Evaluation of five landscape-level metrics for measuring the effects of urbanization on landscape structure: the case of Tucson, Arizona, USA

Landscape-level metrics can be used to measure changes in landscape structure over time. Four landscape-level metrics and rank-size distributions were used to describe changes in landscape structure caused by urbanization in a portion of the Tucson, Arizona metropolitan area between 1984 and 1998. This analysis describes what each metric conveys regarding how urbanization affects landscape structure. It also compares the efficacy of rank-size distributions with the other metrics. Results indicate all five metrics provided information about a specific aspect of landscape structure including patch size, shape, or dispersion. Results indicate that rank-size distributions and their scaling exponents are useful because they provide information not available from the other metrics. Rank-size distributions describe the patch-size scaling properties of specific land-cover types, the relative effect of large and small patches on the distribution of patch sizes, the magnitude of change in patch size, where patch sizes differ from what is expected by the regression model, and the range of patch sizes displaying fractal patterns.     

Rank-size distribution of urban employment in labour market areas

This paper examines the rank-size distribution of employment in cities considering the designation of unified labour market areas (LMAs). The empirical application refers to Greece and the dataset includes population and employment at the municipal and local commune levels as well as LMAs originating from commuting patterns between communes. It is found that the employment rank-size distribution based on municipalities substantially overestimates the size of smaller peripheral town areas, where labour agglomerations typically take place at finer spatial scales, and underestimates agglomerations around larger urban areas. The use of LMAs as an alternative spatial unit of analysis entails a less even geographical distribution of workers, particularly when adopting a 10% commuting threshold. Moreover, a threshold regression is used to facilitate the distinction between urban and rural areas, specifying the LMA size beyond which substantial urbanisation effects arise and signifying that about 80% of the total employment corresponds to urban employment. The findings can have important implications for the formulation and evaluation of policies to manage labour agglomeration economies in metropolitan and peripheral urban and rural areas for the sustainable and equitable growth of a country.     

City‐size distribution in the Saudi Arabian Urban system

The purpose of this paper is to model the national and regional city‐size distribution of the Saudi Arabian urban system using 1987 population estimates, and to examine the factors that have influenced the development of the urban system. The pareto coefficients of the national and regional distributions were found to be low, signifying the prevalence of smaller sized cities in the distribution. The national system was found to have a multi‐city primacy situation, while the regional distributions displayed varied primacy characteristics. Factors noted to influence the development of the urban system include geographical and economic factors, as well as public policies. The paper identified three areas of population agglomeration and it is concluded that future growth might lead to a regional convergence depending on policy initiatives and on whether the urban system follows the typical pattern of other urban systems.     

City-size distribution and the size of urban systems

"This paper is an analysis of the city-size distribution for thirty-five countries of the world in 1975; the purpose is to explain statistically the regularity of the rank-size distribution by the number of cities included in the urban systems. The rank-size parameters have been computed for each country and also for four large urban systems in which several population thresholds have been defined. These thresholds seem to have more influence than the number of cities included in the urban system on the regularity of the distribution." The data are from the U.N. Demographic Yearbook.     

Are South Africa’s cities too small?

Are South African cities to small? Given the history of South Africa’s spatial development, one might expect that South African cities might be under-sized, and not over-sized as in many other developing countries. It is found that the rank-size distribution explains the sizes of South Africa’s cities but that Zipf’s Law does not hold for the country’s cities. The so-called q-coefficient was found to be equal to −0.75 for the 123 places with population in excess of 100 000. It was also found that urbanisation in South Africa over the past decade seems to have taken the form of the parallel (slow, 1.04%) growth of five large cities. Finally, calculating the “H-measure” for 19 metropolitan areas in South Africa yields an inverse H-measure of 11.3. This suggests a reasonable degree of dispersal, which would only be consistent with optimal city size if transport costs were low and manufacturing not in need of scale economies; two conditions unlikely to apply to South Africa. Finally, the primacy ratio for South Africa’s largest urban agglomeration was found to be 38%. This suggests that the size of the Johannesburg-East Rand urban agglomeration (the primate city) may be relatively too large, whereas more efficient growth may come from larger harbour cities.     

