A conceptual framework for the study of human ecosystems in urban areas

The need for integrated concepts, capable of satisfying natural and social scientists and supporting integrated research, motivates a conceptual framework for understanding the role of humans in ecosystems. The question is how to add humans to the ecological models used to understand urban ecosystems. The ecosystem concept can serve as the basis, but specific social attributes of humans and their institutions must be added. Learning and feedback between the human and natural components of urban ecosystems are key attributes of the integrated model. Parallels with familiar ecological approaches can help in understanding the ecology of urban ecosystems. These include the role of spatial heterogeneity and organizational hierarchies in both the social and natural components of urban ecosystems. Although urban watersheds are commonly highly altered, the watershed approach can serve as a spatial basis for organizing comparative studies of ecosystems exhibiting differing degrees of urbanization. The watershed concept can also spatially organize the hierarchically scaled linkages by which the integrated human ecosystem model can be applied. The study of urban ecosystems is a relatively new field, and the questions suggested by the integrated framework can be used to frame ecosystem research in and associated with urban and metropolitan areas.     

Is there a need for a theory of urban ecology?

Although urban ecosystems are governed by the same ecological laws as rural ecosystems, the relative importance of certain ecological patterns and processes differs between the two types of ecosystems. For instance, as compared to rural areas, urban habitats are usually more islandlike, more often represent early successional stages, and more easily invaded by alien species. All these features are results of the intense human influence on urban landscapes. The question then arises whether a distinct theory of urban ecology is needed for understanding ecological patterns and processes in the urban setting. The answer is no, because urban ecosystems can be successfully studied using existing ecological theories, such as the metapopulation theory. However, due to the intense human presence approaches that include the human aspect are useful in studying urban systems. For instance, the human ecosystem model, which emphasizes human impact by identifying social components with connections to ecology, is a useful approach in urban studies. This model, combined with the urban–rural gradient approach, forms an effective tool for studying key ecological features of urban ecosystems. Better understanding of these features would increase our ability to predict changes that land use causes in urban ecosystems, and would help to integrate ecology better into urban planning.     

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.     

Altered resources, disturbance, and heterogeneity: A framework for comparing urban and non-urban soils

We propose a framework of key concepts useful in understanding how urban soils can contribute to general ecological theory. The major factors that can cause urban soils to be different from soils in non-urban ecosystems are identified and related to the familiar state factor approach. We evaluate directly altered resource availability, and the role of stress in mediating resource availability in urban ecosystems. Modified groundwater and stream flow, and atmospheric deposition of nitrogen and base cations are particularly important resource fluxes to soils in urban ecosystems. Disturbance can be conceptualized in the same way in urban as in non-urban ecosystems. However, in addition to biophysical disturbances familiar to ecologists studying wild lands, demographically and socially mediated changes in ecosystem structure must also be considered. These changes include human migration and population structure, institutional shifts, and the effects of human health. Finally, spatial heterogeneity, including fragmentation and differential connectivity, integrates the effects of resources and disturbance, and has an effect on subsequent resource availability and susceptibility to disturbance. Layers of heterogeneity include not only the geomorphic template, but urban climate, biotic composition, buildings and infrastructure, and demographic-social patterns. The complex layering of natural and social factors that constitute urban heterogeneity permit the continuation of important ecological processes, as well as modify ecological fluxes involving soils. We present a modification of the state factor approach as an expanded framework for the study of urban soils. The understanding of urban soils can contribute to general ecological theory by testing the generality of important ecosystem drivers and their linkage with social processes in an under investigated ecosystem type that is increasing in extent and impact worldwide.     

A comparative study of urban fragmentation patterns in small and mid-sized cities of Idaho

Urbanization has a massive impact on ecological function and impedes the provisioning of environmental services. The interaction between urbanization and the environment has been researched extensively. However, the existing research focused on the urbanization characteristics of large metropolitan areas. In this paper, we investigate the urban fragmentation patterns of small and mid-sized cities in Idaho, USA. To capture the urban morphology for each site within the study we use both concentric ring and transect analysis as well as several spatial/landscape metrics. Our results show that the characteristics of urbanization in small and mid-sized cities (and those in second-tier regions that attract relatively little scholarly attention) are consistent with growth phase theory of urbanization, urbanization along a gradient, and urbanization patterns of metropolises.     

Adaptive governance to promote ecosystem services in urban green spaces

Managing urban green space as part of an ongoing social-ecological transformation poses novel governance issues, particularly in post-industrial settings. Urban green spaces operate as small-scale nodes in larger networks of ecological reserves that provide and maintain key ecosystem services such as pollination, water retention and infiltration, and sustainable food production. In an urban mosaic, a myriad of social and ecological components factor into aggregating and managing land to maintain or increase the flow of ecosystem services associated with green spaces. Vacant lots (a form of urban green space) are being repurposed for multiple functions, such as habitat for biodiversity, including arthropods that provide pollination services to other green areas; to capture urban runoff that eases the burden on ageing wastewater systems and other civic infrastructure; and to reduce urban heat island effects. Because of the uncertainty and complexities of managing for ecosystem services in urban settings, we advocate for a governance approach that is adaptive and iterative in nature—adaptive governance—to address the ever changing social order underlying post-industrial cities and offer the rise of land banks as an example of governance innovation.     

