Urban environment - Urban biodiversity

Title

The carbon footprint of urban green space—A life cycle approach

Reference

Landscape and Urban Planning
Volume 104, Issue 2, February 2012, Pages 220–229

Author(s)

Michael W. Strohbach, Eric Arnold, Dagmar Haase

Study type

Peer Review Journal    

Abstract

Cities play an important role in the global carbon cycle. They produce a large proportion of CO2 emissions, but they also sequester and store carbon in urban forests and green space. However, sequestration by urban green space is difficult to quantify and also involves emissions. The carbon footprint analysis is an established method for systematically quantifying carbon sinks and sources throughout the lifetime of goods and services. We applied this method to an urban green space project in Leipzig, Germany. To the best of our knowledge it is the first application in this field. We simulated carbon sequestration by growing trees and contrasted it with all related carbon sources, from construction and maintenance over the lifetime of 50 years. In addition, we explored alternative design and maintenance scenarios. Total net sequestration was predicted to be between 137 and 162 MgCO2 ha−1. Park-like design and maintenance is less effective than forest-like design and maintenance. Much uncertainty is linked to tree growth and tree mortality. Increasing annual tree mortality from 0.5 to 4% reduces sequestration by over 70%. In conclusion, urban green space can act as a carbon sink and the design and maintenance have a strong influence on the carbon footprint. The carbon footprint analysis is a valuable tool for estimating the long-term environmental performance of urban green space projects. Compared to emissions from people, the overall potential for carbon mitigation is limited, even in cities such as Leipzig with widely available space for new urban green space.

Policy theme(s)

Biodiversity >> Habitats >> Green Infrastructure
Climate change and energy >> Climate change mitigation >> Carbon sinks
Urban environment >> Urban biodiversity

Keywords

Carbon sequestration; Urban forestry; Life cycle assessment; Urban decline;
Urban reconstruction

Entry Source:

Selected for Science for Environment Policy News Alert

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http://www.sciencedirect.com/science/article/pii/S016920461100301X
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strohbach@eco.umass.edu

Title

Temporal changes in greenspace in a highly urbanised area

Reference

Biology Letters: Royal Society Publishing

Author(s)

Martin Dallimer ,Zhiyao Tang ,Peter R Biddy ,Paul Brindley ,Kevin J Gaston ,Zoe G Davies

Study type

Peer Review Journal

Abstract

The majority of the world's population now lives in towns and cities, and urban areas are expanding faster than any other land-use type. In response to this phenomenon, two opposing arguments have emerged: whether cities should ‘sprawl’ into the wider countryside, or ‘densify’ through the development of existing urban greenspace. However, these greenspaces are increasingly recognized as being central to the amelioration of urban living conditions, supporting biodiversity conservation and ecosystem service provision. Taking the highly urbanized region of England as a case study, we use data from a variety of sources to investigate the impact of national-level planning policy on temporal patterns in the extent of greenspace in cities. Between 1991 and 2006, greenspace showed a net increase in all but one of 13 cities. However, the majority of this gain occurred prior to 2001, and greenspace has subsequently declined in nine cities. Such a dramatic shift in land use coincides with policy reforms in 2000, which favoured densification. Here, we illustrate the dynamic and policy-responsive nature of urban land use, thereby highlighting the need for a detailed investigation of the trade-offs associated with different mechanisms of urban densification to optimize and secure the diverse benefits associated with greenspaces.

Policy theme(s)

Land use >> Planning
Urban environment >> Urban planning >> Urban land use
Urban environment >> Urban biodiversity

Keywords

Urbanization, ecosystem services, urban ecology, urban greenspace

Entry Source:

N/A

Referred to in EC doc:

Selected for Science for Environment Policy News Alert

View this study at:

http://rsbl.royalsocietypublishing.org/content/early/2011/03/16/rsbl.2011.0025.abstract
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Contact the study author at:

z.g.davies@kent.ac.uk

Title

Positive effects of vegetation: Urban heat island and green roofs

Reference

Environmental Pollution
Volume 159, Issues 8-9, August-September 2011, Pages 2119-2126

Author(s)

T. Susca, S.R. Gaffin and G.R. Dell'Osso

Study type

Peer Review Journal

Abstract

This paper attempts to evaluate the positive effects of vegetation with a multi-scale approach: an urban and a building scale.
Monitoring the urban heat island in four areas of New York City, we have found an average of 2 °C difference of temperatures between the most and the least vegetated areas, ascribable to the substitution of vegetation with man-made building materials. At micro-scale, we have assessed the effect of surface albedo on climate through the use of a climatological model. Then, using the CO2 equivalents as indicators of the impact on climate, we have compared the surface albedo, and the construction, replacement and use phase of a black, a white and a green roof. By our analyses, we found that both the white and the green roofs are less impactive than the black one; with the thermal resistance, the biological activity of plants and the surface albedo playing a crucial role.

