、各树种的应用频繁以及各类园林植物群落的加权平均树种数量的指标,对上海城市绿化树种资源利用现状和影响因子进行初步分析,提出了若干发展对策。     

浅析北方常用造林树种的选择

北方浅山地带或半浅山地带的气候干燥、降雨量少、地表蒸发量大的情况下,于第三纪红土上发育的土壤。风化厚度往往不足一米,土壤最大的特征是干时龟裂,湿时泥泞,土质干燥坚硬,渗水性差,植物适应性也差,全剖面质地为粘土,碎块状或大块状结构。怎样选择适地的造林树种是关键的一步。     

厦门城市生态林改造树种评价选择的研究

对厦门市本岛马尾松生态林实施林相改造,选择44种阔叶树在林下套种,调查分析不同树种的适应性、生长特点和抗逆性.结果表明,木荷等15种树种适应性较强,尾巨桉等7种树种的生长性状良好;结合不同树种的景观效果、美学特性等方面进行综合评价,选出适宜林相改造的11种骨干树种为枫香、木荷、大叶榕、马占相思、天竺桂、小叶榕、山杜英、红锥、樟树、尾巨桉、杨梅等.     

110 Years of change in urban tree stocks and associated carbon storage

Understanding the long‐term dynamics of urban vegetation is essential in determining trends in the provision of key resources for biodiversity and ecosystem services and improving their management. Such studies are, however, extremely scarce due to the lack of suitable historical data. We use repeat historical photographs from the 1900s, 1950s, and 2010 to assess general trends in the quantity and size distributions of the tree stock in urban Sheffield and resultant aboveground carbon storage. Total tree numbers declined by a third from the 1900s to the 1950s, but increased by approximately 50% from the 1900s–2010, and by 100% from the 1950s–2010. Aboveground carbon storage in urban tree stocks had doubled by 2010 from the levels present in the 1900s and 1950s. The initial decrease occurred at a time when national and regional tree stocks were static and are likely to be driven by rebuilding following bombing of the urban area during the Second World War and by urban expansion. In 2010, trees greater than 10 m in height comprised just 8% of those present. The increases in total tree numbers are thus largely driven by smaller trees and are likely to be associated with urban tree planting programmes. Changes in tree stocks were not constant across the urban area but varied with the current intensity of urbanization. Increases from 1900 to 2010 in total tree stocks, and smaller sized trees, tended to be greatest in the most intensely urbanized areas. In contrast, the increases in the largest trees were more marked in areas with the most green space. These findings emphasize the importance of preserving larger fragments of urban green space to protect the oldest and largest trees that contribute disproportionately to carbon storage and other ecosystem services. Maintaining positive trends in urban tree stocks and associated ecosystem service provision will require continued investment in urban tree planting programmes in combination with additional measures, such as revisions to tree preservation orders, to increase the retention of such trees as they mature.     

沈阳城市森林常见树种的物候特征

城市绿化树种的物候配置是城市园林的一个重要组成部分。本文以沈阳城市森林常见树种为对象,利用6年的物候观测数据,绘出了28种主要乔灌木的物候谱。分析各物候现象之间关系,将其划分成4大组:萌动展叶现象组、叶变色现象组、落叶现象组和花果现象组;并根据叶变色和开花早晚对其进行聚类分组,为城市森林树种选择、树种组成和效益评价,提供科学依据。     

兰州市典型绿化树种叶性状间的权衡关系

植物叶性状的权衡关系反映了植物对环境的高度适应性及其在复杂生境下的自我调控能力,了解半干旱区城市绿化树种叶性状间的权衡关系,比较不同生长型(针叶和阔叶)树种异速生长的差异有助于进一步认识植物的进化机制。以兰州市典型绿化树种(13种针叶树和47种阔叶树)为对象,测量部分叶性状,采用标准化主轴估计和系统独立比较分析的方法比较不同性状间的权衡关系。结果表明:不同生长型树种叶面积、叶体积与叶片干重之间均为等速生长关系,针叶和阔叶树种间并无显著差异;叶厚与叶面积间为"此消彼长"的权衡关系,但并不显著;阔叶叶长与叶宽间异速生长斜率为0.764。兰州市典型绿化树种叶性状间的权衡可能是长期适应黄土高原特殊生境的自适应过程,也说明部分性状间存在协变关系,阔叶绿化树种的权衡表明其符合"快速投资-收益"特征。     

4种城市绿化树种叶片PAHs含量特征与叶面结构的关系

用气质联用仪测定了长沙市樟树(Cinnamomu camphora)、广玉兰(Magnolia grandiflora)、桂花(Opsmanthus fragrans)和红檵木(Redrlowered loropetalum)4个主要绿化树种叶片中PAHs含量,同时测定了叶片的气孔密度、气孔长宽比、叶片的宽长比和叶面积等叶面结构特征值,探讨了叶面结构与叶片中PAHs含量的关系。结果表明:红檵木叶片的PAHs含量最高,为11.13mg·kg-1,16种PAHs在4树种叶片中均有不同程度的检出,其中以3环和4环为主,菲的浓度最高。除桂花外,在气温较低的秋冬季节,其余3种植物叶片气孔密度大PAHs含量高。叶面宽长比、气孔长宽比均与叶片PAHs含量呈极显著正相关,而叶面积与PAHs含量呈极显著负相关。表明叶面结构是影响叶片PAHs含量的重要因素。研究结果可为城市绿化树种合理选择与配置提供科学依据。     

