An excellent briefing paper ‘Urban Green Infrastructure and Ecosystem Services’ has just been released – this is a responsive policy briefings developed by the Parliamentary Office of Science and Technology based on mini literature reviews and peer review.
Ecosystem services are the benefits provided to humans by natural systems that range from food and water to recreation and climate regulation and elements of the natural environment that provide benefits to humans are referred to as ‘natural capital’ . The best outcome for ecosystem service provision is optimal human health and subjective well-being.
The EU defines green infrastructure strategy as: ‘a strategically planned network of natural and semi-natural areas with other environmental features designed and managed to deliver a wide range of ecosystem services – incorporating green spaces and blue if aquatic ecosystems are concerned plus other physical features in terrestrial and marine areas’. However, existing urban green infrastructure in the UK has not been strategically planned to deliver ecosystem services.
Research points to the benefits of exposure and frequency of exposure to green infrastructure for well-being – although the specific elements of the natural environment need further research to demonstrate clear correlation. In addition, there is growing evidence that green infrastructure can provide other ecosystem services in urban areas such as reducing the risk of flooding and cooling high urban temperatures. The demand for this will increase in relation to climate change.
The report goes on to define what constitutes an urban area plus the effects of increased urbanisation on the environment such as excessive air pollution form increased traffic in cities such as London and Birmingham and the statistically significant relationships between soil metal content and respiratory illness reported in Glasgow.
Natural capital – elements of the natural environment that provide benefits for humans -is discussed. The report states that the value of green infrastructure may be enhanced through appropriate management of its natural capital and that the Natural Capital Committee’s 4th Report recommends that local authorities and major infrastructure providers ensure that natural capital is protected and improved.
The Department for Business, Energy and Industrial Strategy has funded an Ordinance Survey open data initiative to map green spaces throughout Great Britain. The data collected, along with property information, will be used to value natural capital in urban environments. [Ordnance Survey releases open dataset and free map of Britain’s Greenspaces + OS MasterMap Greenspace Layer ] This will allow you to identify the variety of different greenspaces in any location plus provide information on their extent, function and accessibility, and the provision of ecosystem services.
The report identifies the following key services provided by ecosystem services with accompanying up-to-date references for links to research, reports and policy documents:
- Urban temperature regulation
- Provision of community food
- Improving air quality
- Reducing surface water flooding
- Noise Reduction
- Carbon Storage
- Environmental Settings and Biodiversity
The report discusses how levels of service provision can be assessed and rcognises that further research in relation to how biodiversity generates ecosystem services benefits in different urban habitats and at different scales may be required to be able to effectively assess ecosystem condition. The EU Biodiversity Strategy to 2020 requires member states to map and assess ecosystems with guidance for mapping and assessing urban ecosystems provided by the European Commission. [Mapping and Assessment of Ecosystems and their Services, Urban ecosystem, 4th Report, Technical Report 102]
The report also recognises that not all contributions from ecosystem services are positive – these may be actual or perceived – such as the negative effects on human health from pests and diseases. Cultural perceptions in relation to green infrastructure is mentioned and these may vary between individuals depending on factors such as age, gender and socioeconomic status. The importance of public consultation is recognised when green infrastructure strategies are being developed to overcome such cultural perceptions.
Planning Green Infrastructure
Strategically designed and planned, green infrastructure can deliver multiple benefits for human well-being with Birmingham, Manchester and London already developing green infrastructure plans to address this. [ Green Infrastructure Task Force Report, 2015, Natural Capital: Investing in a Green Infrastructure for a Future London] England’s National Planning Policy Framework requires that Local Plans should take account of climate change over the longer term, including factors such as flood risk, coastal change, water supply and changes to biodiversity and landscape. Two variables are the combination of low density urban areas of built land interspersed with green spaces and compact urban areas alongside separate, large, contiguous green space, such as city greenbelts with the proviso that some interspersion of accessible green infrastructure may be necessary to ensure that people continue to gain benefits. The report notes that despite the development of new ‘garden’ cities and towns in the UK and proposals for legislation for New Towns Development Corporations there are no planning rules based on available evidence for ecosystem service provision from garden cities and new town developments.