Policy theme(s)

Urban environment >> Urban biodiversity
Biodiversity >> Ecosystem services
Urban environment >> Urban planning >> Healthy cities
Climate change and energy >> Climate change adaptation >> Social and health impacts

Keywords

Vegetation, Green roof, Surface albedo, Urban heat island

Entry Source:

Selected for Science for Environment Policy News Alert

Referred to in EC doc:

N/A

View this study at:

http://www.sciencedirect.com/science/article/pii/S0269749111001539
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Contact the study author at:

Tiziana.susca@gmail.com

Title

Urban forests and pollution mitigation: Analyzing ecosystem services and disservices

Reference

Environmental Pollution
Volume 159, Issues 8-9, August-September 2011, Pages 2078-2087

Author(s)

Francisco J. Escobedo, Timm Kroege and John E. Wagner

Study type

Peer Review Journal

Abstract

The purpose of this paper is to integrate the concepts of ecosystem services and disservices when assessing the efficacy of using urban forests for mitigating pollution. A brief review of the literature identifies some pollution mitigation ecosystem services provided by urban forests. Existing ecosystem services definitions and typologies from the economics and ecological literature are adapted and applied to urban forest management and the concepts of ecosystem disservices from natural and semi-natural systems are discussed. Examples of the urban forest ecosystem services of air quality and carbon dioxide sequestration are used to illustrate issues associated with assessing their efficacy in mitigating urban pollution. Development of urban forest management alternatives that mitigate pollution should consider scale, contexts, heterogeneity, management intensities and other social and economic co-benefits, tradeoffs, and costs affecting stakeholders and urban sustainability goals.
Environmental managers should analyze ecosystem services and disservices when developing urban forest management alternatives for mitigating urban pollution.

Policy theme(s)

Urban environment >> Urban biodiversity
Biodiversity >> Ecosystem services   
Air pollution >> Managing emissions >> Reduction measures

Keywords

Scale, Context, Management intensity, Heterogeneity, Economic value

Entry Source:

Shortlisted for Science for Environment Policy News Alert

Referred to in EC doc:

N/A

View this study at:

http://www.sciencedirect.com/science/article/pii/S0269749111000327
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fescobed@ufl.edu

Title

Reference

Journal of Applied Ecology doi: 10.1111/j.1365-2664.2011.02021.x

Author(s)

Study type

Peer Review Journal

Abstract

1.Despite urbanization being a major driver of land-use change globally, there have been few attempts to quantify and map ecosystem service provision at a city-wide scale. One service that is an increasingly important feature of climate change mitigation policies, and with other potential benefits, is biological carbon storage.
2.We examine the quantities and spatial patterns of above-ground carbon stored in a typical British city, Leicester, by surveying vegetation across the entire urban area. We also consider how carbon density differs in domestic gardens, indicative of bottom-up management of private green spaces by householders, and public land, representing top-down landscape policies by local authorities. Finally, we compare a national ecosystem service map with the estimated quantity and distribution of above-ground carbon within our study city.
3.An estimated 231-521 tonnes of carbon is stored within the above-ground vegetation of Leicester, equating to 3•16 kg C m-2 of urban area, with 97•3% of this carbon pool being associated with trees rather than herbaceous and woody vegetation.
4.Domestic gardens store just 0•76 kg C m-2, which is not significantly different from herbaceous vegetation landcover (0•14 kg C m-2). The greatest above-ground carbon density is 28•86 kg C m-2, which is associated with areas of tree cover on publicly owned/managed sites.
5.Current national estimates of this ecosystem service undervalue Leicester's contribution by an order of magnitude.
6.Synthesis and applications. The UK government has recently set a target of an 80% reduction in greenhouse gas emissions, from 1990 levels, by 2050. Local authorities are central to national efforts to cut carbon emissions, although the reductions required at city-wide scales are yet to be set. This has led to a need for reliable data to help establish and underpin realistic carbon emission targets and reduction trajectories, along with acceptable and robust policies for meeting these goals. Here, we illustrate the potential benefits of accounting for, mapping and appropriately managing above-ground vegetation carbon stores, even within a typical densely urbanized European city.