Species of street tree is important for southern hemisphere bird trophic guilds

Abstract Urban environments are highly modified with unique assemblages of bird species. Much of the research on urban bird assemblages comes from the northern hemisphere. Southern hemisphere bird assemblages differ from northern hemisphere assemblages in that they contain a large proportion of nectarivores. In this study we focus on bird use of street trees in Australia. We investigate the relative influence of tree species (plane tree, Platanus x acerifolia; red gums, Eucalyptus camaldulensis; jacaranda, Jacaranda mimosifolia; bottlebrush, Callistemon citrinus), season and the environment surrounding street trees, on the abundance and species richness of birds in Adelaide, South Australia. Our study considers birds in terms of granivore, nectarivore and insectivore trophic guilds. Nectarivores accounted for the greatest proportion of observations, in terms of abundance, in each of the tree species investigated. Species of street tree was a significant influence on bird use of the trees for all birds and each dietary guild. Red gums were used more than the other tree species by nectarivores, while plane trees were used more than the other trees by insectivores. Use of the tree species by granivores varied with the season. The measures of the environment surrounding street trees were largely unimportant with the exception of traffic for nectarivores in some cases. Urban avifauna use street trees and the species of tree will strongly influence its use by birds. However, the pattern of use of street tree species varied at different times of year and differed between different trophic guilds of birds. The dominance of nectarivores in the southern avifauna will likely produce different patterns of urban environment use to northern hemisphere avifaunas.     

基于边际回归的沈阳市绿化树种人工油松冠形模拟

构建城市典型绿化树种树冠外部轮廓预估模型,可以为城市绿化树种的空间配置优化奠定基础。本研究以辽宁省沈阳市典型绿化树种人工油松为对象,基于Crown Window装置获取60株样木树冠形状,利用幂函数、分段抛物线方程和修正Kozak方程选取基础模型,通过再参数化引入树冠结构因子(最大树冠半径)和相邻木竞争变量(相邻木平均树高、平均胸径、平均冠幅、相邻木株数,以及样木与其相邻木平均树冠接触高),构建耦合相邻木竞争及树冠结构因子的油松树冠外部轮廓预估模型。结果表明: 修正Kozak方程R_a²最大、均方根误差(RMSE)最小,模型稳定性良好,选取其为构建油松冠形模型的基础模型。通过再参数化在基础模型中引入最大树冠半径和相邻木平均胸径后,模型的R_a²提高0.0693,MSER为14.4%。分析最大树冠半径和相邻木竞争对油松树冠形状的影响发现,最大树冠半径对树冠形状影响较大,树冠半径随最大树冠半径增大而增大;相邻木平均胸径对树冠形状影响相比最大树冠半径较弱,树冠上半部分随相邻木竞争增强而增大,树冠下半部分随相邻木竞争增强而变小。本研究构建的耦合相邻木竞争及最大树冠半径的油松树冠外部轮廓边际回归模型具有良好的拟合优度,能够合理地模拟及预测沈阳市典型绿化树种人工油松的树冠形状。     

阿克苏市5种常见绿化树种滞尘规律

绿化树种在截留沙尘、降低大气颗粒污染物浓度、改善城市生态环境等方面发挥着不可替代的作用。该文选取新疆南部典型绿洲城市——阿克苏市不同功能区的绿化树种, 用多重比较法对比分析了二球悬铃木(Platanus × acerifolia)、新疆杨(Populus alba var. pyramidalis)、圆冠榆(Ulmus densa)、天山梣(Fraxinus sogdiana)和垂柳(Salix babylonica) 5个树种叶片平均滞尘量随时间变化及不同高度叶片的滞尘能力, 探讨了阿克苏市主要绿化树种的滞尘规律, 得出以下结论: 不同绿化树种单位叶面积滞尘量差异显著, 差距在1.15-2.17倍之间, 绿化树种滞尘量随着时间延长而增加; 同一树种在城市不同功能区的滞尘能力不同: 工业区>交通枢纽区>居民区>清洁区; 不同高度的叶片, 其滞尘量在工业区和交通枢纽区差异显著: 高度1 m的叶片滞尘量>高度2 m的叶片滞尘量>高度4 m的叶片滞尘量。     

Coalescent-based species tree inference from gene tree topologies under incomplete lineage sorting by maximum likelihood

Incomplete lineage sorting can cause incongruence between the phylogenetic history of genes (the gene tree) and that of the species (the species tree), which can complicate the inference of phylogenies. In this article, I present a new coalescent-based algorithm for species tree inference with maximum likelihood. I first describe an improved method for computing the probability of a gene tree topology given a species tree, which is much faster than an existing algorithm by Degnan and Salter (2005). Based on this method, I develop a practical algorithm that takes a set of gene tree topologies and infers species trees with maximum likelihood. This algorithm searches for the best species tree by starting from initial species trees and performing heuristic search to obtain better trees with higher likelihood. This algorithm, called STELLS (which stands for Species Tree InfErence with Likelihood for Lineage Sorting), has been implemented in a program that is downloadable from the author's web page. The simulation results show that the STELLS algorithm is more accurate than an existing maximum likelihood method for many datasets, especially when there is noise in gene trees. I also show that the STELLS algorithm is efficient and can be applied to real biological datasets.