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.     

Erklärt die Rational Choice Theorie die Ungleichheit der Bildungschancen?

There are several plausible arguments which make it obvious to apply Rational Choice Theory to the process of educational opportunities and equality. Looking more closely at an empirical application or RC theory, several serious problems emerge: They concern the operationalization of the variables, the explanatory power of the central variables related to Subjective Expected Utility, the systematic omission of important variables relating to individual persons and their identity, and to social structural and institutional factors; the latter seem to be much more important than those indicated by RC approaches.     

Gender,Race/Ethnicity,and Deviant Drinking: A Longitudinal Application of Social Structure and Social Learning Theory

Aker's (1998) theory of social structure and social learning (SSSL) argues that structural variations in deviant behavior, such as gender or race/ethnic differences in underage or heavy drinking, are mediated by social learning variables. However, longitudinal analyses of deviant drinking in an urban sample of white, black, and Hispanic adolescents fail to support the SSSL mediation hypothesis. Significant gender and race/ethnic differences persist after controls for social learning variables as well as for social bonding variables. Interaction effects involving two social bonding variables—family attachment and moral belief—point to theoretically important conditions that maintain a gender gap in underage drinking and relatively low levels of deviant drinking among African American adolescents.     

Rural population density: its impact on social and demographic aspects of rural communities

Using the settled areas of South Australia as a case study, this paper seeks to demonstrate the specific importance of rural population and settlement density as an important variable in understanding the social, population and settlement geography of sparsely settled rural regions, where sparse and falling density presents both practical and conceptual problems for rural planners. After a review of the literature on population density, the case is argued for the use of net rural rather than gross density in the analysis of settlement patterns. The paper then tests a series of hypotheses on the empirical relationship between rural density as independent variable and selected demographic and socio-economic indicators as dependent variables, at two specific points in time. For the same region, points in time and set of indicators, it goes on to compare the predictive power of rural density as an independent variable with that of three other important qualities of rural settlement patterns (remoteness, settlement size and urban concentration). Rural density is found to be a significant explanatory variable, both in its own right and in comparison with the three other variables tested. In conclusion, the findings are related to policy development measures for rural Australia.     

Suicide in Rural Areas: The Case of Japan 1960–19801

Abstract Rural suicide rates are higher than urban suicide rates in industrialized Japan in contrast to the traditional pattern of higher urban suicide rates found in the West. The pattern is attributed to areal differences in social disintegration. This explanation is operationalized for Japan and tested empirically using data (1979–1981) on 47 prefectures. Higher suicide rates are observed in areas with a sparse population, a stagnant economy, and a population over-represented by elderly people. The explanatory power of the structural variables in the present study is also tested for each decade since 1960. These variables are found to be increasingly effective in predicting suicide rates as industrialization proceeds. Variation in social integration, rather than the degree of industrialization and urbanization, is the key to understanding the differentials in suicide rates.     

Bird responses to housing development in intensively managed agricultural landscapes

Housing a growing human population is a global issue and designing environmentally friendly developments requires identifying the species likely to be negatively impacted and finding mitigation solutions. Existing studies that consider fragmentation of natural habitats have limited application in countries such as Britain where a prime target for development is agricultural land where decades of intensive management have already diminished biodiversity. Here I used citizen science data on the abundance of 146 breeding and wintering birds to develop models linking abundance to human population density and habitat features. I used these as a proxy for the urbanisation process, finding that impacts of urbanisation were species-specific and context dependent. Low-density developments benefited a high proportion of birds, with wetland birds benefitting most and farmland birds least, but as human densities increased further, up to 75% of species were negatively impacted. Almost half of species currently occurring at 14 flagship residential development sites were predicted to decline based on projected human population density increases, with a third predicted to increase. Presence of wetlands, canopy cover and patches of trees all benefited certain species but efforts to identify more detailed habitat associations were hampered by collinearity among variables. I conclude that even in heavily degraded agricultural landscapes, a high proportion of species will be negatively impacted by residential development and that some will require spared land to persist in the wider landscape. As no single habitat benefited the entire bird community, urban planners wishing to design bird-friendly developments will need to make difficult decisions over which aspects of the bird community to prioritise.