The development of urban green space strategies
The House of Commons Communities and Local Government Select Committee has recommended that local authorities work collaboratively with Health and Wellbeing Boards, and relevant bodies, to develop and publish joint park and green space strategies. The UK’s National Planning Policy Framework requires planning to be based on robust and up-to-date assessments of the needs for open space, sports and recreation facilities and opportunities for new provision. The assessments should identify specific needs and deficits or surpluses of open space, sports and recreational facilities in the local area. However, in the UK, local authorities directly manage only a small proportion of the green space in urban areas, creating challenges for strategic management of urban green space.
How best then to optimise urban green infrastructure? At present the emphasis on green space provision is its amenity outcomes rather than the benefits derived from ecosystem service. Lack of evidence in relation to the economic benefits is commonly sited as the most significant gap in the case for investing in green infrastructure.
Green walls, designed so they are covered in vegetation, could help cut the amount of noise that enters buildings, a new study has found. In laboratory tests, researchers found that a modular green wall system reduced sound levels by 15 decibels (dB). This may be a promising sound reduction device that could improve quality-of-life for city residents.
Source: Azkorra, Z., Pérez, G., Coma, J. et al. (2015). Evaluation of green walls as a passive acoustic insulation system for buildings. Applied Acoustics 89: 46–56. DOI:10.1016/j.apacoust.2014.09.010.
Green walls and green roofs can provide ecosystem services in urban areas. Their benefits include: lower energy use in buildings, support for biodiversity and storm-water control. Studies have also shown that they reduce noise levels. However, most studies have focused on green roofs’ ability to insulate buildings from external sound, and very little research has looked specifically at green walls.
This Spanish study, carried out under the EU-funded SILENTVEG project (1), conducted laboratory tests on green walls’ acoustic properties. Its aim was to help predict their sound insulation performance in the real world. The design of green walls can affect their sound insulation properties with the type of plant grown having a big effect. In this case, the study focused on a modular green wall system, which is composed of compartments or boxes attached to a vertical frame and is the most widely used system.
The boxes in this study were made of recycled plastic and filled with coconut fibre, acting as ‘soil’. They were all planted with Helichrysum thianschanicum, a popular shrub for gardening in the Mediterranean region, with an average height of 40 cm. The researchers placed 10 of the boxes, totalling 2.4 m2 in area, onto a wall which separated two rooms. They emitted noise in one room at frequencies ranging between 100 hertz (Hz) and 5 000 Hz, and then measured the reduction in noise levels in the neighbouring room caused by the green wall.
The green wall reduced noise levels in the neighbouring room by an average of 15 dB. The researchers note that this reduction is quite low compared with other solutions; thermal double-glazing can reduce noise by 30 dB, for example. A sound barrier made from two layers of plasterboard, separated by a wool-filled cavity, can reduce noise by 70 dB.
Nonetheless, they believe it still has good potential to help cut noise levels in urban buildings and could be used effectively in public places, such as hotels and restaurants. Furthermore, if its design was improved by sealing the joints between the boxes, then it could reduce noise by an extra 3 dB. The other benefits of green walls, such as increased biodiversity, visual attractiveness, air purification or climate regulation, also make them an attractive option.
This experiment considered noise that is transmitted directly through a wall, but in a realistic situation noise bounces off different surfaces and can be transmitted indirectly through a number of routes. Therefore the logical next step in this research would be to test the green wall on actual building façades, the study’s authors say.
To further improve their understanding of the wall’s basic acoustic properties, the researchers also investigated how much sound a green wall can absorb. In this experiment, they placed the green wall (this time 10 m2 in area) on the floor of a room in which sound was emitted, again at frequencies of 100–5 000 Hz. The wall was calculated to have a ‘sound absorption coefficient’ of 0.40, i.e. it absorbed 40% of the sound.
