The effects of scatter-hoarding rodents on Mongolian oak (<Emphasis Type="Italic">Quercus mongolica</Emphasis>) acorn dispersal and seedling distribution in urban woodland

Scatter-hoarding by animals is an effective mechanism for seed dispersal and plant regeneration in natural ecosystems, however, studies on the interaction between hoarding animals and urban forest are insufficient. By methods of acorn placement experiment, cache and seedling survey, the relationship between acorn dispersal and seedlings distribution of Mongolian oak (Quercus mongolica) and scatter hoarding rodents was investigated at the Northeast Forestry University Woodland of Harbin, China. Results indicated that main scatter hoarding rodents of acorns were squirrels (Sciurus vulgaris) and chipmunks (Eutamias sibiricus). Mongolian oak seedlings were distributed primarily in Mongolian Scotch pine, birch and larch parcels (df = 3, χ ² = 1502.77, P < 0.01). Most seedlings were 4 ~ 6 years (df = 3, χ ² = 408.23, P < 0.01) and mainly dispersed within range of 100 m from the parent trees. The activity frequency and cache habitats of squirrels coincided with the distribution pattern of Mongolian oak seedlings, which meant scatter hoarding rodents had important effects on acorn dispersal and seedling establishment of urban Mongolian oaks.     

Silphids in urban forests: Diversity and function

Many ecologists have examined the process of how urbanization reduces biological diversity but rarely have its ecological consequences been assessed. We studied forest-dwelling burying beetles (Coleoptera: Silphidae)—a guild of insects that requires carrion to complete their life cycles—along an urban-rural gradient of land use in Maryland. Our objective was to determine how forest fragmentation associated with urbanization affects (1) beetle community diversity and structure and (2) the ecological function provided by these insects, that is, decomposition of vertebrate carcasses. Forest fragmentation strongly reduced burying beetle diversity and abundance, and did so far more pervasively than urbanization of the surrounding landscape. The likelihood that beetles interred experimental baits was a direct, positive function of burying beetle diversity. We conclude that loss of burying beetle diversity resulting from forest fragmentation could have important ecological consequences in urban forests.     

Connectivity in urbanizing landscapes: The importance of habitat configuration,urban area size,and dispersal

Human activities affect both the amount and configuration of habitat. These changes have important ecological implications that can be measured as changes in landscape connectivity. I investigated how urbanization interacts with the initial amount and aggregation of habitat to change dispersal potential, restoration potential, and the risk of spatially extensive disturbances. I used a factorial set of simulated landscapes and subjected each landscape to habitat loss by overlaying 66 different US urban areas. I used a common connectivity metric, CONNECT, to assess the magnitude and direction of changes for a range of dispersal distances. My results show that the relationship between habitat loss and connectivity loss is non-linear and subject to interactions between the spatial patterns of habitat distribution, urban morphology, and dispersal capabilities. The implications of a given urban form vary widely as a function of habitat distribution and dispersal capabilities. This implies that impact assessments, restoration activities, and conservation planning should consider historical habitat distribution when evaluating observed changes in connectivity. While my results clearly show that more aggregated or continuous habitats are more vulnerable to connectivity loss, this approach can also be used to identify landscapes where restoring connectivity will be particularly effective, for example through placement of stepping stone habitats.     

Restructuring for growth in urban China: Transitional institutions,urban development,and spatial transformation

This research examines government policies and urban transformation in China through a study of Hangzhou City, which is undergoing dramatic growth and restructuring. As the southern center of the Yangtze River Delta, an emerging global city region of China, Hangzhou has been restlessly searching for strategies to promote economic growth and survive the competition with Shanghai. This paper analyzes Hangzhou’s development strategies, including globalization, tourism, industrial development, and urban development, in the context of shifting macro conditions and local responses. We hold that urban policies in China are situated in the broad economic restructuring and the gradual, experiential national reform and are therefore transitional. The paper suggests that China’s urban policies are state institution-directed, growth-oriented, and land-based, imposing unprecedented challenges to sustainability and livability. Land development and spatial restructuring are central to urban policies in China. Last, while Hangzhou’s development strategies and policies to some extent reflect policy convergence across cities in China, local/spatial contexts, including local settings, territorial rescaling and land conditions, are underlying the functioning of development/entrepreneurial states.     

