Intrinsic and extrinsic drivers of yard vegetation in urban residential areas: implications for conservation planning

Residential green areas often represent a significant portion of a city’s green infrastructure which has generated great interest in studying the factors that contribute to the formation of plant associations in residential yards. This project evaluated the external factors to the household social-ecological system that influence the availability of plants for residential landscapes and how they may influence the presence of native plants in residential yards on households within the Río Piedras watershed in the metropolitan area of San Juan, Puerto Rico. The methods used included a residential survey with open and closed questions that addressed the sources of plants used in landscaping and an evaluation of ornamental plant species inventories from local nurseries. A total of 432 yards were surveyed. Yard plants in this watershed have multiple sources. Aside from obtaining plants at local nurseries, natural dispersion, exchanges among family and friends and historical plantings can be just as important sources of yard plants. Our results also suggest that the majority of residents do not know where to get native plants which could represent a challenge for the development and implementation of initiatives for natives gardening. At the same time, most commercial nurseries have a deficit of native plants in their inventories. This information is critical to species conservation strategies that seek the inclusion of urban residential areas and may help improve initiatives about the involvement of individual citizens in sustainable gardening practices at the residential scale.     

Stream restoration in Andean cities: learning from contrasting restoration approaches

Urban Ecosystems - The Andes region is one of the fastest urbanizing regions of the world. The current rate of environmental degradation of streams in this region create an urgent need for...     

Engaging urban nature: improving our understanding of public perceptions of the role of biodiversity in cities

In recognition of the value of biodiversity for cities and citizens, a number of international programs have been designed to help municipal governments sustain, protect, and augment the biodiversity and ecosystem services within their jurisdictions. A key component of these programs is public engagement, where citizens assume a more active role in maintaining urban biodiversity and associated ecosystem services. Yet, there are few studies which have as their focus public knowledge of the importance of nature, biodiversity, and ecosystem services in cities. To these ends, this study was conducted to develop a better understanding of how the public understands and interacts with urban biodiversity, particularly in comparison to subject matter experts. Using topics generated from expert interviews and the literature, an interview guide was developed for the general public, structured around the general themes of a definition of urban biodiversity, as well as the perceived benefits, costs, and threats related to urban biodiversity. While there were similarities in the responses of citizens and experts, some differences did emerge in terms of accounting for specific urban ecosystems, acceptable interventions to support and enhance biodiversity, and the character and extent of the cultural services derived from urban nature. Insights from this work can be used to inform education and information efforts for the public, as well as raise awareness among city planners and nature professionals of the array of urban ecosystem services recognized and made use of by the public.

     

A spatial analysis of indigenous cover patterns and implications for ecological restoration in urban centres,New Zealand

High levels of endemism, the sensitivity of species that have evolved without humans, and the invasion of exotic species have all contributed to severe depletion of indigenous biodiversity in New Zealand. We considered the contribution that urban restoration can make to maximising biodiversity by analysing landcover patterns from two national databases along an urban–rural gradient. Thirteen of 20 land environments in New Zealand are represented in cities, and nearly three-quarters of all acutely threatened land environments are represented within 20 km of city cores nationally. Despite this, remaining indigenous landcover is low within urban cores, with less than 2% on average, but increasing to more than 10% on average in the periurban zone. Threatened lowland environments are most commonly represented within cities, and least represented within protected natural areas. Restoration of existing urban habitat is insufficient to halt biodiversity loss. Ecosystem reconstruction is required to achieve a target of 10% indigenous cover within cities. A co-ordinated national urban biodiversity plan to address issues beyond a local and regional focus is needed. Analysis of national patterns of urban land environments, indigenous cover and remnant ecosystems will support action at a regional and local level while enhancing national and global biodiversity goals.     

Urban bird conservation: presenting stakeholder-specific arguments for the development of bird-friendly cities

Following the call from the United Nations Convention on Biological Diversity “Cities & Biodiversity Outlook” project to better preserve urban biodiversity, this paper presents stakeholder-specific statements for bird conservation in city environments. Based upon the current urban bird literature we focus upon habitat fragmentation, limited habitat availability, lack of the native vegetation and vegetation structure as the most important challenges facing bird conservation in cities. We follow with an overview of the stakeholders in cities, and identify six main groups having the greatest potential to improve bird survival in cities: i) urban planners, urban designers and (landscape) architects, ii) urban developers and engineers, iii) homeowners and tenants, iv) companies and industries, v) landscaping and gardening firms, vi) education professionals. Given that motivation to act positively for urban birds is linked to stakeholder-specific advice, we present ten statements for bird-friendly cities that are guided by an action perspective and argument for each stakeholder group. We conclude with a discussion on how the use of stakeholder-specific arguments can enhance and rapidly advance urban bird conservation action.     