Path-dependent processes and the emergence of the rank size rule

Many things in the natural world consist of an ever-larger number of ever-smaller pieces. This is called a fractal, which implies both the power law and rank size rule. Various models have been applied to explain the power law or Zipfs law in the distribution of city size. Gibrats law proposes general and neat interpretations for this regularity in a city distribution, but the homogeneity assumption in Gibrats law shows a disregard of the agglomeration effect that is essential in economic interpretation. The purpose of this paper is to examine the relation between the feature of increasing returns in the dynamic growth process and the property of power law in the static limiting distribution. We apply the path-dependent processes in Authur (2000) called nonlinear Polya processes to analyze the relation between the feature of agglomeration in the path-dependent processes and rank-size relations in the limiting distributions. The simulation result shows that the growth process with a diminishing returns agglomeration economy or a bounded increasing returns agglomeration economy converges to a stable limiting distribution with a constant expected proportion. On the contrary, the growth process with an unbounded increasing returns agglomeration economy could generate a fractal kind of limiting distribution with a time variant expected value. The unbounded increasing returns agglomeration economy is the necessary condition to generate the rank size rule in the limiting distribution. Given the assumption of agglomeration economies and robust evidence of Zipfs in city distribution, our result suggests that agglomeration benefits increase without a ceiling as residents are added to the city. The increase of the diseconomies of agglomeration (congestion, pollution, crime, etc.) is not too severe to confine the limiting level of the net agglomeration effect.The author acknowledges the National Science Council for the financial support on the study (Project NSC 91–2415-H-004–016).Received: July 2002 / Accepted: March 2003     

中国城市规模分布及原因分析

对中国城市规模分布的帕累托指数进行计算,在选取的27个省区中有4个省区帕累托指数显著大于1。全国各省区帕累托指数的平均值为0.9337,说明中国的城市规模分布比较分散。随后,将全国27个省区按区域分为东部地区、中部地区、西部地区,应用逐步回归方法对各个地区分别进行分析。结果发现,不同的地区,与城市规模分布关系显著的因素并不完全相同。     

山区多镇连体式小城镇空间发展模式探讨

多镇连体式小城镇普遍存在于山区市县,在定时期具有较大的辐射和聚集效应,然而随着城市的扩展,其行政区划的制约、地域界限的不清、功能的重复等弊端逐渐显现,因此,根据各个城镇的发展特点、经济实力、城市规模和地域结构,对多镇连体式小城镇分别采取单中心、团状紧凑式和多中心、组团并进式等空间发展模式,最终实现城镇一体化的融台。     

Size distributions for all cities: Which one is best?

This paper analyses four statistical distributions used to describe city size distributions: lognormal, double Pareto lognormal, q-exponential, and log-logistic. We use un-truncated city size data for the US, Spain and Italy from 1900 until 2010, and, in addition, the last available year for the remaining countries of the OECD. We estimate the four functions by maximum likelihood. To check the goodness of the fit we use the Kolmogorov-Smirnov and Cramér-von Mises tests, and compute the Akaike information criterion and Bayesian information criterion. The results show that the distribution which best fits data in most of the cases (86.76%) is the double Pareto lognormal.     

低碳城市与智能建筑电气

随着城市规模的扩大，建筑行业快速发展，但经济发展和环境问题之间的矛盾也在不断加剧。因此，低碳城市理念应运而生，并发展成了现代城市建设的最重要的理念。文章分析了低碳城市和智能建筑电气二者之间的关系与特征。     

Spatial patterns of population turnover in a Japanese Regional City for urban regeneration against population decline: Is Compact City policy effective?

