Ecological consequences of fragmentation and deforestation in an urban landscape: a case study

Landscape change is an ongoing process even within established urban landscapes. Yet, analyses of fragmentation and deforestation have focused primarily on the conversion of non-urban to urban landscapes in rural landscapes and ignored urban landscapes. To determine the ecological effects of continued urbanization in urban landscapes, tree-covered patches were mapped in the Gwynns Falls watershed (17158.6?ha) in Maryland for 1994 and 1999 to document fragmentation, deforestation, and reforestation. The watershed was divided into lower (urban core), middle (older suburbs), and upper (recent suburbs) subsections. Over the entire watershed a net of 264.5 of 4855.5?ha of tree-covered patches were converted to urban land use??125 new tree-covered patches were added through fragmentation, 4 were added through reforestation, 43 were lost through deforestation, and 7 were combined with an adjacent patch. In addition, 180 patches were reduced in size. In the urban core, deforestation continued with conversion to commercial land use. Because of the lack of vegetation, commercial land uses are problematic for both species conservation and derived ecosystem benefits. In the lower subsection, shape complexity increased for tree-covered patches less than 10?ha. Changes in shape resulted from canopy expansion, planted materials, and reforestation of vacant sites. In the middle and upper subsections, the shape index value for tree-covered patches decreased, indicating simplification. Density analyses of the subsections showed no change with respect to patch densities but pointed out the importance of small patches (??5?ha) as ??stepping stone?? to link large patches (e.g., >100?ha). Using an urban forest effect model, we estimated, for the entire watershed, total carbon loss and pollution removal, from 1994 to 1999, to be 14,235,889.2?kg and 13,011.4?kg, respectively due to urban land-use conversions.     

Sustaining urban development through participation: an Ethiopian case study

Under the Mengistu regime, Addis Ababa was divided into six zones, 28 woredas, and 303 kebeles, the kebeles being the smallest grassroots administrative unit. To enhance community participation, the Kebele 29 Project promoted the establishment of grassroots community groups by dividing the kebele into four zones and 37 neighborhoods. Each neighborhood is represented by a chairperson and a deputy who take responsibility for reviewing the priority needs of households, relaying information between the project and the community, and following up the project interventions. The author considers the sustainability of income-generating activities established as part of many urban development projects instigated by development agencies, the likelihood of inhabitants generating enough income for the upkeep of new or improved infrastructure, and whether the necessary commitment from the community can be created in a situation in which civil organizations have been banned or discouraged. These issues are considered in the context of Oxfam UK/I's involvement in the Kebele 29 Project.     

Ecological resilience in urban ecosystems: Linking urban patterns to human and ecological functions

Urban ecosystems evolve over time and space as the outcome of dynamic interactions between socio-economic and biophysical processes operating over multiple scales. The ecological resilience of urban ecosystems—the degree to which they tolerate alteration before reorganizing around a new set of structures and processes—is influenced by these interactions. In cities and urbanizing areas fragmentation of natural habitats, simplification and homogenization of species composition, disruption of hydrological systems, and alteration of energy flow and nutrient cycling reduce cross-scale resilience, leaving systems increasingly vulnerable to shifts in system control and structure. Because varied urban development patterns affect the amount and interspersion of built and natural land cover, as well as the human demands on ecosystems differently, we argue that alternative urban patterns (i.e., urban form, land use distribution, and connectivity) generate varied effects on ecosystem dynamics and their ecological resilience. We build on urban economics, landscape ecology, population dynamics, and complex system science to propose a conceptual model and a set of hypotheses that explicitly link urban pattern to human and ecosystem functions in urban ecosystems. Drawing on preliminary results from an empirical study of the relationships between urban pattern and bird and aquatic macroinvertebrate diversity in the Puget Sound region, we propose that resilience in urban ecosystems is a function of the patterns of human activities and natural habitats that control and are controlled by both socio-economic and biophysical processes operating at various scales. We discuss the implications of this conceptual model for urban planning and design.     