- SILENTVEG: Barreras vegetales autónomas y sostenibles para la mitigación acústica y compensación del CO2 en vías de transporte, con seguimiento telemático, was supported by the European Union’s Regional Development Fund. See: http://www.aopandalucia.es/innovacion/principal.asp?alias=al_barreras&zona=proyectos&t=0 (in Spanish)
This study is free to view at: http://www.sciencedirect.com/science/article/pii/S0003682X14002333
- Natural capital is a term used to describe those elements of the natural environment that provide benefits for humans.
- In 2015, the Natural Capital Committee, a Government advisory group, made nine recommendations on how to account for natural capital. These included the creating of a 25-year plan for the environment.
- Valuing natural capital in this way can help to manage environmental risks and to inform a wide range of decisions.
- There are a number of challenges to accounting for natural capital including a lack of financial, environmental and social data and the UK’s use of other countries’ natural capital.
It has been estimated that the UK’s population will rise by nearly 10 million in the next 25 years, increasing demands on natural resources. Evidence suggests that degradation of ecosystems will negatively affect human wellbeing. Reports such as the UN’s Millennium Ecosystem Assessment and The Economics of Ecosystem and Biodiversity (TEEB) global reports have highlighted the importance of incorporating the natural environment into national accounting frameworks. One way to achieve this is through natural capital (NC) valuation.
What is Natural Capital?
NC is defined as ‘elements of nature that directly or indirectly produce value to people, including ecosystems, species, freshwater, land, minerals, the air and oceans’. The UK’s national accounts do not consider the depreciation of natural assets and many of the benefits of NC are not included in GDP. The failure to account properly for NC has led to a situation where benefits derived from natural assets are over-exploited for short term gains rather than maintained for their long term benefits. For example, the destruction of woodland to make way for a new railway would yield financial benefits from reduced transport time, but also incur costs from reductions in carbon sequestration, water filtration and recreational use. By assigning a value to these less obvious benefits of NC, advocates argue that they can be more easily incorporated into decision-making processes and that this would lead to better management of our natural assets. Many national and international NC groups exist, including the UK’s Natural Capital Committee (NCC). The NCC was initially set up for three years (2012 to 2015). Its final report made nine recommendations for improving the UK’s NC. The Government response broadly accepted five of these, including to establish a 25-year plan for the environment -recommendations 1, 2, 4, 6 and 9 – see below for details:
Natural Capital Committee Recommendations
The NCC was re-established this year (2016-2020) to provide advice on the development and implementation of the 25-year plan for the environment. The NCC has emphasised the importance of four unfunded ‘pioneer projects’ to Defra to identify good practice and innovative solutions for the plan. These 3-5 year projects include: a ‘Catchment’ Pioneer in Cumbria; an ‘Urban’ Pioneer in the Greater Manchester area; a ‘Landscape’ Pioneer in North Devon; and a ‘Marine’ Pioneer across two sites, one in East Anglia and an additional component in Devon to complement the Landscape Pioneer.
Renewable and Non-Renewable Natural Capital
Natural capital assets are divided into two classes: nonrenewable and renewable.
- Non-renewable assets cannot regenerate within human timescales and so can only be used once. These assets are traded and therefore have a market price, they include fossil fuels (oil and gas) and minerals such as lithium and phosphorous.
- Renewable assets such as forests, fish and peat bogs can provide benefits indefinitely so long as they are exploited sustainably. However, renewable assets are frequently degraded through the unsustainable management practices such as deforestation, over-fishing and drainage.
POST is an office of both Houses of Parliament, charged with providing independent and balanced analysis of policy issues that have a basis in science and technology.
Restoration of the Mayes Brook in Mayesbrook Park, in the London Borough of Barking and Dagenham, was an opportunity to create an ecological and community focal point within a broader environmental regeneration project. It was designed to produce the UK’s first climate change adaptation public park. This restoration of an urban river within a barren park landscape is a good example of an approach that combines flood storage, biodiversity enhancement and adaptation to climate change within a city environment. This study explores some of the key benefits of the planned river restoration and the wider park ‘greenspace’ improvements, in terms of their impact on ecosystem services. The urban setting means that restoration and improvements contribute to ‘regulatory services’ (regulation of air and water quality, microclimate and flood risk) affecting the local community. Enhanced recreation and tourism (cultural services) are also likely to bring benefits, since many people in the borough lack gardens or ready access to other green spaces.
