Scale-dependent habitat relations of birds in riparian corridors in an urbanizing landscape

As the amount of urbanization in the landscape surrounding a riparian zone increases, local riparian vegetation structure and composition change in complex ways. The impact of increasing urbanization on birds in and around riparian zones will depend on their differential sensitivity to local- versus landscape-scale habitat variation. Thus, our principal objective was to determine which spatial scale has a greater association with the distribution of each bird species using riparian corridors in a landscape mosaic comprised of anthropogenic land uses and undeveloped native shrublands in coastal southern California. We surveyed 137 points in riparian vegetation along an urbanization gradient, and used logistic regression and information theory to select best supported models describing the distribution of each of 52 bird species. Models based only on local-scale vegetation variables were best supported for 19 species, whereas landscape-scale (amount of urbanization within a 1000-m radius) models were best supported for 13. Ten species were best described by models combining local- and landscape-scale variables, and 10 had no well-supported models. Within guilds, woodland and riparian-dependent species appeared to respond to local vegetation variables whereas shrubland species appeared more sensitive to landscape context. Likewise, insectivores were more likely to be associated with variation in local-scale variables. In contrast to other studies, Neotropical migrants were not sensitive to increasing urbanization. Provided that local vegetation remains in good condition, our results suggest that riparian bird species may persist even in areas with extensive urbanization.     

Exurban development influences woodland bird composition

One of the fastest growing types of land-use change is exurban development—low-density housing outside urban service boundaries. However, how individual species are responding to exurban development remains uncertain. We monitored birds for 5 years across three housing density levels in northern California oak woodlands. We compared community and species responses to exurban development (4–16 ha parcels) with suburban and undeveloped natural areas. We found that individual species and groups of species exhibited variable responses to exurban development. Some species and guilds were impacted by exurban development to the same extent as suburban development while others were less sensitive to this type of land use. For example, the proportion of the bird community composed of tree-and-shrub feeders was similar between exurban and natural areas, whereas proportions of temperate migrants showed significant reductions at both suburban and exurban sites. Similarly, Northern Flicker, Hutton's Vireo, and Orange-crowned Warbler were equally rare in exurban and suburban sites, making large, undeveloped parcels essential for their conservation. By explicitly measuring ecological changes associated with parcel size and density this research provides valuable information to land-use planners on the consequences of zoning for biodiversity conservation.     

The effects of high-density suburban development on commuter mode choices in Seoul,Korea

This study empirically assesses the effects of high-density suburban development on commuter mode choices in Seoul, Korea. We separated the impacts of densification and new suburban development on mode choice through an examination of interaction effects between population density and the sizes of newly developed suburban areas in logistic regression models. As expected, population and employment densities are positively related to public transit use, while new suburban residential and nonresidential developments are positively related to automobile use. However, the interactive logistic model empirically confirms that a one-unit increase in development density of the new suburban residential increased automobile usage by 27% in 1996 and 17% in 2006 (13% in 1996 and 16% in 2006 for new nonresidential developments), indicating that suburbanization and density are not at odds, but rather are corroborative in encouraging automobile use in the Seoul metropolitan area (SMA). One of the primary explanations for this finding is the strong housing preference for suburban high-rise apartment buildings among SMA residents.     

Seeking density and mix in the suburbs: challenges for mid-sized cities

Examining patterns in suburban density and mix in a mid-sized Canadian city illustrates the challenges of trying to achieve planning targets for urban intensification and mixed use in mid-sized cities with relatively slow rates of growth. A mixed methods study documents trends in Halifax over a 50-year period. Although planning theory and policy often promote growth nodes and corridors, the case study illustrates the ways in which market forces, conflicting regulations, demographic shifts, and local conditions may undermine efforts to increase densities and generate fine-grained mixing of uses and housing types in suburban areas.     