Birds biodiversity in urban and periurban forests: environmental determinants at local and landscape scales

A significant decline in biodiversity is associated with the current and upcoming degree of urbanization. A challenging strategy to address this conflict is to make urban growth compatible with biodiversity protection and in this context urban parks can play a crucial role. Urban systems are highly dynamic and complex human-shaped ecosystems, where the relationship between species and environment may be altered and make the preservation of biodiversity within them a challenging goal. In this study, we analysed how different environmental features affect bird biodiversity in one of the most urbanized areas of Italy (the metropolitan area of Milan) at different spatial scales. Bird surveys were conducted in fifteen urban and peri-urban parks and environmental variables at landscape and local scale recorded. Results showed that a mixture of land covers and the presence of water bodies inside urban parks favoured species occurrence and abundance at landscape scale, but a surrounding dense urban matrix deflated biodiversity. At local scale, woodland cover and presence of water bodies were key determinants in ensuring overall high biodiversity but local-specific vegetation management produced an unusual pattern for forests species. In particular, the maintenance of large trees may not result in biodiversity support for forest bird species if large trees are not located in woodland areas with a significant tree density. To understand biodiversity patterns and provide useful information for urban planning and design, we need to provide insights into species/environment relationships at multiple scales in the urban environment.     

Culture,place and urban growth in the U.S. South

People’s connection to land is an important contributor to identity in traditional southern society. In small southern communities, to know where someone lives is to know who someone is because place assigns biography. Studies have investigated the physical and economic implications of landscape change in the South, but comparatively little research focuses on the impacts to culture of urban growth. We consider how sense of place (as an indicator of culture) may be impacted, over time, by physical and structural changes in a locale. This point of departure examines the temporal dimension of sense of place, or how place perceptions may vary as familiar places and practices are altered by landscape moderations. We review the literature on sense of place and changing Southern landscapes and also offer a conceptual framework for analyzing sense of place over the long-term.

Managing urban growth and development in the Riyadh metropolitan area, Saudi Arabia

The paper examines public sector management of urban growth and development in the Riyadh Metropolitan Area, Saudi Arabia. The focus of the paper is on institutional capacity building and development intervention. The paper traces changes in public sector management structures and development activities over the history of the city with the aim of assessing development impact and identifying forces that have shaped the evolving state of urban management. The paper notes that urban management has significantly improved with time but the persistence of urban problems coupled with projections of future growth point to the need for further improvements. The paper, in conclusion, while acknowledging the utility of the metropolitan development strategy (MEDSTAR) being formulated for the city, points to the need for broader administrative reform to improve the ability to cope with long-term challenges of growth in the city. Some issues that reform could address are suggested.     

Relationships between landscape pattern metrics,vertical structure and surface urban Heat Island formation in a Colorado suburb

Change in land surface temperature (LST) due to urbanization is a critical influence on the ecohydrological function and human health in cities. Past research has emphasized land cover composition and planimetric landscape pattern as drivers of LST patterns, but there have been few empirical studies examining the effects of vertical structure on thermal variation in cities. We used agglomerative cluster analysis to group 5 ha grid cells with similar land cover composition from high-resolution land cover data for our Aurora, Colorado, USA study area. We then compared the importance of different planimetric landscape pattern metrics and lidar-derived vertical structure variables as predictors of LST estimated from Landsat 5 thermal band data for each group. Variation in LST between cluster groups was analyzed with landscape and vertical structure data using random forest regression models and conditional variable importance metrics. Cluster analysis produced 7 distinct groups differing in land cover composition, planimetric landscape pattern, and vertical structure. Clusters with greater tree cover and higher mean tree height were generally cooler, while the height difference between buildings and trees had high conditional variable importance in random forest regression models. We found that the specific planimetric landscape pattern and vertical structure metrics most important for individual clusters differed, suggesting that the relative importance of variables depends on land-use and land cover. Our results highlight the importance of including vertical structure in empirical analyses of urban LST.     