Learning about restoration of urban ecosystems: a case study integrating public participation,stormwater management,and ecological research

Restoration of ecosystem functions in urban environments is made challenging by 1) a public that often lacks understanding of ecological principles, 2) inadequate evidence of the effectiveness of restoration practices, and 3) difficulty integrating social and biophysical factors in studies of urban ecosystems. This paper describes a case study in which potential solutions to these challenges were explored. We facilitated collaborative learning through public participation in the design and implementation of an urban riparian buffer along a headwater stream in a neighborhood park, a process that was informed by ecological research. Learning outcomes were evaluated using surveys and qualitative assessment of discussion. Results indicated that participants’ knowledge about water quality problems associated with urbanization, stormwater, and nonpoint-source pollution increased, familiarity with stormwater management practices increased, and perceptions about the importance of stream ecosystem functions changed. In-stream monitoring of sediment delivery, as well as direct measurements of buffer infiltration capacity, provided early evidence of buffer effectiveness in prevention of sediment inputs to the stream and absorption of runoff from surrounding surfaces. This study provides a useful model for integration of collaborative learning through participation, ecological restoration, and ecological research in an urban setting. Elements deemed essential to success of this model included an opportunity for dialog focused on a specific natural feature, sustained interaction between participants and researchers, opportunities for hands-on participation by urban residents, and flexibility in restoration practice installation.     

The role of urban indicators in city management: a proposal for Croatian cities

Cities are dynamic economic and social structures that play a dominant role in both national and international economies. They are centers of population, production, consumption, and development. Cities utilize all advantages of economy of scale, proximity, and concentration. On the other hand, they produce high environmental pressures and diminish thereby the quality of life for urban residents. Indicators (environmental, economic, and governance and management) are seen as a tool that would help policy-makers in formulating urban policy that would lead cities towards sustainability and provide assistance for monitoring their development and municipal performance. The aim of this paper is to consider the role that urban indicators can play in city management. We present basic features of urban indicators that will determine their usefulness in urban management. This paper provides the framework to include environmental and economic indicators, as well as governance and management indicators, in successful urban management.     

Beyond the urban stream syndrome: organic matter budget for diagnostics and restoration of an impaired urban river

In response to water quality standard violations linked to excessive organic matter (OM) and a lack of sampling data informing the Total Maximum Daily Load (TMDL), an organic matter budget was created to quantify and identify sources of OM in the lower Jordan River (Salt Lake City, UT). By sampling dissolved, fine, and coarse particulate OM, as well as measuring ecosystem metabolism at seven different sites, the researchers aimed to identify the origin of excess OM, and understand pathways by which different size classes of the OM pool are generated. The dissolved fraction (DOM; 94 %) was found to be the dominant form of OM transported within the river with fine particulate organic matter (FPOM; 6 %) the second most abundant, and coarse particulate organic matter (CPOM; 1 %) transport relatively insignificant in the overall OM budget. Primary production exceeded respiratory losses in the upper river, and this, along with OM inputs from two tributaries (where water reclamation facilities discharge into the river) delivered excess OM to the impaired lower reaches. Increasing stream metabolism index (SMI) with distance downstream (>1 in the lower river) further demonstrated that transport of excessive organic matter into the lower river was from upstream sources and not due to lateral inputs. This simple approach to characterizing the organic matter budget as it relates to water quality in the Jordan River was effective and could serve as a model for future studies attempting to quantify and identify sources of OM in urban ecosystems.     