Modeling urban landscape dynamics: A case study in Phoenix,USA

Urbanization has profoundly transformed many landscapes throughout the world, and the ecological consequences of this transformation are yet to be fully understood. To understand the ecology of urban systems, it is necessary to quantify the spatial and temporal patterns of urbanization, which often requires dynamic modeling and spatial analysis. In this paper, we describe an urban growth model, the Phoenix Urban Growth Model (PHX-UGM), illustrate a series of model calibration and evaluation methods, and present scenario-based simulation analyses of the future development patterns of the Phoenix metropolitan region. PHX-UGM is a spatially explicit urban landscape model and is a modified version of the Human-Induced Land Transformations (HILT) model originally developed for the San Francisco Bay Area. Using land use and other data collected for the Phoenix area, existing growth rules were selectively modified and new rules were added to help examine key ecological and social factors. We used multiple methods and a multi-scale approach for model calibration and evaluation. The results of the different evaluation methods showed that the model performed reasonably well at a certain range of spatial resolutions (120–480 m). When fine-scale data are available and when landscape structural details are desirable, the 120-m grain size should be used. However, at finer levels the noise and uncertainty in input data and the exponentially increased computational requirements would considerably reduce the usefulness and accuracy of the model. At the other extreme, model projections with too coarse a spatial resolution would be of little use at the local and regional scales. A series of scenario analyses suggest that the Metropolitan Phoenix area will soon be densely populated demographically and highly fragmented ecologically unless dramatic actions are to be taken soon to significantly slow down the population growth. Also, there will be an urban morphological threshold over which drastic changes in certain aspects of landscape pattern occur. Specifically, the scenarios indicate that, as large patches of open lands (including protected lands, parks and available desert lands) begin to break up, patch diversity declines due partly to the loss of agricultural lands, and the overall landscape shape complexity also decreases because of the predominance of urban lands. It seems that reaching such a threshold can be delayed, but not avoided, if the population in the Phoenix metropolitan region continues to grow. PHX-UGM can be used as a tool for exploring the outcome of different urban planning strategies, and the methods illustrated in this paper can be used for evaluating other urban models.     

A socio-ecological perspective of urban green networks: the Stockholm case

Landscape fragmentation threatens habitats, biodiversity and other ecosystem services. In tackling this threat, the dynamic processes of social-ecological systems should be recognised and understood. Although network analysis based on graph theory has been recognised as an efficient way of spatially understanding landscape or habitat connectivity, only few studies have offered specific approaches or suggestions for integrating detailed social-ecological values into geographical distributions. As a contribution to bridging this gap, this paper introduces a social-ecological network model for the issue of landscape or habitat fragmentation applied to the case of Stockholm, Sweden. Graph theory was used in combination with sociotope and biotope maps for simple visualisation of network situations in two-dimensional maps. The European crested tit (Lophophanes cristatus), European common toad (Bufo bufo) and human beings were selected as indicator species, based on a landscape ecology analysis in Stockholm Municipality in 2009. Slope, land use and human disturbance maps were assessed in order to decide cost values of travelling from node to node. Lease-cost-path accumulation was used to create ideal reference maps of green networks. Three separate maps were then developed for suggesting efficient routes for three indicators in city scale that mainly connect from the Royal National City Park to the other parts of the city. The model in Hjorthagen neighbourhood to highlight two practical paths that link this fragmented community to its neighbouring park areas. Findings make it possible to address two scales of network improvement strategies, namely first for the city-scale green network that connects geographical habitats (nodes) and the regional green wedges of the city, and the second that of neighbourhood links between habitats in detailed layers of green networks. Strategic improvement potentials are presented based on ideal reference maps of green networks correspondingly.     

Urban growth and heat islands: A case study in micro-territories for urban sustainability

Urban Ecosystems - Rapid urbanization contributes to the development of phenomena such as climate variability, especially in tropical countries, which negatively impact ecosystems and humans,...     

Strategies for urban conservation: A case example of George Town, Penang

George Town, Penang has more than 200 years of urban history and the largest collection of heritage shophouses in Southeast Asia. These heritage buildings have remained unchanged since the 1800s in spite of the lack of conservation legislation. The objective of this paper is to determine which public policy instruments have been effective in protecting the urban heritage of George Town. In particular, the role played by the Control of Rent Act, 1966, is evaluated. Upon examination of records on property transaction, rent-control records, development applications and demographic trends, no conclusive evidence was found that this Act was instrumental in protecting heritage buildings. Instead it was the unintentional effects of various development policies that saved George Town's urban heritage.     