Policy theme(s)

Sustainable development and policy assessment >> Sustainable economic development >> Sustainable urban development
Urban environment >> Urban biodiversity

Keywords

Backyard, carbon pool, domestic gardens, land-use change, urban ecology, urban forestry, urban vegetation, urbanization

Entry Source:

Selected for Science for Environment Policy News Alert

Referred to in EC doc:

N/A

View this study at:

http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2664.2011.02021.x/pdf
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z.g.davies@kent.ac.uk

Title

How to manage the urban green to improve bird diversity and community structure

Reference

Landscape and Urban Planning
Volume 101, Issue 3, 15 June 2011, Pages 278-285

Author(s)

Simone Fontana, Thomas Sattler, Fabio Bontadina and Marco Moretti

Study type

Peer Review Journal

Abstract

Urbanization is a fundamental environmental change, today happening at accelerated speed worldwide. Despite the strong and permanent human impact, urban biodiversity has generally proved to be surprisingly high. Quantitative information on the effect of management actions on biodiversity is often lacking but is an indispensable basis for decisions by urban planners and managers. We therefore quantified key urban variables to predict changes in avian biodiversity when their urban habitat is modified. We analysed species richness, diversity (Simpson index) and community composition of 63 bird species with reference to major urban environmental gradients at 96 sampling points in three Swiss cities. Best explanatory models were selected from candidate models following information theory, and their respective predictions were averaged based on AICc-weights. Bird species richness and diversity are negatively affected by increasing fractions of sealed area or buildings, while increasing vegetation structures, in particular trees, show positive effects. Our models predict an increase from 13 species in the absence of trees to 20 species with 46% tree cover (+54%). Coniferous trees help to maximize bird species richness, with the models predicting an increase from 14 species at sites with only deciduous woody plants to 20 species (+43%) at places with equal representation of coniferous and deciduous plants. While the analysis of the Simpson index did not show any influence of the coniferous and broadleaf woody plants mixture, partial redundancy analysis revealed such an influence on bird community composition, highlighting the importance to consider several measures when analyzing biodiversity.

Policy theme(s)

Urban environment >> Urban biodiversity
Biodiversity >> Habitats >> Urban biodiversity

Keywords

City, Coniferous woody plants, Structural complexity, Bird biodiversity, Switzerland

Entry Source:

Selected for Science for Environment Policy News Alert

Referred to in EC doc:

N/A

View this study at:

http://www.sciencedirect.com/science/article/pii/S0169204611000995
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simone.fontana@wsl.ch

Title

Urban green zones and related pollen allergy: A review. Some guidelines for designing spaces with low allergy impact

Reference

Landscape and Urban Planning
Volume 101, Issue 3, 15 June 2011, Pages 205-214

Author(s)

Paloma Cariñanos and Manuel Casares-Porcel

Study type

Peer Review Journal

Abstract

Urban green spaces are a key element in the planning of today's cities, since they favor the interaction between citizens and the environment, as well as promoting human health. However, lack of planning in the design of urban spaces and in the choice of ornamental species has been among the factors triggering one of the most widespread diseases in urban populations: pollen allergy. In this paper are reviewed the major causes of this extensive allergenicity, including: low species biodiversity at planting; the overabundance of given species acting as key specific pollen sources; the planting of exotic species prompting new allergies in the population; the choice of male, pollen-producing individuals in dioecious species; the presence of invasive species; inappropriate garden management and maintenance activities; the appearance of cross-reactivity between phylogenetically related species; and the interaction between pollen and air pollutants. The findings of this analysis highlight the clear need for guidelines regarding the design and planning of urban green spaces with a low allergy impact. Proposals include increased biodiversity, careful control when planting exotic species, the use of low pollen producing species, the adoption of appropriate management and maintenance strategies, and active consultation with botanists when selecting the most suitable species for a given green space.

Policy theme(s)

Biodiversity >> Habitats >> Urban biodiversity
Urban environment >> Urban biodiversity
Urban environment >> Urban planning >> Healthy cities

Keywords

Allergenicity, Pollinosis, Urban green spaces, Ornamental species, Aerobiology

Entry Source:

Selected for Science for Environment Policy News Alert

Referred to in EC doc:

N/A

View this study at:

http://www.sciencedirect.com/science/article/pii/S016920461100137X
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Contact the study author at:

palomacg@ugr.es