Tools for Planning and Evaluating Urban Green Infrastructure: Bicester and Beyond

A NERC Green Infrastructure Innovation Project
February 2016 to April 2018

Overview

This project aimed to test a range of existing tools for planning and evaluating green infrastructure, using the rapidly expanding town of Bicester in Oxfordshire as a case study. The ECI and Forest Research worked in partnership with many stakeholders to develop a set of simple tools and methods that can be applied relatively quickly and easily.

These form a toolkit that can help local authorities to:

  • map green infrastructure and the ecosystem services it provides
  • map ecological networks (wildlife corridors)
  • check whether a new development achieves net gain in biodiversity and natural capital
  • assess the benefits of new and existing green infrastructure
  • decide where new or improved green infrastructure is needed
  • follow best practice guidance.

Although the toolkit has been tested in Bicester we hope it will be useful to local authorities in other parts of the UK.


About

What is green infrastructure and why do we need it?

Green infrastructure is the network of green space and water features, both urban and rural, that provides multiple environmental benefits for people. It includes semi-natural habitats such as woodland, grassland, heath, wetland, lakes and rivers, as well as parks, gardens, sports fields, playgrounds, cemeteries, allotments, orchards, amenity grassland and canals. On a smaller scale it covers roadside verges, street trees, flowerbeds, shrubs, hedgerows, footpaths and cycle paths, and engineered features such as sustainable drainage systems (e.g. retention ponds, swales or raingardens) and green walls and roofs. Sometimes water features are referred to separately as 'blue infrastructure', but here we use 'green infrastructure' to refer to both green and blue infrastructure.

Green infrastructure is essential to our quality of life. It provides places for recreation and relaxation, attractive views, connection to nature and a sense of place, as well as practical benefits such as flood protection, shading and cooling, improved air and water quality, carbon storage and habitat for pollinators and other wildlife.

Tools for planning green infrastructure

Green and blue space is often threatened by new development, and is also under pressure from air and water pollution, climate change and invasive species. At the same time, new development offers opportunities for building new high quality green and blue infrastructure, or releasing funds to upgrade existing habitats to compensate for any losses. As budgets are squeezed, local councils need tools to show the value of existing green infrastructure, find out where new or improved green space is needed and make the business case for investment. However, although many tools exist, few are freely accessible, robust, easy to use, capable of assessing a wide range of ecosystem services, suitable at the urban scale and valid in the UK context.

Bicester and beyond

Bicester will double in size over the next 15 years. However, the Cherwell District Council Local Plan aims to create high quality and sustainable new developments including a high proportion of green and blue space. The council approached the University of Oxford to help identify suitable tools for planning and evaluating green infrastructure, given their limited time and budgets. Working with a wide range of stakeholders, and with funding from NERC, we tested a set of tools which are cheap or free, relatively quick and easy to use and draw on readily available datasets. Although we used Bicester as a case study, we hope that the results will be useful to other local authorities.

The methods developed for the Bicester study are now being applied more widely. We have applied the ecosystem service scoring method to produce natural capital maps of Oxfordshire to help inform development of the Oxfordshire Plan to 2050, and we have also produced natural capital maps of the Oxford-Cambridge growth arc, as a tool to feed in to development of Local Natural Capital Plans.


Toolkit

The toolkit includes tools that can be used for:

  • Mapping green infrastructure
  • Mapping the ecosystem services provided by green infrastructure
  • Mapping ecological networks
  • Assessing land-use change (including net gain in biodiversity and natural capital)
  • Valuing the benefits of new or existing green infrastructure, in monetary or non-monetary terms
  • Opportunity mapping: deciding where new or improved green infrastructure is needed
  • Guidance: following best practice guidance and learning from case studies

The focus of this project has been on finding relatively quick and simple tools that could, in theory, be applied by local councils with limited time and resources. However, most of the tools listed below require a certain amount of time and expertise, with many relying on use of a Geographic Information System (GIS) to generate maps and analyse spatial data. Realistically, councils with limited in-house GIS expertise may choose to use third party consultants or facilitators such as their local Environmental Records Centre to carry out much of the analysis.

