The data below is derived from a randomised sample plot across the city as a whole, regardless of ownership. Good species diversity is another metric of the health of the urban forest.

Source: Analysis and interpretation of tree audit data for Cambridge City Council (ADAS, 2013) [PDF, 6.5MB].

Cambridge city species profile

• Ash (Fraxinus): 22%
• Cherry (Prunus): 15%
• Lime (Tilia): 8%
• Apple (Malus): 6%
• Cupressus (Cupressus): 6%
• Sorbus (Sorbus): 5%
• Maple (Acer): 5%
• Birch (Betula): 5%
• Yew (Taxus): 4%
• Poplar (Populus): 3%

Tree canopy cover is the metric used to indicate the benefits provided by the urban forest, and is measured as a tree canopy cover percentage of the total area under review.

In 2008 and 2018, tree canopy cover was measured at 17.1% and 17.6% respectively, by analysing Proximitree™ data. This is a slight improvement of 0.5% representing an increase of 20 hectares over 10 years. In 2019 it was measured at 20.1% using sample plot analysis as part of our i-Tree Eco project.

Tree canopy cover by ward

• Abbey: 14.3%
• Arbury: 18.4%
• Castle: 18.4%
• Cherry Hinton: 13.1%
• Coleridge: 17.4%
• East Chesterton: 19%
• King’s Hedges: 17.5%
• Market: 16%
• Newnham: 21.2%
• Petersfield: 17.3%
• Queen Edith’s: 17.9%
• Romsey: 17.5%
• Trumpington: 18.1%
• West Chesterton: 21.1%

The bulk of tree canopy cover in Cambridge is in private ownership. Most of this is in residential gardens which make up the largest single land use (around 39%).

Source: Tree canopy cover in Cambridge between 2008 and 2018 (Dr T Jackson, 2023) [PDF, 3MB].

Ash trees have been estimated to make up around 22% of the total number of trees in Cambridge.

They are currently under threat from Ash Dieback Disease which is predicted to kill around 95% of all ash trees in the UK. Ash Dieback has been officially recorded as being present in the Cambridge area since 2014.

We have over 1400 individual ash recorded on our tree management database (excluding groups and woodlands). The following ash species where present in May 2018.

Ash species in Cambridge by proportion

• Fraxinus americana: 1.2%
• Fraxinus angustifolia: 0.4%
• Fraxinus excelsior: 77.4%
• Fraxinus excelsior 'Diversifolia': 1.7%
• Fraxinus excelsior 'Jaspidea': 1.1%
• Fraxinus excelsior 'Pendula': 0.6%
• Fraxinus excelsior cultivar: 0.1%
• Fraxinus ornus: 6.5%
• Fraxinus oxycarpa: 0.1%
• Fraxinus oxycarpa 'Raywood': 6.7%
• Fraxinus pennsylvanica: 0.2%
• Fraxinus (not identified to species level): 4%

A randomised sample of 99 trees from this population was taken in 2017 and surveyed in September of that year. The aim is not to identify ash die back disease but to monitor ash condition as indicative of the spread and effect of the disease.

Follow-up surveys have been undertaken annually except in 2020 and 2022. The survey measured the amount of defoliation, deadwood and regrowth present in each tree and the results are presented below.

• Survey methodology [PDF, 0.4MB]
• Survey report 2024 [PDF, 0.2MB]

The amount of tree canopy cover depends on a number of different factors including population and built density, land use type, and age of primary development.

We have selected a list of four towns and cities of similar size, populations and land uses. Cambridge fairs pretty well in these comparisons. The same methods have been used for measuring each of the factors for each of the towns to allow for more accurate comparisons.

Sources:

• Population: List of English districts by population – last accessed 21 May 2019
• Population density: List of English districts by population density – last accessed 21 May 2019
• Land use: How much is your area built on (BBC) – last accessed 21 May 2019
• Tree cover: Doick, K., et al., (2017) The Canopy Cover of England’s Towns and Cities: baselining and setting targets to improve human health and well-being

• Overall canopy cover increased from 17.1% in 2008 to 17.6% in 2018. This increase was mostly due to the growth of medium and large trees, since young trees have smaller crowns.
• The only wards to experience a decrease in canopy cover were Castle, due to the large construction projects, and Newnham, because of a substantial decrease in canopy cover in gardens. Nevertheless, Newnham remained the ward with highest canopy cover in 2018.
• Gardens account for a high proportion of canopy cover, given their relatively small area. The area of land dedicated to gardens decreased in all wards between 2008 and 2018 due to densification. However, in some wards, the canopy cover in these gardens increased. This suggests that gardens are a potential target for tree planting or preservation.
• Tree preservation orders are currently located mostly in the wards with high canopy cover, so targeting wards with lower canopy cover would be valuable.
• Protected open spaces contain a high proportion of tree canopy cover, particularly for large and massive trees in those wards with lower total canopy cover. Therefore, protected open spaces are important for protecting and increasing tree canopy cover in the areas of Cambridge which need it most.
• Between 2008 and 2018, canopy cover increased substantially in most parts of Cambridge with a high index of multiple deprivation. These areas now have canopy cover comparable to the rest of the city. To increase this further, efforts should focus on adding new tree preservation orders.
• Source: Tree canopy cover in Cambridge between 2008 and 2018 (Dr T Jackson, 2023) [PDF, 3MB].