Responding to the international trend of urban population decline, a sustainable urban form has been pursued around the world, with the compact city movement a typical example. However, compact city debate has often been criticized for its inclination to bio-physical environmental and economic goals and a lack of treatment of empirical social aspects like residential behavior. The present study was thus aimed at examining the gap between Japanese compact city policy and actual spatial patterns of population turnover, inheritance and migration. The case study was of residential areas of a Japanese regional city, Utsunomiya. The study used a four-step procedure: a) identifying the distributions of inheritors and migrators; b) constructing a detailed database of five characteristics of the residential areas, i.e., age of development, orderliness, road width, transport access, and social cohesion; c) identifying relationships between the number of inheritors and migrators and residential characteristics using a Poisson regression model; d) comparing the compact city plan underway with established patterns of population turnover. The results show that the number of inheritors has positive relationships with age of the residential area and access to rail transport and downtown. The migrators tend to have a random distribution in comparison with inheritors. These empirical residential patterns appear irrelevant to the government's bus-oriented compact city policy, so the government should reconsider approaches to realize an acceptable sustainable urban form.     

厦门市低碳城市总体规划研究

在研究低碳城市内涵的基础上,提出厦门市建设低碳城市的总体目标,并就建筑、交通、工业生产三大领域的CO2减排量提出控制要求。结合厦门市空间形态、气候特征、人口分布等特点,就厦门市低碳城市建设,提出不同区域的规划策略。从可再生能源利用、建筑节能、低碳交通、生态城市建设等方面提出相应措施。     

浅谈西部城市群空间结构发展研究——以成渝城市群为例

城市群在区域经济的竞争中扮演着越来越重要的角色,其发展已上升到国家宏观战略层面。西部大开发是未来中国经济发展的一个重要关键点,是中国未来十年甚至是几十年经济发展的高点。到目前为止,国内学者对长三角城市群、珠三角城市群和京津冀城市群的研究成果较多,而对西部城市群的研究相对较少。成渝城市群作为现阶段中国西部地区规模最大、发展基础最好的城市群,既是当前西部大开发的重点城市群,又是未来十年甚至是几十年我国经济重要的增长点。通过对比分析研究,该文拟从城市群空间结构的角度,分析成渝城市群的空间分布特征、存在的不足和城市群潜力,并找出优化城市群空间结构的对策。     

Manufacturing employment,city size,and inter-urban wage differentials

The positive correlation between city size and money wage rates has been an important factor in the spatial redistribution of population in the United States. Previous studies of inter-urban wage differentials have emphasized labor productivity differences (arising from sex, age, racial, and educational characteristics) and variations in labor demand associated with factor proportions, scale of firm, and industry mix. The analysis presented here expands this research base by articulating a theoretical model of the labor demand-supply relationships which incorporates (1) the implied predictive assumptions underlying regression studies of the relation between wage rates and city size and (2) the conflicting locational forces of local demand for products and/or labor and the competitive disadvantage of distance from intermediate or final markets for output. Statistical estimation and testing of the important relationships implied by the model confirm the significance of its principal variables.     

Same Neighbourhood … Different Views? A Confrontation of Internal and External Neighbourhood Reputations

Residents and non-residents are likely to think differently about a neighbourhood's reputation. Relatively little is known about the similarities and differences between these internal and external types of neighbourhood reputation or the relationship between reputations and ‘real’ or ‘objective’ neighbourhood characteristics. This paper addresses two points: first, the extent to which neighbourhood reputations differ between and within groups; second, the extent to which these neighbourhood reputations are associated with measured neighbourhood characteristics. Data from a specially designed survey carried out in 24 neighbourhoods in Utrecht, the fourth largest city in the Netherlands, are used. Analysis of the data showed that neighbourhood reputations are rated higher by residents and estate agents than by other city residents. Within the group of other city residents, differences were found in how neighbourhood reputations are rated by socio-economic status, ethnicity and educational background. Further, it was found that neighbourhood reputations are correlated with measured social characteristics of the neighbourhood, while physical and functional neighbourhood characteristics are of less importance.     

