Trees valued at over £4.6m are under threat at Bonnington Walk, Lockleaze

Whatever the merits of this application of achieving its primary goal to provide much needed housing may be, it should not be permitted to proceed unless and until it has properly addressed how it will replace and build upon the Green Infrastructure (including trees) that will inevitably be lost if this application proceeds as presently formulated.

Summary of our submission

We object to this application for the following reasons.

Bristol City Council has:

Declared climate and environmental emergencies.

Committed to becoming carbon neutral by 2030.

Committed to doubling tree canopy cover by 2046.

As currently formulated, these plans to build new houses can only set back the work needed to resolve these emergencies and achieve these commitments.

  1. The need to build housing to meet sustainable economic or social development objectives should not be allowed to take precedence over ensuring that the development is also both environmentally sustainable and meets Net Gain objectives.
  2. Whatever the merits of this application of achieving its primary goal to provide much needed housing may be, it should not be permitted to proceed unless and until it has properly addressed how it will replace and build upon the Green Infrastructure (including trees) that will inevitably be lost if this application proceeds as presently formulated.
  3. The existing trees have a significant asset value which should not lightly be ignored. Using CAVAT, we have valued them at £4,674,918.
  4. Under the Mitigation Hierarchy, trees should not be removed unless there is no realistic alternative. One alternative would be to build around the trees rather than remove them.
  5. BCS9 of the Core Strategy also states that “Individual green assets should be retained wherever possible and integrated into new development”. Clear felling nearly all the trees to the east of the cycle/footpath should not, as it so often is, be the default option.
  6. Trees should not be removed merely because they are diseased or self-sown, or because they are small or not perfect specimens of their species.
  7. The removal of existing trees inevitably means that the eco-services they provided will not be replaced for decades, if at all.
  8. The adverse knock-on environmental impact on biodiversity of removing existing trees far outweighs any short-term benefits achieved by replacing them.

Our submission

The planning background

The National Planning Policy Framework

The National Planning Policy Framework (NPPF) seeks to ensure that new development is sustainable. It stresses the importance of Green Infrastructure as one of three overarching, interdependent objectives – economic, social, and environmental. This means that the presumption in favour of sustainable environmental development is just as important as any in respect of economic or social development objectives.

Trees are an integral part of this because of the importance of trees in relation to the management of air, soil and water quality along with other associated ecosystem services, climate change adaptions and beneficial health effects. The NPPF also seeks to achieve the protection and enhancement of landscapes and achieve Net Gain in biodiversity.

The Natural England Joint Publication JP029 – Biodiversity Metric 2.0 (BDM2) provides a way of measuring and accounting for biodiversity losses and gains resulting from development or land management change. It defines Net Gain as an:

“approach to development that aims to leave the natural environment in a measurably better state than beforehand. This means protecting existing habitats and ensuring that lost or degraded environmental features are compensated for by restoring or creating environmental features that are of greater value to wildlife and people. It does not change the fact that losses should be avoided where possible, a key part of adhering to a core environmental planning principle called the mitigation hierarchy.”

The Mitigation Hierarchy

Avoid – Where possible habitat damage should be avoided.

Minimise – Where possible habitat damage and loss should be minimised.

Remediate – Where possible any damage or lost habitat should be restored.

Compensate – As a last resort, damaged or lost habitat should be compensated for.

This is a cascading decision process – only if the preceding choice is unavailable is the next considered.

Local Planning Authorities (LPA) in the UK have a statutory duty to consider both the protection and planting of trees when considering planning applications. The potential impact of development on all trees is therefore a material consideration. In particular, BCS9 of the Core Strategy states that “Individual green assets should be retained wherever possible and integrated into new development”.

We have summarised Bristol’s planning policies as they relate to trees here – Planning obligations in relation to trees in Bristol.

Summary of the proposal in relation to trees

This site covers just over six hectares. The Lockleaze Allotments (a 0.8 hectare Statutory Allotment[1]) is located to the south east of the widest part of the site. It appears to be disused. Most of the substantial trees growing on the site are growing in or around this allotment or to the north of it. We have calculated that, taken together, they cover at least 1.3 hectares of the site – a tree canopy cover (TCC) of around 20% which is well above the estimated TCC for Bristol as a whole which is just under 12%.

All our calculations, summarised below, can be examined in this linked spreadsheet.

The Arboricultural Impact Assessment Report (the AIS) dated June 2020 (based on a survey done on the 19th and 20th of September 2019) identified a combined total of 58 individual trees and 40 tree group features. The number of trees in each group is not given, so it is not possible to say how many trees in total are growing on the site.

Of all the trees growing on site 24 individual and at least 251 group trees are identified for removal. The trees growing in Groups G69 and G74 are all to be removed, but the number of trees in each group is not identified so we have not been able to include or count these in our calculations.

The only reason for given for felling these two groups is because they show evidence of Ash Dieback (Hymenoscyphus fraxineus). As the AIS recognises, the mere presence of Ash Dieback is not a sufficient reason for the removal of a tree. We oppose the removal of these tree unless it can be shown that they there is a better reason for their removal.

The CAVAT calculation

Using CAVAT we have calculated that those identified trees which have a measured stem Diameter (DBH) are worth £4,674,918.  As the AIS fails to give the upper life expectancy ranges[2] of the majority of trees, we have assumed that all those trees given a 10+ or 20+ years life expectancy will survive between 40 and 80 years. This attracts a 5% discount on the base valuation. We have applied a CTI factor for Bristol of 150[3]. All the other factors are set to their default values.

The BTRS calculation

These two tree groups and five individual trees are categorised as Category ‘U’ trees under BS5837:2012 Trees in relation to design demolition and construction, and so have not been taken into account for the purpose of the Bristol Tree Replacement Standard (BTRS) calculation. A further 10 trees are also excluded from the BTRS calculation because their stem diameters are under 15 cm. We advocate that all trees identified for removal should be replaced no matter what their size.

Notwithstanding this and based on the current guidance, we have calculated the BTRS value at 455 trees as per the AIS calculation.

Net Gain calculation

No Net Gain calculation has been undertaken using BDM2 in support of this application.