Robert Oates, Executive Director of the Thames River Restoration Trust introduces a field visit. Source: Ecosystems Knowledge Network
The benefits for ‘supporting services’, which are hard to quantify but important in maintaining ecosystem functions, are significant in terms of nutrient cycling and providing habitats for wildlife. This latter ensures there are animals and plants capable of colonising the wider landscape as the habitat improves. These improved habitats also serve as ‘stepping stones’ for wildlife to move across and between limited and fragmented suitable habitat in the urban landscape. Due to the urban setting and lack of biodiversity in Mayesbrook Park and the Mayes Brook, restoring the river does not boost ‘provisioning services’ (things that can be taken from ecosystems to support human needs, such as fresh water, food, fibre and fuel, and so forth). Many of the more important benefits of the Mayesbrook Park restoration can be seen in social and health aspects, enhancing the quality of life in the borough and the wellbeing of local communities.
In fact, if the annual value of services to health, risk and culture are pooled, despite there remaining many unmeasured or possibly unquantifiable benefits, they will account for over 90% of the total annual ecosystem service benefits for the Mayesbrook Park restoration scheme. The overall benefits are substantial relative to the investment. The lifetime value of restoring the site across the four ecosystem service categories (provisioning, regulatory, cultural and supporting) yields a grand total of calculated benefits of around £27 million, even if ‘likely significant positive benefits’ for the regulation of air quality and microclimate are excluded. This is compared to the estimated costs of the whole Mayesbrook Park restoration scheme at £3.8 million including the river restoration works. This produces an excellent lifetime benefit-to-cost ratio of £7 of benefits for every £1 invested. Urban river restoration would therefore be of major public value, fully justifying the planned investment and providing firm evidence that investment in urban ‘green infrastructure’ is highly favourable for the health and wellbeing of local people and the economic improvement of deprived wards. Restoring the vitality and function of the natural environment tends to enhance or maintain benefits across all ecosystem service categories. This contrasts with traditional single element solutions, which tend to maximise only the targeted services and often are associated with unintended consequences for other interconnected services. The case for the application of ecosystem-based solutions to environmental management problems is thus substantiated.
View of one of the lakes to be restored. Source: Thames Rivers Trust
The study sets out a range of options for further enhancing public value from
the restoration scheme, through new or redesigned initiatives or in management
practices. These include:
- enhancing the hydrological function of the whole park landscape and infrastructure
- using reed bed filtration to improve water quality in a bypassed reach of river and at lake inflows and outflows
- improving climate regulation through energy-efficient building design, installation of renewable energy sources and reusing tree and other park trimmings as biomass fuel (or mulch) on site
- optimising park restoration design to provide health and educational resources to the local community.
Assessing the ecosystem service implications for all of these options, and others that may be identified in later phases of planning and research, would help to support the economic case for their implementation. This case study provides evidence to help improve the current scheme design and the greater integration of social, economic and ecological benefits in future initiatives. The results of this assessment are valuable not only in the Mayesbrook Park restoration project but are also applicable to wider urban river and urban area restoration initiatives and will support future research in this field. It will also help in achieving ‘good ecological potential’ for the Seven Kings water body as part of the Water Framework Directive.
Restoration of the Mayes Brook – Executive summary – full text
What is this initiative about?
This project illustrates how an assessment on the services that nature provides for people helped in the regeneration of Mayesbrook Park. The transformation allows the park to better serve the local community and also the city of London under a changing climate with increased flood risks.
The park is in the Borough of Barking and Dagenham, one of the twenty most deprived boroughs in the UK. It was previously under-used and had few amenities, whilst the river was confined to a concrete channel and lay behind a metal fence, providing little value to wildlife or people.
How does it reflect the ecosystem approach?
An assessment of the ecosystem services provided by the park both now and in the future identified its role in reducing flood risk, as well as its value for recreation and wildlife. The assessment illustrated that £7 of benefits will be provided for every £1 invested in restoration of the park, which provided the basis for a funding partnership worth £1.6 million.
