Amy L. Nelson

Socioeconomics drive urban plant diversity

Spatial variation in plant diversity has been attributed to heterogeneity in resource availability for many ecosystems. However, urbanization has resulted in entire landscapes that are now occupied by plant communities wholly created by humans, in which diversity may reflect social, economic, and cultural influences in addition to those recognized by traditional ecological theory. Here we use data from a probability-based survey to explore the variation in plant diversity across a large metropolitan area using spatial statistical analyses that incorporate biotic, abiotic, and human variables. Our prediction for the city was that land use, along with distance from urban center, would replace the dominantly geomorphic controls on spatial variation in plant diversity in the surrounding undeveloped Sonoran desert. However, in addition to elevation and current and former land use, family income and housing age best explained the observed variation in plant diversity across the city. We conclude that a functional relationship, which we term the “luxury effect,” may link human resource abundance (wealth) and plant diversity in urban ecosystems. This connection may be influenced by education, institutional control, and culture, and merits further study.

Urbanization and warming of Phoenix (Arizona, USA): Impacts, feedbacks and mitigation

This paper examines the impacts, feedbacks, and mitigation of the urban heat island in Phoenix, Arizona (USA). At Sky Harbor Airport, urbanization has increased the nighttime minimum temperature by 5°C and the average daily temperatures by 3.1°C. Urban warming has increased the number of “misery hours per day” for humans, which may have important social consequences. Other impacts include (1) increased energy consumption for heating and cooling of buildings, (2) increased heat stress (but decreased cold stress) for plants, (3) reduced quality of cotton fiber and reduced dairy production on the urban fringe, and (4) a broadening of the seasonal thermal window for arthropods. Climate feedback loops associated with evapotranspiration, energy production and consumption associated with increased air conditioning demand, and land conversion are discussed. Urban planning and design policy could be redesigned to mitigate urban warming, and several cities in the region are incorporating concerns regarding urban warming into planning codes and practices. The issue is timely and important, because most of the worlds human population growth over the next 30 years will occur in cities in warm climates.

Bonding and Bridging Understanding the Relationship between Social Capital and Civic Action

This study investigates the relationship between social connections and collective civic action. Measuring social capital in eight Phoenix, Arizona, neighborhoods allowed the authors to determine that individuals with strong social bonding (i.e., association and trust among neighbors) are more likely to take civic action. However, while social capital lessens the relationship between an individual’s social status and the likelihood of taking action, it does not eliminate the positive relationship. The analysis also suggests that bonding and bridging are distinct forms of social capital that have some different antecedents

The Ecology of Technological Risk in a Sunbelt City

In this paper we examine the spatial distributions of four types of technological hazards in the Phoenix, Arizona, metropolitan area. The focus is on the locations of hazardous industrial and toxic waste sites in relation to the demographic composition of adjacent neighborhoods. Our interest is to determine whether hazardous sites, including industrial facilities in the EPAs Toxic Release Inventory, Large Quantity Generators of hazardous wastes, Treatment, Storage, and Disposal Facilities, and federally identified contamination sites, are disproportionately located in areas with lower income and minority residents. We examine patterns of environmental inequity in Phoenix, a sprawling Sunbelt city with a growing post-Fordist industrial sector. First, using 1996 EPA data for four types of technological hazards, and 1995 Special Census data for Maricopa County, we employ a GIS to map the spatial distributions of hazardous sites and to analyze the demographic characteristics of census tracts with and without point-source hazards. A second methodology is used to produce a cumulative hazard density index for census tracts, based on the number of hazard zones—one-mile-radius circles around each facility—that overlay each tract. Both methodologies disclose clear patterns of social inequities in the distribution of technological hazards. The cumulative hazard density index provides a spatially sensitive methodology that reveals the disproportionate distribution of risk burdens in urban census tracts. The findings point to a consistent pattern of environmental injustice by class and race across a range of technological hazards in the Phoenix metropolitan region.

Modeling urbanism: Economic, social and environmental stress in cities

The time has come for urban social indicator research to converge with the basic substantive efforts of urban researchers. Such a convergence may propel both basic and applied researchers toward more fruitful outcomes. This paper argues that the traditional model of urbanism provides the medium for the convergence. When urbanism is conceptualized to be multidimensional, seemingly discreet indicators of demographic, economic, social, and environmental conditions in cities may be incorporated into a more general model of urban structure and change. Specifically, using social indicators for 195 cities from ZPGs Childrens Stress Index and the 1990 U.S. Census, we show empirically: (1) Urbanism is a complex factor with four distinct dimensions: demographic scale, economic stress, social stress, and environmental stress. (2) These four dimensions of urbanism may be reliably measured with standard composite variables used in todays social indicator research. (3) Within the Urbanism factor there are causal connections among the separate dimensions, the most basic of which is that asserted by arguments from the traditional theory of urbanism; specifically, that population size, density, and social heterogeneity are causally linked to stress in economic, social, and environmental systems of the city.

Examining the Significance of Housing Enclaves in the Metropolitan United States of America

A significant number of Americans now live in housing that is marked by walls and in many instances by gates. While an increasing amount is written on these enclaves, relatively little research has been done on the developments themselves, the Home Owner Associations (HOAs) that run them, or their residents. This paper draws on the American Housing Survey and the Phoenix Area Social Survey to present demographic information on the housing and to indicate some of the attitudes of these homeowners. The data are used to question some popular conceptions concerning both gated communities and common interest neighborhoods, especially those relating to issues of fear and security, and to the functioning of the HOA. It is argued that it is important to continue the process of empirical research as these phenomena diffuse globally and are the focus of speculation, comment and policy development.

The Effect of Economic Restructuring on Family Poverty in the Industrial Heartland, 1970–1990

Abstract This study examines changes in family poverty in Ohio cities, suburbs and nonmetropolitan counties at the hands of economic restructuring for the periods 1970–1980 and 1980–1990. The restructuring process involves both a loss of manufacturing jobs and an increasing reliance on the service industry for employment. As such, restructuring is conceptualized as a major transformation that is disruptive to the social system, at least in the short run. It is hypothesized that loss of manufacturing jobs increases family poverty, that central city location is associated with greater poverty in comparison to suburbs and nonmetropolitan counties and that gains in service sector employment alleviate family poverty. Results support the manufacturing and location hypotheses. However, the analysis demonstrates that in the later period, increases in service industry employment increased family poverty.