Beyond the urban stream syndrome: organic matter budget for diagnostics and restoration of an impaired urban river

In response to water quality standard violations linked to excessive organic matter (OM) and a lack of sampling data informing the Total Maximum Daily Load (TMDL), an organic matter budget was created to quantify and identify sources of OM in the lower Jordan River (Salt Lake City, UT). By sampling dissolved, fine and coarse particulate OM, as well as measuring ecosystem metabolism at seven different sites, the researchers aimed to identify the origin of excess OM, and understand pathways by which different size classes of the OM pool are generated. The dissolved fraction (DOM; 94 %) was found to be the dominant form of OM transported within the river with fine particulate organic matter (FPOM; 6 %) the second most abundant, and coarse particulate organic matter (CPOM; 1 %) transport relatively insignificant in the overall OM budget. Primary production exceeded respiratory losses in the upper river, and this, along with OM inputs from two tributaries (where water reclamation facilities discharge into the river) delivered excess OM to the impaired lower reaches. Increasing stream metabolism index (SMI) with distance downstream (>1 in the lower river) further demonstrated that transport of excessive organic matter into the lower river was from upstream sources and not due to lateral inputs. This simple approach to characterizing the organic matter budget as it relates to water quality in the Jordan River was effective and could serve as a model for future studies attempting to quantify and identify sources of OM in urban ecosystems.     

Sustainable urban greening strategies for compact cities in developing and developed economies

Urban greening contributes notably to quality of life and ecosystem services in cities. Compact cities in developing and developed countries are commonly beset by greenspace deficit. Based on literature review supplemented by field studies in different cities, a sustainable urban greening strategy is proposed. Urban renewal and new developments without a greening vision could miss the opportunities to bring relief. The public and private sectors can join hands to insert plantable spaces into the urban fabric. Urban greenspaces (UGS) with good connectivity forming a green network to permeate the city constitute the hallmarks of a naturalistic design. Preservation and creation of natural areas with rich biodiversity offer a new dimension to UGS design. Greening benefits could be expressed in economic terms to complement conventional ecological-environmental emphasis. Outstanding trees could receive high-order conservation efforts, and trees in construction sites warrant enhanced protection. Tree transplanting demands an overhaul in concepts and skills. Improving roadside tree planting and maintenance offers a cost-effective way to upgrade the townscape. Ameliorating widespread soil limitations could remove a major hindrance to tree growth. Innovative ideas of development right transfer, street pedestrianization, river and canal revitalization, green roofs and green walls could mobilize hitherto underused plantable resources. Lacking appropriate institutional setup and scientific capability pose intractable bottlenecks. Innovative public policies and greening technologies are needed for sustained improvements. Amalgamating natural and social sciences in a multidisciplinary approach and reinforcing the link between science and public policies could overhaul greening.     

Managing urban wetlands for multiple use: research,restoration, and recreation

Conservation of urban wetland habitat is challenging, because multiple uses must coexist. We use examples from California and Wisconsin to describe potential synergies among recreation, restoration and research activities (the 3 R's). Allowing passive recreation is often essential to garner public support for habitat protection, restoration, and research. In turn, restoration activities can improve the appearance of degraded sites, and designing the work as a research experiment can serve the scientific community. Two projects at Tijuana Estuary support the 3 R's. (1) Oneonta Tidal Linkage is a 0.7-ha tidal channel and salt marsh that was excavated from disturbed upland to bring wetland habitat closer to the Visitor Center (thereby reducing visitor intrusion into natural marsh habitat, where endangered species would be disturbed). It supports an ambitious field experiment that is testing the importance of species diversity in restoration; it also includes a bridge that serves the interpretive program, and it adds 0.7 ha of wetland habitat that helps restore regional biodiversity. (2) A larger excavation (8 ha) of former tidal wetland will soon add wetland habitat, while testing the importance of tidal creek networks in ecosystem functioning and offering views and interpretive opportunities. A third situation, at the 485-ha University of Wisconsin–Madison Arboretum, concerns restored wet prairies, which provide habitat for native species and serve many hikers. Urban stormwater flows into and degrades the Henry Greene Prairie, allowing aggressive plants to invade. Research and restoration efforts are planned to sustain the habitat and recreation functions. These three models suggest that recreation, restoration, and research are compatible uses of urban wetland habitats.     

Are larger cities more central in urban networks: A meta-analysis

As cities develop more and longer-range external relations, some have challenged the long-standing notion that population size indicates a city's power in its urban system. But are population size and network centrality really independent properties in practice, or do larger cities tend to be more central in urban networks? To answer this question, we conducted a systematic literature search and meta-analysed 41 reported correlations between city size and degree centrality. The results show that population size and degree centrality are significantly and positively correlated for cities across various urban systems (r = 0.77), but the correlation varies by network scale and type. The size-centrality association is weaker for global economic and transportation networks (r = 0.43), and stronger for non-global social and communication networks (r = 0.91). This clarifies seemingly contradictory predictions in the literature regarding the association betweensize and centrality for cities.     

