A COMPARATIVE PERSPECTIVE ON RACIAL RESIDENTIAL SEGREGATION:

This article takes a first step to compare the residential segregation of blacks and Asians from whites in American and Canadian cities. The analysis is based on census data from 404 American and 41 Canadian cities. African Americans in the United States experience a higher level of residential segregation than Asians in U.S. cities. On the other hand, blacks in Canada experience the same low level of segregation as Asians. To explain the different experiences of blacks in the United States and Canada, a multivariate model is proposed and tested. The results reveal several patterns. First, African Americans are consistently obstructed much more than Asian Americans by their proportion in the city. In contrast blacks in Canada are not. Second, the residential segregation patterns of African Americans are affected strongly by the labor market and strucutral changes of the economy in the city. However, the structural change of the economy in the city has a very weak effect on the level of residential segregation of Asian Americans, black Canadians, and Asian Canadians.     

Direct and indirect effects of urbanization on soil and plant nutrients in desert ecosystems of the Phoenix metropolitan area,Arizona (USA)

Desert landscaping has become a dominant land cover type in arid US cities and often includes native plant species. Does replacement of native plant distribution in urban areas also reestablish ecological functioning characteristic of natural deserts? We compared ecological processes in three landscape types that are common to the metropolitan area of Phoenix, Arizona (USA): residential desert yards created from former lawns, Sonoran Desert preserves within the city, and Sonoran Desert preserves outside the city boundaries. Canopy cover, abundance of herbivorous insects, and soil properties (concentration of inorganic nitrogen (N), soil moisture and organic matter content, and water-holding capacity) were higher in residential desert yards than in native desert sites located both within and outside of the city. Furthermore, soil resources in desert yards were not organized around plant canopies, departing from the predictable resource island pattern that is characteristic of natural deserts. Intentional human manipulation and land use history accounts for these differences, while the urban environment contributes only subtly to soil N concentrations beneath plant canopies. While the use of desert landscaping may have important water conservation benefits, it does not help to mitigate the well-documented excess of reactive N within the Phoenix metropolitan area.     

Influence of urban landscape structure on bird fauna: a case study across seasons in the city of Valencia (Spain)

Studies on bird fauna of urban environments have had a long history, but the potential of studies mapping the distribution of birds in cities probably has not fully developed. The bird fauna of the municipality of Valencia (Spain) was studied to determine the influence of urbanization on bird species richness and abundance. Birds were censused during winter and the breeding season of years 1997–1998 in 197 squares measuring 49 ha each from a rural and an urbanized area. Across seasons the number of species decreased around 40% in the city compared with the rural landscape surrounding it. Such pattern could be attributed to the low number of farmland species capable to use the habitats inside the city, and the limited ability of urban parks in attracting woodland species. In the urban landscape, the influence of the dimensions and spatial arrangement of habitat patches was outweighed by the amount of each habitat per square. Bird richness and the abundance of most species were negatively related with the amount of built-up habitat per square and positively with the amount of urban parks, and of habitat diversity. Conversely, bird fauna was largely independent of mean park size per square especially during winter, indicating that at the landscape scale even small patches of habitat could play an ecological role. Conservation of urban bird diversity could benefit of two complementary strategies: (i) the protection of the surrounding rural landscape from urban development; (ii) habitat enhancement within the city. Particularly, a proper design and habitat management of urban parks could improve their suitability for urban bird fauna.     

Indexes of Racial Residential Segregation for 109 Cities in the United States, 1940 to 1970

Abstract

An index of racial residential segregation for a city may be calculated from census data reporting the number of white and nonwhite households resident in each city block. Such an index summarizes the dissimilarity in residential location of the two groups. Segregation indexes for 109 cities for the years 1940, 1950, and 1960 were published in Taeuber and Taeuber Negroes in Cities (1965).

Segregation indexes for 109 cities for 1970, together with the previously published indexes for the three earlier census dates, are presented in Table 1. The trend data from 1940 through 1970 refer to residential segregation of whites and nonwhites. For 1970 only, segregation indexes are also presented comparing whites and Negroes.

The trend data reveal a distinctive pattern of change during each of the three decades. From 1960 to 1970, declines in segregation prevailed among cities in each region of the country.

The indexes for 1970 were calculated from Public Use Summary Tapes issued by the Bureau of the Census. Certain difficulties were encountered in the use of these tapes. A methodological appendix describes the data source and retrieval procedure for calculation of city segregation indexes for 1970.     

