Last edited 08 Jul 2021

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Biodiversity in the urban environment

Report by Katie Johnson, --BRE.


[edit] Executive Summary

Urban development can have a significant impact on our natural habitats. With habitat modification having been identified as one of the most important drivers of biodiversity loss, the urban environment is becoming an increasingly expanding geographical area that could be used to support wildlife.

From the introduction of green infrastructure, to the engagement and active participation of local communities and city residents, there are numerous ways in which the urban environment can be developed to promote the integration of biodiversity.

This report examines the feasibility studies carried out by thirty UK councils for the Future Cities Demonstrator Programme. 90% of participating cities identified the environment as a key challenge that needed to be addressed, while half of the cities presented strategies that would be beneficial for biodiversity, supporting and encouraging urban wildlife such as pollinator and bird species. UK case studies and innovative ideas combining biodiversity and the urban environment are also presented in this report. They highlight the range of initiatives that are being implemented within urban environments across the UK, presenting actions that are being taken to promote biodiversity within new developments, as well as improving biodiversity within existing towns and cities.

With the expected continued expansion of the world's urban environment, natural habitats and biodiversity are in a fragile position. However, as highlighted, numerous methods and innovative solutions are being developed and integrated into urban landscape. This indicates that the issues surrounding biodiversity loss are slowly being realised, with actions being taken to try to address them within the urban environment.

[edit] Introduction

The term biodiversity has prompted several definitions since its emergence in the field of conservation. A formal definition from the International Convention on Biological Diversity [1] indicates it is the variety of living organisms across all ecosystems, and the ecological complexes they are part of, including diversity within, and between, species and ecosystems. Although humans have been aware for centuries that nature helps support societies, the explicit acknowledgment of 'ecosystem services' i.e. the conditions and processes provided by natural ecosystems and species that support and sustain human life, is comparatively recent [2].

As well as obvious food sources, nature provides countless crucial 'ecosystem services' that allow human existence. From the creation of breathable air to the supply of clean water, even seemingly insignificant insects provide vital ecological services including pest control, pollination, and wildlife nutrition [3]. Conservation of biodiversity will assist in maintaining ecosystem services that are essential for human life to persist. However, anthropogenic impacts have devastated, degraded or influenced almost all natural habitats on earth and species extinction rates are now 1000 times higher than background rates [4].

With the continued expansion of towns and cities, urban development can significantly impact on natural habitats. Habitat modification, i.e. the replacement of natural, native habitats with urban areas, or cultivated land, has been identified as one of the most important drivers of biodiversity loss, hence the urban environment is becoming a predominant area that could be used to support wildlife. From the development of green spaces, such as public parks, to the construction of green walls and roofs, these areas can provide a refuge for wildlife and play an important role within the urban landscape.

In addition to providing important habitats for wildlife in urban areas, the introduction of green walls and green roofs to the urban environment has been linked to numerous other benefits including; reduction in energy consumption, and therefore CO2 emissions, of a building (due to the insulating properties of green roofs), helping to reduce the urban heat island effect, and filtering airborne particles and pollutants from the atmosphere so improving air quality. Green spaces within cities can play a significant role in preventing localised flooding as part of sustainable drainage systems (SuDS), while also providing community engagement through activities such as communal gardening, food growing and outdoor recreation.

[edit] Future Cities visions and interactions with biodiversity

Thirty UK councils were selected to carry out feasibility studies for the Future Cities Demonstrator Programme that identify how they could integrate their transport, communications and other infrastructure to improve the local economy, increase quality of life and reduce impact on the environment [5].

An analysis of these feasibility studies highlighted that 90% of participating cities identified the environment as a key challenge, while half of the cities presented ambitions and strategies that would be beneficial for biodiversity, supporting and encouraging urban wildlife. Several key biodiversity linked themes were identified within the innovative development schemes submitted by the 30 UK cities including community engagement and integration, quality of life and green infrastructure.