We have undertaken our own BDM2 calculation in respect of just the trees surveyed in support of this application. A full calculation needs to be undertaken in respect of the whole of the site. This will inform any future decision about achieving Net Gain if this development is to be allowed to proceed.

Using BDM2, we have calculated that the combined tree canopy cover[4] of just the known, measured trees is 1.21 hectares. We have set the A-1 Site Habitat Baseline Habitat Type to Urban – Street Tree in the calculation. This assumes, amongst other things, that any replacement trees will reach maturity in 27 years and so uses a multiplier of 0.3822 to reflect this.

This gives Base Habitat Units of 5.864 and a Base Replacement value of 3.17 hectares. If we add an arbitrary Net Gain value of 10%[5], then the Base Habitat Units increases to 6.451 and the Base Replacement value to 3.49 hectares. Assuming that a 27-year-old tree has a canopy of .00403 hectares, then 866 replacement trees are needed to replace what has been removed and to achieve Net Gain.

Loss of the ecosystem services of trees

We invite you to consider the decades-long damage that felling just one tree (let alone over 277 trees) will cause by inputting the DBH of any tree identified for removal into our Tree CO2 Calculator.

As you will see, when an equivalent tree is replaced on a one-for-one basis, the lost CO2e is never recovered. Even when the largest tree (with a DBH of 100 cm) is replaced with eight trees in accordance with BTRS, it will still take some 40 years to recover the 10.4 tonnes of lost CO2e. And this is just one of the eco-services that trees provide us!

Impact on wildlife from tree loss

We endorse the following passages from the Bonnington Walk Breeding Bird Survey Report which observes at 5.2 Habitat Loss:

The Proposed Development will include the loss of scrub, trees and buildings which provide habitat for breeding birds. The extent of habitat loss is likely to include all the scrub and trees in the centre of the Site with some edge habitat along the boundaries retained…The loss of this habitat will have an impact on any birds using it for foraging or breeding at the time. The Site is located within an urban landscape with limited natural habitats. Alternative habitats are not readily available adjacent to the Site, though alternative habitat is available in the wider landscape including Stoke Park Estate and connected habitats further east. Habitat loss on Site will have an impact at a Local level by reducing breeding bird habitat in the local area…

and at 6.2.1 Habitat Loss:

Where possible, habitat loss should be avoided, and natural habitats retained. Scrub and trees are of most value to breeding birds at this Site. When natural habitats are retained these should be protected during construction to prevent damage including root compaction and knocking off or damaging over hanging limbs.

This is just one example of the likely adverse impact on wildlife resulting from these tree removal plans. There is evidence of a diverse range of both flora and fauna that likewise will also be adversely affected by the loss of these trees.

The Bristol Tree ForumJuly 2020

You can find more detail about the application here:

20/02523/FB – Land on south side of Bonnington Walk, Bristol


[1] Owned by BCC under its asset number 8397.

[2] CAVAT uses six age ranges to set the discount factor.

[3] Bristol has a population of 459,300 and a land area (as opposed to the Administrative area which covers large parts of the River Avon and coastal margins) of 10,970 hectares. Using this gives a population per hectare of 41.9 (459,300/10,970) and so a CTI Index value of 150.

[4] Under BDM2 each tree’s Root Protection Area (RPA) is calculated at 12 times its stem diameter. RPA is roughly equivalent to a tree’s canopy.

[5] The choice is arbitrary chosen only for the sake of illustration. We are not advocating a Net Gain of 10%, though the concept of Net Gain implies an improvement on the base values.

Wales and West Utilities helps to protect Bristol’s precious trees

Wales and West Utilities has been congratulated by the Bristol Tree Forum, and thanked mightily for their understanding and practical approach to a possible future environmental catastrophe at one of their installations in Bristol.

Stoke Lodge Playing Field is a 26-acre site in Stoke Bishop in Bristol. In the north west corner of the field is a gas “kiosk” which houses gas pressure regulation equipment. It was built in 2009, replacing a smaller installation nearby which was not on the same land. It is the responsibility of Wales and West Utilities.

Many locally and nationally notable trees grow on the parkland, a number of them getting quite old now, and in need of some love and our protection.

The access to the compound is over the roots of some of these important trees, most of which are the subject of Tree Preservation Orders. Protected trees surround the compound, and their roots, which are very superficial (as is the way with tree roots) and in places even exposed, are at risk of damage from vehicles driving over them and parking on them.

The W&W gas kiosk

Tree Roots

Tree roots extend radially in every direction to a distance equal to at least the height of the tree (assuming no physical barriers) and grow predominantly near the soil surface.

Typically, 90% of all roots, and virtually all the large structural supporting roots, are in the upper 60cm of the soil.

Soil disturbance within the rooting area should be avoided, whenever and wherever possible as this can significantly adversely affect tree health and tree stability. 

Associated with roots are much finer, thread-like, mycorrhizae. Mycorrhizae are symbiotic fungi which grow on or in roots, an association which is mutually beneficial to both the tree and the fungus. They are extremely efficient at nutrient absorption, especially phosphorus, and many trees cannot survive without them.

Diagram of a typical tree root system:

Cars, lorries and vans are heavy. They leak oil and hydraulic fluids from braking systems and power steering pipework and pumps. They also leak windscreen washer fluids. These chemicals are toxic for trees.  In the root area of a tree soil compaction caused by vehicles and the deposit of toxic or impermeable materials should be avoided. The nearer to the trunk these things take place the greater is the damage done and the greater the loss of roots.

Local residents are very protective of the trees – this whole Parkland is hugely important for them, and they have taken its care to their hearts.

Vans and lorries from Wales and West attend the site, both for routine maintenance visits and for any “emergencies”.

Recently one of the residents noted a Wales and West van parked on the exposed roots of one of the trees, so they contacted the Company to point out the dangers for the tree’s future that could be caused by this.

The response from a manager at the Company was immediate and most gratifying. Within hours a site meeting had been arranged with the W&W Manager, the Resident and the BTF BS9 Tree Champion in attendance – all suitably socially-distanced!