There is also a trade-off between simplicity and robustness of the tools. More complex tools are available, such as InVEST (free), LUCI (proprietary), SENCE (consultancy) and Viridian (consultancy), which model processes such as rainwater runoff and soil erosion taking into account rainfall, soil type and the slope of the land. These require more time, expertise and data (or payment to consultants), but can produce more robust results for the services of flood protection, soil erosion and water quality regulation. Further details of these tools and others can be found on the EKN Tool Assessor website.

Finding the tools you need

We have grouped tools into four main categories.

Mapping existing assets
  • What green infrastructure assets do we have already?
  • What should be protected?
Opportunity mapping
  • Where are there gaps in supply?
  • Where are the best opportunities for investing?
Site design
  • How can we plan good Green Infrastructure?
  • Are we achieving net gains of ecosystem services?
Valuation
  • What will the benefits be?
  • Can we make a business case?
Mapping existing assets Opportunity mapping Site design Valuation

Mapping existing assets

The first step in assessing green infrastructure is to map existing assets. This can help to identify high value assets that should be protected from inappropriate development – not just the obvious assets such as parks and nature reserves, but also smaller patches of high value habitats that might otherwise be overlooked.

Tools for mapping and assessing existing assets include:

  • Base maps.We have created a short guidance note on how to create a green infrastructure map using freely available datasets
  • Ecosystem service scores. We have developed a method for rapidly assessing potential supply of 18 different ecosystem services using a simple scoring system based mainly on habitat type and other freely available datasets. The scores were initially developed during a stakeholder workshop in Warwickshire, and were subsequently refined based on a literature review of 780 papers. Read about how we applied this method in Bicester here. After the Bicester project, we have continued to refine and improve the scores as part of the development of the eco-metric tool for Natural England. We also introduced the use of multipliers to reflect factors such as agricultural land class (which affects the service of food production), public accessibility (which affects recreation) and nature or cultural designations (which affects cultural services such as aesthetic value, interaction with nature, education (learning about nature), and sense of place). We have applied the improved scoring matrix and multipliers to generate natural capital maps for Oxfordshire and then for the whole Oxford-Cambridge growth arc.
  • Participatory maps: a method of gathering local knowledge and assessing the values attached to local green spaces, to refine the generic values generated by the ecosystem service scoring method. In Bicester, we mapped the value of local green spaces using four different participatory methods: a street event (stall at the Bicester Big Lunch), a week of drop-in sessions at Bicester library; an in-depth focus group at the library and an online app. Our report (Public value of green space in Bicester) was used to demonstrate the value of green space for health and wellbeing as part of the 2018-2020 Cherwell District Council Community Nature Plan.
  • Social media. We investigated the use of Flickr photos and Strava running and cycling routes to demonstrate the popularity and usage of local green infrastructure assets. A brief report will be provided soon.

Opportunity mapping

Having mapped existing green infrastructure assets, the next step is to identify suitable opportunities for enhancing existing assets or creating new assets. This generally involves identifying gaps in supply, places where demand for a service exceeds supply, or gaps in potential ecological networks or green travel routes. The aim is to draw up a prioritised list of investment opportunities. This can be used to channel funds that arise from sources such as biodiversity net gain payments from developers, landfill tax, or other grants.

We have investigated the following tools for identifying investment opportunities.