In valuing the ecosystem services, the project reflects the ecosystem approach, in that “Conservation of ecosystem structure and functioning, in order to maintain ecosystem services, should be a priority target of the ecosystem approach”. The project also considers the long term effects of climate change and the associated risk of increased flooding and increased summer temperatures. As such it reflects the ecosystem approach, which states “consider mitigating actions to cope with long-term changes such as climate change”.
Progress so far
The first phase of the project includes re-routing the Mayes Brook along a more natural course, renewing the disused lakes and planting trees. The second phase includes the restoration of the two lakes, one for boating and one for angling, which will also improve habitat conditions for wildlife. A visitor and facility centre will be built, along with a café and permanent exhibition on what the park is doing to adapt to climate change.
Challenges and lessons learned
The project highlights how an economic appraisal of the benefits that an area of land can provide for people, can bring about significant change. The clear demonstration of the value of the project helped reassure and engage representatives of the local community.
It is also an example of partnership working, and of a scale of park regeneration that was only made possible by the combination of staff, funding and technical resources provided by the various partners involved. It illustrates the potential for such a project to cause a resurgence of public interest in nature and access to the outdoors. The involvement of the Environment Agency as a partner helped in the process of securing the numerous approvals needed (flood risk, contaminated land, soil disposal etc.).
In addition to being of value in their own right, natural systems and processes provide a broad range of goods and services which help to support human health, well-being and economic success. Ecosystem services are the benefits which nature provides for human well-being, society and the economy. They include:
- Provisioning services: the goods people obtain from ecosystems, including food, water, fuel, raw materials and genetic resources
- Regulating services which control conditions, including the processes that regulate the climate and water flows; air, water and soil quality; pollination; and pests and diseases
- Cultural services, including aesthetic, spiritual, educational and recreational benefits
- Supporting services, which provide the basic infrastructure for life, including photosynthesis, nutrient cycling, and soil formation
Understanding and working with nature where possible will enable us to achieve more sustainable outcomes. This means taking a more proactive approach than assessing and mitigating the environmental impacts of policies, strategies and projects through formal processes including Strategic Environmental Assessment, Sustainability Appraisal, Environmental Impact Assessment and Habitat Regulations Appropriate Assessment.
The ecosystem approach is a holistic and inclusive approach to planning and decision making, which takes account of the benefits and services we derive from nature and seeks to maintain or enhance them. It involves understanding the ecosystem services provided across a given area; valuing them appropriately; and involving the relevant stakeholders to make balanced and effective land management decisions, based on the best possible understanding of the implications.
It is important that ecosystem services are accounted for in decision-making for their own sake, but in these economically constrained times, applying the ecosystem approach will also help ensure that limited funds are targeted at the interventions which will deliver the maximum benefits to the environment, people, and the economy.
The ecosystem approach has been fundamental to the development of the Partnership Management Plan for the South Downs National Park. An overview of the ecosystem services provided by the National Park is included in the introduction to the document, and this understanding informs the policies on farming, forestry and woodland, water, tourism and other aspects of management.
The ecosystem approach is reflected in major projects in the National Park, including the South Downs Way Ahead Nature Improvement Area. This £3 million project is bringing together farmers, community groups, government bodies, research organisations, charities and local businesses to protect, restore and reconnect endangered chalk down land, enhance biodiversity and improve water quality.
In addition to informing planning and decision making, applying this kind of thinking can help to identify, develop and raise funding for projects which support adaptation to climate change and sea-level rise while enhancing the natural environment and benefiting local communities. The Medmerry coastal realignment scheme in Sussex is a great example of what can be achieved by working with nature (see case study).
When the social and economic benefits provided by the natural environment are clear, their value can be estimated and used to make the business case for funding or direct payments to those who help to maintain them.
Payments for Ecosystem Services (PES) schemes provide incentives to farmers and landowners to manage the land in a way which will deliver these services to an agreed standard through a voluntary agreement. A number of pilot studies have been undertaken across England, including the Slowing the Flow project in Pickering, North Yorkshire, which sought to reduce flood risk downstream and improve water and soil quality, by changing land management practices and planting additional woodlands to slow the flow of water through the river catchment. This approach builds on established schemes such as Environmental Stewardship and the Woodland Grant Scheme which are already widely taken up by landowners.