Racial and Ethnic Residential Patterns in Canada

The aim of this study is to understand how city factors explain racial and ethnic residential patterns in contemporary multiethnic cities. We examined residential patterns among 17 groups in 12 Canadian cities. The results suggest that we should be cautious in taking factors derived from literature based largely on European experiences at the beginning of the last century and applying them uniformly to different groups in Canadian multiethnic cities. Our results show that the residential segregation of different racial and ethnic groups is affected by different sets of city factors. In addition, most factors suggested in that literature do not relate to the segregation patterns among visible minority groups.     

Effects of area size,heterogeneity, isolation,and disturbances on urban park avifauna in a highly populated tropical city

We assessed bird diversity and nesting activity in 54 urban parks in the core of a highly populated East-Asian tropical city to investigate the effects of area, isolation, habitat heterogeneity, and human disturbances on avifauna. Tree density and heterogeneity were lower while isolation was greater in small than in large or medium-sized parks. Yet, park features were often interrelated, with isolation variables negatively correlated to each other, heterogeneity positively correlated to area, and habitat variables mostly positively correlated with one another but variously to disturbances; whereas pedestrian densities wee positively correlated with green area proportions (ISO3) but negatively with the distances to large green areas (ISO2). Park size played a primary role by positively affecting species richness and numbers of nesting species, thus contributing to higher total and nesting species heterogeneity, and determining the occurrence of a greatest number of species. Pedestrian density, canopy cover, and ground heterogeneity played secondary roles, whereas isolation appeared less influential at the community level. Omnivores, granivores, and aerial insectivores appeared more abundant but were dominated by several common species. Nesting was restricted to even fewer species. While species varied in the occupancy responses to these factors, tree heterogeneity positively affected the nesting of Zosterops japonicus and cavity-nesting birds, and predator density negatively affected those of Lonchura punctulata and Streptopelia doves. Improved urban land use planning and park management incorporating these effects should be implemented to enhance breeding and avoid compositional homogenization for long-term sustainability of urban avian diversity.     

Interracial homicide: A macrostructural-opportunity perspective

Using data for 154 cities, we test a model of the determinants of interracial homicide that is informed by both Blau's macrostructural theory and elements of the general criminal opportunity perspective. Consistent with Blau's theory, in a multivariate analysis the relative frequency of interracial homicide is positively related to racial heterogeneity, population size, and population density, and inversely related to racial residential segregation and racial socioeconomic inequality. We also find that the level of employment is positively related to the rate of interracial homicide. This result is consistent with the hypothesis, derived from routine activities theory, that the dispersion of activities away from primary group locations and toward more racially heterogeneous settings increases the volume of intergroup contacts. Overall, our analyses reveal that a macrostructural-opportunity perspective offers considerable insight into the determinants of intercity variation in the racial patterning of homicide.An earlier version of this paper was presented at the annual meeting of the American Society of Criminology, Reno, Nevada, November 8–12, 1989.     

A spatial analysis of indigenous cover patterns and implications for ecological restoration in urban centres,New Zealand

High levels of endemism, the sensitivity of species that have evolved without humans, and the invasion of exotic species have all contributed to severe depletion of indigenous biodiversity in New Zealand. We considered the contribution that urban restoration can make to maximising biodiversity by analysing landcover patterns from two national databases along an urban–rural gradient. Thirteen of 20 land environments in New Zealand are represented in cities, and nearly three-quarters of all acutely threatened land environments are represented within 20 km of city cores nationally. Despite this, remaining indigenous landcover is low within urban cores, with less than 2% on average, but increasing to more than 10% on average in the periurban zone. Threatened lowland environments are most commonly represented within cities, and least represented within protected natural areas. Restoration of existing urban habitat is insufficient to halt biodiversity loss. Ecosystem reconstruction is required to achieve a target of 10% indigenous cover within cities. A co-ordinated national urban biodiversity plan to address issues beyond a local and regional focus is needed. Analysis of national patterns of urban land environments, indigenous cover and remnant ecosystems will support action at a regional and local level while enhancing national and global biodiversity goals.     