Erratum to: Beyond the urban stream syndrome: organic matter budget for diagnostics and restoration of an impaired urban river

Urban Ecosystems - This article was unintentionally published twice in this journal, by the same authors.     

Institutional determinants of saving: implications for low-income households and public policy

There is an emerging policy and academic discussion, supported by a growing body of empirical evidence, regarding the potentially positive effects of asset accumulation in low-income households. However, at least two questions precede this discussion: Can the poor save? And, if so, how can programs and policies promote saving by the poor? This paper begins to address these questions by examining the effects of institutional variables on saving behavior. We posit that four institutional variables—institutionalized saving mechanisms, targeted financial education, attractive saving incentives, and facilitation—promote saving. However, low-income households are substantially less likely to have access to these institutions, a phenomenon that may help explain their below-average saving rates. This discussion has implications, especially as policy-makers consider various proposals to increase the saving rates of low- and middle-income Americans.     

Habitat equivalency in urban estuaries: An analytical hierarchy process for planning ecological restoration

Ecosystem restoration is critically important in urbanized landscapes because habitat degradation is severe and ubiquitous in such areas. Because successful restoration requires specification of desired environmental endpoints, a generally applicable method for valuing and comparing possible restoration endpoints is needed. One method available for comparative valuation is the Analytical Hierarchy Process (AHP). AHP allows a suite of alternatives to be valued on a rank scale based on simple, tractable, paired comparisons among all alternatives. Given a sound technical foundation for the paired comparisons, the method yields an objective set of rank values. By incorporating the relative values of various restoration alternatives in a restoration scaling evaluation such as a Habitat Equivalency Analysis (HEA), restoration programs can be designed effectively both qualitatively (in terms of the kinds of resources or habitats desired) and quantitatively (in terms of the amounts or areas of each). In this study, we develop and apply AHP in the context of a specimen HEA for US Mid-Atlantic coast estuaries. By ranking various habitat types as potential restoration targets based on their value for a suite of key natural resources, a series of restoration ratios is produced, relating relative habitat areas of each type needed to offset specific impairment levels. These ratios provide a basic tool for restoration planning in urbanized estuaries, as these comprise nearly entirely built environments with little or no natural habitat. Under these conditions, restoration planners must specify desired states of the ecosystem, and the restoration ratios allow various permutations of presumed post-restoration environments to be valued and compared.     

Diversity and structure of urban forests of Sahel cities in Niger

Urban Ecosystems - Urbanization in the Sahel is constantly competing with and greatly affecting the woody flora in urban areas. Urbanization can replace the species mix, leading to changes in plant...     

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.     

Embeddedness and cohesion: regimes of urban public goods distribution

Theory and Society - Why do some urban governing regimes realize a more equal distribution of public goods than others? Local government interventions in São Paulo, Brazil, have produced...     

Ecology and conservation of strangler figs in urban wall habitats

Hong Kong’s rugged topography demands creation of developable land by reclaiming the harbor and terracing hillslopes. The vertical faces between adjoining hillslope-platforms are often stabilized by stone retaining walls. Such artificial cliffs embedded in the urban matrix, as a habitat analogue of rocky cliffs, have been colonized by spontaneous-ruderal vegetation. Detailed field assessment of 289 walls with 793 trees permitted in-depth analysis of this unique tropical urban ecology to inform conservation. The 28 stonewall tree species, mainly native, are dominated by six keystone and companion Ficus (Moraceae) species. They can develop into large cliff hangers >?20 m height on the apparently precarious and inhospitable walls. The many joints between masonry blocks provide opportunities for lodging and germination of seeds brought by frugivorous birds and bats. The aft-soil behind walls provides catchment for normal root functions. Beginning as pioneers and persisting as climax members, they short-circuit the seral processes. Wall-gripping capability as large epilithic woody hemi-epiphytes is due to the strangler-fig habit, an evolutionary trait that originated in the tropical forest. The polymorphic roots with morphological plasticity and self-grafting ability, and their multiple modes of interactions with wall niches, account for firm attachment on the vertical habitat and exploration of proximal soils. A model of strangler-fig growth on stone walls serving as surrogate host tree is developed. The diverse and versatile rooting modes are the basis to sustain strangler-fig wall conditions to permit continuation of strangler-fig habit. Such unique nature-in-city and natural-cum-cultural gems deserve conservation as urban ecological heritage.     

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.