Case study: Medmerry managed realignment, West Sussex
The following case study is part of the No Regrets: Planning for Sea Level Rise and Climate Change and Investing in Adaptation Good Practice Guide sponsored by the Southern Regional Flood and Coastal Committee, August 2015. Local authorities and other organisations involved in planning, decision-making and infrastructure investment are encouraged to follow these case studies and plan for the long-term future of coastal communities in the South East of England and further afield.
Medmerry is the largest coastal realignment scheme on the open coast in the UK. It is sited on the west side of the Manhood Peninsula, which juts out into the English Channel south of Chichester. This is a flat coast line protected by shingle beaches, which are vulnerable to breaching and over-topping in storm conditions, resulting in regular flooding by the sea. Rather than building up the beaches to ever higher levels, as sea levels rise, the Agency decided to work with nature.
The scheme involved building up some 7km of new earth walls inland, breaching the existing shingle beach and forming a large new saltmarsh habitat. This helps to absorb wave energy and manage flood risk for 350 homes, two holiday parks, and a sewage treatment works. It also provides important compensation for loss of intertidal saltmarsh habitat elsewhere, allowing other flood defence schemes to proceed around the Solent.
The new habitat is now an RSPB Reserve with extensive walks and cycle tracks for people to enjoy and benefits for local businesses. It is a model for win-win climate change adaptation, combining improved flood defences with new natural habitats and opportunities for recreation and business on the coast.
The £28 million scheme was carried out by the Environment Agency from 2011 to 2013. At all stages, the scheme was developed in close consultation with a stakeholder group embracing a wide range of local interests.
Qunli Stormwater Park: Heilongjiang Province, China
Principal Designers: Turenscape.
Design Director: Kongjian Yu.
Collaborators: Long Xiang, Han Xiaoye, Song Benming, Li Hongli, Zhang Wenjuan, Men Fanxin, Meng Xiangyun, Li Guo, Zhang Li, Giuan Miaomiao, Xu Bo, Yuan Enkai, He Chong, Chen Feng, Lin Hong.
This project presents a stormwater park that acts as a green sponge, cleansing and storing urban stormwater, which can be integrated with other ecosystem services including the protection of native habitats, aquifer recharge, recreational use and aesthetic experience, thus fostering urban development.
Beginning in 2006, a 2,733 hectare (6,753 acres) new urban district, Qunli New Town, was planned for the eastern outskirts of Haerbin in northern China. Thirty-two million square meters (344,445,133 sq. ft.) of building floor area will be constructed in the next 13 to 15 years. More than one third of a million people are expected to live there. While about 16 percent of the developable land was zoned as permeable green space, the majority of the former flat plain will be covered with impermeable concrete. The annual rainfall there is 567 millimeters (22 inches), with the months of June, July, and August accounting for 60 to 70 percent of annual precipitation. Floods and waterlogging have occurred frequently in the past, while at the same time the ground water table continues to drop due to its overuse.
Several design strategies and elements were employed:
- The central part of the existing wetland is left along to allow the natural habitats to continue to evolve.
- Cut-and-fill strategy to create an outer ring of mounds and ponds. The cut-and-fill around the perimeter is a minimum earthwork strategy to transform the site. Earth is excavated and used to build up a necklace of ponds and mounds around the perimeter of the park. This ring acts as a stormwater filtrating and cleansing buffer zone for the core wetland, and a transition between nature and city. Stormwater from the newly built urban area is collected around the perimeter of the wetland and then released evenly into the wetland after having being filtered through the ponds. Native wetland grasses and meadows are grown on ponds of various depths, and natural processes are initiated. Groves of native silver Birch trees (Betula pendula) grow on mounds of various heights and create a dense woodland. A network of paths links the ring of ponds and mounds, allowing visitors to have a walking-through-forest experience. Platforms and seats are put near the ponds to enable people to have close contact with nature.
- The network of paths and platforms: A network of paths links the ring of ponds and mounds, allowing visitors to have a walking-through-forest experience. Platforms and seats are put near the ponds to enable people to have close contact with nature.