[edit] Community engagement and integration

Engaging communities and encouraging the active participation of city residents in local events and activities can have several benefits for both people and nature. Community engagement opportunities can help to raise awareness of biodiversity whilst providing informal education opportunities for residents to learn about their local environment.

Enhancing public understanding and enjoyment of nature can help foster positive public attitudes towards biodiversity and the natural environment [6], while involving the community at the initial stage of local decision making, such as the development of green spaces, can enable residents to gain an improved sense of ownership of a project or area. This can generate numerous benefits, from encouraging positive behavioural change (e.g. refraining from littering), to promoting engagement in conservation activities, or activities to enhance the natural environment [7].

Engaging and involving residents can also provide opportunities for the regeneration of local community areas as well as empowering neighbourhood initiatives. Groundwork [8], a nationwide charity, works with local communities delivering thousands of projects each year to help re-connect people with nature and transform whole neighbourhoods, whilst also provide training and improving people's prospects.

Engagement with the local communities is a key point highlighted by almost all cities involved with the Future Cities Demonstrator Programme, recognising the role local citizens can play in the growth and development of an area. Cardiff city council has a Sustainability Unit specifically aimed at maintaining sufficient connectivity between external, community-led, and internal, government-led, sustainability initiatives operating across the city, while Swindon has developed a strong green spaces network, established in partnership with local community organisations. Swindon is also aiming to increase the level and diversity of community participation in the city planning process.

The London Borough of Camden and Belfast City both focus on community food production schemes. Camden are planning to engage with local food growing networks to initiate the community schemes, and the support provided for resident-led micro enterprises allows local citizens to generate income from their produce, increasing the local sustainable food supply. Belfast City has instigated a project enabling a suburban community to become a resilient, self-sustaining part of the city by establishing a community led food and energy production project. As well as developing a partially self-reliant area of the city this scheme will also promote community cohesion and improved community relations

[edit] Quality of Life

Recent research has highlighted the significant benefits urban green space can deliver for mental wellbeing, recording lower levels of mental distress and significantly higher wellbeing (life satisfaction) in citizens living in areas with more green space [9]. The Faculty of Public Health, in association with Natural England, has also emphasised that increasing contact with green spaces can reduce symptoms of poor mental health and stress, whilst improving mental wellbeing across all age groups [10].

Green spaces can include a wide range of environments, from formally designated parks and recreational grounds, to more 'natural' areas such as river bank corridors [11]. Within urban environments, green spaces can also be generated through the construction of green roofs, living walls and tree-lined streets. The promotion of green spaces both within and surrounding urban environments is strongly associated with the positive biodiversity benefits highlighted within the Community engagement and Green Infrastructure sections of this report.

Green open spaces have also been shown to encourage physical activity, a key factor in living a healthy lifestyle and reducing weight related medical issues [12]. Studies have revealed a positive relationship between access to natural environments and increased rates of physical activity [13], with tree-lined routes offering extra motivation to walk, in comparison to routes without trees [14], green space within walking distance promoting physical activity outside the home [15] [16] and increased access to urban green space associated with increased amounts of play [17] and improved concentration and motor skills in children.

Several city feasibility studies submitted to the Future Cities Demonstrator Programme promote encouragement of health and wellbeing through the improvement of green open spaces, and commitments to greener cities or boroughs to ensure a greater quality of life for residents. Leeds-Bradford include in their vision an aim to understand the value of green urban spaces, identifying green areas in which to promote engagement of communities with their green spaces, encouraging exercise to promote weight loss and the reduction of poor health. Swindon also has ambitions to further improve access to, and quality of, parks, open spaces, in conjunction with improving links to surrounding rural areas, promoting and guaranteeing health and wellbeing benefits for all Swindon citizens.

[edit] Green infrastructure

Green infrastructure (GI) is one of the most commonly recurring themes in the feasibility studies for the Future Cities Demonstrator Programme. Proposals range from increasing green civic space to initiatives involving green walls, green roofs, streetscape greening, and urban agriculture programmes.