The Manager listened to everything we said. He told us that Wales and West had not previously been aware of the importance of these trees, nor aware of the peculiarities of the siting of the compound in relation to the trees.

He went on to say that he would do everything he could to inform future Wales and West employees visiting the site of the sensitive nature of the ground they would have to drive over, and that they would keep traffic passing over the root areas to a minimum, allowing only one vehicle to park on site at a time, parking any others required nearby on the highway. The one vehicle needed would not park under the canopies of the trees. It is possible for one vehicle to park clear of tree canopy areas.

He arranged for good quality signs to be affixed to their entrance gate and to the fence enclosing the kiosk, so that Wales and West operatives would be aware of the need to avoid damage to tree roots at this particular site.

This is the sign W&W attached.

The Bristol Tree Forum has been working hard in recent years, with local residents and their representatives, to encourage Bristol City Council, as owners of the land and as Landlord, to ensure that Tree Preservation Order regulations are complied with by their tenant using the Playing Field, and if necessary enforced. We have had some limited success. This made the attitude and actions of Wales and West Utilities all the more overwhelming.

So, we would like to thank W&W’s manager again for his actions on behalf of the trees, and to compliment Wales and West Utilities for supporting an ethos which encourages community engagement and action like this.

Postscript

The sign (see above) riveted to the main entrance gate onto the site and to the gas kiosk has been removed. It looks like the rivets have been drilled out, rather than the sign being removed by snapping it off, so it must have taken some effort and maybe even some planning to do this. The sign appears to have been taken away.

Who could possible think that doing this ‘vandalism’ could be for anyone’s benefit? It cannot have been Bristol City Council and it is hard to imagine who else would do such a thing. We are investigating.

Post Postscript

Wales & West have now told us that they removed the sign, saying “We put them in the wrong place. Now moved to the right place as agreed with the leaseholders of the land.” What leaseholders? As far as we know this bit of land is not leased. It belongs to Bristol City Council.

Finally

This is the notice that was on the gate:

This is the sign W&W attached.

It is all about protecting precious trees and safeguarding our environment.

There is no single Leaseholder with control of this gate. It is owned by Bristol City Council and the use of the gate and the access to the Field it grants is shared between Cotham School and Wales and West Utilities (W&W), two Leaseholders who use separate parts of the land beyond the gate. We do not know who asked W&W to remove the notice from the gate, but we are bound to ask what reasonable person, with any regard at all for trees, the environment and climate change, would ask W&W to remove it from a shared gate that they may not control, and why would they? Own up please?!

Bristol City Development – Where did all the Green go?

The Climate and Ecological Emergency

In 2018, with much fanfare, Bristol City Council (BCC) declared a Climate Emergency, the first UK city to do so, preceding the UK government by over a year. This has been followed up by the declaration of an Ecological Emergency, and a raft of sustainability aspirations detailed in the Bristol One City plan including doubling the tree canopy by 2046, doubling wildlife abundance by 2050, and City-wide carbon neutrality by 2030.

So why is it that so much of our informal green spaces are still being lost, and so many of our trees continue to be felled?

Is the BCC Development Office blocking Climate and Environmental Action?

A clue to this came out of a recent planning application to build a 4-storey block of flats in St Paul’s, in a street with one of the highest illegal levels of pollution in Bristol, above recommended noise levels, in a known high flood risk area and on land thought to be contaminated.  It was shown that the planned development would increase pollution and noise levels. Furthermore, in an area with one of the lowest tree density in Bristol, five mature maple trees were to be felled, removing the last mitigation for noise, pollution and flooding in the street. The trees are on the very edge of the development site and could therefore have been retained, readily complying with BCS9 which states “Individual green assets should be retained wherever possible and integrated into new development”.

Bristol’s Planning policies are contained in two main documents:

These are supplemented by the Planning Obligations Supplementary Planning Document. All were variously adopted and implemented by the Council between 2011 and 2014.

Despite contravening core strategy planning policies on green infrastructure (BCS9, DM15), pollution (BCS23, DM33), climate change (BCS13), flood risk (BCS16), noise (BCS23, DM35) and health (DM14), the Development Office did everything in its power to promote and advocate this development.

The reasons for this became clearer when officers were asked during the Planning process specifically why they supported a development which breached so many core policies aimed at protecting the health of citizens, the environment and the City’s crucial green infrastructure.

The Head of Development Management responded, “With regard to this application, the policy aims of the Core Strategy could be seen as the delivery of housing (BCS5), including affordable housing (BCS17)”. Further, “Loss of green infrastructure will only be acceptable where it is…… necessary, on balance, to achieve the policy aims of the Core Strategy”.

The statement effectively says that, whilst the need for new and affordable houses remains, BCS5 and BCS17 can override other policies including those mentioned above. Thus, green infrastructure that could have been retained is ignored, pollution and noise levels above legal limits are permitted, and the worsening health of residents would be tolerated. This position seems to be contrary to that previously held, with development under BCS5 and BCS17 needing to be also in compliance with the other core policies. As there will always be a need for new homes and affordable homes, the concern is that all other policies can be set aside indefinitely.

We would suggest that BCC Development Office interpretation is in contravention of the National Planning Policy Framework (NPPF) which states that: “the purpose of the planning system is to contribute to the achievement of sustainable development (remember that phrase), including “an environmental objective” – to contribute to protecting and enhancing our natural environment, including helping to improve biodiversity, mitigating and adapting to climate change and moving to a low carbon economy”.

So how has the BCC Development Office responded to BCC’s Climate and Ecological declarations?

The Development Office was also asked how implementation of planning policies had been influenced by the Climate and Ecological Emergencies. Their response was:

“Whilst Climate and Ecological Emergencies have been declared by the Council, the Bristol Local Plan has not been fully reviewed in the light of these and the policies referred to remain unchanged. Changes to Local Plan policies would have to balance the objectives of the respective declarations with the requirement to deliver sustainable development for the city”.   