THE SUBURBANIZATION OF DECLINE: FILTERING,NEIGHBORHOODS, AND HOUSING MARKET DYNAMICS

This study explores how the locations and characteristics of neighborhoods affected the process of housing filtering in the Orlando metropolitan area during the 2000s. The results show that racial composition was an important determinant of filtering down and that the foreclosure rate and income composition of neighborhoods became more important factors during the housing market bust period. The filtering process tended to be more affected by neighborhood attributes than by changes in the housing market, especially during the housing market bust period. As the filtering down process was not sensitive to the neighborhood location itself, suburban areas were also susceptible to filtering down processes like inner city areas. Moreover, there was a high probability of suburban decline through filtering down during the housing market bust period. These results may be the reflection of recent trends of central city rebound and suburban decline in the Sun Belt.     

Proximity to source populations and untidy gardens predict occurrence of a small lizard in an urban area

Very little is known about how lizards respond to urbanization. Given their small space requirements, opportunist lizard species can potentially exist in small patches of suitable urban habitat. This study identified the relative importance of landscape and habitat-level factors that influenced the occurrence of an opportunist and generally abundant species, the common skink Oligosoma nigriplantare polychrome in suburban private gardens in New Zealand. Private gardens are potentially important in sustaining urban wildlife as they make up a significant proportion of the total area of many cities. Common skinks were largely absent from the central suburbs and distributed in less highly ordered gardens around the city edge. Skink occurrence was influenced mainly by landscape-level features that reflect opportunities for dispersal into gardens from source populations (distance to city edge; presence of an adjacent grassy paddock) and habitat quality (messiness). To a lesser extent skink occurrence was associated with lower cat densities, less native vegetation and south-facing sites. Within private gardens common skinks were associated with areas with a high proportion of basking surfaces, lower plant species diversity, shorter distances to potential cover, and vegetation that was low in height and made up mainly of long exotic grasses. Despite common skinks’ ability to thrive in exotic vegetation and their small spatial requirements, it is unlikely that they will thrive in urban areas unless gardening practices change to increase resource availability and provide refuges from predators.     

Coal,community, town planning and the management of labour: South Wales,c.1900–1920

The current drive to promote high densities in the planning and construction of new communities should not be allowed to obscure the success of low-density new towns. Both Reston in Northern Virginia, and Milton Keynes, in the county of Buckinghamshire, England, planned during the 1960s, have become popular with their residents: they now live in new towns recognized for their overall low densities and suburban ethos. Yet the original planners of these towns had markedly ‘urban’ intentions in mind. They aimed for compact living clusters within a tamed countryside of parks and open spaces. Local employment parks would also obviate the need for large-scale commuting. These intentions, however, were not fully implemented. This was most clearly evident in relation to housing. The original planners had preferred a vision predominantly characterized by late-modern urban housing styles. However, popular tastes within the housing market led the subsequent managers of Reston and Milton Keynes to more fully embrace traditional-vernacular models of suburban domestic architecture. These styles complemented the wider countrified setting of the new towns. The following discussion demonstrates the gentle paradox that Reston and Milton Keynes, planned as alternatives to suburban sprawl, became rationalized and attractive suburban entities. The comparative approach within the article also proves the undoubted popularity of suburban living in both England and the USA.     

RACIAL AND ETHNIC TRENDS IN THE SUBURBANIZATION OF POVERTY IN U.S. METROPOLITAN AREAS, 1980–2010

This research examines recent trends in the suburbanization of poor non‐Latino Whites, Blacks, and Asians, and Latinos of all races in the United States. The authors find strong associations between a temporally lagged measure of suburban housing supply and poverty suburbanization during the period 2006–2010 for all groups, but these associations are largely attenuated by similarly lagged controls for suburban affordable housing and employment, as well as for other characteristics of metropolitan areas. Findings indicate that poor non‐Latino Whites and Asians have higher suburbanization rates in metropolitan areas with higher levels of suburban employment, while the suburbanization of the Black and Latino poor is more strongly related to the availability of affordable suburban housing. Increases in housing supply are associated with change in poverty suburbanization over time for Whites, Blacks, and Latinos. In addition, increases in affordable rental housing are associated with increases in the suburbanization of the Latino poor.     