A social ecology approach and applications of urban ecosystem and landscape analyses: a case study of Baltimore,Maryland

The early interactions between plant, animal, and human ecology in the 1920s in the United States provide an initial basis for understanding and directing an integrated ecosystem approach to the study of sociocultural and biophysical patterns and processes of present day cities. However, whereas the human ecology approach of the 1920s and 30s was interested in metaphorical similarities with plant and animal ecologists, we propose a more integrated approach to human ecosystem observation and analysis. A critical feature to an integrated, urban ecosystem approach is the ability of researchers to address the spatial heterogeneity of urban ecosystems; i.e. the development and dynamics of spatial heterogeneity and the influences of spatial patterns on cycles and fluxes of critical resources (e.g. energy, materials, nutrients, genetic and nongenetic information, population, labor, and capital). An important question in this context is how differential access to and control over critical resources affect the structure and function of urban ecosystems.To address this heterogeneity, we illustrate a human ecosystem and landscape approach and how the concept of social differentiation can be applied spatially at different scales with a case study from our research in Baltimore, Maryland. Further, we identify different methods, tools, and techniques that can be used for an integrated, urban ecosystem approach.     

Nested patterns in urban butterfly species assemblages: respective roles of plot management,park layout and landscape features

Increasing numbers of cities are currently developing sustainable policies aimed at promoting urban biodiversity and ecological dynamics through the planning of green networks and the implementation of more sustainable management practices. These human activities can strongly influence environmental factors on which the organization of ecological communities at different scales depends. Thus, it is of fundamental importance to understand the relative impact of local management, green space design and landscape features on the distribution and the abundance of species in urban areas. On the basis of 2 years of butterfly surveys in urban public parks within an extensive Mediterranean metropolitan area, Marseille (South-East France), the aim of this paper is to provide a better understanding of the effect of these three environmental scales (plot, park, landscape) on the composition and organization of species assemblages. Using variation partitioning and nestedness analysis on ecological data aggregated at plot-level and park-level respectively, we demonstrate the preponderant effect of landscape scale features on urban butterfly assemblages. Our results also highlight an important co-variation of plot management, park layout and urban landscape features, in their interaction with the community structure of urban butterflies. Although there is no significant species-area relationship, significantly nested patterns arise in species composition. Selective colonization appears as a driving force constraining the constitution of species assemblages within the city. However, a prospective study on adjacent more natural areas suggests that biotic limitations, interspecific competition and habitat filtering may play an important role if a larger portion of the urbanization gradient is explored, which remains to be investigated.     

The future of urban biodiversity research: Moving beyond the ‘low-hanging fruit’

In this era of rapidly urbanising human populations, urban practitioners are under increasing pressure to create resilient and sustainable cities and towns. Urban ecologists currently have a unique opportunity to apply solid, evidence-based research to help create biodiversity-rich and sustainable cities and towns for the future. Unfortunately, there is currently a mismatch between the questions planners, designers and decision-makers are asking urban ecologists that would allow them to improve the biodiversity outcomes in urban areas, and the questions urban ecologists must ask to contribute to the development and application of the science of urban ecology. For a number of reasons, urban ecologists over the past 25 years have primarily focused on describing the patterns of biodiversity in cities and towns using broad, aggregate predictor variables (e.g., distance to city center, land-use, percent cover of impermeable surfaces and vegetation, etc.). We refer to these results as ‘low-hanging fruit’. If the discipline of urban ecology is going to provide the necessary information to inform actions to preserve and enhance urban biodiversity, we need to move beyond place-based research, and work towards the development of confirmed generalizations regarding the relationship between the structure and function of urban ecosystems and biodiversity. We propose three essential strategies for achieving this refined understanding: 1) defining the study window to place the study into a broader global context, 2) collecting and using more explicit question-driven measures of the urban condition in order to improve our understanding of urban ecological drivers, as well as recording more detailed ecological responses to provide insights into the ecological mechanisms underlying an observed response, and 3) expanding studies to include multiple cities, regions and countries. These strategies will help to expedite the ability of urban ecology to contribute to the creation of biodiversity-rich, healthy, resilient cities and towns.     