GI can be viewed as a network of green features, delivering a wide range of environmental and quality of life benefits [18]. It can include parks, playing fields, woodlands, grasslands, open spaces, wetlands, river and canal corridors allotments and even private gardens. It should aim to enhance and restore areas, as well creating new wildlife habitats, integrating biodiversity into the built environment. Connectivity is a key theme encouraged in the development of GI, allowing the movement of species and enabling the built environment to be permeable to wildlife.

GI can also provide numerous other environmental benefits as well as offering a refuge for wildlife within the urban environment. The majority of ground surfaces within cities are made from impermeable materials such as concrete. This prevents draining of rainwater through permeation, leading to a high volume of surface run-off and increasing the issue of localised flooding within the urban environment. Research by the University of Manchester [19] has shown that increasing the green space cover in urban areas by 10% reduces surface run-off by almost 5%. As urban trees intercept large quantities of rainfall, increasing tree cover in urban areas by 10 % can reduce surface water run-off up to a further 6 %.

The permeability and absorption properties of GI that help moderate runoff can help to buffer cities from flooding impacts, preventing localised flooding as part of sustainable drainage systems (SuDS). A study focusing on New York City has analysed the costs of upgrading and developing additional hard 'grey' infrastructure (such as sewer systems, tanks, pipes etc.) to cope with the flooding and sewer overflow issues within the city. Results have indicated that a GI plan, design to deal with the same issues of flooding and sewer overflow within the city, would not only bring the additional benefits associated with GI but also cost approximately $1.5 billion less than the hard 'grey' infrastructure strategy [20].

Green walls and green roofs within cities also provide the opportunity to replace some habitats that have been lost to the development of an urban area. They can be specifically designed to provide habitats and food sources for insects, birds and rare species of plants whilst also benefiting the urban environment in numerous other ways. Green walls and roofs have been strongly linked to a reduction in the urban heat island effect, a temperature disparity between urban and rural areas which exacerbates ground-level ozone production, predicted to increase with global temperatures. The evaporation and evapotranspiration associated with vegetated walls and roofs lowers surrounding air temperature, hence reducing the urban heat island effect [21].

The thermal properties of vegetated walls and roofs has also been shown to positively impact on the energy consumption of a building [22]. Improving the insulating qualities can help reduce heating requirement during winter months while also reducing the need for air conditioning in summer, hence contributing to lower CO2 emissions. The modelling of buildings by Environment Canada has shown that a saving of 4.15 kW/hours/m2/year can be made in reduced air conditioning costs by installing a green roof, and the installation of a green roof at Paradise Park in the London Borough of Islington has negated the need for air conditioning to be installed, leading to an energy reduction of 800kW/hrs and a saving of 1.6 CO2 tonnes [23].

Increasing vegetated building surfaces in urban areas can also help improve local air quality by reducing the production of ozone. Furthermore, vegetation can assist with the removal of airborne particles, heavy metals and volatile organic compounds from the local atmosphere.

Over half of the cities feasibility studies for the Future Cities Demonstrator Programme incorporated the improvement and development of comprehensive green infrastructure strategies. Many highlight the link between GI and health and wellbeing; Leeds-Bradford plan to identify areas for investment in green infrastructure on the basis of health and care demographics, and Plymouth promote GI development for its 'significant health benefits', while Camden and Salford specifically identify greening programmes designed to mitigate the urban heat island effect. Camden borough council also highlight the green employment and training opportunities that could arise from the development of GI across the borough, helping establish a local greening social enterprise.

[edit] Innovation in biodiversity

[edit] Urban Farming

A primary driving force behind land conversion and intensification of agriculture is the global human population increase, an indirect driver of biodiversity change identified by the Millennium ecosystem assessment [24]. As natural ecosystems are converted to agricultural land to meet an increasing global food demand for the growing population, two proposed methods to meet these growing demands have emerged, increasing habitat conversion to agricultural production, or increasing agriculture intensification (Green et al., 2005). Both of these ideas could potentially be extremely detrimental to natural habitats and wildlife, however some alternative solutions have begun to emerge.