     

Spatial disintegration and arable land security in Egypt: A study of small- and moderate-sized urban areas

While commonly associated with regional ‘mega-cities’, rapid urbanization in the less-developed world has also begun to define growth in small- and moderate-sized settlements on the periphery of major metropolitan areas. The dispersal of population growth to these smaller areas holds significant implications for environmental, economic, and social health, and threatens local food security, increases congestions, and induces difficulty in service provision. This study examines the effects of spatial disintegration and rapid urbanization in the stock of arable land in Egypt. To assess this issue, the study will meet three objectives. First, we evaluate the relationship between population growth and urban land cover expansion in small- and moderate-sized settlements in Egypt. Second, we consider the role of selected geographic determinants in influencing the growth of these areas through the use of a regression model. The selection of an appropriate model type is a sub-objective and will be discussed further. Third, these drivers of growth will be assessed through their effects on the country’s stock of arable land. These objectives will be met through the development and application of the regression models, in order to examine the relationship between urban land expansion and several independent variables. An increase in population is found to have a positive and statistically significant effect on corresponding urban land cover area. Surprisingly, the variables commonly associated with urbanization in Egypt - proximity to major roads, the capital of Cairo, and the Nile River - though exhibiting a positive relationship with urban growth, are not statistically significant in the selected case studies. This research underlines the necessity for a combined approach to policy formation - with input from policy fields as varied as agriculture, urban planning, and land reclamation - to slow outward growth and maintain arable land stocks.     

Effects of Rural and Urban Population Dynamics and National Development on Deforestation in Less‐Developed Countries, 1990–2000*

While prior research and theorization establish connections between population growth and environmental degradation, there is a relative paucity of research on what particular aspects of population dynamics are most closely associated with specific types of degradation. Considering all less‐developed countries for which data are available, using Ordinary Least Square (OLS) regression we generate quantitative, cross‐national models for rates of deforestation in the last decade of the twentieth century. The opposite effects of rural and urban population dynamics are of particular concern. While both influence deforestation rates, the effects of rural population change tend to be more profound and more robust. We discuss these findings in light of theoretical work about circular migration and rural encroachment. In addition, we examine the impact of economic development on deforestation while controlling for political and social welfare variables. Findings suggest a trend toward rapidly increasing rates of deforestation in the least‐developed countries. We conclude with a discussion of how rural–urban population dynamics, in combination with other aspects of national development, affect the natural environment, particularly in light of an increasingly interconnected world economy.     

Examination of the relationship between urban form and urban eco-efficiency in china

The present study aims at exploring whether aspects of urban form are associated with urban eco-efficiency in China. Quantitative indicators relating to urban form (form, compactness ratio, elongation ratio and population density) and urban eco-efficiency (resource efficiency, environmental efficiency and overall eco-efficiency) were selected and quantified using remote sensing and data envelopment analysis methods. The urban form aspects of form and compactness ratios were positively correlated with urban eco-efficiency and resource efficiency. Conversely, the urban elongation ratio exhibited negative correlations with urban eco-efficiency and resource efficiency. Regarding environmental efficiency, no significant correlation is found with compactness though a negative correlation is found with population density. These results indicate that, within China, designing cities to be compact may be lead to increases in eco-efficiency and resource efficiency, but if the population density is too high the increased pollution costs will result in a decrease in environmental efficiency.     

Perceived density, social interaction and morale in New South Wales rural communities

This paper explores the relationships between population density, social interaction patterns, and morale in rural communities. It tests two apparently competing hypotheses concerning rural population density, social interaction patterns and overall levels of morale: one, that low (and rapidly declining) rural densities lead to feelings of isolation and low morale in response to contractions in local social interaction networks; or two, that communities facing the demographic scenario just provided might provide more social space for individuals to assume leadership roles, thereby developing their self-confidence. This situation could be expected to produce higher levels of morale and satisfaction with community life. Drawing upon quantitative and qualitative survey research conducted within the social catchment areas of three contrasting rural New South Wales (Australia) communities, the paper finds that some of the key hypotheses of ‘manning theory’ are confirmed: declining population densities can open up space for previously less self-confident individuals to assume important public roles. However, while overall levels of community morale are high across all three communities, regardless of population density, there is also obvious dissatisfaction in the community of greatest density decline with the declining local educational and economic opportunities, and the increasingly concentrated burden of community responsibility. This suggests that rate of change in actual measured density, and in perceived density, may be more influential than the level of density in affecting community morale.     

People or place? An exploration of social and ecological drivers of urban forest species composition

Urban forests have garnered increasing attention as providers of an array of beneficial ecosystem services. However, urban forest ecosystems are highly complex and heterogeneous systems whose structure are shaped by interacting social and ecological processes. Approaches to reliably identify and differentiate these processes could be valuable for addressing complexity and reducing uncertainty in decision-making in urban forestry. The purpose of this study is to identify and quantify a range of social and ecological drivers of urban forest species composition, distribution, and diversity. This was done using hierarchical cluster analysis and discriminant analysis with empirical plot data describing the tree species composition in Toronto, Canada. Tree density and imperviousness were by far the most influential drivers of species composition. Increasing imperviousness saw not just reduced tree density but a decline in native species abundance. Additionally, single-detached housing, homeownership, and income were closely associated and explained higher tree densities and abundances of native species. However, income had a lower than expected influence on urban forest species composition given its importance in canopy cover research. Continuous forest patches were highly distinct compared to the remainder of the urban landscape, which highlights the ecological distinctiveness of residual forests within cities and lends support to their conservation. Increasing the understanding of social and ecological drivers of tree species composition, distribution, and diversity within cities is an integral part of urban forest ecosystem classification, which can be a valuable decision-support tool for ecosystem-based management in urban forestry.     