Bird communities of the Colorado Rocky Mountains along a gradient of exurban development

Most insights about the effects of residential development on wildlife are based on research from urban and suburban areas. Yet exurban development is an increasingly prevalent form of human settlement in many parts of the world. Moreover because such development often occurs near the periphery of protected areas, it may have a disproportionate influence on native species. We examined bird community patterns in the Rocky Mountains of north-central Colorado across a gradient of exurban development to determine how avifauna responded to this form of settlement. Using fixed-radius point counts, we surveyed the occurrence and abundance of breeding birds in 11 developed sites and in 6 nearby undeveloped sites, all occurring in a forested matrix. We sampled ground-level habitat features at each survey point and derived digital land-cover maps from aerial photographs to characterize and quantify road development and building density. We found little evidence that land-cover varied with development intensity, yet bird abundance increased significantly with building density. Patterns of species richness were equivocal due to a highly influential observation. Principal components analysis (PCA) distinguished two axes that explained nearly 50% of the variation in the bird community and were strongly associated with road and building density. Weighted average analysis showed a marked decline in the abundance and richness of species that were insectivorous or nested in snags, suggesting that reductions in dead wood may have influenced the bird community. However, no conclusions could be drawn because dead wood was confounded with building density. Logistic regression of species occurrence and building density indicated that the incidence of some generalist species increased with building density, whereas the incidence of specialists decreased. Overall, our results suggest that development at low densities can favor habitat generalists. Similar patterns have been observed in more urbanized areas. If exurban development persists as a popular form of settlement in the Rocky Mountains, a regional plan for protecting avian habitat and limiting development dispersion will be necessary to maintain native bird communities.     

Housing density as an indicator of spatial patterns of reported human–wildlife interactions in Northern New York

Compromises in biodiversity and biotic integrity from human development alter native wildlife communities. Anecdotal evidence suggests that increases in residential development contribute to increases in human–wildlife interactions; however, little empirical research has addressed this issue. We tested whether housing density could be used to indicate patterns of reported human–wildlife interactions in Northern New York. We used a novel application of univariate and bivariate K-functions to assess the spatial relationship of reported human–wildlife interactions along a gradient of housing densities. We found that reported human–wildlife interactions are not completely spatially random in Northern New York State and the reports tend to cluster more in areas dominated by suburban and exurban housing densities compared to areas with urban or wildland housing densities. Low-density developments have unintended ecological consequences including an increase in reported human–wildlife interactions. Further work is needed to determine specific reasons for clustering of reported human–wildlife interactions in suburban and exurban areas. However, planners should consider human–wildlife interactions as a potential negative outcome of low-density development and devise development designs, such as clustering, to reduce future human–wildlife conflicts.     

Biotic homogenization and alien bird species along an urban gradient in South Africa

Similar to the process seen in invasion biology, urbanized environments lead to biotic homogenization with a few species, often alien, dominating the urban habitat. We investigated avian communities across an urban gradient in Pretoria (South Africa). We defined three urbanization zones: urban, suburban and semi-natural, based on land-cover. We conducted point counts of all species at each of 13 sites in these zones over a 4-month period. We found significantly more species in the semi-natural zone than the urban zone but abundance was significantly lower in semi-natural than urban. The increase in abundance was mainly as a result of alien species with the three most abundant species in the urban zone being all alien. Semi-natural contained fewer alien species than urban and significantly fewer than suburban. The Common Myna Acridotheres tristis was the only alien species that was observed in all three urbanization zones and was the second most abundant species in the suburban and urban zones. Our study supports the process of biotic homogenization, where an increase in alien species occurs in the urban compared to semi-natural zone. Although the suburban zone made an important contribution towards native bird abundance in a larger city environment, this environment was also an important environment for alien species, especially for the Common Myna.     