By “balance”, it seems they may effectively mean “ignore”. Clearly their definition of sustainable development is somewhat different to that defined in the NPPF, with no intrinsic “environmental objective”, and, as one Councillor on the Committee remarked, the development will “lead to poorer people having shorter lifespans”. Unpacking their response still further, the implication is that there are currently no core policies in place to implement the Climate and Ecological emergencies. As described above, this is not true. Were BCS9, DM15, BCS23, DM33, BCS13, BCS16, DM35 and DM14 to be applied as intended in the NPPF, there would be sufficient policy support at least for the principles of the two emergency declarations.

Is this being led by bureaucratic or political decision making?

It is not clear why the Development Office has taken this position, but there are two possibilities that should be of concern:

  • The Development Office is acting contrary to the aspiration of the City’s political leaders.
  • Senior Council politicians who have made much political capital from the highly praised environmental declarations, have at the same time permitted, or perhaps even encouraged, Council Officers to disregard existing planning policies that would otherwise enable implementation of these declarations.

Thus, selective policy compliance allows development of second-rate housing in a race for quantity over quality.

It seems that Bristol City Council are choosing to emphasise some core strategic policies aimed at hastening house building, whilst demoting other core strategic policies aimed at protecting public health, green infrastructure, air quality and the environment. This is a recipe for slum development, and we deserve to know whether these decisions are being taken at a political or bureaucratic level.

Professor John Tarlton.

A letter to our Councillors

Dear Bristol City Councillors,

We recognise the fundamental importance of the natural environment, the value that nature has in an urban setting and the global threat posed by the ongoing climate catastrophe. We also recognise that trees are a crucial component in all these concerns.

We are supportive of Bristol City Council’s declaration of a Climate Emergency and an Ecological Emergency and the goals detailed in the One City Climate Strategy, including the commitment to carbon neutrality by 2030 and doubling the abundance of wildlife by 2050. We are also supportive of their commitment to doubling the tree canopy by 2046.

However, we have a real concern that the commendable words are not being matched by effective actions.

A principle aim of the BTF is to promote the planting and preservation of trees in Bristol for the well-being of its citizens, the sustainability of urban habitation, the enhancement of nature in the cityscape and as our contribution to combating climate change (see A Manifesto for protecting Bristol’s existing Urban Forest).

A recurrent concern we have is the continued loss of trees as a result of environmentally insensitive developments that are not sympathetic to the City’s declared commitments outlined above. On the other hand, the BTF supports developments that favour a sustainable environment over high density occupancy, and those that prioritise retention of existing trees.

Bristol’s policy on replacing trees lost to development – adhering to the Bristol Tree Replacement Standard (BTRS) – is widely well regarded. As such, decision makers believe that tree loss is mitigated by subsequent tree replacement. However, recent studies undertaken by the BTF have shown that this is not the case over the timescales committed to by Bristol City Council and the Green Party.

Typically, tree planting undertaken under the BTRS takes between 30 and 50 years to recover the biomass (and therefore the CO2e) lost by felling, well beyond the 10-year commitment on carbon neutrality, and even beyond dates set for doubling the tree canopy or doubling wildlife abundance.

The BTF study has been developed into a versatile online tool for calculating the extent and timescale of the carbon deficit, with a wide range of inputs. This can be accessed via the link Tree Carbon Calculator, and we encourage you to try this yourself. See also the BTF blog Tree replacement and carbon neutrality.

In the example shown here, a mature tree felled in 2020 is replaced by four trees (as per BTRS) of the same species. The carbon released (2 tonnes CO2e) is not recovered until 2064, a full 34 years beyond the date Bristol aims to be carbon neutral.

This model can also be used to determine how many replacement trees are needed to recover lost carbon within a particular timescale. In the example shown, to be carbon neutral by 2030, a reasonable expectation as this is the declared aim of BCC, the felled tree would need to be replaced by 37 plantings of the same species. Scaled up to, for instance, 500 trees, new plantings would need to number 18,500 to mitigate the lost carbon.

This new information represents a fundamental change in the evidence base for tree replacements, and emphasises the need to retain existing mature trees, and not to consider replacement by new plantings as adequate mitigation.

We request that you consider this new information with urgency and make a commitment to oppose developments where mature trees are removed and tree replacements do not deliver carbon neutrality by 2030.

Tree replacement and carbon neutrality

The UK aims to be carbon neutral by 2050. Bristol is more ambitious and aims to reach that goal in 2030. Both are massive challenges in which trees have been enrolled to play their part in mitigating the carbon dioxide (CO2) created by human activity.

Background

There are plans for extensive tree-planting.  The government pledged to plant 30 million trees a year, nationally. This a huge challenge partly because seedlings and land has to be found for these trees. However even when planted, these trees will take a long time to grow and extract CO2 from the air.  We in Bristol Tree Forum are concerned that not enough attention is given to the role of existing mature trees.  

Trees grow and add to their mass each year. Most of this mass is in the form of cellulose and lignin and about 50% of those organic compounds is carbon, obtained through photosynthesis using the energy of sunlight and CO2 from the atmosphere.  The rate at which mass is accumulated increases with age so whilst a 10 year old tree might put on a few kilograms a year, a 50 year old tree might add 50 kg.  So the older the tree the better for CO2 fixation. However mature trees are constantly under threat – from development for housing and industry, from home owners overshaded by large trees, from councils assessing maintenance costs and risks.

Here in Bristol, the Bristol Tree Replacement Standard (BTRS) is part of local planning regulations and specifies how many replacement trees are needed to be paid for by the developer and planted to mitigate the loss of mature trees. The BTRS is a very welcome and forward-thinking strategy, but is it enough to support the Carbon Neutrality goals? Should BTRS  apply also to council-owned and indeed privately owned trees for which no funded replacements are available?

The Bottom Line

In an attempt to understand how this standard works in practice, we have developed an on-line calculator to explore different scenarios.

Tree CO2 Calculator

The general conclusion from this analysis is stark:  it will take 25 to 40 years before the replacement trees are able to compensate for the loss of the mature tree.

The graph shows the scenario of the replacement of a mature tree such as a Maple with a diameter of 60 cm by the 6 trees as determined by BTRS which are faster growing but shorter lived such as Rowens.