The Myth of the Independent Variable: Reconceptualizing Class,Gender, Race,and Age as Subcultural Processes

Although social class, religion, gender, ethnicity and age are often treated as independent variables (e.g., factors, forces, structures) and invoked as causal explanations for various outcomes, this paper approaches these constructs in more distinctive, humanly-engaged terms. Rather than representing forces that almost mysteriously impose themselves on people, these constructs are to be understood more fundamentally as the products and processes of human group life. We are not denying the linkages of social categories with other aspects of community life but contend that these correlates represent comparatively superficial reflections of the much broader underlying sets of processes that characterize social life. Indeed, we argue that it is these sets of humanly engaged social processes rather than correlational research that constitute the more authentic subject matter of the social sciences.     

Exposure to Community Violence,Suicidality, and Psychological Distress Among African American and Latino Youths: Findings From the CDC Youth Violence Survey

The present investigation explored risk and protective factors for suicidal ideation and behavior in a sub-sample of African American and Latino adolescents (n = 2,626) who participated in the 2004 Centers for Disease Control Youth Violence Survey. Structural equation modeling was used to explore exposure to violence at the community level as a contextual factor that could potentially influence depressive symptomatology, substance abuse, parental support, social support, and suicidality among study participants. Findings indicated that exposure to violence at the community level was not directly related to suicidality among this population of urban adolescents. However, it was directly related with several other variables under study in the model, which in turn were directly related with suicidality. Tests of invariance revealed several across-group differences, particularly by race and gender, in how the identified risk and protective factors in the model related to suicidality. Implications for research and practice with urban, ethnic minority, adolescent populations are discussed.     

Untangling Fear of Crime: A Multi-theoretical Approach to Examining the Causes of Crime-Specific Fear

Fear of crime has been a major research topic over the past several decades. However, multiple explanations have been proposed and no comprehensive theoretical model exists. In this study, we assess the predictive power of three theoretical models—vulnerability, disorder, and social integration—on offense type-specific, emotionally-based fear of violent and property crime. Results suggest that the predictors of fear of property and violent crime vary, and some theoretical models are a better explanation of one type of fear than the other. Overall, the models are a better fit with fear of violent crime than fear of property crime. The vulnerability model is more strongly related to fear of property crime, while the social integration model is more strongly related to fear of violent crime. Implications and suggestions for future research are discussed.     

Worldviews or Social Groups as the Source of Moral Value Attitudes: Implications for the Culture Wars Thesis

Individual moral value attitudes are typically explained by reference to social experiences as indicated by social group variables. Contrary to this view, the emergent culture wars perspective claims that two worldviews that transcend social groups are ultimately and fundamentally responsible for moral value attitudes. Although this relationship has been claimed for the general population, it has not been investigated with national representative data. This paper contrasts the worldview and social group explanations by examining the relative importance of the worldviews implicated in the culture wars literature and the social groups found to be important in previous research. I find social groups to be more important than worldviews, but that worldviews also have explanatory power. I conclude with a discussion about possible clarifications of the culture wars thesis.     

Environmental and social predictors of phosphorus in urban streams on the Island of Montréal,Québec

Researchers have identified the importance of social characteristics for understanding ecological patterns in cities but the use of these characteristics in urban stream research has yet to be fully explored. Urban development is currently the second-largest cause of stream impairment in North America due in part to nutrient loading. However, research into factors that influence nutrient concentrations in urban streams is lacking. We sampled seven streams on the island of Montréal daily to measure phosphorus (P) concentration and P flux in each stream. We then compared stream P concentration and flux to several watershed characteristics commonly used to predict stream nutrients (e.g., watershed imperviousness, land use, existence of a riparian buffer) as well as several socio-economic characteristics of the watersheds (e.g., average home value, median household income). Overall, impervious surface cover and measures of land use were most effective at explaining the variation in P concentration and P flux in streams on the island of Montréal, while the riparian buffer and socio-economic variables were less effective. However, dollars spent on fertilizer per hectare of residential land and percent residential land use became important predictors of stream P concentration when impervious surface cover was removed from the regression model. This suggests that after accounting for the impact of physical watershed characteristics, social factors may be important predictors of urban stream P concentration. The results of our study suggest that more research is needed to determine the role that socio-economic variables play with respect to urban stream P.     