Neighborhood Affordability and Housing Market Resilience

Problem, research strategy, and findings: Although many researchers have examined factors associated with vulnerability to foreclosure, few have investigated the role neighborhood affordability plays in foreclosures in metropolitan areas. In this study, we examine the effects of location affordability (i.e., housing and transportation affordability combined) on resilience to foreclosure in more than 300?U.S. metropolitan areas during the U.S. housing recovery period. Using hierarchical linear regression with changes in zip code–level home foreclosure rates, our findings suggest the relationship between affordability and foreclosure resilience varies according to urban form (central/high-density city versus suburban low-density area) and types of metropolitan housing markets (boom–bust versus strong versus weak). In the national analysis, where location affordability was high, home foreclosure rates dropped substantially in central/high-density areas but not in suburban low-density areas. When we disaggregated the zip codes according to the market type, location affordability contributed to recovery in central cities in strong and weak metros and in the suburbs of boom–bust metros. There was no positive association in the suburbs of strong and weak metros. With improved data, future studies could measure an association between affordability and lower income renter households.

Takeaway for practice: Our study of the affordability crisis that followed the foreclosure crisis shows that planners can foster resilient and affordable housing markets by expanding and densifying affordable neighborhood locations and considering interactions between the costs of housing and transportation. Planners can improve neighborhood affordability with local and regional strategies based on the local residential density and the type of metropolitan housing market.     

Untapped density: site design and the proliferation of suburban multifamily housing

Suburban multifamily housing is an often overlooked housing typology that is the fastest growing housing market in the United States and holds strong potential for achieving smart growth goals in suburbia. This paper focuses on understanding the roots of suburban multifamily site design and development. Through case studies of suburban multifamily development in Oregon, Arizona, Florida, and Massachusetts, this paper looks at the specific ways in which regulation, typical development practice, and design culture have shaped the current pattern of suburban multifamily development. It then proposes ways in which current planning, development, and design practices might shift in order to take advantage of this growing housing trend to create multi‐modal, more livable, and less congested suburban communities.     

Nature reserve selection on forest fragments in a suburban landscape (Rome, Central Italy): indications from a set of avian species

A set of avian forest species, known from the literature as fragmentation-sensitive, was considered as the target in nature reserve planning following a conceptual framework. Their abundance was investigated in an 'archipelago' of oak woodland fragments embedded in a suburban landscape matrix of central Italy. None of the four species were found in any wood fragment smaller than 10 ha. The presence/absence analysis of woodland fragments studied showed that the study species were present, however, in larger fragments, highlighting the strategic role of habitat size and isolation for the persistence of these species at local scale. Species numbers and their total abundance were significantly and directly correlated to overall species richness of each fragment: in this landscape context our study species shows characteristics of serving as focus and surrogate species of bird richness. The selected species are area-sensitive and poor dispersers: however, they are still relatively widespread, at a regional scale. Although the abundance of individual species may be affected by stochastic factors, total abundance of this forest bird guild may constitute a useful dependent variable that can provide rapid quantitative data needed for planning strategies at local scales.     

Do landscape factors affect brownfield carabid assemblages?

