An inventory of trees in Dublin city centre

While urban areas are often considered to be comprised chiefly of artificial surfaces, they can contain a substantial portion of green space and a great diversity of natural habitats. These spaces include public parks, private gardens and street trees, all of which can provide valuable environmental services, such as improved air quality. Trees play a particular role in cities as they are often placed along roadsides and in the median strip of busy streets. As such they regulate access to sunshine, restrict airflow, provide shelter, scavenge air pollutants and manage noise at the street level. A tree planting policy can be an important part of a broader environmental strategy aimed at improving the quality of life in urban areas but this requires up-to-date knowledge of the current tree stock, which does not exist for Dublin. This article presents an inventory of trees in Dublin's city centre, defined as the area between the Grand and Royal canals. The results show that there are over 10,000 trees in the study area representing a density of 684 trees km-2 or one tree to approximately every 50 residents of the city centre. The tree canopy extent when in full foliage was nearly 1 km2 in extent or 6% of the study area. A more detailed analysis of those trees planted along streets shows little species variation but clear distinction in the sizes of trees, which is indicative of the age of planting. These data are used to estimate the carbon stored in Dublin's trees.     

Spatial and Temporal Patterns Associated with Permitted Tree Removal in Austin,Texas, 2002–2011

A wide-ranging set of physical, urban, demographic, socioeconomic, and policy characteristics determines the spatial distribution of urban forests. Information on the characteristics surrounding tree removals on both public and private properties has received less attention in the literature. The purpose of this research was to analyze the spatiotemporal trends and geographic patterns of tree removals in Austin, Texas, between 2002 and 2011 in an effort to understand how site-specific characteristics influence urban tree removal and affect the overall distribution of Austin's urban forest. We examined permitted tree removals using a geographic information system (GIS) as well as spatial and statistical analyses. Specifically, we evaluated the degree to which variables related to various physical, urban, and socioeconomic conditions predicted tree removals. The results indicate that permitted tree removals and their associated characteristics in Austin have varied over the ten-year study period. Permitted tree removals increased over the study period and took place in the urban core and along the urban periphery. Permitted tree removals were more likely to be undertaken by college graduates and owner-occupants and to occur in more densely populated areas, closer to major streets, and on properties with older structures. The results of this research provide urban forest professionals with information on the location and intensity of permitted tree removals and the significant characteristics driving urban tree loss.     

北京社会治安公共安全空间结构及其影响机制——以城市110警情为例

维护社会安全与稳定是城市公共安全研究的重要课题,随着社会经济转型和城市空间结构变化的影响,北京市的社会治安公共安全呈现出明显的空间规律和特点。本文基于2006-2011年北京市110警情治安数据,结合GIS的空间密度分析方法,刻画北京社会治安公共安全的空间格局,并进一步探讨其空间分异机制。研究发现:①北京社会治安公共安全状况明显改善,犯罪空间形成小集聚多分散的演化特征,形成了多个警情高发的集聚区;②北京公共安全空间变化具有明显的偏向性和差异性,形成西北—东南的极化现象。③不同的犯罪类型其空间分布特征也不同,不同的犯罪类型都存在明显的、各具特色的空间分异特征。④从社会治安公共安全空间分异机制来看,经济功能区、人居环境、交通、流动人口和居民居住环境安全感等要素差异会引发不同的犯罪类型和形成不同的犯罪集聚区。本研究可为首都社会治安防控的空间管理策略和城市公共安全政策制定提供参考。     

Urban Biogeographical Analysis of Spontaneous Tree Growth on Stone Retaining Walls

Stone retaining walls in urban Hong Kong provided vertical habitats for spontaneous colonization by a diversified humid-tropical flora with large trees. A citywide survey assessed wall and tree characteristics to understand wall-tree relationships and identify conservation candidates. Nonparametric correlations were computed between 28 wall attributes versus tree count, tree biomass, and species-vegetation factors. Most of the 245 walls, with 1275 trees, were in residential areas. Moraceae dominated the 30 tree species, predominantly genus Ficus, and especially F. microcarpa. Natives formed the overwhelming majority, largely with pioneer and ruderal traits. The positive effect of adjacent built-up land use and negative effect of wall exposure indicated sheltering from wind could facilitate tree growth. Wall height was a key determinant as taller walls furnished more surfaces free from human disturbance and conducive to seed deposition by frugivorous birds and bats. Stone width offered more horizontal microsites for seeds to lodge. Stone roughness operated at the microscale to encourage nonarboreal vegetation. Joint attributes exerted strong influence on tree growth and less so on nontree affiliates. The walls-cum-vegetation, many older than 100 years, presented a precious natural-cum-cultural heritage, deserving protection as an urban ecological asset.     