Urban farms, allotments, even rooftop permaculture farms could assist in reducing the pressure to convert further land to agriculture by supplying city dwellers with locally sourced produce. As well as providing a refuge for wildlife, community managed city farms can also provide education as well as promoting well-functioning and sustainable communities. The development of urban farms, which can provide multi-functional habitats for wildlife within the built environment, has been on the increase for some time however other forms of urban farming are also beginning to appear.

[edit] Vertical farming

Vertical farming is an innovative concept that has attracted a great deal of attention in recent years, with high potential for reducing the area of land that would need to be converted to agricultural land. Vertical farming is the cultivation of vegetation on a vertically inclined surface, or within a 'skyscraper greenhouse'. 'Edible walls' are those which are commonly constructed on an external vertical surface of a building, or on purposely built inclining surfaces, design solely for edible vegetation.

This concept of vertical farming benefits biodiversity in much the same way as the previously mentioned green walls. As well as increasing green corridors and connectivity throughout the urban environment, these 'edible walls' can offer an essential food source for pollinator species such as bees, butterflies and hoverflies within a city. They can provide habitats for invertebrate species which in turn can attract birds and bats into the urban environment.

Vertical farming (on a commercial scale) which utilises high rise buildings has a number of floors supporting crops which are grown in carefully selected and monitored environmental conditions. The advantages and disadvantages of this method of vertical farming have been thoroughly debated, including those for biodiversity [25]. As previously mentioned, agriculture has been strongly linked to the loss of biodiversity at a worldwide scale. The development of vertical farming in skyscrapers has the benefit of theoretically being able to return a large proportion of currently farmed land back to its natural state, allowing ecosystem services and functions to be restored, recreating natural habitats. Current estimates suggest that one acre of vertical farm could be equivalent to ten to twenty traditional soil-based acres depending on the crop [26]. The pollution of waterways from sediment and nutrient runoff from agricultural landscapes has been well documented [27], and it has been suggested that vertical farming can eliminate agricultural runoff. This reduction of excessive nutrients in waterways could potentially improve freshwater biodiversity and reduce issues associated with eutrophication [28].

[edit] Aquaponics

Aquaponics is a method of growing vegetation and aquatic animals, such as fish and snails, in a mutually beneficial cycle. Excretion from the fish is deposited in the water, bacteria convert this waste into nutrients suitable for plant uptake, and this water is then transferred to the tank in which the vegetation is growing for the vegetation to use the nutrients for growth. This 'filtered' water is then recycled back to the tank containing the fish.

Without the need for fertile land, aquaponic crops can be grown on land that is otherwise unsuitable for agriculture (land with poor fertility, contaminated land etc.) providing alternative areas of land rather than converting further natural habitats into agricultural land. Tanks can also be stacked vertically therefore having the potential to provide a significant food source whilst reducing the area of land needed to be converted to agricultural land.

The volume of water required for plant growth in aquaponic systems is minimal in comparison to conventional agricultural activities where water is lost through runoff and ground water supplies [29]. In aquaponic systems water is re-used through biological filtration and recirculation, hence reducing the burden on water supplies, especially in hotter months. In addition, aquaponics does not require chemical fertilisers, due to the recirculation of nutrients in the fish waste, hence helping to reduce the vast quantities of nutrients entering our freshwater systems [30] and affecting aquatic biodiversity, as previously discussed.

[edit] Citizen science

Citizen science is a method of involving general public participation in scientific data collection. Including the general public directly in the monitoring, recording, and outcomes of a project can lead to large volumes of data being recorded over a wide area, and participation is usually on a voluntary basis, therefore a cost-effective method of environmental data collection. Participants collect data following a set procedures and data is usually submitted to a central location for examination and analysis by researchers and scientists.