The carabid fauna of 28 derelict sites in the West Midlands (England) were sampled over the course of one growing season (April-October, 1999). The study aimed to investigate the relationship between carabid assemblages and five measures of landscape structure pertinent to derelict habitat. At each site measurements of landscape features pertinent to derelict habitat were made: (i) the proximity of habitat corridors; (ii) the density of surrounding derelict land; (iii) the distance between the site and the rural fringe; and (iv) the size of the site. Concurrent surveys of the soil characteristics, vegetation type, and land use history were conducted. The data were analysed using a combination of ordination (DCA, RDA), variance partitioning (using pRDA) and binary linear regression. The results suggest that: 1. There is very little evidence that the carabid assemblages of derelict sites were affected by landscape structure, with assemblages instead being principally related to within-site habitat variables, such as site age (since last disturbance), substrate type and vegetation community. 2. No evidence was found to support the hypothesis that sites away from railway corridors are impoverished in their carabid fauna than sites on corridors. 3. There are some suggestions from this study that rarer and non-flying specialist species may be affected by isolation, taking longer to reach sites. We infer from this that older sites with retarded succession, and sites in higher densities of surrounding derelict land may eventually become more species rich and that these sites may be important for maintaining populations of rarer and flightless species. 4. Conservation efforts to maintain populations of these species should focus principally on habitat quality issues, such as maintaining early successional habitats that have a diversity of seed producing annuals and perennial plants and enhancing substrate variability rather than landscape issues.     

The successes and failures of a key transportation link: accessibility effects of Taiwan’s high-speed rail

Taiwan does not only have a high population density; its population exhibits a strong preference for high-density downtown living. Rich Taiwanese thus live downtown, not in the suburbs. In addition, the expected negative relationship between accessibility and the spaciousness of housing is weak or non-existent in Taiwan’s metropolitan areas. Taiwan should therefore be highly suited to rail transportation investments. In 2007, a new high-speed railroad was inaugurated, connecting seven metropolitan areas. Hedonic estimates show that high-speed rail accessibility has a substantial impact on house prices in at least four of the regions. Interregional downtown-to-downtown commuting time seems to be the most important determinant of success in generating a station-centered price-distance gradient. Neighborhoods around HSR stations in suburban locations are not likely to spawn residential communities for commuters, since most Taiwanese prefer downtown residential locations.     

Biodiversity relationships in urban and suburban parks in Flanders

Urban and suburban parks can play an important role in the conservation of biodiversity, especially in a strongly urbanised region like Flanders (Belgium). A previously developed method for monitoring biodiversity was applied to 15 parks in Flanders. This method took both habitat and species diversity into account and resulted in 13 biodiversity indicators. The results show that urban and suburban parks can have a high species richness, especially if they consist of different more or less semi-natural habitats. The relationships between the biodiversity indicators and the ecological factors affecting the biodiversity were examined using multivariate analyses and correlation techniques. Park area was the main factor explaining the variation in biodiversity indicators, so larger parks could contribute more to the conservation of biodiversity than small ones. A biodiversity score based on habitat diversity and species richness was proposed to summarise and evaluate the biodiversity. This score is not correlated with the park area and is therefore considered as a reliable indicator for comparing biodiversity in parks of different area.     

If You Build Rail Transit in Suburbs,Will Development Come?

Problem, research strategy, and findings: There is little consensus about the effects of rail transit on residential development, especially in suburbs, despite high expectations. I revisit this issue by examining a “best case”: I test the impacts of rail transit on housing development around suburban rail stations in Portland (OR), a region with multiple supportive transit-oriented development policies. I conducted longitudinal analyses of housing development in quarter-mile catchment areas around 57 suburban rail transit stations in suburban Portland from 2004 to 2014, a longer time period than many previous studies, evaluating factors that helped station areas attract residential development. Housing developments, most multifamily, grew much faster in the quarter-mile catchment areas around suburban stations put into service in or before 2004 than the regional average. Areas around stations opened after 2004 have few residential developments. More residential development is associated with higher system ridership, more vacant land zoned for residential and mixed-use purposes, greater shares of nonresidential land, and higher shares of the White population. Faster density increases were associated with more vacant land zoned for high-density and mixed-use purposes.

Takeaway for practice: Rail systems may need to be in operation longer to affect land use than the study periods in some previous research. Rail transit can guide suburban residential development in neighborhoods with enough vacant land, some nonresidential destinations, and appropriate zoning. Multiple supportive public policies and incentives appear to have a major impact, but may not be effective alone unless these preconditions are met.