Assessing Natural and Cultural Determinants of Urban Forest Quality in Nanjing (China)

This study assessed underlying natural and cultural determinants of tree health and ways to improve urban forest performance in compact Nanjing city. Two groups of factors were investigated: (1) habitat conditions, including planting site, ground-cover, land cover, and district; and (2) tree traits, including species provenance and seasonality, and tree dimensions. A stratified sampling strategy selected 6351 trees for detailed assessment. The data were analyzed by multivariate logistic regressions. Institutional, park-garden and industrial trees with more open-space sites with vegetated ground-cover performed better than roadside and residential ones. Poor trees in confined residential sites deviated from those in other cities. Park-garden sites did not always nurture meritorious, large and diversified trees. District differentiation in tree performance was related to land cover. Exotic and evergreen species grew better than indigenous and deciduous, offering hints on species-habitat matching. Detailed field and statistical analyses could yield tree-environment information to enhance urban forestry research and management.     

Variations of the Treescape in Relation to Urban Development in a Chinese City: The Case of Nanjing*

Urban trees, as prominent and pertinent landscape elements of cities, are increasingly studied by both practitioners and academics. Trees in Chinese cities have hitherto received little detailed analysis from the viewpoint of urban forestry or landscape analysis. This study attempts a comprehensive evaluation of the tree population in Nanjing, focusing on the association between urban development and treescape attributes. Six districts, covering the main built‐up area of 130 km², formed the study area. Nine land‐use types with varied urban morphology and three urban zones with different development history were identified, within which subareas and trees were sampled for field study of tree dimensions, tree performance, and site characteristics. Statistical analyses on the 6,527 surveyed trees verify that tree performance is significantly associated with land use, site condition, and related human activities. Treescape is associated with housing ownership, town planning, and the history of urban expansion. The relationship between treescape and urban landscape units can furnish hints for improved urban forest planning and management and better coordination between planners and landscape professionals.     

基于遥感影像的城市森林分类提取及生态价值估算研究

以北京通州新城区城市森林为研究对象,提出一种基于信息论的决策树分类方法,以提取Aster遥感影像中城市森林平面量,改善传统分类方法仅利用影像光谱特征信息的不足,高分辨率影像和地面调查数据验证显示其分类精度达84.6%.结合分类影像图,引入城市森林生态价值评估模型(CITYgreen模型)估算出通州新城区森林的生态价值约为598.87万美元.研究表明,该方法适合大面积区域的城市森林分类提取及其生态价值估算.     

中国居民耕地资源保护偏好研究：选择实验法的应用

耕地资源保护有效方案与政策一直是国内外政府决策者和学术界关注的热点。本文利用武汉市农民和市民实地调查数据,基于选择模型法构建假设的政策与交易市场,模拟在此假设市场下主要相关利益群体耕地资源保护偏好意愿。依据选择实验法的基本原理选取耕地面积、耕地质量、耕地周边景观与生态环境、支付耕地保护费用作为环境商品的属性。首先考查了主要相关利益群体的偏好,并获得了对于保护属性主要相关利益群体农民和市民不同偏好的实验证据;然后分析不同环境商品属性组合方案所可能引起的福利变化水平。本文研究所得出的结论,为中国的农地保护制度和目前实施的耕地保护基金、农业补贴制度提供理论上的支持和决策参考。     

Mine your data: open data,digital strategies and entrepreneurial governance by code

Investment in the release of open data has become increasingly central to the implementation of smart city programs by governments around the world. Though originally arising out of a push towards “open government” and the pursuit of more transparent decision-making by public authorities at multiple scales, open data programs have more recently been adopted by municipal governments to support entrepreneurial goals of enhanced competitive positioning and attracting investment. As urban scholars now subject the smart city project to critical scrutiny for its role in advancing urban entrepreneurialism, this article considers the relevance of the open data agenda as it shapes wider understandings of the smart city. In particular, I address the collection of policy practices, aspirations, stakeholders and entrepreneurs active in framing the opportunities and values of open data for urban governments. Both the momentum of support for open data, along with a recent shift in the rhetorical aspirations of the open data movement away from the values of openness and transparency and towards a more confined focus on value generation, raise important critical questions for urban geographers concerned with the nature of urban governance in an age of big data.     