- A skywalk links the scattered mounds allowing residents to have an above-the-wetland and in-the-canopy experience. Platforms, five pavilions (Bamboo, Wood, Brick, Stone, and Metal), and two viewing towers (one made of steel and located at the east corner, the other one made of wood and looking like a tree at the north-west corner) are set on the mounds and connected by the skywalk, allowing visitors to have views into the distance and observation of nature in the center of the park.
The project proposes creating a 34ha park in the middle of this new town, which is listed as a protected regional wetland. The site is surrounded on four sides by roads and dense development. As such, the wetland had been severed from its water sources and was under threat. The proposal included the transformation of the area into an urban stormwater park that will provide services to multiple ecosystems.
All images: Turenscape – Articles first posted in https://urbannext.net/ and https://www.asla.org/
Following our last post featuring the publication of results of the London iTree Urban Forest Survey, this week’s post focuses on an in-depth analysis of the green assets of the Victoria in the Borough of Westminster, London highlighting the wide range of benefits (or ecosystem services0 green infrastructure provides in urban settings.
The Green Benefits in Victoria Business Improvement District Report – An analysis of the benefits of trees and other green assets in the Victoria Business Improvement District. The following is a summary of the full report.
Victoria, London Borough of Westminster, is a major transport hub, tourist destination and centre for business and commerce. Like many urban areas Victoria suffers from the effects of a high density built environment with an overall lack of natural features and this contributes to overheating in the summer through the urban heat island effect as well as surface water flooding, when the drainage system cannot accommodate the volume of water running off of hard surfaces. The Victoria Business Improvement District (BID) acts as a platform for business to take a lead in enhancing the overall urban environment of Victoria and to help shape the area for future development.
Trees intercept rainwater thus reducing the burden on the drainage system; they cool the air and provide invaluable shade on a sunny day, and, of immediate benefit to Victoria in the face of major redevelopment, they can contribute to cleaning the dust and pollution from the air we breathe. So clearly Victoria’s street trees and those in public and private green space have a central role in mitigating these environmental challenges and so contribute to making Victoria a better place to do business. The Victoria Business Improvement District considers trees to be a core component of the local infrastructure and has therefore commissioned the research presented in this report to provide a clearer understanding of the financial benefits of trees in a specific location so that we can say with confidence that our trees are saving the business community thousands of pounds per annum.
Green infrastructure can deliver benefits to urban areas. Trees in particular can provide a wide range of benefits (or ecosystem services) such as storing carbon, reducing the urban heat island effect and improving air quality. Understanding the structure, function and value of Victoria Business Improvement District’s green infrastructure can inform decisions that will improve human health and environmental quality. This report presents a baseline quantitative assessment of the air pollution, amenity, carbon storage and sequestration benefits of trees as well as the storm water and surface temperature benefits of existing green infrastructure in the Victoria BID.
This report also estimates the additional benefits that could be generated if the 5% canopy cover increase target set by the Mayor of London for Greater London, by 2025, and the potential green roofs and ground level green spaces investments identified by the BID are both realised in Victoria. This assessment was conducted using the i-Tree Eco model (also known as UFORE1 ), as developed by the U.S. Forest Service, Northern Research Station, Capital Asset Valuation for Amenity Trees (CAVAT) and tools within the Green Infrastructure Valuation Toolkit. It considers the impact of public and private trees as well as other types of green infrastructure assets including green roofs and gardens.
Existing trees, green spaces and other green infrastructure assets in Victoria divert up to 112,400 cubic metres of storm water runoffs away from the local sewer systems every year. This is worth between an estimated £20,638 and £29,006 in reduced CO2 emissions and energy savings every year. The total structural value of all trees in Victoria, (which does not constitute a benefit provided by the trees, but rather a replacement cost) currently stands at £2,103,276. The trees in Victoria remove a total of 1.2 tonnes of pollutants each year and store 847.08 tonnes of carbon. London plane currently dominates the treescape within Victoria BID, storing 59% of all carbon, filtering 67% of all pollutants and making up 29% of the tree population.
