The relationship between the distribution and use patterns of parks and their spatial accessibility at the city level: A case study from Tehran,Iran

Parks are recognised as important elements of urban green infrastructure and for providing many benefits to city residents. In countries where urban growth is unplanned and sprawling, green space provision falls behind, inadequate amounts are provided or spaces are not located in the most effective places. Tehran, the capital of Iran, has experienced huge growth in population and corresponding sprawl in recent years. There has been no study of the effectiveness of parks as part of the range of green spaces in the city − their location, accessibility within the urban structure, relationship to the socio-demographic character of the population, amount per capita or quality and condition. Using a combination of existing data supplemented by new data from site surveys, this study firstly looked at the citywide scale of public open space in relation to population and socio-economic patterns. Second, a representative sample of 16 parks was examined in terms of their accessibility within the urban street structure using space syntax. The syntactical results were correlated with several different aspects of each park collected and rated on a 1–5 scale. The results showed a wide range of availability of parks with no specific pattern related to whether the district is better off or poor. The data on green space per district was often heavily biased by the presence of large areas of forest park or non-recreational land which gives a false picture.Many of the best parks are poorly integrated into the street network and found in the better off districts yet are very popular because they are “destination” parks in cooler, hilly areas. Poorly integrated parks in the inner city districts tended to show lower levels of maintenance, were often little used and had vandalism. Much more attention is needed to provide green space in an equitable way.     

基于果农受偿意愿的绿肥种植生态补偿标准探讨

为探讨果农绿肥种植合理的生态补偿标准,以效用理论为指导,运用生态补偿理论,依托陕西省423份果农绿肥种植样本,构建果农受偿意愿的效用函数,测定果农绿肥种植的生态补偿标准,并通过BinaryLogistic回归模型检验果农受偿意愿的影响因素。研究表明:绿肥种植生态补偿标准参数估计结果为2 611.80$·hm~(-2),非参数估计结果为3 660.75$·hm~(-2),两个数值作为陕西省果园绿肥种植生态补偿标准的动态调整区间。调研结果显示,约有77%的果农倾向于在果园种植绿肥,但是具有不同个人特征、家庭特征、认知水平的果农会表现出不同的绿肥种植意愿。回归分析表明,在陕西果农绿肥种植中,果农的个人禀赋以及家庭生产经营特征对受偿意愿的影响并不显著,村干部建议、果农对绿肥的认知和果农对国家绿肥产业政策的认知是主要影响因素,政策认知中种植补贴是农户绿肥种植的根本动因。基于上述结论,建议绿肥种植的大力推行首先应尊重果农意愿,其次应确定适当的生态补偿标准,建立管控与激励相结合的市场化、多元化的生态补偿制度。     

猪德尔塔冠状病毒SYBR Green Ⅰ实时荧光定量PCR方法的建立及应用

为建立一种猪德尔塔病毒(PDCoV)的快速检测方法,本研究根据NCBI公布的PDCoV序列设计了1对特异性引物,利用RT-PCR方法扩增PDCoV的S基因,将其连接至pMD 19-T载体上,以构建正确的重组质粒作为标准品,建立SYBR Green Ⅰ实时荧光定量PCR检测方法,并对该方法的敏感性、特异性及重复性进行了验...     

条斑紫菜(Pyropia yezoensis)绿斑病病原菌的分离鉴定

绿斑病(Green spot disease)是一种常见的海区栽培条斑紫菜(Pyropia yezoensis)病害,在整个紫菜栽培期间都可能发生,以每年11~12月份最为严重,主要出现在幼叶期和成叶期。首先,在叶状体上出现红色或淡红色小斑,而后逐渐转变为绿色,病斑继续扩展,在叶状体表面形成若干孔洞,后期几乎整个藻体变绿。本研究对日照地区患绿斑病的条斑紫菜进行病原菌分离纯化,得到5株优势菌(编号为Y1~Y5),人工回感实验结果显示,Y1可以引起健康条斑紫菜发生绿斑病。对Y1进行了生理生化检测、16S rRNA、dnaA和dnaN基因序列分析,确定病原菌为海洋假交替单胞菌(Pseudoalteromonas marina)。对绿斑病的发病进程进行了观察,并检测了培养温度、海水比重和养殖密度等环境因子对绿斑病发生的影响,结果显示,高温和高密度养殖会加速绿斑病病情的发展,海水比重为1.022时,绿斑病发病较严重。本研究确定了一株引起条斑紫菜绿斑病的病原菌,并分析了部分理化因子对感染的影响,为条斑紫菜绿斑病的防控提供了基础数据。     

Perception and preference of trees: A psychological contribution to tree species selection in urban areas

Trees can enhance human mental and physical well-being in urban environments. However, the tree benefits in urban planning are insufficiently recognised, and there is little knowledge on the tree characteristics that are relevant to humans and how they are evaluated. This paper presents perceptual tree parameters and their relation to human preferences. In study 1, participants sorted 24 tree images by perceived similarity. Hierarchical cluster analysis and multidimensional scaling (MDS) revealed the distinction between conifers and deciduous trees, crown shape, the two-dimensional crown size to trunk height ratio and the crown density as important to humans. In study 2, participants rated the trees based on their preferences. Multiple linear regression analyses showed that a high two-dimensional crown size to trunk height ratio and a high crown density predicted deciduous tree preferences. These findings are discussed in light of the savannah hypothesis and the Gestalt grouping principle of closure. In the task of tree selection and placement for urban areas, the identified perceptual tree parameters may allow for achieving a coherent overall picture with a simultaneous increase of tree species richness. Thus, urban landscape planning can apply the presented findings for increasing ecosystem health and residential satisfaction.     