Assuming that the original tree is felled, chipped and used as fuel in a biomass boiler (the practice in Bristol), the carbon stored in the mature tree is returned to the atmosphere within months of felling.  The replacement trees start to grow, but absorb much less carbon than the original mature tree would have done, so they take many years to catch up. In the case shown in the graph, it takes 35 years (ie, to 2055) before the new trees mitigate the loss of the original tree.

Modelling

A model of this scenario needs to take into account:

  • the rate at which different species of tree grow at different ages in different conditions.
  • the estimated mortality of the tree over time.
  • the calculation of a tree’s biomass from its girth for different species.
  • the relationship between the tree’s biomass and the amount of carbon stored.

There is a lot of uncertainly in these relationships, partly because of the paucity of data on urban, as opposed to forest, trees. Urban trees are under threat not only from natural processes and disease, but also from the vagaries of vehicles and humans. Planting sites are often less than optimal and urban trees have no support from the ‘wood wide web’.

The interactive calculator allows the user to vary the parameters of the model using the sliders. This allows the sensitivity of the overall outcome to variation in values to be tested. Different policy choices can also be explored and can be used in a predictive sense to determine the number of replacements needed to achieve a given carbon neutral date.

Summary

Documentation on the website explains the thinking behind the model in more detail, and the sources of data used. The model is still under development, in particular to make it easier to select conditions for different species and situations, and to improve the quality of the model itself. The research literature is extensive but often of limited applicability to urban conditions.

We would be grateful to receive additional or better sources of this information, and indeed any comments on the model itself at co2@bristoltrees.space.

Chris Wallace, Bristol Tree Forum

In Defence of Dead Wood

It was once believed that when a tree died, it was no longer of use. For decades, we have actively removed trees at the first signs of rot or fungal attack, felling them at the base and removing all evidence of their existence…

Our guest editor, Nick Gates, Naturalist, writes

Storm damaged trees are hastily sectioned for firewood or bio-fuel. Sometimes, we replace them with a new, younger version of themselves. It was thought that this in turn kept other trees healthy, and that the wider environment benefited as a result.

The fall of a tree opens up new opportunities…

But nothing is further from the truth. By removing this deadwood, we are stripping out a most vital layer of the natural world. Because when a tree dies, it isn’t actually dead.

As a tree grows, its core begins to die. Have you ever looked at a majestic old oak, its core completely hollowed out, and wondered how on earth it was still producing green leaves and fresh shoots? The reason is that only the outer layers of the wood, just below the bark, are alive. They transport all the water and nutrients that a tree needs to survive. Simultaneously, under the soil, a massive network of fungi around its roots help the tree collect all of the vital nutrients and minerals it needs. As the tree grows, the wood core, the growth rings left behind and superseded from previous season, slowly dies.

Left to fade away…

Over time, this core wood is slowly broken down by fungi. In the very oldest trees, the core is lost completely. Perhaps the most famous of these wood-feeding specialists is one you may well have eaten, the Shiitake mushroom. The fungi in turn are eaten by many species, from bacteria to nematodes, insects to mammals, whilst the rotten wood supports many more. Therefore, this soft rotting deadwood actually hosts a complex living food web.

St Andrews Park – The fallen Black Poplar

An oak tree supports over 350 different varieties of insect. But over half of these feed on dead parts of the oak tree.  Bats rely on deadwood cavities to roost, whilst feeding on many species of night-flying beetle that feed solely on deadwood. Redstarts require hidden cavities to nest, whilst searching for bark beetles and moths that grew up in the deadwood. Everything from blue tits to woodpeckers and wood mice to tawny owls rely on deadwood for some part of their existence. By the time an old tree falls completely, upended from its rotting root network, the wood may be dead but the vast diversity of creatures it is feeding are very much alive. 

When we strip out deadwood from a natural environment, often under an aesthetic tidiness premise, we aren’t just taking the wood away. We are slowly eroding the complex living food web that the deadwood feeds. The Bristol Downs has suffered from this for many years. We could have hedgehogs snaffling snails from deadwood retreats and spotted flycatchers nesting amongst the craggy cavities in gnarled out stumps. Animals just need food and shelter to thrive. By removing deadwood, we take away both. There are many ways of leaving deadwood that look aesthetic whilst appreciating the enormous ecosystem service it provides. Good signage can help explain this.

In a time of unprecedented ecological collapse, we must all do what we can to help the natural world. Leaving deadwood in situ is one of the easiest ways to do this. So please, next time you see a fallen tree, don’t look on it as an untidy addition to the landscape, but enjoy it as the next opportunity for nature to reclaim a part in our everyday lives.

@NTGates Feb. 2020

A Manifesto for protecting Bristol’s existing Urban Forest

We invite all candidates standing in this May’s Mayoral and Councillor elections to endorse our tree manifesto which we set out here.

Bristol has declared a climate and ecological emergency. An emergency means making radical changes now – in every council department, by every developer, and by all those who own or care for trees.

All these proposals fit under Bristol’s existing 2011 Bristol Development Framework Core Strategy – BCS9 Green Infrastructure Policy which should now be implemented.  We must stop the needless destruction of so many trees in our city and instead learn to work around and with them.

Everyone from all sides of the political spectrum is talking about planting trees.  We fully endorse this, but it will take time for these new trees to mature. In the meantime, retaining existing trees will have the biggest immediate effect.

We propose that

  • There needs to be genuine community engagement in Bristol’s tree management decisions.  The council needs to listen to communities that want to save trees, not just to those who want to remove them.
  • Urban trees (planted or self-sown) have a tough life. Many bear the wounds and scars of previous damage or interventions.  These trees, though they may not be perfect, should be valued for the ecosystem services they provide and retained with appropriate and careful management wherever possible.
  • Alternatives to felling must be given priority, whether for street trees, or for those threatened by planning applications, or for other trees in the public or the private space.  
  • We need to strengthen planning policies to help retain trees on development sites by building around them, especially when the trees are on the edge of the site. 
  • Veteran and ancient trees require specialist management to ensure their retention whenever possible.
  • When surveys identify trees that present a risk, there should be consultation about the range of options available to mitigate the risk. This should always balance risk with the benefits the tree provides. Felling is only ever a last resort.
  • If trees must be felled, then more trees need to be planted to replace them. This should be based on well-established metrics used to calculate how to increase (not just replace) the natural capital of the lost tree.