Vegetation composition and structure of woody plant communities along urban interstate corridors in Louisville,KY, U.S.A.

Urban forests adjacent to interstate corridors are understudied ecosystems across cities. Despite their small area, these forests may be strategically located to provide large ecosystem services due to their ability to act as a barrier against air pollutants and noise as well as to provide flood control. The woody vegetation composition and structure of forests adjacent to urban interstates is an important determinant of their ability to provide these services. However, these forest communities may be particularly susceptible to the introduction of exotic invasive species via the interstate and the surrounding city that can potentially alter current and future forest composition. The purpose of this study was to investigate the distribution of native and exotic woody vegetation and tree regeneration in forests along three interstate corridors in Louisville, KY, and to determine potential factors (e.g., traffic density) that are correlated with patterns in the woody vegetation community. We found the most important determinants of vegetation composition along these interstate corridors were the distance from the city center and the presence of an exotic invasive shrub, Amur honeysuckle (Lonicera maackii). Compared with forested plots within 10 km of the city center, plots further from the city center had 81% lower stem density of Amur honeysuckle, 96% higher tree seedling regeneration, and 51% greater woody plant species richness. The primarily native species composition of adult trees in forests alongside urban interstates in Louisville and the regeneration of native tree species provide optimism that these forests can maintain native species while experiencing multiple impacts from the interstate as well as from the surrounding city, emphasizing their important potential for maintaining natural forest functions across the urban landscape.     

Distributive justice revisited: A reconceptualization and an empirical test

Research on distributive justice has classified allocative standards into three distinct categories: equity, need, and equality. We empirically test the notion that equality should be further divided into two distinct constructs: absolute and bounded equality, thus leading to four distinct categories of distributive justice. Using a sample of 240 individuals (119 managers and 121 union activists), we further test for differences between managers and public and private sector unionists in their endorsement of these four standards. Results support all four of our specified hypotheses. Results are discussed in terms of their implications for distributive justice issues in the workplace, and future research directions are proposed. The authors thank John Delaney, Jean Phillips, and Linda Stroh for their comments on an earlier version of this paper.     

The economic advantages of large cities: A case study of China's urban centres

This paper reviews the guidelines for China's urbanisation with respect to the national contribution in terms of economic efficiency achieved by cities of different sizes. The findings indicate that, although lower order cities (especially small towns) indisputably prove to be of great assistance to the national economy, chiefly in absorbing the enormous surplus labour force from rural areas and alleviating the ponderous pressure of population influx upon giant cities, yet under no circumstances can they generate substantial productivity growth, originating from agglomeration economies characteristic of large metropolises. The work makes extensive use of available statistics.     

Microclimate in an urban park and its influencing factors: a case study of Tiantan Park in Beijing,China

Urban Ecosystems - Construction of urban green spaces may effectively mitigate urban heat island effect. Better design of green spaces may improve their thermal performance, and therefore provide...     

A study of low birth weight infants in an urban community

The study concerns the problem of low birth weight as seen in a prospectively studied cohort from a South Delhi urban community covering 23,700 families and 1,19,799 population over a four year period from 1969-73. The incidence of low birth weight was 22.9 per cent of which 2.7 per cent had a birth weight of 2000 gms. or less and 20.2 per cent had a birth weight 2001-2500 gms. Maternal height of 140 cms or less and pregravid weight of 35 kg or less were associated with the occurrence of low birth weight infant. The mortality was related inversely to birth weight and the gestation affected the outcome directly. The mortality rates declined sharply in infants of birth weight 2001-2500 gms but was still high as compared to infants of birth weight more than 2.5 kg. The later physical growth was affected by the initial birth weight. The study was conducted under the research project 01-658-2 funded by the National Centre for Health Statistics, 3700 East West Highway, Hyattsville, Maryland-20782, U.S.A.     