In summer, Cambridge can be one of the hottest places in the UK. The shade provided by urban trees is valuable, especially to pedestrians and cyclists. Increasing this tree-shade can improve people’s wellbeing and encourage more active travel.

We commissioned a report to map tree shade in the city – it assessed shade at 8am, midday and 4pm. It also looked at opportunities to plant trees on public land and in adjacent private gardens. It recommends concentrating tree planting and protection efforts in areas with lower levels of tree-shade.

• Mapping tree shade in Cambridge (Dr T Jackson) [PDF, 2.5MB]

Significant findings

• Shade varies through the day. Most streets in Cambridge have more than 50% shade at 8am, while many have less than 20% shade at midday.
• West Cambridge, particularly Castle and Newnham, has the highest level of shade.
• The variation in shade level is greatest at 4pm. At this time, many streets have low levels of shade but with planning it is possible to find shaded routes through the city. Because of this, we plan to use the 4pm shade map to prioritise streets for new planting.
• The streets with least shade include Castle Street, Daisy Close, Frank’s Lane, Hatherdene Close and Kilmaine Close.
• Road shade is not related to the proportion of the road bordered by gardens. This could signify an opportunity to increase tree planting and protection in private gardens to increase road shade. It could also be a methodological issue, as we focused on gardens and did not include parks and other green spaces.
• Roads with more council-managed street trees had higher levels of shade. This suggests that our management of these trees has increased the shade on these roads. Future protection of street trees should increase it further.

Some urban areas have a lot of tree cover, while others lack these essential natural assets. Tree equity is the idea that all communities should have equitable access to the benefits of trees where they live.

A tool called Tree Equity Score UK launched in 2023. It generates scores from 0 to 100 for most urban neighbourhoods, and composite scores based on them for local authorities.

The tool uses tree-canopy data from Google and six climate, health and socioeconomic indicators to calculate its scores. It shows that, in areas of lower tree cover, there is a direct link to more pollution and poorer air quality.

Composite scores ranged from 61 to 96 across the 327 local authorities that were assessed. The score for Cambridge was 91, putting us in the top 19% of local authorities for this score. 45 other local authorities scored 91 or more.

The tool was co-developed by American Forests, the Woodland Trust and the Centre for Sustainable Healthcare.

As part of the City’s urban forest approach to managing tree canopy cover we have published a series of ward tree canopy and land use profiles. There is one for each ward. The aim of this project was to:

• understand tree canopy distribution, composition, structure and change at a granular geographical scale for each ward
• create baseline evidence from which to measure future change
• aid decision-makers and stakeholders about tree canopy at a local/ neighbourhood scale

These ward summaries give absolute and relative measurements, as well as ranking wards and comparing data to the city average, for several variables. These variables include:

• Tree canopy cover distribution and change between 2008-2018 across each ward. Canopy cover is the proportion of the land area under tree canopy as viewed from above. Newnham for example currently has the highest canopy cover, at the same time it has lost the most canopy.
• Canopy height distribution and change. The canopy height is a metric that measures canopy height as it might be experienced from the ground. Petersfield for example ranks 4^th in canopy height but is one of two wards (incl. Castle) that has experienced a reduction in canopy height.
• Tree density distribution. All wards have seen an increase in numbers of trees over 18m tall but reductions in the 6-12m size class. This can be explained by a developing canopy.
• Land use distribution. We measured tree canopy on three types of land use: 1. manmade; 2. natural; and 3. gardens. Gardens are a subset of the natural type and were chosen for their important contribution to tree canopy in the City (on the front of each profile document is an aerial photograph of each ward - the important contribution to tree canopy of gardens can be clearly seen). Across the city we have lost gardens and canopy to manmade land uses.
• Protected trees. Queen Ediths has the highest canopy protected by TPOs. Market has the highest canopy protected by conservation area and TPOs. TPOs remain until they are revoked, conversely trees change over time. Our ‘% TPOs covered by canopy’ metric is a measure of our TPOs effectiveness and indicates where, if we had available resource, we might wish to review existing TPOs – Arbury and West Chesterton are two such wards.
• Protected Open Spaces measures canopy in designated ‘protected open space’ and how important such spaces are within each ward and the canopy within to each ward.
• Land ownership looks at tree canopy distribution and contribution across City Council, County Highways and Private ownerships within each ward. Understanding who owns tree canopy and how it is distributed across ownerships is an important aspect to developing our strategic approaches to canopy protection and enhancement.
• Shade and gardens. This looks at how much shade our roads receive, an important mitigation to increasingly hot summers and the encouragement of active travel. Tree can increase shade and perceptions of thermal cooling. The most important locations for trees to help ameliorate heat street along our roads are County Highway land and adjacent gardens. This data helps us identify priority areas of low shade for green interventions to increase shade (e.g. planting in the Highway verge, engaging with residents to plant up front gardens).
• Tree canopy and deprivation. The Government’s Index of Multiple Deprivation allows us to rank areas of deprivation and understand their tree canopy within each ward. This gives us another tool to help prioritise our strategic tree resources.