Click here to print a copy of the manifesto. Candidates are welcome to download and use to support our aims.

Our Blogs contain many examples of the sorts of issues that have caused us to write this manifesto.

The trees at Stoke Lodge Park and Playing Fields – a letter to the Council

5th February 2020

Dear Bristol City Council Parks Department,

As you are aware, we have been expressing our continuing concerns about the welfare of the trees growing at Stoke Lodge Park and Playing Fields for the best part of a year now.

At the moment, our particular concerns are threefold:

  1. The potential for damage to trees caused by pedestrians being obliged to pass over their root zones and under their canopies since Cotham School erected its boundary fence last year.
  2. The potential for damage being caused to the trees growing within the new fence being caused by the school’s grass mowing regime.
  3. The potential for damage to trees caused by vehicles passing over their root zones and under their canopies.

To a large extend, our concerns about issue three may have been allayed by the school’s adoption of a new access point at the eastern end of the fields, but we will have to see how this develops.

The new vehicle access point at the eastern end.

As for the other two issues, we attach images showing how the very muddy and disturbed path running around the outside of the school’s fence is causing disruption to the root zones of a number of trees – these are not all the trees being affected by this.

The eastern end of the fields.
The path leading to the Pavilion on the northern boundary.
created by dji camera
The path leading to the Pavilion.

These images show how the current mowing regime encroaches within the root zone of one of the Turkey oaks inside the fence.

The Turkey growing at the eastern end of the playing fields seen from above.
The Turkey growing at the eastern end of the playing fields – the mowing line is clearly visible.

Here is a video which shows the mowing issue more clearly.

In our view, something needs to be done about this before any damage being caused becomes irreversible.

Can you advise me what action the Council plans to take to protect these trees, please?

Best Regards,

The Bristol Tree Forum

Council no longer manages trees on educational sites – Part II

Our worst fears have been realised. Schools have been left to care for the trees growing on their own sites, including those growing on school playing fields.

This blog follows on from our recent article on this subject – Council no longer manages trees on educational sites.

We have now had a response to a recent Freedom of Information request.

Trying to avoid the Council’s earlier refusals to answer our earlier FoIs about this, we asked for the same information as before, but just about one school which we selected randomly.

The school’s identity has no particular significance. We believe that these responses reflect the same situation across many other schools in Bristol (and the rest of the country?) – the lease disclosed is a Department for Education (DfE) standard Academy Lease’.

We asked…

[We] have been advised that Bristol City Council no longer maintains or manages trees growing on some sites owned by it.

In respect of Henleaze Junior School, is it a site where the responsibility for the care of the trees growing on its site has been passed to the school?

If so, please provide the following information:

1. Does the Council retain the ownership of the trees on the site?
2. If it no longer retains ownership, who does?
3. Does the Council still retain liability for any damage caused by trees on this site?
4. If it no longer retains liability, who does?
5. is this site available for tree planting by the public through sponsorship schemes such as TreeBristol or through tree-planting initiatives such as One Tree Per Child or the Urban Tree Challenge Fund?
8. Who makes decisions about the planting, maintenance or felling of trees on this site?
9. If it is not the Council, is the decision maker obliged to consult the Council before proceeding to maintain or fell a tree, whether or not the tree is growing in a Conservation area, or is protected by a Tree Preservation Order or is the subject of a planning application?

Please provide a copy of any lease entered into between to Council and Henleaze Junior School for the lease of its site.

The Council has responded to say…

The site is let to the Academy on a 125 year Department for Education standard Academy Lease.  The Council holds the Freehold of the site, but the responsibility for the management of the trees has passed to the Academy and the Council no longer retains liability for any damage caused by trees on this site?  The Academy does.

While the the site is available for tree planting by the public through sponsorship schemes such as TreeBristol or through tree-planting initiatives such as One Tree Per Child or the Urban Tree Challenge Fund, consent by the Academy is required for this.

The Academy is not obliged to consult the Council regarding the maintenance, removal or planting of trees on site and has the sole responsibility for these activities. This is subject only to any Tree Protection Orders (TPO’s) and/or Conservation Area requirements that may exist for trees on the site. In these cases, a planning application must first be made and permission given before the school can proceed.

A copy of the lease is available here. There is no mention of trees in the lease.

We are intrigued to note however, that the Council retains the right to develop the school and playing fields – Schedule Three – Rights Excepted and Reserved:

It appears very likely that similar arrangements to this will be found across most of the city’s 78 Academy schools (and possibly many Maintained and Special schools), by leaving them to make their own ad hoc arrangements to care for and/or plant trees as they may/or not desire.

Given that the One City Plan aims to double tree canopy cover over the next 25 years, it seems a great shame that this important land bank (we estimate some 188 hectares – land and buildings – for Academies alone) of possible new planting sites might have been excluded from helping to achieve Bristol’s ambitious plans.

What about protecting all the trees with a TPO?

There are already at least 3,400+ established trees growing on educational sites that could be at risk. As far as we can tell, very few of these trees are protected by a TPO, though some will be are growing in a Conservation area.

So, is it possible possible to protect all the remaining unprotected trees with TPOs? At least then all schools would be obliged to get planning permission before removing or ‘managing’ trees and we will be able to see what is planned.

Local Authorities have the power to make four types of TPO:

  • Individual TPOs: A single tree, illustrated as a trunk and approximate canopy spread. If trees merit protection in their own right, authorities should specify them as individual trees in the Order. 
  • Group TPOs: A group of trees, usually shown as a canopy, or group of canopies, with or without stems shown. The group category should be used to protect groups of trees where the individual category would not be appropriate and the group’s overall impact and quality merits protection. 
  • Woodland: Shown as an area of land. The woodland category’s purpose is to safeguard a woodland as a whole. So it follows that, while some trees may lack individual merit, all trees within a woodland that merits protection are protected and made subject to the same provisions and exemptions. 
  • Area TPO: Shown as an area, without stems highlighted. The area category is one way of protecting individual trees dispersed over an area. Authorities may either protect all trees within an area defined on the Order’s map or only those species which it is expedient to protect in the interests of amenity. 