移民融合与城市层级的定位——有关移民研究中地方性问题的理论化

本文在新自由主义全球化背景下研究城市重构的理论化,建议用层级比较的方法研究移民的定居问题和跨国联系。通过提出"城市层级"的概念,本文探讨了后工业化城市重构的不同结果与移民融合的不同路径之间的关系。在"地方性"的理论化上,移民问题学者以民族国家和族群为分析的主要单位,而城市重构问题学者则未关注移民的研究。移民路径形成并反过来作用于城市的差异化定位。移民被视为城市层级的缔造者,城市在全球力场下的不同定位,决定着移民在其中扮演的角色。     

What is the Place for Megachurches? A Comparison of 22 American Cities Based on the Causes of Effects Approach1

The success of megachurches in America is often traced back to their strategic ability of mobilizing new members in a competitive, religious marketplace. This paper shifts the attention to the push factors of megachurch success. It develops a causes of effects approach, in which local place-based conditions in 22 metropolitan statistical areas (MSAs) are compared and related to megachurches. First, correspondence analysis (CA) is used to take into account a large set of explanatory conditions such as religious and ethnic group affiliations, social structural conditions as well as value orientations. CA reveals that megachurches are typically successful in MSAs characterized by an evangelical hegemony. Second, qualitative comparative analysis shows that population growth and suburbanization are necessary conditions for a high share of megachurches. An analysis of sufficient conditions leads to three propositions: Megachurches grow in cities (1) where a large closed evangelical community exists; (2) where a large upward oriented Christian immigrant community exists; (3) and in tolerant (and educated) areas—in conjuncture with the presence of a larger community of Protestants.     

From feedbacks to coproduction: toward an integrated conceptual framework for urban ecosystems

Research in urban ecology depends on frameworks that meaningfully integrate our understanding of biophysical and social change. Although the coupled nature of urban ecosystems is widely accepted, the core mechanisms we use to integrate the social and biophysical aspects of urban ecosystems – their social-ecological feedbacks – are poorly understood. This paper considers how feedbacks are used to conceptualize social-ecological change, noting their utility and their limitations. In so doing, we suggest that coproduction provides a meaningful alternative to feedbacks, one that captures not only the structure-function relationships usually assumed in studies of biophysical landscape change, but also the structure-agency relationships that facilitate our most comprehensive understanding of social change. By addressing both the stepwise forms of transformation that a feedback approach captures and the simultaneous forms of transformation captured by a coproduction approach, a more comprehensive assessment of the ways that social and ecological change take place is afforded. We contend that thinking in terms of coproduction is essential for moving beyond the interdisciplinary approach that usually guides urban ecology models, toward a more integrated, trans-disciplinary approach.

     

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.     

A case study of urban ecological networks and a sustainable city: Tehran’s metropolitan area

The aim of this study is to propose the application of landscape ecology in planning urban ecological networks to conserve nature in urban landscapes and to develop a sustainable use of urban lands. Compared to the classical planning approach based on socio-economic land suitability, the principles of landscape ecology are helpful simultaneously conserving the ecological processes of landscapes and their steady changes. This approach could help in defining sustainable landscape development, aiming for a balance between both physical and natural systems in urban areas. This research is focused on the ecological networks in Tehran’s metropolitan area as a case study to provide a model for network planning in other urban areas, where urbanization seriously threats the natural environment. In concluding this research, the spatial structure and function of the area are studied and categorized based on the patch-corridor-matrix model. The paper concludes with methods of intervention and suggestions for the structural and functional improvement of urban landscapes towards achieving a more sustainable form of land use planning.     

Urban wildlife ecology and conservation:A brief history of the discipline

Urban wildlife ecology and conservation is a discipline worldwide in scope. Although some attention was given the subject in the early to mid-1900s, most activity in the field is of more recent origin. Many European countries have active programs and activities, including the United Kingdom-Man and the Biosphere (UK-MAB) Urban Forum and The Wildlife Trusts of England, the United Nations Educational, Scientific, and Cultural Organization's MAB Program, and urban ecology research in Germany and Poland. The Netherlands' concept of “ecological landscapes” introduced a new approach to design of urban open space. Durban, South Africa followed with “D'MOSS,” a metropolitan open space system founded on the principles of island biogeography theory. The park connector network of Singapore combines principles of conservation biology and landscape planning. Urban wildlife programs and activities exist in the United States at the federal, state, and local levels as well as in private conservation organizations. The Wildlife Society established an Urban Affairs and Regional Planning Committee in the mid-1970s that later became the Urban Wildlife Committee and then evolved into the Urban Wildlife Working Group. Urban wildlife research is providing knowledge of wildlife and plant populations and communities in urban areas that hopefully will lead to better understanding and greater sustainability of urban ecosystems.     