  • Scores and rules. Starting from an ecosystem service map generated using the scoring system, simple rules can be applied using a GIS (geographical information system) such as ArcGIS or QGIS to identify gaps in supply. For example, superimposing a map of scores for the service of air quality regulation with areas of high air pollution and high population density can show where there are opportunities to create vegetation barriers between pollution sources (such as busy roads) and houses or schools. An example of this type of map for Oxfordshire is on page 21 of Natural Capital Mapping in Oxfordshire.
  • EcoServ-GIS. The EcoServ-GIS model is an open source model developed by the Wildlife Trusts which automates the generation of opportunity maps using scores and rules. Unfortunately the model has become unusable because it has not been updated to be compatible with current versions of ArcGIS. However it is still applied by Natural Capital Solutions, a small consultancy company, who have adapted and updated it to overcome these problems. We are currently involved in a small project with Natural Capital Solutions, Liverpool John Moore University and Chloe Bellamy (one of the original developers of EcoServ-GIS) aimed at starting to rewrite EcoServ-GIS to make it freely available to all users, using a method developed by our visiting student Martin Besnier for generating the base map.
  • Proprietary models for opportunity mapping. There are three other models for opportunity mapping: LUCI, SENCE and Viridian. These are available on a consultancy basis. We did not test them and we do not list them as part of the toolkit because they did not meet the criteria of being freely available. However, if resources are available, they could be a cost-effective way of identifying opportunities to enhance GI.
  • Accessible Natural Greenspace Standards (ANGSt). These standards were developed by Natural England in 2010. They recommend that everyone should have accessible natural greenspace:
    • Of at least two hectares in size, no more than 300 metres (five minutes' walk) from home.
    • At least one accessible 20 hectare site within two kilometres of home.
    • One accessible 100 hectare site within five kilometres of home.
    • One accessible 500 hectare site within ten kilometres of home.
    • A minimum of one hectare of statutory Local Nature Reserves per thousand population.

    We applied this method in Bicester, for the first two of these criteria. We found that only 13% of properties in Bicester are within 300m of a natural green space over 2 hectares (Bure Park and Charbridge Way), and no properties are currently within 2 km of a large (20 hectare+) natural green space. The results can be seen here.

  • Participatory maps. A key method of identifying suitable opportunities to enhance green infrastructure is though participatory mapping with stakeholders and residents. As well as assessing the current value of green infrastructure assets, participants can be asked to identify gaps between supply and demand, threats to existing assets, and opportunities for improvement. Read about how we applied this method in Bicester here.
  • Ecological network mapping. Ecological networks (also known as wildlife corridors) allow species to travel through a connected route of suitable habitats, in order to access food, shelter, mates, breeding sites or more suitable climate conditions. They can be identified through participatory work, modelling, or (ideally) a combination of both. Local wildlife groups, local authorities, researchers and landowners can work together to identify suitable sites for habitat restoration that will help to link existing sites together. This can be informed by habitat connectivity modelling, which identifies existing networks and how these could potentially be extended and linked together. Forest Research used their BEETLE model to map ecological networks for woodland, grassland and wetland species in and around Bicester (see report here). However, due to the lack of semi-natural habitats in the area, few obvious options for improving connectivity were identified. We are continuing to work on additional options for network mapping that takes better account of the green spaces within urban areas. Local wildlife groups in the Oxford-Cambridge Arc are also developing potential 'Nature Recovery Networks' and we expect these to be released soon. Other potential networks include Natural England's National Habitat Networks and Buglife's B-lines for pollinators.
  • Working with Natural Processes (WWNP) is an interactive map developed by JBA consulting, the Environment Agency and Lancaster Environment Centre (available via the EA here and via JBA here) which identifies the best places to plant trees for three types of flood regulation: intercepting rainfall in the upper catchment; slowing the flow on floodplains; and intercepting floodwater along stream and river banks. This takes account of soil permeability (i.e. it is assumed that trees will be more effective when planted on relatively impermeable soil, as they will help to improve infiltration. However it does not take account of the number of properties downstream that are at risk of flooding. The datasets can be downloaded. The Forestry Commission's Woodland for Water maps are very similar and can be viewed on the MAGIC website, but these cannot be downloaded to GIS.
  • Green infrastructure strategies identify existing assets and list opportunities for creating multifunctional networks of green infrastructure. They incorporate not only ecological networks but also areas of high natural capital which provide multiple services for people. It would be possible to use the methods identified in this toolkit to inform development of such a strategy: by mapping existing assets, modelling how they could be connected, and using participatory workshops to refine the strategy. A good example is the GI strategy for Cambridgeshire, which includes connected networks of green infrastructure for wildlife and people as well as prioritised investment opportunities for enhancing and restoring habitats and green spaces within the network.