Over recent years there has been a large expansion in the diversity and scale of projects involving citizen science. The issue of biodiversity is currently high on the agenda, with the accelerating rate of biodiversity decline and increasing impact of threats, making it critical to detect trends in biodiversity as quickly as possible and requiring large volumes of data. The advancement of technological developments has increased the ease at which people can become involved with research, and is revolutionising citizen science.

Smart phone apps are creating a new era in the world of data collection, especially with the addition of GPS which has accurate locating abilities. The ease at which members of the public can submit geolocated photographs has made the validation and verification of species, habitats and diseases a fast and feasible process [31]. Numerous biodiversity related research projects have already implemented the use of smart phone apps such as BirdTrack [32], using web-based platform for recording bird sightings, Leaf Watch [33], allowing the collection of geolocated photographs for tracking horse chestnut disease, and Project BudBurst [34] which collects plant observations throughout the seasons. Web-based data capture and smartphone apps are becoming commonly applied to biodiversity research, and developments are currently underway to integrate environmental sensors into citizen science, for example, by integrating increasing advanced software into smartphones.

These technological advances provide a great potential for crowd-sourcing (the collection of data by large numbers of volunteers) which is crucial in the urban environment. When studying biodiversity within any environment, landowner consent is often required. In urban environments this problem is magnified by the issue that numerous small parcels of land are owned by individual home owners. Any habitat or wildlife monitoring and research that takes place is therefore often regulated by landowner approval of a project. The promotion of citizen science often gives participants a sense of involvement and opportunity to influence the outcome of the project, hence encouraging participation. Although the scale of activity that each individual city landowner can contribute is often minimal due to the size of their land, the combined efforts could generate cumulative impacts at a much larger, meaningful scale.

[edit] Case Studies

[edit] Glasgow and Clyde Valley Green Network Partnership

Formed in 2007, the Glasgow and Clyde Valley Green Network Partnership brings together eight regional authorities as well as Forestry Commission Scotland, the Scottish Environmental Protection Agency (SEPA), Scottish Enterprise, Scottish Natural Heritage and the Glasgow Centre for Population Health [35]. With the aim to create a large, functional green network, connecting green spaces across the Glasgow and Clyde Valley regions, one of the key outcomes is protecting and enhancing wildlife and the environment by providing accessible, quality green spaces.

Glasgow and clyde.jpg

Image Courtesy of the Glasgow and Clyde Valley Green Network Partnership

Significant urban regeneration and expansion is expected across the Glasgow and Clyde Valley regions in the coming years, hence the Partnership are suggesting an Integrated Green Infrastructure approach for the future developments. This approach incorporates GI at the initial design stage of a built environment, integrating it within the planning of 'grey' infrastructure- transport, energy, water and waste. Including GI at the initial planning stage of a development allows the consideration of the process of linking green space, creating green corridors and providing active travel routes and habitats for wildlife.

For new developments in Scotland, surface water runoff should be directed through SUDS. The Partnership feel this legal obligation provides substantial opportunities to develop 'naturalised' SUDS features, such as wetlands and ponds. By integrating these into the built environment they can become multi-functional GI features, benefiting wildlife, local communities as well as functioning as a flood defence mechanism. Integrated Habitat Network models (spatial planning tools) are used to identify potential wildlife habitats within a proposed development, allowing GI to be incorporated into the urban environment in the most beneficial way for biodiversity, while also aligning with surface water management needs.

[edit] Bristol's urban farms

Bristol has five large urban farms spread across the city as well as numerous allotment sites and community gardens. Many have been developed on disused and brownfield sites, including those of The Severn Project which has converted a fly tipping site and contaminated land adjacent to one of the main railway stations, into several acres of thriving urban farms [36]. As well as regenerating large areas of disused urban land to provide locally sourced food, urban farms also promote ecological diversity. Bee hives have been introduced to the sites to promote ecosystem pollination services, and corridors of land have been set aside for wildlife providing access to the wetlands created within the urban farm and providing a safe refuge.