We were recently been copied this answer when this issue was raised about some trees growing in the Bearpit:

Thank you for your email requesting a Tree Preservation Order for trees within the St James Barton roundabout/ Bearpit area. We have reviewed these trees following your TPO request. We understand that you are concerned about any future plans for the Bearpit which could affect these trees and the amenity they provide. 

The national guidance on ‘Tree Preservation Orders and Trees in conservation areas’ (https://www.gov.uk/guidance/tree-preservation-orders-and-trees-in-conservation-areas#making-tree-preservation-orders ) advises: 

“though some trees or woodlands may merit protection on amenity grounds it may not be expedient to make them the subject of an Order. For example, it is unlikely to be necessary to make an Order in respect of trees which are under good arboricultural or silvicultural management.” 

Furthermore, the potential effect of development on trees, whether statutorily protected (e.g. by a tree preservation order or by their inclusion within a conservation area) or not, is a material consideration. This means that tree matters must be taken into account by Bristol City Council as the Local Planning Authority when dealing with planning applications, and when undertaking consultations, and that members of the public can make clear their views. 

Given that these trees are already under existing arboricultural management, and that they would automatically be a material consideration should any future planning application come forward, it is not expedient or necessary for a Tree Preservation Order to be placed on these trees.

It appears that trees on educational land can, in theory, have TPO protection if it can be shown that they are not ‘under good arboricultural or silvicultural management’. But, how can the Local Authority know this?

However, our experience when we have requested that TPOs are made, is that the council will rarely do so, unless the trees are considered to have Amenity value and they are shown to be under immediate threat of destruction or damage. But, how can the Local Authority know this if the school is not obliged to tell them?

And…bitter experience has taught us that, whilst ‘…the potential effect of development on trees, whether statutorily protected…or not, may be ‘a material consideration’, other considerations often result in the welfare of trees being a very distant secondary consideration, with the result that they are frequently sacrificed to the too-oft-repeated argument that it is either the development or the trees, when there is no reason why it cannot be both.

So, the reality is that these trees are unlikely to be granted TPO status, save in exceptional circumstances and, even if they are, this is no guarantee of their future protection.

Our original concerns remain

We remain concerned that school governors (quite apart from lacking the necessary skills to manage the trees growing on their sites) may not yet have realised the full implications of the practical and strategic obligations that taking on such an important part of Bristol’s Natural Capital places upon them.

As a result, they are likely to buy in (at our eventual expense) ad hoc expertise, with the risk that they will overlook the wider strategic considerations that are needed when it comes to managing and promoting Bristol’s trees.

This, coupled with the distinct possibility that well-meaning, but unqualified Council officers in departments with no expertise in the management of trees may be making critical decisions about the welfare of trees across a wide range educational sites across the city, makes for a very worrying situation.

Our view is that the Council should take back the control and management of trees growing on land owned by it whether it is leased or not. Only then can we be assured that there is at least some degree of oversight and accountability, while helping us to achieve the wider strategic vision for the development of Bristol’s urban forest.

Shocking treatment of Lower Ashley Road trees shows urgent need for Bristol Planning rethink

Bristol has declared a climate emergency. There is an urgent need for all council departments to re-think the way that they work.

At the time of writing, four of the trees in this image have been felled (two Norway Naples and two Indian Bean trees on a different plot).  The value of the five maple trees along Lower Ashley Road was calculated at £200,000 using CAVAT.  Local residents are desperately trying to save the three remaining maples.

This blog discusses six changes that are desperately needed to protect trees on development sites.

  • Planning Decisions regarding important or TPO trees should be considered by committee and not delegated to one officer.
  • It is practically impossible for local residents and other stakeholders to wade through all planning documents online. Planning Officers must highlight important tree issues and have a duty of care to act positively in favour of trees.
  • Bristol should implement policies to retain trees on development sites in the way that has been done in London, Oxford and elsewhere. This includes enforcement and a presumption to retain trees at the edge of development sites.
  • An emergency number to address immediate tree felling issues. 
  • It is a false choice to say that we can either have social housing or trees. With clever designs, we can retain existing trees and have better social housing.
  • Replacing felled trees, even when applying the Bristol Tree Replacement Standard, is second best to retaining existing large urban trees. We get the benefits from existing trees now – we have to wait decades for their replacements to grow.

Over the last six months there have been half a dozen articles in the local press and now one Guardian article about the shocking planning decision to allow removal of five Norway maple trees with Tree Preservation Orders (TPOs) on Lower Ashley Road, one of the most polluted streets in Bristol. There have been two meetings with the mayor who also visited the site and there is now a vigil by protesters on the site: police have been called on several occasions. All this indicates a planning process that has marginalised local residents and failed to take into account the value of the trees.

The Bristol Tree Forum appreciates the efforts by Mayor Marvin Rees to try and resolve the situation after the event. He visited the site and then convened two meetings in City Hall which he chaired. We have been impressed by his serious engagement and the way that he has brought all the interested parties into the room and handled the discussion. But, as we think he would agree, this is the wrong way around. Discussions such as this should happen before the planning decisions are taken so that there is community engagement in the decision making.

Planning Decisions regarding important or TPO trees should be considered by committee and not delegated to one officer

That we have got to this stage shows a serious failure of both Bristol City Council Planning policy and its implementation. The decision to remove the trees was taken in 2015/16 by one planning officer as a reserved decision. It did not go for to the Planning Development committee for a considered decision. Looking over the documents it doesn’t seem that any time or thought was given to the trees. The Arboricultural Report provided by the developer does not even state whether the trees had TPOs, and indeed there is no discussion of the TPOs in any of the documents in that planning application, with the only mention on the “constraints” page. In 2015, The Bristol Tree Forum commented in opposition to the proposal but even the BTF was unaware that the trees had TPOs. Whilst BCC insists that the decision was “valid”, without a mention of the TPOs there was insufficient information to allow intelligent consideration of the proposal, so we question that decision. Sufficient information for intelligent consideration is one of the fundamental principles of a “proper consultation” as decided by Lord Woolf*. The first mention of the TPOs in a document is in the Officer’s Report outlining the delegated decision. 