However the London planes represent an ageing population and in order to maintain the current level of tree benefits to Victoria BID more trees capable of attaining a larger stature will need to be planted. When implemented, the green infrastructure opportunities identified by Victoria BID have the potential to:
- Divert up to 67,500 additional cubic meters of storm water runoff every year, representing an estimated extra £12,392 in avoided CO2 emissions and £17,417 in energy savings annually. Future design choices – particularly in relation to green roofs – will have a determining impact on the scale of water management benefits realised.
- Reduce peak summer surface temperatures by up to 5.1˚C in the area surveyed. This will moderate local air temperatures, helping to ensure that the BID remains an attractive and comfortable environment for residents, visitors and workers alike. It will also reduce the need for air conditioning in office buildings, lowering energy costs and carbon emissions.
- The high CAVAT value of London plane in particular justifies the investment required to establish and maintain very large trees in the urban environment, yet equally points to the vulnerability arising when such a high proportion of value resides in a single species.
Public and private trees in the Victoria BID provide valuable benefits. Realising the Mayor’s target for increasing canopy cover together with the creation of additional green roofs and ground level green space would dramatically enhance the scale of ecosystem services the area enjoys. These conclusions highlight some key recommendations in order to ensure that benefits currently arising from the BID’s green infrastructure are sustained and future green investments fulfill their potential for generating returns:
- Conduct succession planting for London planes. The local tree resource is characterised by a good diversity of species, which makes it more resilient to pressures such as pests and diseases or climate change. However, most of the canopy area and therefore most of the benefits arising from the Victoria BID’s treescape are provided by London planes. Many of these trees are mature specimens, as has already been highlighted in previous studies (Kelly 2012). Provision should be made to ensure that adequate succession planting is carried out in order to maintain benefits at the current levels.
- Target private trees owners for awareness raising and best practice on tree management. Many of the BID’s trees are in the private realm and in the buffer area. Therefore, a reduction in privately owned trees will reduce this benefit. Strategies and policies that will serve to conserve this important resource (through education and community engagement for example) would be one way to address this.
- Focus on large canopy trees both for planting and maintenance. The amount of healthy leaf area equates directly to the provision of benefits (or ecosystem services). Canopy cover can be increased through new tree plantings. However, the most effective strategy for increasing average tree size and tree canopy is to preserve and manage the existing trees within the BID so that a good proportion can grow to maturity. Where new trees are planted the Westminster Trees and the Public Realm SPD (Westminster City Council 2009) recommends using the tree species with the largest canopy a site can accommodate. Ensuring this is well-enforced in the future will be key to maintaining tree benefits at their current level.
- Engage with Thames Water to ensure the benefits from proposed green investments can more directly reach BID members. Trees currently make a positive contribution to the management of storm water in Victoria. The proposed investment to increase canopy cover, create new ground level green spaces and dramatically extend the area of green roofs and will significantly alleviate the local drainage system. This will unarguably result in public benefits, by contributing to reducing the prevalence of flooding events which regularly damage and interfere with the local infrastructure. It will also reduce the amount of water that will need to be treated by the local water company, Thames Water, thus offering real savings. All efforts should be made to ensure local owners and occupiers in Victoria who, as part of their water bill, pay for the drainage of the area get access to their share of this saving. Thames Water grant a rebate to its customers on drainage fees based on pipe diameter rather than based on volume reduction. This doesn’t provide a strong incentive for green approaches such as those envisaged for Victoria. Direct engagement with Thames Water on this issue could result in an innovative pilot – offering a model that could be rolled out to other parts of London.
The Landscape Institute featured Greening for Growth in Victoria as a case study in their 2011 publication ‘Local Green Infrastructure: helping communities make the most of their landscape’
“ The Victoria BID is championing a sustainable green agenda for the area and is looking to become the leader in the development of sustainable business environments through the retrofitting of green infrastructure. We are working closely with public and private sector partners to achieve a positive change in the physical landscape in the area. The increase in green infrastructure will not only benefit the environment but also the workers, residents and visitors that come into Victoria every day.” Ruth Duston, Chief Executive Officer Victoria BID