Community engagement is another key ambition for Bristol's city farms. The majority of allotments are volunteer and community based such as the Easton Community Garden [37], and The Golden Hill Community Garden [38], providing opportunities to be involved with growing local produce as well as pond dipping biodiversity education for younger age groups, while some of the larger urban farms provide therapeutic support, training, education and employment opportunities for the local community [39]. Providing productive communal land can unite local residents, raise health awareness and morale among the community. The Seven Project urban farms also provide social re-integration opportunities and have a policy of creating employment for people facing significant barriers to the workplace. They help socially excluded groups to build new and rewarding lives through their experiences at the urban farms.

[edit] Green walls and roofs in London

The Mayor of London has a current target to increase green cover by 5% across central London by 2030 [40]. As a results GI, especially green roofs and walls, are being promoted across the city with an aim to increase installation on both new developments and through the retrofit of existing buildings. As well as enhancing the biodiversity of the city the principle benefits of green walls and roofs in London are; helping London to adapt to climate change, reducing energy emissions, reducing urban heat island effect, enhancing amenity value and providing effective SUDS.

Rubens.jpgImage courtesy of Rubens at the Palace

London already has numerous green walls and roofs across the city, and with a city policy that expects major developments to incorporate living roofs and walls where feasible, and encourages the use of living roofs in smaller developments and extensions, the number of new and retro fitted developments that incorporates GI is expected to increase. The Greater London Authority has also funded numerous Green Infrastructure Audits, a mapping process that identifies new locations suitable for green space, including green walls and roofs. Over 500 hectares of the city have been audited, which identified the potential for over 300 rain gardens, 200 green walls and more than 100 hectares of green roofs [41].

London's largest green wall has recently been constructed at The Rubens at the Palace Hotel in Victoria. Covering 350 m2 and composed of 16 tons of soil and 10,000 plants, the entire façade of the hotel has been transformed. In an area of London where surface water drains can become overwhelmed during heavy rainfall, the green wall has been specifically designed to minimize surface water flooding by irrigating the vegetation using harvested rainwater. Species of plants used were recommended by The Royal Horticultural Society as key species for attracting and supporting butterflies, bees and birds.

[edit] Summary

With the expected continued expansion of the world's urban environment, natural habitats and biodiversity are in a fragile position. However, as highlighted, numerous methods and innovative solutions are being developed and integrated into the urban landscape. With 90% of cities participating in the Future Cities Demonstrator Programme identifying the environment as a key concern, issues surrounding the natural environment are beginning to play a significant role in future developments of the urban landscape.

As the greening of towns and cities has been linked to the numerous benefits discussed within this paper, the increasing introduction of green spaces, GI and urban farming initiatives indicates that the issues surrounding biodiversity loss are slowly being realised, with actions being taken to try to address them within the urban environment.

A concept repeatedly occurring across the theme of biodiversity within towns and cities is that of community engagement and integration. Involving local residents in decision making not only provides a sense of ownership of a project or area but can also encourage positive behavioural change, promote engagement in conservation activities and increasingly educates citizens about biodiversity related issues. The advancement in citizen science and the ease with which people can contribute to research activities, assisting with the provision of vast quantities of data and information, can allow increased investigation into issues that would otherwise often be costly and time consuming.

Although habitat loss and species extinction rates deliver alarming figures, the issues surrounding biodiversity change are beginning to be addressed within the urban environment. The case studies highlight the range of initiatives that are being implemented within urban environments across the UK, presenting actions that are being taken to promote biodiversity within new developments, as well as improving biodiversity within existing towns and cities. If future councils and government take a lead from the positive examples that are emerging in isolated areas across the UK, and the implementation of these initiatives is allowed to continue, the negative impacts urban development can impose on biodiversity may begin to be minimised, while at the same time integrating biodiversity into our towns and cities.

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[edit] External references

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