Loud callings limit human tolerance towards invasive parakeets in urban areas

Biological invasions represent today one of the main cause of the global biodiversity crisis, particularly in urban and suburban areas. Research on this topic have traditionally focused on ecological impacts, with poor regards to the social components. The ring-necked parakeet Psittacula krameri is one of the most successful invaders and it is widely appreciated by the general public, being introduced through the pet trade. In this work we assessed whether long-term introduction, total population size and number of loud flight-calls affected social perception of this species in three populations from Italian cities. We used a visual survey (N?=?414 questionnaires), which has been proven to be successful for testing attitudes on ring-necked parakeets. Tolerance towards this invasive species declined sharply with increasing number of loud calls by this species, thus providing support to the hypothesis of involvement of the ring-necked parakeet in noise pollution. Conversely, total population size and years since the first local introduction were not found out to be important variable determining social attitudes. Awareness on invasive species impacts is mostly obtained only when invasive populations are already affecting native biodiversity and human wellness, thus when management becomes challenging. Thus, at early invasion stages, intervention towards invasive species, particularly if charismatic, are often hampered by social public and animal right movements, especially in urban ecosystems. Educational campaigns on ecological and social impact by invasive alien species in urban ecosystems are therefore strongly recommended to implement effective management actions.

     

Residential landscapes as social-ecological systems: a synthesis of multi-scalar interactions between people and their home environment

Residential landscapes are a common setting of human-environment interactions. These ubiquitous ecosystems provide social and ecological services, and yard maintenance leads to intended and unintended ecological outcomes. The ecological characteristics of residential landscapes and the human drivers of landscape management have been the focus of disciplinary studies, often at a single scale of analysis. However, an interdisciplinary examination of residential landscapes is needed to understand the feedbacks and tradeoffs of these complex adaptive social-ecological systems as a whole. Our aim is to synthesize the diversity of perspectives, scales of analysis, and findings from the literature in order to 1) contribute to an interdisciplinary understanding of residential landscapes and 2) identify research needs while providing a robust conceptual approach for future studies. We synthesize 256 studies from the literature and develop an interdisciplinary, multi-scalar framework on residential landscape dynamics. Complex human drivers (attitudinal, structural, and institutional factors) at multiple scales influence management practices and the feedbacks with biophysical characteristics of residential landscapes. However, gaps exist in our interdisciplinary understanding of residential landscapes within four key but understudied areas: 1) the link between social drivers and ecological outcomes of management decisions, 2) the ecosystem services provided by these landscapes to residents, 3) the interactions of social drivers and ecological characteristics across scales, and 4) generalizations of patterns and processes across cities. Our systems perspective will help to guide future interdisciplinary collaborations to integrate theories and research methods across geographic locations and spatial scales.     

Habitat origins and microhabitat preferences of urban plant species

Urban vegetation is commonly described as dominated by weedy species that are adapted to human disturbance. In this study, we determined the original (pre-agriculture) habitats of urban plant species sampled quantitatively in the spontaneous vegetation of a university campus in Halifax, Nova Scotia (eastern Canada). We sampled 11 distinct patch types corresponding to different built forms. Differences in vegetation among patch types were related in part to environmental variables such as soil moisture and light availability. The urban vegetation was dominated by species from rocky habitats such as cliffs and talus slopes, with lesser representation from grassland and floodplain habitats. When compared to a null model of species origins based on the global area and species richness of different original habitats, species from rock outcrops and grassland habitats were overrepresented in the urban vegetation. These results contrast with the received view that cities represented highly “unnatural” ecosystems: built form appears to replicate the habitat templates required by rock outcrop species. Urban ecological theory should incorporate the replication of habitat analogs by built forms in addition to the creation of ecologically novel habitats.     

Notes on the evolution and organization of the urban ecosystem

The continual spread of human settlements over the world’s surface has transformed the natural environment on a global scale. Human’s intervention has changed primary ecosystems (protoecosystems or euecosystems) into anthropoecosystems. The spread of urban ecosystems, cultivated surfaces (agroecosystems), and various areas differentiated by their level of anthropization has facilitated the progressive reduction of euecosystems. The evolution of urban areas over the course of history with transformations of cities and surrounding territory, has created very complex mosaics. A proper study of the city, drawing together historical, cultural, social, and other factors, as well as abiotic ones (urban climate, soil, water, air), requires appropriate, uniform terminology for expressing the complex relationships existing among these factors. We therefore propose that the city (or metropolis) be considered as a set of ecosystems, a “synecosystem”. The entire urban area should be termed a “synbiotope”. It is divided into numerous partial biotopes (macro-, meso- and microbiotopes), the result of modifications wrought through the historical and cultural vicissitudes of the human population. Urban biotopes host not only humans, but also a characteristic vegetable and animal component, the “biosyncoenosis”, formed of numerous plant and animal communities, selected on the basis of the environmental conditions of the individual biotopes, which differ from each other in structure, dynamics, age, and position in the urban space. This terminology should facilitate study of the biotic component and its connection to the urban territory, as well as interpretation of results obtained in the different disciplines in terms of the human population’s quality of life.