中国城市公园的标度律特征分析

科学研判城市公园面积与人口规模的关系,有利于客观认识和指导城市的可持续发展。采用1996—2019年中国291个地级及以上城市公园面积与人口规模数据,探究二者之间的标度关系及其标度因子的时空演化规律,进而采用基于标度律的公园规模修正模型度量各城市公园面积达到预期值的程度,并对规模修正指标和人均公园面积进行比较分析,得到如下结果。1)我国公园面积与人口规模整体呈亚线性规模缩放关系,公园具有显著规模效应,符合城市标度律特征;时间上呈现亚线性-超线性-亚线性的阶段性波动演变特征,空间上分异明显：华南接近线性标度关系,华中、东北、华北、西南呈典型亚线性关系,华东、西北呈亚线性,但标度因子偏离度较大。2)大城市在人均公园面积排序中相对靠后,在考虑规模效应后,排名普遍提高,说明规模修正指标能在消除人口规模影响的基础上,有效衡量不同规模城市公园面积的水平。标度律视角下的城市公园规模测度能够为城市人口管理和公园面积发展的决策提供科学指导,为不同规模城市公园建设提供可借鉴的比较标准,促进公园与人口的协调发展。     

RANK-SIZE DISTRIBUTION OF SETTLEMENT SYSTEMS: A STABLE ATTRACTOR IN URBAN GROWTH

ABSTRACT A further step towards a dynamic model for the observed size distribution of a system of settlements is presented. The occurrence and temporal stability of the rank-size distribution is obtained as the result of a dynamic self-organizing process of the nested system of settlements. The inherent time scale of this self-organizing process and the obtained hierarchical structure are related to the generally low inter settlement mobility of urban population, the tendency of the population to agglomerate, distance effects and preference effects. The well-known migration model of Weidlich and Haag is used as starting point and three approaches to express the attractivity in the system are compared. The stationary state is investigated in detail under some limiting conditions.     

The influence of a large city on some soil properties and metals content

Urban soils differ from the rural ones by the fact that they are more strongly influenced by anthropogenic activities. This influence is often reflected by a high degree of contamination. To investigate the influence a large city can have on its soils and on the surrounding ones, samples within the city of Torino, Italy were compared with a set of surrounding soils developed from the same alluvial parent material. City-country trends were investigated by spatially managing the samples. Results show that the city plays a key role in concentrating some pollutants, such as Pb, Zn, and Cu within its borders. Lead is the element most enriched in the city, presenting a pollution index of 7.5 calculated comparing the two sets of samples. Ni and Cr appear to have a strong natural contribution. The spatial distributions for Pb, Cu and Zn present an abrupt division between urban and rural samples. Unexpectedly, the transport of pollutants from the city to the surrounding areas seems to be limited as no city-country trends with distance are identified. The pH and the sand fraction result also influenced by the city, showing high values. The investigation of possible city-country distance trends has shown to be effective in evaluating the impact a city can have on its soils and on the transport and deposition of contaminants on the surrounding ones.     

An experimental study of aerosol distribution over a Mediterranean urban area

In this study an attempt is made to investigate the aerosol spatial and size distributions at different heights over the Greater Athens Area (GAA), Greece, under sea breeze conditions and clear sky and to further discuss possible implications for aerosol characteristics. The data used are airborne measurements of aerosol collected during two flights that were performed within the context of the 1997 STAAARTE experimental campaign. The aerosol measurements cover particle diameters from 0.1 to 45.5 microm. The horizontal and vertical distribution revealed that higher concentrations exist within or just above the atmospheric boundary layer, while greater concentrations are observed over the sea compared to land at high altitudes. At all altitudes the number size distributions show dominant diameter ranges between 0.1 and 0.3 microm at all altitudes. The volume distributions are characterised by two modes, one in the accumulation and the other in the coarse particle regime. At lower altitudes, fresh combustion emissions more likely cause the predominance of the size range 0.1-0.3 microm while enhanced physical and chemical processes that favour the growth of smaller particles to larger sizes could also act. The relative humidity does not seem to affect the observed number size distributions at low altitudes, where relative humidity is below 70% while at 4000 m the distributions seem to change over the sea where the humidity increases.     

最优城市规模理论与实证研究评述

中国城市在规模高速扩张过程中面临诸多问题,需要最优城市规模理论给予解释与指正。西方许多学者从不同的角度、不同学科对城市规模问题进行了一系列理论和实证研究。本文对该领域内主要贡献者的观点进行归纳、分类,并做简要评述,以期为最优城市规模研究提供一些新的视角和文献参考。