Chemical toilet for persons with disabilities: proposal for an urban furniture affordable

Street furniture is an important element to the social and democratic life in the cities. In this case, public restrooms must be available to practically all kinds of citizens that inhabit the city. However disabled people have many difficulties in using the existing models, particularly public chemical toilets. Through a design project, a new proposition for a public chemical toilet addressed to wheelchair users was conceived. In this way, the main aspect of this work refers to the actual participation of the disabled expressing their opinion through interviews and usability analysis as well as the observation on technical recommendations for accessibility.     

Marriage and female labour supply in Brunei Darussalam: A case study of urban women in Bandar Seri Begawan

We analyse the relationships between marriage and female labour supply for urban householders in Bandar Seri Begawan, capital city of Brunei Darussalam in Southeast Asia. This analysis is based on a survey of 151 adult women. We establish that age, total number of career work position(s) held, expressing the degree of labour mobility, and the level of educational attainment influence participation of women (both married and single) in formal labour markets. A major factor influencing the likelihood of married women working is the number of their children below the age of 18. Higher propensity to work occurs with decreasing number of children. Wage incomes of working women are largely determined by the level of educational attainment, work experience and social class status. Married women are more likely to work than unmarried women and on average earn about 53% more than unmarried women assuming other things constant. The main factors influencing the value of time in marriage of currently married women are the income of husband, their work experience, educational attainment and age. This value decreases with increasing age of the woman spouse but it increases with higher levels of work experience and educational attainment of the woman, and higher income of her husband.     

Staying with it: A case study

Abstract

This is a case study which illustrates some of the conflicts and dilemmas facing local authority social workers in child protection. The worker had to learn to understand and deal with his feelings about a client, who was at different times unable to communicate verbally, sexually procative and seductive, hostile and aggressive. For the client there was a gradual shift from acting out her fears and fantasies about men, to being able to verbalise and trust the worker.

The worker moves towards an understanding of the client's problems and also of his own difficulties in dealing with the case. He believes that his personal involvement was of value to the client.     

Soil-atmosphere exchange of carbon dioxide,methane and nitrous oxide in urban garden systems: impact of irrigation,fertiliser and mulch

Urban green spaces provide important ecosystem services, such as amenity, biodiversity, productivity, climate amelioration, hydrological and biogeochemical cycling. Intensively managed urban gardens can sequester carbon through vegetation growth and soil C increase, but may experience nitrous oxide (N₂O) emissions and reduced soil methane (CH₄) uptake from irrigation and fertiliser use. Soil atmosphere exchange of N₂O, CH₄ and carbon dioxide (CO₂) was measured in lawn and wood chip mulched garden areas in Melbourne, Australia in winter, spring and summer under various water and fertiliser regimes. Gas exchange before and after lawn fertiliser application was measured continuously for three weeks using an automated chamber system. Applying fertiliser led to a peak N₂O emission of >60 μg N m⁻² h⁻¹, but overall only weekly irrigation (10 mm) significantly increased mean soil N₂O emissions above that in other treatments. Under mulch, mean soil N₂O emissions (14.0 μg N m⁻² h⁻¹) were significantly smaller than from irrigated lawn (27.9 μg N m⁻² h⁻¹), whereas mean soil CH₄ uptake under mulch (−30.7 μg C m⁻² h⁻¹) was significantly greater (p < 0.01) than in any lawn treatment. Lawns were either a weak CH₄ sink or source. Soil C density (0–25 cm) under mulch (12.5 kg C m⁻²) was greater that under lawn (8.0 kg C m⁻²). On a carbon dioxide equivalent (CO₂-e) basis, soil N₂O emissions offset the benefits of soil CH₄ uptake. Mulched garden areas provide greatest C sequestration potential in soil and vegetation and the smallest non-CO₂ emissions, as soil CH₄ uptake offsets a large fraction of soil N₂O emissions. Results of this study suggest that reducing the irrigation and fertiliser application to lawns can help mitigate GHG emissions from urban garden systems, and increasing the area of mulched perennial garden beds can also provide net GHG benefits; however, this needs to be tested in other garden systems with different soil types and environmental conditions.     

Analysis of the spread of Rhynchophorus ferrugineus in an urban area,using GIS techniques: a study case in Central Italy

Urban Ecosystems - The spread of the red palm weevil is now a very severe problem on a global scale. In this paper, we investigate its spread during the 2007–2013 period in a coastal urban...