Prepared by Dr T Jackson for Matthew Magrath, Cambridge City Council.

• Abbey [PDF, 4MB]
• Arbury [PDF, 4MB]
• Castle [PDF, 3MB]
• Cherry Hinton [PDF, 3.5MB]
• Coleridge [PDF, 3.5MB]
• East Chesterton [PDF, 3.5MB]
• King's Hedges [PDF, 4MB]
• Market [PDF, 3.5MB]
• Newnham [PDF, 3MB]
• Petersfield [PDF, 3.5MB]
• Queen Edith's [PDF, 4MB]
• Romsey [PDF, 4MB]
• Trumpington [PDF, 3.5MB]
• West Chesterton [PDF, 3.5MB]

Using the i-Tree Eco tool, and with the support of resident volunteers, we have quantified the environmental benefits provided by the city’s trees.

The report reveals the following key findings about the city’s trees:

• they capture approximately 2,040 tonnes of carbon each year, valued at £524,000
• they store around 88,000 tonnes of carbon, valued at £22,500
• they remove about 22.2 tonnes of pollution annually, valued at £990,000
• they prevent roughly 97,600m³ of stormwater runoff each year, valued at £153,000

The tree canopy covers approximately 20.1% of the city. The total value of the city’s urban forest is estimated at £1.03 billion, with a replacement cost of £172 million.

The data below is derived from our own tree inventory. Good species diversity is another metric of the health of the urban forest.

• Source: Analysis and interpretation of tree audit data for Cambridge City Council [PDF, 6.5MB]

Council parks and street trees

• Cherry (Prunus): 14%
• Maple (Acer): 12%
• Lime (Tilia): 8%
• Birch (Betula): 8%
• Sorbus (Sorbus): 8%
• Ash (Fraxinus): 6%
• Apple (Malus): 4%
• Thorn (Crataegus) 4%
• Willow (Salix): 3%
• Horse chestnut (Aesculus): 2%

The figures below relate to individual street and parks trees only. Figures are from the last 10 years. The data is recorded by our tree officers using Ezytreev™ tree management software. It should be treated as indicative as it does not show, for example, trees in groups, recently planted trees that have been removed within the first year of planting, or trees felled in emergency situations.

The figures below relate to planting ‘standard’ trees that are between 2.5 and 3.5 metres tall at planting, and planted in our streets and parks trees only.

In 2016 we approved a ring-fenced budget for tree planting that meant we can ensure no-net-loss to our tree population.

Between 2019 and 2023 we were a partner in the Nature Smart Cities across the 2Seas green infrastructure which funded the planting of over 2000 trees as part of it’s green infrastructure pilot, the Cambridge Canopy Project.

Since 2021 we have used Forestry Commission grant funding to boost our tree planting numbers.

• Find out more about how we manage trees in Cambridge
• Request a tree to be planted in a street or park

This has been running for over 30 years to incentivise tree planting in the city. In 2017 we approved a ring-fenced budget for the scheme of £5000. In 2018 we changed the way we delivered the scheme enabling us to increase the amount of trees could give away under the scheme.

• Find out more about our Free Tree for Babies Scheme

Number of Tree Preservation Orders (TPOs) served

The council has served over 800 TPOs since 1955. The table below shows the numbers served in the last 10 years.

• 2013: 35
• 2014: 38
• 2015: 20
• 2016: 24
• 2017: 33
• 2018: 45
• 2020: 36
• 2021: 39
• 2022: 24
• 2023: 28

Number of tree work applications assessed each year

Applications and notifications of works to trees protected by TPO or that grow in conservation areas have to be submitted to Cambridge City Council for assessment over the last 10 years.

• 2012: 452
• 2013: 445
• 2014: 474
• 2015: 589
• 2016: 510
• 2017: 547
• 2018: 632
• 2019: 606
• 2020: 559
• 2021: 661
• 2022: 551
• 2023: 657

Find out more about protected trees.

Number of high-hedge complaints received each year

Under the Anti-Social Behaviour Act 2003, local authorities must deal with disputes between neighbours regarding high hedges, where a complaint has been made under the Act.

• 2013-15: 0
• 2016: 1
• 2017: 0
• 2018: 1
• 2019: 0
• 2020: 1
• 2021-22: 0
• 2023: 1

How to make a High Hedges complaint