The role of dispersal and local environment in urban land snail assemblages: an example of three cities in Central Italy

Ecologists increasingly appreciate the central role that urban biodiversity plays in ecosystems, however much urban biodiversity is neglected, especially some very diverse groups of invertebrates. For the first time in southern Europe, land snail communities are analysed in four urban habitats along a geographical gradient of three cities, using quantitative methods and assessing the relative roles of local environmental conditions (“distance from sea”, “distance from city centre”, “vegetation cover”) and spatial effects by principal coordinate analysis of neighbour matrices, redundancy analysis and variation partitioning. A total of 53 species was recorded, a richness similar to that of natural areas. At habitat level, species richness did not show a clear increasing trend from more to less urbanized habitats, but rather a homogeneous pattern. At city level, study areas hosted rather heterogeneous species assemblages and biotic homogenization did not seem to have any impact; indeed, only three species could be considered alien. Variation partitioning showed that land snail communities were mostly structured by environmental factors, even when spatial structures independent of measured environmental variables were included: “vegetation cover” and “distance from city centre” were the environmental variables that explained most of the variation in species composition. The lack of strong spatial structure also unexpectedly suggested that transport by humans aids dispersal of organisms with low mobility, which are usually limited by spatial constraints in natural environments. These results provide ecological and conservation implications for other invertebrate groups, suggesting to set priorities in management strategies that include habitat conservation at local scale.     

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,...     

The regional distribution of skill premia in urban China: Implications for growth and inequality

Based on urban household survey data, the authors find that skill premia increased significantly across all regions of China between 1995 and 2002, but only in coastal regions between 2002 and 2007. By then, these regions also displayed much wider wage inequality and thus contributed more to overall urban wage inequality than non‐coastal regions. While privatization was the main driver of skill premia in 1995–2002, China's (regionally uneven) integration into the global economy became the dominant influence in 2002–07. Reducing skill premia and inequality, the authors argue, calls for reform of the Hukou registration system which impedes skilled labour mobility and possibly also growth.     

Determinants of urban tree canopy in residential neighborhoods: Household characteristics, urban form, and the geophysical landscape

The aesthetic, economic, and environmental benefits of urban trees are well recognized. Previous research has focused on understanding how a variety of social and environmental factors are related to urban vegetation. The aim is often to provide planners with information that will improve residential neighborhood design, or guide tree planting campaigns encouraging the cultivation of urban trees. In this paper we examine a broad range of factors we hypothesize are correlated to urban tree canopy heterogeneity in Salt Lake County, Utah. We use a multi-model inference approach to evaluate the relative contribution of these factors to observed heterogeneity in urban tree canopy cover, and discuss the implications of our analysis. An important contribution of this work is an explicit attempt to account for the confounding effect of neighborhood age in understanding the relationship between human and environmental factors, and urban tree canopy. We use regression analysis with interaction terms to assess the effects of 15 human and environmental variables on tree canopy abundance while holding neighborhood age constant. We demonstrate that neighborhood age is an influential covariate that affects how the human and environmental factors relate to the abundance of neighborhood tree canopy. For example, we demonstrate that in new neighborhoods a positive relationship exists between street density and residential tree canopy, but the relationship diminishes as the neighborhood ages. We conclude that to better understand the determinants of urban tree canopy in residential areas it is important to consider both human and environmental factors while accounting for neighborhood age.     

Study on the ecosystem services of urban forests: implications for climate change mitigation in the case of Adama City of Oromiya Regional Sate,Ethiopia

Urban Ecosystems - This study was conducted to explore the ecosystem services of urban forests in Adama city, central Ethiopia. Attempts were made to quantify the carbon storage and sequestration,...     