Towards a theory of the American rural residential land market

Since the late 1960s there has been a notable acceleration in America in the demand for rural residential land within commuting range of urban and suburban employment and service opportunities. American rural residential households do not seem to purchase acreage tracts primarily for their ‘productive’, or resource value, however. Instead, they purchase rural land for its ‘consumptive’ or residential value, as its value is primarily derived from the bundle of residential attributes associated with it. Over time, rural land within commuting range of metropolitan areas becomes underproductive and idled — a situation which precedes urban sprawl. Rural residential development has thus become a focus of debate on the effects and inefficiencies associated with urban sprawl. Yet, not enough is known about the nature of the rural residential land market. It is argued that American rural residential households are different from their suburban and urban counterparts for at least three reasons. First, they are distinguishable for their pursuit of self-sufficiency, self-expression, and the cultural status that a rural residential lifestyle offers. Second, they seek low cost rural jurisdictions in order to afford more housing and land than they could afford in higher cost urban and suburban locations. Third, they value distance from the city center colinearly with externalities such as pollution, crime, overcrowding, and noise associated with central city areas. In the latter sense, American rural residential households value land more highly the farther away it is from the city center, but discount land value the farther away it is from the boundary of urban development. In light of these considerations, this paper (a) reviews the literature describing the motivations of American rural residential households, (b) poses a theory of the American rural residential land market, (c) applies the theory to a case study, and (d) offers implications of the theory to planning efforts aimed at preserving resource land and containing urban sprawl.     

Land-cover fragmentation and configuration of ownership parcels in an exurban landscape

The rate of low-density development beyond the urban and suburban periphery, known as exurban areas, has occurred at a rate faster than both urban and population growth and has the potential to affect water quality, carbon storage, and habitat availability. This paper is aimed at understanding the relationships between the heterogeneity of the human and natural components of the land system and their interactions, through assessment of residential land-cover characteristics and ownership parcels in these poorly understood exurban lands. New data are presented that describe the distribution of land-cover quantities and their degree of fragmentation in three townships in Southeastern Michigan. Analysis of land-cover data, collected from aerial photographs from 1950–2000 and digitized with a 10 m minimum mapping unit, provide an empirical link between lot-size and vegetation. Results show, among other findings, 1) the quantity and pattern of land-cover types significantly differ with parcel size, 2) the degree of difference was greatest between small parcels and all other sizes and least among large parcels, and 3) of five landscape metrics used to evaluate the quantity and fragmentation of land-cover types in residential parcels, the percent of parcel area provided the strongest delineation of differences in land cover among parcel sizes. Capturing quantities and patterns of land-cover at different sizes of land (parcel) ownership provide new data that can be coupled to ecosystem literature and models to link the outcomes of residential land-cover processes with simple ecosystem functions (e.g. carbon storage, albedo). Understanding how residential land-use and management processes collectively create regional land-cover patterns can provide insight into how residential lands might be managed to mitigate the effects of land change on climate.     

GOVERNMENT INTERVENTION,LAND MARKET,AND URBAN DEVELOPMENT: EVIDENCE FROM CHINESE CITIES

This article investigates how government intervention in land market affects China's urban development, using data from prefecture‐level cities between 2000 and 2010. We find that government intervention enlarges the impact of positive productivity shocks on housing price appreciation, through mainly the government control over residential land supply. However, we find no significant evidence that high government intervention constrains population growth and leads to wage increase. Such patterns of urban dynamics can be explained by the fact that migrant workers are the driving force behind China's urbanization, but they have limited housing demand and are not well compensated. (JEL P52, R12, H11)     

Effects of urbanism,race, and class on happiness and physical health

The joint effects of urbanism, race, and socioeconomic status on self reported health and happiness are studied. Relationships of “neighborhood fear” and unemployment with health and happiness are also studied within different urban/rural race‐class categories. It is hypothesized that 1) lower socioeconomic status (SES) blacks residing in central cities will report the poorest health and lowest happiness and 2) “neighborhood fear” and unemployment will be most strongly related to health and happiness among central city lower SES blacks. The sample is pooled data from the 1972–1983 National Opinion Research Center (NORC) General Social Surveys. Findings indicate that urbanism has a modest negative relationship to happiness, but low SES urban blacks are not uniquely low in happiness. Contrary to the central city hypothesis, neighborhood fear is most strongly related to health among suburban blacks with less than high school or high school graduation attainment. A relative deprivation explanation is advanced. Unemployment negatively relates to the happiness of blacks and whites in a variety of urban‐SES‐race categories.     