Unfortunately this is not an isolated failure: trees all over Bristol are being unnecessarily sacrificed as a result of applying ideology from the 1960s. For example a single planning officer gave the green light for the removal of some 25 trees on the Redland Girls School site, in a conservation area, despite the fact that the removal is purely for landscaping.

Redland Green Trees: damage to tree roots caused by driving construction vehicles over them can result in the eventual failure of the trees. In a failure of planning, no root protection zones or Arboricultural Methods Statements were ever established for these trees, despite permission being given for the construction company to store materials on Redland Green.
It is practically impossible for local residents and other stakeholders to wade through all planning documents on line.  Planning Officers must highlight important tree issues and have a duty of care to act positively in favour of trees

Important tree issues need to be highlighted and openly discussed during the planning process. Planning Officers already implement policy regarding flood risk, traffic management and other construction matters. The Bristol Tree Forum is asking that tree protection is included too as is done in other local authorities (Examples are Oxford and Islington, below). In addition, trees on or near active development sites must be properly protected.

We see applications with no information on the Bristol Tree Replacement Standard calculations, or obviously incorrect information being supplied. Documents such as these should be rejected by the planning officer.

Redland Green Trees. Permission was given for this TPO Ash tree on Redland Hill to be removed (in addition to several others on the site) to allow articulated lorries to enter the building site. In the event, the gateposts were never widened, articulated lorries didn’t enter the site as this would have been extremely difficult even with gate widening and the tree was retained until Aug 2019, when it was removed anyway.
The Indian Bean trees growing on the next-door site on Lower Ashley Road before they were felled. Together with the Maples nearby, they formed a welcome green oasis in an otherwise treeless urban setting.
All that remains of the Indian Bean trees which were chainsawed following rejection of an application that was refused because the trees were felt important and merited TPOs.  The trees were removed anyway. We are trying to find out why the trees were not then protected with TPOs.
An emergency 24-hour number to address immediate tree felling issues. 

Bristol is at risk of becoming known as a Mad Max world now that unqualified people are wielding chainsaws from ladders above passing pedestrians with no enforcement consequences, often on public holidays, sometimes in the evenings and even at night. A proper approach for addressing this problem needs to be developed in collaboration with the police. It is unfair to send a single tree officer on their own to deal with issues of public order. Multiple phone calls and sometimes hundreds of emails to numerous council departments very quickly overload already overstretched council officers. It is no good passing the buck to the Health and Safety Executive. Therefore we need one emergency Bristol City Council number.

Lower Ashley Road.  Bristol City Council urgently needs to come up with a procedure to address dangerous activities by unqualified people using chainsaws over pavements and roads.
A Maple with the arrow sign captioned ‘here’ pointing at a partially sawn limb : Following complaints over an entire week, this dangerous almost severed branch was only addressed after an article appeared in the Bristol Post.
Trees growing at Cotham School were removed by Skanska (2008) in the afternoon before Good Friday when no enforcement action could be taken.
Bristol should implement policies to retain trees on development sites

Where possible we should build developments around existing trees. There should be a presumption to build around existing trees and particularly to retain trees at the edge of development sites. 

The developer’s arboricultural report for Lower Ashley Road states that “In order to retain the trees within any new scheme, the front of any new building will need to be sited a minimum of ten metres from the existing site boundary”. We have heard this assertion stated by developer and planner as “the ten metre rule”.

There are many examples where mature trees are retained close to new buildings, in London, Oxford and elsewhere. This must become commonplace in Bristol too.  A Trees and Design Action Group article describes the construction of the Angel Building (Islington, London) around existing mature trees. No cowboy chainsawing there. Instead extreme care was taken in a project that was led by landscape architects. For example:

Deliveries needed to be conducted on a daily basis. To enable this, the Tree Protection Plan (TPP) and Arboricultural Method Statement (AMS), developed by appointed tree specialist JCA, in coordination with the project landscape architect and the council tree officer, proposed the use of a porous load-spreading cellular confinement system (Geoweb) braced with timber frames.

All existing trees were irrigated during the two-year construction period following a sporadic pattern imitating rain. Because irrigation was fed with calcium-rich London tap water, the system was fitted with filters to avoid increasing the soil pH.

The Clifton Suspension Bridge visitor Centre (Alec French Architects) in North Somerset, not Bristol, is within 2 metres of an important tree.  The roof line has been cut away to accommodate a branch.
Aurora Building, Counterslip, Bristol.  Energy efficient, outstanding architecture and built extremely close to an existing plane tree.
It is a false choice to say that we can either have social housing or trees. 

Although the 2015/16 planning approval that is being used to justify removal of the trees was for student accommodation, the current proposal, still under consideration, is for social housing that Bristol desperately needs.  We are surprised that, despite this new undecided application, the developer is still able to undertake work under the old approved application which they no longer intend to pursue.  Shouldn’t the slate be wiped clean so we have a chance to revisit the whole plan with the trees still in place rather than be forced to decide without them?

The developer, planners and others have presented a false choice stating either we retain the trees, keep the site derelict and leave 28 families homeless, or we remove the trees. 

These trees are right on the edge of the development site. With clever designs, led by a landscape architect (not even apparent that one has been engaged for this project), and carefully constructed foundations (e.g. screw piling), the developer could build close to the existing trees. The result? Better social housing which benefits from existing green infrastructure and provides a more pleasant environment with some protection from the noise and pollution of this busy road.


  • Lord Woolf MR in R v North and East Devon Health Authority, ex parte Coughlan [2001] QB 213, [2000] 3 All ER 850, [108] as follows: whether or not consultation is a legal requirement, if it is embarked upon it must be carried out properly; to be proper, consultation must be undertaken at a time when proposals are still at a formative stage; it must include sufficient reasons for particular proposals to allow those consulted to give intelligent consideration and an intelligent response; adequate time must be given for this purpose; and the product of consultation must be conscientiously taken into account when the ultimate decision is taken.