The interaction of size and density with graph-level indices

The size and density of graphs interact powerfully and subtly with other graph-level indices (GLIs), thereby complicating their interpretation. Here we examine these interactions by plotting changes in the distributions of several popular graph measures across graphs of varying sizes and densities. We provide a generalized framework for hypothesis testing as a means of controlling for size and density effects, and apply this method to several well-known sets of social network data; implications of our findings for methodology and substantive theory are discussed.     

Planning for community: understanding diversity in resident experiences and expectations of social connections in a new urban fringe housing estate,Australia

Master-planned estates are a major source of new housing for growing cities. Much research finds these residential developments lack genuine social connections between residents despite marketing of ‘close-knit’ community. Selandra Rise is a new residential development on the urban fringe of Melbourne, Australia. The estate was planned with a focus on community infrastructure and resident well-being. The resident population was younger and more culturally diverse than most other master-planned community case studies. A longitudinal research design was used to explore resident understanding, experiences and needs relating to place-based community. Interviews were conducted with residents before moving to the estate and 9–18 months after moving. Some residents considered community as an amenity provided by the master-planned environment that did not require their social participation. Others aspired to make social connections with neighbours but had varying levels of success. Past experiences which contributed to aspirations for connecting with local community, and the ways that these aims were realised or hindered, are discussed. Understanding diverse resident expectations of community and insights from their lived experience are used to make recommendations for planning new neighbourhoods and designing community development programmes.     

The Intergenerational Transmission of Social Capital: A Developmental Approach to Adolescent Social Capital Formation*

Previous scholarship has demonstrated the importance of individual characteristics and structural context for understanding social capital formation. However, a developmental approach to social capital formation has, so far, been absent. In this study, I argue that social capital formation must be understood intergenerationally as well as structurally. Using hierarchical linear modeling, I investigate the hypothesized intergenerational transmission of social capital using Waves 1 and 2 of the National Longitudinal Study of Adolescent Health. The results show that, in addition to individual characteristics, neighborhood‐level factors, and school‐level variables, parental social capital is an important predictor of adolescent social capital. This study also suggests that the intergenerational transmission of social capital functions, in part, through family structure and that structural differences account for only a relatively small share of the variation in adolescent social capital. Potential explanations for these findings are discussed.     

Restoring complex vegetation in urban settings: The case of tidal freshwater marshes

Tidal freshwater marshes have diverse plant communities that vary spatially and temporally due to hydrology, animal activity, and other factors. Development of urban centers along rivers of the U.S. Atlantic coast has reduced the historic extent and quality of these and other coastal wetlands. Because the vegetation of these wetlands is more complex than that of salt and brackish marshes (where restoration of vegetation typical of natural systems has sometimes been successful), restoration of tidal freshwater marsh vegetation is likely to be more difficult, particularly in urban areas. Watershed urbanization alters hydrology, sediment load, propagule availability and composition, nutrient status, and other variables that together create an environment different from that of wetlands in less developed areas, possibly precluding restoration of typical marsh vegetation. Tidal freshwater wetlands were historically extensive along the Anacostia River in Washington, DC, but most of these were lost due to filling, dredging, or hydrologic alteration. Over the last decade, the U.S. Army Corps of Engineers has implemented projects designed to restore tidal freshwater wetlands along the Anacostia, which involved increasing elevation with dredged river sediment and planting native vegetation. To illustrate some of the mechanisms affecting vegetation development in restored tidal freshwater marshes in urban areas, I present a case study on one of these wetlands, Kingman Marsh, that also includes research at another restored wetland and two natural reference sites. Studies by my research groups indicate that the restored wetlands undergo essentially a planting-modified process of primary succession. Low densities of seeds are initially present in the substrate, and prolific seed dispersal into the restored sites results in high initial plant diversity comprised of plantings and ruderal (i.e. weedy) natives and exotics. Seed banks develop rapidly at the restored sites, probably due to colonization and early reproduction by ruderal species. Hydrology and disturbance by non-native animals (including resident Canada goose) are important variables controlling establishment of vegetation in these systems. Recent literature and the case study indicate that the environmental conditions of urban settings impose constraints in restored wetlands that result in plant communities more like those of urban natural wetlands than those of wetlands in less urbanized watersheds. This suggests that rather than design wetland restoration projects with the goal of creating pristine wetland vegetation, restorationists must identify, accept, and if possible capitalize on the ecological constraints of the urban environment in setting achievable and desirable restoration goals.