Mammals in and around suburban yards,and the attraction of chicken coops

Urban areas are an important and growing land use class. Nearly 5 % of the world is covered with urban development and residential yards make up a large proportion of that area. Yards have unique but homogenous biological characteristics and are known to be rich with bird fauna, but little is known about backyard mammals. We used camera traps to sample mammal communities in backyards and urban woodlots in Raleigh-Durham, North Carolina, USA and related species activity to yard characteristics and levels of neighborhood development. We found a vibrant community of smaller herbivores and carnivores using residential yards in urban areas, but larger ungulates and carnivores were only detected on the urban fringe, or in woodlots. Backyard chicken coops were positively correlated with raccoon activity but were not positively correlated with other predators, suggesting that chicken coops are attracting raccoons, but not other predators, to yards. Fenced-in dogs were negatively correlated with most mammals suggesting that confined dogs keep mammals out of yards. Unfenced dogs and fences without dogs, showed a more varied relationship with mammal activity. These results show an encouraging sign of how humans can coexist with wildlife, even in urban areas, and suggest some strategies to minimize conflict regarding backyard chicken coops and dogs.     

THE COURSE OF RESIDENTIAL SEGREGATION: Ethnicity, Socioeconomic Status, and Suburbanization in Israel

As is well documented, today, 40 years after the establishment of statehood, ethnicity figures importantly in determining educational and occupational attainment in Israel. The present study measures residential patterns to examine the relevance of ethnic differences in generating social distance.
Census data on the Jewish population and pairs of ethnic groups depict residential pattern changes in the central city and suburban ring for the largest metropolitan area, Tel Aviv, in 1972 and 1983. Segregation patterns are moderate in the central city, low in the suburban ring; in both localities, moreover, segregation declines during the decade studied. Although ethnicity significantly affects a group's separation, its relative importance declines. With Socioeconomic status, ethnicity, and other intervening variables controlled, Jewish ethnic groups' attainments significantly differ by locale: Suburban residence increases spatial assimilation.     

Does urbanization explain differences in interactions between an insect herbivore and its natural enemies and mutualists?

Urbanization can alter the composition of arthropod communities. However, little is known about how urbanization affects ecological interactions. Using experimental colonies of the black bean aphid Aphis fabae Scopoli reared on Vicia faba L, we asked if patterns of predator-prey, host-parasitoid and ant-aphid mutualisms varied along an urbanization gradient across a large town in southern England. We recorded the presence of naturally occurring predators, parasitoid wasps and mutualistic ants together with aphid abundance. We examined how biotic (green areas and plant richness) and abiotic features (impervious surfaces and distance to town center) affected (1) aphid colony size, (2) the likelihood of finding predators, mutualistic ants and aphid mummies (indicating the presence of parasitoids), and (3) how the interplay among these factors affected patterns of parasitoid attack, predator abundance, mutualistic interactions and aphid abundance. Aphid abundance was best explained by the number of mutualistic ants attending the colonies. Aphid predators responded negatively to both the proportion of impervious surfaces and to the number of mutualistic ants farming the colonies, and positively to aphid population size, whereas parasitized aphids were found in colonies with higher numbers of aphids and ants. The number of mutualistic ants attending was positively associated with aphid colony size and negatively with the number of aphid predators. Our findings suggest that for insect-natural enemy interactions, urbanization may affect some groups, while not influencing others, and that local effects (mutualists, host plant presence) will also be key determinants of how urban ecological communities are formed.     

Growth Management and Agriculture: An Examination of Local Efforts to Manage Growth and Preserve Farmland in Wisconsin Cities,Villages, and Towns*

Abstract In this paper we examine the effectiveness of growth management policies in Wisconsin cities, villages, and towns. Unlike most other studies, we consider the impact of growth management policies on agriculture, specifically the preservation of farmland, in addition to population growth. Our analysis examines these relationships separately in towns and in cities/villages because of differences in their institutional structures. We mailed a survey to every city, village, and town in Wisconsin; the surveys were supplemented by data collected from several secondary sources. For both towns and cities/villages, growth management policies are related positively to the rate of population growth. The fiscal structure of localities proved to have a stronger effect on population growth for cities and villages than for towns. Growth management capacity had little effect for either type of municipality. The analysis of farmland preservation suggests that exclusive agriculture zoning is marginally effective in limiting farmland conversion in towns, but ineffective in cities/villages.     