Accumulating history: dirt,remains and urban decay in Nairobi

Abstract

In anthropology and related fields, “ruin” and “decay” are terms that are often used interchangeably. By paying close attention to the materiality and politics of dirt and decay in a colonial-era housing estate in Nairobi, Kenya, this article argues for their uncoupling. Instead of implying loss or oblivion, decay is explored as a process of accumulation: an excess that constitutes a material history. Remains, rubbish and dirt continue to be active in the present, effecting and constraining certain atmospheres, attitudes and politics. Drawing a distinction between “urban decay” as a policy category and as a material process, the article also considers what happens if these remains are wiped away in schemes of urban renewal. The loss usually associated with ruination may emanate not so much from decay as from its elimination.     

Tree diversity,distribution, history and change in urban parks: studies in Bangalore,India

Urban parks constitute critical biodiversity hotspots in crowded, concrete-dominated city environments. Despite the importance, they remain little researched. This paper assesses the biodiversity and distribution of trees in urban parks in the southern Indian city of Bangalore. 127 plots were used to survey tree distribution in parks across the city. The distribution is largely dominated by a few common species. The proportion of exotic species was very high, with 77% of trees belonging to introduced species. Park history had an impact on distribution. Old parks had fewer but larger trees, and greater species diversity compared to recently established parks. Old parks also differed in species composition, having a greater proportion of large canopy trees compared to young parks. Examination of size distributions revealed that large canopied species were gradually being phased out, and replaced by narrow and medium sized tree species which are easier to maintain, but which may not provide the same environmental and ecological benefits. Greater attention requires to be paid to the selection of trees in cities, not just with a view to easy maintenance as is currently the case, but to select an appropriate mix of trees that supports biodiversity and maximizes environmental and ecosystem services.     

Correction to: Planning for active management of future invasive pests affecting urban forests: the ecological and economic effects of varying Dutch elm disease management practices for street trees in Milwaukee,WI USA

Urban Ecosystems - In Table 4, the column headings that explain the table data was not included in the published version     

A balancing act in urban social-ecology: human appreciation,ponds and dragonflies

Green spaces in cities provide cultural ecosystems services (CES) such as nature connection, wildlife interaction and aesthetic appreciation which can improve aspects of human well-being. Recognising these benefits, researchers are now examining the complex relationship between humans and nature in urban social-ecology. Most studies investigate people’s appreciation and valuation of different green space features and their contribution to urban biodiversity. Recommendations arising from such studies are best practices to achieve a balance between landscape aesthetic and ecological objectives, but many knowledge gaps still exist. In a social-ecological project in Greater London, appreciation of ponds and dragonflies in urban green spaces, and the environmental factors determining dragonfly diversity were investigated. We found ponds and their appearance were valued by people as enhancing their green space experience. The preference for wild-looking ponds was moderate. Dragonflies were enjoyed for their colour and high visibility, especially by those who had basic dragonfly knowledge. Species richness of dragonflies was positively associated with habitat heterogeneity in and around a pond. However, people were unable to relate a heterogeneous pond to more dragonfly species. For the first time, some factors that influence the human appreciation-ponds-dragonflies (HPD) relationship in an urban context are revealed. To fully realise the CES potential of ponds and dragonflies in Greater London, a HPD framework is proposed. The framework underpins strategies that foster cultural sustainability for ponds and dragonfly conservation.     

Envisioning a feminist urban ethnography: Structure,culture, and new directions in poverty studies

A “risk” discourse, characterized by the focus on behaviors of the economically marginalized especially as it relates to drugs, gangs, violence, and teen parenthood, has traditionally dominated poverty research in the United States. More recently, this hegemonic risk discourse has become contoured by the so‐called new cultural turn in urban poverty studies, which has been marked as a departure from the earlier “blame the victim” perspectives. In this article, we review the role of urban ethnographers in shaping the structure versus culture debate in the sociology of poverty sub‐discipline. We then point to a scant, but growing, body of work that is encouraging urban ethnographers engaged in poverty research to expand their vision. To conclude, we contend that this new direction can be conceptualized as a feminist urban ethnography frame that advocates for transformation of the poverty research agenda.