Site design

This is a placeholder and will be expanded soon.

  • How can we plan good Green Infrastructure?
  • Are we achieving net gains of ecosystem services?

Potential tools:

Valuation

This is a placeholder and will be expanded soon.

  • What will the benefits be?
  • Can we make a business case?

Potential tools:


Acknowledgements

We are very grateful to all our project partners and stakeholders (listed to the right), who gave up their time to co-design the project, participate in meetings and workshops, give feedback on the toolkit as it developed, and help in many other ways. Many individuals were involved and we apologise to those who are not explicitly named below. The project was steered by Jenny Barker at Cherwell District Council (with valuable inputs from Sue Marchand, Gill Munday, Sharon Whiting and many others), Nicole Lazarus and Lewis Knight at Bioregional, and Sam Shippen at Bicester Town Council. We had valuable feedback throughout from Nick Mottram and Vicky Fletcher at Oxfordshire County Council, Dan Carpenter at Thames Valley Environmental Records Centre, Dawn Pettis at OxLEP, Chris Johnson from Bicester Town Council, Chris Williams, Haidrun Breith and others from BBOWT, Hilary Philips of Wild Oxfordshire, Mike Pollard from the RSPB, Stuart Malaure at the Environment Agency and Pam Roberts at Bicester Green Gym. A2 Dominion kindly provided data on the design for North-west Bicester eco-town. We are especially grateful to Chris Fairbrother and Adam Brown from the South Downs National Park Authority for coming to talk about their work with EcoServ-GIS. Teams led by Kieron Doick and Darren Moseley at Forest Research carried out the excellent iTree-eco analysis and the habitat network mapping using their BEETLE toolkit. Several tool developers and users gave us invaluable help: Paul Nolan at Mersey Forest (GI-Val), Jim Rouquette at Natural Capital Solutions (help with applying EcoServ-GIS), Oliver Hölzinger of CEEP (Natural Capital Planning Tool) and Maggie Keegan at the Scottish Wildlife Trust (Natural Capital Standard for GI). Anne Manwaring and Carolyn Grillo kindly allowed us to use Bicester Library for the public drop-in sessions. For the hedgehog survey, Steph McNeil of Bicester Technology Studio very kindly offered the services of her students to make the hedgehog tunnels, and the local magazine Your Letterbox publicised the online survey of hedgehog sightings. At ECI, the project benefited from the outstanding work of two MSc students (Helen Mason and Sierra Kennison), our research assistant Jo Thompson, and a visiting student from the Université Paris Sud (Martin Besnier). Finally, we are grateful to Bruce Howard at the Ecosystems Knowledge Network for organising the webinar, to Julia Thrift at the Green Infrastructure Partnership for inviting us to speak at their excellent annual conference, and to Alister Scott at Northumbria University for inviting us to several very useful seminars and inviting us to contribute a paper to the special issue of the TCPA journal as part of his Mainstreaming Green Infrastructure fellowship. The project was funded by NERC as a Green Infrastructure Innovation Project.

Partners

  • Environmental Change Institute, University of Oxford
  • Forest Research (BEETLE and iTree-Eco tools)
  • Cherwell District Council
  • Bioregional Development Group
  • Bicester Town Council
  • Oxfordshire County Council
  • Oxfordshire Local Enterprise Partnership
  • A2Dominion Housing Group Ltd
  • Berkshire, Buckinghamshire and Oxfordshire Wildlife Trust (BBOWT)
  • Wild Oxfordshire
  • Environment Agency
  • South Downs National Park Authority
  • The Mersey Forest
  • Green Infrastructure Partnership, Town & Country Planning Association (TCPA)
  • Ecosystems Knowledge Network

Outputs


Useful Links

January 2020 - this web page is still under development and further material will be added as the research continues.