黄河三角洲湿地柽柳林生长动态密度结构的响应特征

为了阐明滨海湿地不同密度柽柳(Tamarix chinensis)林的生长动态,探索滨海湿地柽柳林的密度合理性,在黄河三角洲莱州湾南岸的山东昌邑海洋生态特别保护区内,利用标准木树干解析法,对10a生的3种密度(2400株/hm2、3 600株/hm2和4400株/hm2)的柽柳林地上生物量、林木生长动态和基径分布特征进行研究.结果表明,3种密度林分的地上生物量、树高生长量和林木基径生长过程差别较大.随着林分密度增大,林木单株生物量和基径减小,但单位面积林分生物量增加;树高、基径的速生期都出现滞后现象.3种密度林分基径分布的偏度系数(SK)差别较大;密度为3 600株/hm2林分的SK值为0.085,接近正态分布,林分密度结构和基径分布较为合理;密度为2 400株/hm2和4 400株/hm2林分的SK值分别为-0.842和0.303,偏离正态分布,林分密度结构不合理.密度为2 400株/hm2林分的峰度系数(K)为0.017,林木生长相对整齐;密度为3 600株/hm2和4 400株/hm2林分的K值相差不大;密度因素对林木分化作用较小.若不考虑10a间的林木间伐利用,该区柽柳人工造林合理的初植密度建议为3 600株/hm2(株行距约2.0 m×2.0 m).     

运用树木活力度进行城市生态环境质量分区--以吉林市为例

城市生态环境质量是影响城市景观和居民身心健康的重要因素，环境质量分区是进行生态环境评价的基础性工作。在以往生态环境质量评价中，通常采用单一的环境污染指标，难以全面综合的反应生态环境质量状况。植被的面貌是一定时期内大气、土壤、水分、人类活动综合作用的结果。由于树木有生命而又不能移动，它的健康状态是一定时期因素内，综合地反映其生活环境条件的最好尺度。借鉴国外环境诊断的研究方法，提出“树木活力度”，即树木的枝、叶、梢、树形等各个部位的生长状况和健康程度这一新的综合生态指标，并结合实际，以吉林市为例，对运用这一指标进行城市生态环境质量评价的方法、原理、问题等进行了初步探讨。指出运用树木活力度进行城市生态环境质量分区，具有迅速目测、计算简便，快速经济的特点，是当前较为流行的一种景观诊断的简便易行的方法。     

Interdisciplinary,Cross-Cultural Research: Double Trouble∗

U.S. housing policy strengthens the local specificity of capital through support for homeownership and the mortgage lending industry. As access to capital and homeownership rates have grown, predatory lending has emerged as a significant danger to homeowners and their surrounding communities. The geographic distribution is not well understood, likely due to the unavailability of mortgage data to identify instances of predatory lending. This article examines the spatial distribution of predatory lending in Philadelphia, Pennsylvania, using public mortgage and property data. Predatory lending is spatially clustered within the city, suggesting a spatial component of abusive lending patterns not previously addressed. U.S. housing policy and intervention strategies designed to prevent and reduce the incidence of predatory lending should address the spatial aspects of predatory lending to target efforts and prevent weakening local connections between capital and communities.     

Forest Beliefs in an Urbanizing World: Views on and Usage of Forest Areas Among Persons with and Without a Migration Biography in Germany and Sweden

Previous studies have shown that environmental values of inhabitants of urban areas differ to some extent from those of people living in rural contexts. In the light of increasing urbanization, it is sometimes argued that these differences are becoming even greater, as people are becoming more and more alienated from nature. In the context of a larger survey study on beliefs about forests and forest management among the general public in Germany and Sweden, the influences of people’s migration biographies on their patterns of forest usage, their environmental concerns about forests, and the expectations and values they ascribe to forests are explored. While previous findings on differences between urban and rural populations are confirmed, we also find variation within these groups depending on their history of moving between the two spatial categories. This study thus adds a dynamic aspect to the discussion on the urban–rural perspective on beliefs about forests.     

基于神经网络模型技术的南京市主城区城市森林遥感调查

城市森林调查是城市森林研究和规划建设的前提和基础工作,而遥感和GIS技术已成为现代城市森林调查的主要方法。遥感信息源和遥感分类技术是决定城市森林遥感调查质量的两个关键因素,研究认为,根据城市森林特点及城市森林研究和规划建设的要求,城市森林遥感调查采用的遥感影像分辨率以8¹0m为宜,神经网络模型分类技术应用于城市森林遥感调查效果较好。本文以南京市主城区为例,以10m分辨率多光谱spot卫星图像与2.5m分辨率全色spot卫星图像的融合图像作为解译信息源,采用dARTMAP神经网络模型进行监督分类,提取了一套具有较高精度的南京市主城区城市森林空间属性数据和图件,并在此基础上分析了南京市城市森林基本特点及规划建设方向。     