How small cities affect the biodiversity of ground-dwelling mammals and the relevance of this knowledge in planning urban land expansion in terms of urban wildlife

Fundamental principles regarding urban biodiversity are based on studies conducted in large cities. However we cannot know whether the same phenomena occur in smaller cities or how small cities affect biodiversity. Small cities are an inherent element of urbanization and in the future, most global urban growth is expected to take place in small and medium-sized cities. Understanding the effects of small cities on biodiversity will be an important aspect in planning urban land expansion. Our study examined the effects of a small city on communities of small ground-dwelling mammals on 41 sites arranged in a four step gradient of urbanization. In 6700 trap-days, we caught 2333 individuals comprising 15 species. In the downtown area the same phenomena as those described for large cities were observed: a reduction in species richness and diversity, a decline in the abundance of urban sensitive species and an increase in synurbic species. However, in contrast to large city studies, green areas outside the downtown area did not differ from rural sites in small mammal population parameters. This phenomenon of relatively unchanged fauna outside the downtown area shows that small cities have the potential to maintain a high level of diversity of small ground-dwelling mammals if appropriate planning of further building expansion is implemented. More studies of small cities are needed to better assess their impact on biodiversity. This knowledge can then be applied in better planning for urban wildlife. Generalizations based solely on large city studies are inadequate and may lead to incomplete or inappropriate conservation strategies for small cities.     

City dwelling wild bees: how communal gardens promote species richness

Urban areas consist of wide expanses of impervious surfaces which are known to negatively affect insect biodiversity in general, but green spaces within cities have the potential to provide necessary habitat and foraging resources. Although, communal gardens were primarily intended to provide fresh, regional food to denizens, these green islands also host a surprisingly high number of wild bee species.

The gardens were characterized based on structural elements such as flower frequency, the relative percentage of lawn, trees, shrubs, planted crops and infrastructure (e.g. seating possibilities or garden houses). Further, the effects of different landscape structures surrounding the gardens and distance to the city center were analyzed on the total wild bee species richness and functional traits. Focusing on these putative influencing factors, statistical analyses calculating random decision forests along with generalized linear mixed models were applied. With 113 observed wild bee species, communal gardens provide habitat for a quarter of all known species in Vienna. In conclusion, results revealed that only elements within the gardens had an effect on species richness, with flower frequency as the major positive driver. The examined communal gardens promote and conserve wild bees independent from the location within the city or garden size. Furthermore, these green patches are important sanctuaries, hosting rare and threatened species as well as remarkably special wild bee communities.

     

Racial Segregation,the Concentration of Disadvantage,and Black and White Homicide Victimization

Discriminatory housing market practices have created and reinforced patterns of racial residential segregation throughout the United States. Such segregation has racist consequences too. Residential segregation increases the concentration of disadvantage for blacks but not whites, creating African-American residential environments that heighten social problems including violence within the black population. At the same time, segregation protects white residential environments from these dire consequences. This hypothesized racially inequitable process is tested for one important type of violence—homicide. We examine race-specific models of lethal violence that distinguish residential segregation from the concentration of disadvantage within racial groups. Data are from the Censuses of Population and Federal Bureau of Investigation's homicide incidence files for U.S. large central cities for 1980 and 1990. Our perspective finds support in the empirical analyses. Segregation has an important effect on black but not white killings, with the impact of segregation on African-American homicides explained by concentrated disadvantage.     

NEIGHBORHOOD IMMIGRATION AND NATIVE OUT-MIGRATION

This study combines data from the Panel Study of Income Dynamics with data from four censuses to examine the effects of foreign-born populations in the immediate neighborhood of residence and surrounding neighborhoods on the residential mobility decisions of native-born black and white householders. We find that the likelihood of out-mobility for native householders is significantly and positively associated with the relative size of, and increases in, the immigrant population in the neighborhood. Consistent with theoretical arguments related to the distance dependence of mobility, large concentrations of immigrants in surrounding areas reduce native out-mobility, presumably by reducing the attractiveness of the most likely mobility destinations. A sizable share of local immigration effects can be explained by the mobility-related characteristics of native-born individuals living in immigrant-populated areas, but the racial composition of the neighborhood (for native whites) and local housing market conditions (for native blacks) also are important mediating factors. The implications of these patterns for processes of neighborhood change and broader patterns of residential segregation are discussed.