THE OCCURRENCE AND DEVELOPMENT OF THE ADVENTITIOUS ROOTS FORMING GREEN SHOOT CUTTING OF LARIX OLGENSIS

The experiment with the green shoot cutting propagation of Larix olgensis wasmade in the Maoer Mountain Forestry Farm on July 5,1990.After the callus formed ofthe cutting base before adventitious roots came out the materials were collected from thecutting base and fixed in FAA solution.By the paraffin sections and anatomical observatio-n.the results indicted that it needed 40 days from the cutting to the rooting.The inducedprimordium of the cutting was endogenous in origin,which came from:(1)vascularcambium of the callus,and became roots;(2)meristematic cell population in the intersectbetween the cambium and xylem ray of the cutting base.There were extruding,crushingprocess and enzymolysis when the adventitious roots broke through the outer layers in tworooting types.     

效应剂和氢离子浓度对玉米绿苗和黄化苗PEP羧化酶活性的协同作用

以玉米为材料，研究了效应剂和ＰＨ对绿色和黄化玉米ＰＥＰ羧化酶活性的协同作用，发现绿苗和黄化苗中ＰＥＰ羧化酶对效应剂的敏感性不同，前者比后者Ｇ６０、Ｇｌｙ敏感，而后者比前者对Ｍａｌ敏感。黄化苗３ｈ光处理后，其ＰＥＰ羧化酶对Ｇ６Ｐ对敏感性与绿苗趋于相同。同时发现ＰＨ不同，ＰＥＰ羧化酶对效应剂的敏感性也不同，低ＰＨ比高ＰＨ时酶对效应剂更敏感。根据绿苗和黄化苗ＰＥＰ羧化酶活性和对效应剂敏感性的差异推测黄化     

城市群绿地系统建设刍议——以长株潭(CZT)城市群绿地系统为例

绿地是形成城市特色的重要组成部分,从区域规划的角度构思长株潭(CZT)城市群的绿地体系,作为一个整体,CZT绿地景观特色可以概括为:"丘陵、江洲、名城",绿地景观构架是"三城一星环二带",结合CZT现状,提出了城市群绿地特色的构建对策。     

Urban domestic gardens (V): relationships between landcover composition,housing and landscape

The contribution to urban green space by private or domestic gardens in residential zones was investigated in the city of Sheffield, UK, as part of a wider study of the garden resource and its associated biodiversity. The attributes of 61 gardens, including patterns of landcover and vegetation cover, were explored in relation to housing characteristics and the nature of the surrounding landscape. The number of surrounding houses, and the areas of buildings and of roads were negatively correlated with garden area. The proportion of a housing parcel comprising garden increased with parcel size, although the proportion that was rear garden remained relatively constant. Garden size played an overwhelming role in determining garden composition: larger gardens supported more landcovers, contained greater extents of three-quarters of the recorded landcovers, and were more likely to contain trees taller than 2 m, vegetable patches, and composting sites. Unvegetated landcovers made greater proportional contributions as garden size declined. All categories of vegetation canopy increased with garden size, and large gardens supported disproportionately greater cover above 3 m. House age was a less significant factor determining garden landcover. Gardens of newer houses were more likely to occur towards the edge of the urban area, and older properties, that contained fewer hedges, possessed less canopy between 2–3 m. The extent and occurrence of different landcovers in gardens, and their consequences for wildlife, are considered for residential patches in urban areas. The implications for urban planners are discussed.     

微生态制剂等在重茬西葫芦栽培上应用技术研究

明确微生态制剂、生物有机肥等对西葫芦重茬病及其产量的影响,为大棚西葫芦安全、高效生产提供依据。研究以耐寒性较强的“寒玉”为材料,比较供试微生态制剂、生物有机肥等肥料的控病增产作用。结果表明：微生态制剂处理播种后55d平均叶片数增加25.76%、单株花量增加120.59%、单株结果量增加87.61%、平均株冠扩大30.651%、叶柄粗度增加18.35%;根腐病发病株率减少77.83%～92.63%,灰霉病发病株率减少72.71%～84.27%;平均产量提高78.45%～90.88%。微生态制剂5 kg/667 m²+基施施氮磷钾复合肥20 kg/667 m²、生物有机肥120 kg/667 m²+基施施氮磷钾复合肥20 kg/667 m²对西葫芦重茬病有较好的控制效果,增产效果明显,可在生产中应用。