北京居民生活满意度的多层级定序因变量模型分析

传统经济学视角出发的个体生活满意度研究往往忽略了数据的嵌套性,多层级模型更适用于地理学中分析不同层级地理单元特征对个体生活满意度的影响。采用多层级定序因变量模型,以北京为例,研究居民生活满意度在城市内部街道和居住小区尺度内的异质性,并研究了高层级地理空间单元的属性特征对居民生活满意度的影响。结果表明,生活满意度在居住小区层级的异质性远高于街道层级,个体自身的社会经济属性对个体的生活满意度有显著影响,总的来说,高收入、老年人、北京户口居民的生活满意度更高。除个体属性特征以外,居住小区的类型是影响生活满意度的重要因素,商品房小区居民的满意度显著高于保障房和单位房小区居民。     

基于树轮资料重建森林净初级生产力的研究进展

森林净初级生产力(NPP)反映了森林植被固定和转换光合产物的能力,表示了森林碳汇功能强度,也是评价森林植被的演替状况以及陆地生态系统承载力的主要指标。基于遥感、清查资料等方法估算NPP已经取得了一些进展,但传统的研究方法受限于观测(调查)年份,难以有效获取长时间尺度的区域森林种群或群落年际NPP。树轮资料较为有效地反映了历史时期森林植被的逐年生长状况,从而在估算高精度且长时间尺度区域森林种群及群落NPP中具有较大的优势。本文对利用树轮资料重建区域森林NPP的两种主要方法进行了总结,第一种方法主要是依据树轮资料提供的立木逐年生长量进行生物量以及NPP的估算;第二种方法则是利用树轮指数与其他植被指数的相关性间接反演过去时间段区域森林群落NPP的变化。上述两种估算NPP的方法均存在较多的限制性,未来利用树轮资料估算NPP的时空精度仍有待提高。     

红树林造林技术

红树林在海岸防护方面的重要作用越来越受到人们的广泛关注,红树林的造林也掀起了新一轮的热潮。广东湛江是开展红树林造林比较早的地区,多年来积累形成一套自成体系的造林技术。     

大型公园绿地对住宅价格的时空影响效应——以上海市黄兴公园绿地为例

随着居民生活质量的提高和环保意识的增强,居民对环境舒适的支付意愿不断提高。居住环境的价值评估研究受到关注,但对其作用时间和空间影响程度差异的量化研究明显不足。本文以上海市黄兴公园绿地为例,综合运用市场比较法、特征定价法和多元回归分析等方法,并引入加权距离,从时间和空间两个层面分析黄兴公园绿地对周边住宅价格的影响效应,结果表明:黄兴公园绿地所带来的住宅价格增值效应既具有时间上的差异性,又与加权距离存在着显著的二次函数关系,随着距离增加其增值幅度呈下降趋势;其影响效应与加权距离存在着显著的三次函数关系,最大影响半径为1.59km,最强影响区位为0.29km。     

Public perceptions of foreign and Chinese real estate investment: intercultural relations in Global Sydney

Moving foreign human and financial capital through landed property is not a new phenomenon in Sydney. It is a recurring geopolitical strategy that is replete with intercultural tension and deep colonial roots. In contemporary Australia, there is an assumption in public policy and media rhetoric that there is a high level of public concern about foreign investment. However, there is little empirical data that examines public perceptions. In this study, we are interested in whether the dominant voices in this debate represent broad public views about this issue. We sought to fill this gap by conducting a survey of almost 900 Sydney residents, looking at their perceptions of foreign and Chinese investment. We find high levels of public concern and discontent about foreign investment amongst Sydneysiders, with Chinese investors being a key target of this discontent. In the context of high housing prices in Sydney, there were widely held concerns about housing affordability. Survey respondents had a sophisticated understanding of what influences house prices, but with an overemphasis on the role of foreign investment. There is a general lack of support for policy that encourages foreign investment, and a lack of confidence in how the government is regulating foreign investment. Half of our participants reported that they would not welcome Chinese foreign investment in their suburb.     

Beliefs about Ecological Impacts Predict Deer Acceptance Capacity and Hunting Support

Ecological impacts of deer overbrowsing often lead resource managers to recommend deer control through hunting, which may be strongly opposed by local residents. Adaptive impact management argues that understanding wildlife impacts of concern to the public can improve wildlife management. However, research on public wildlife acceptance capacity for deer, and on support for hunting, has emphasized concerns about household impacts and deer well-being, general environmental beliefs and attitudes, and beliefs about consequences of hunting, but not public concerns about deer ecological impacts. Our survey of neighbors of urban wetlands shows that beliefs about deer ecological impacts are statistically significant predictors of deer acceptance capacity and of support for hunting, controlling for other factors. Including ecological-impact beliefs adds substantially to the explained variance in deer acceptance capacity, and slightly to the explained variance in support for hunting.