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.
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.
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.
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.
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 firstname.lastname@example.org.
We want to put on record our congratulations for the successful bid that your Parks Strategy team led for Bristol City Council to the DEFRA Urban Tree Challenge Fund (UTCF). It has been some time in the resolution, but it is great that we now know for sure that it has succeeded.
We are delighted that there will now be more funds available to plant and maintain trees in the streets and green spaces of local communities that have perhaps been been overlooked in the past.
Thanks to you and to your excellent tree planting team, the Council has built an enviable reputation for planting urban trees across the city. Long may it continue!
We look forward to helping you with the planning and consultation that will be needed for adding these UTCF trees to next winter’s tree planting season.
We also applaud your decision to involve us in the collaborative partnership preparing the initial bid. As the only group specialising in protecting and caring for Bristol’s urban forest, we are very pleased to have been able to:
Survey a representative sample of some of the 1,471 sites you have identified across the city, thereby relieving overstretched BCC officers who simply didn’t have the time to undertake this work.
Develop our Tree Care site which communities will be able to use for post-planting tree maintenance and care – an important part of match funding the UTCF grant.
We have also developed a comprehensive network of ward-based tree champions who are ready to be involved both in engaging with their local communities in the planned consultation and in helping with the ongoing care of newly planted trees.
As you can imagine, it was a lot of work, but we believe that it provided the sort of detail that helped clinch the bid.
Now that the funding has been secured, we look forward to meeting with you and the other partners to help with the next important planning phase of engaging with local communities and getting trees actually planted come next winter.
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.
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.
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.
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.
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 acopy 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.
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:
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.
The potential for damage being caused to the trees growing within the new fence being caused by the school’s grass mowing regime.
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.
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.
These images show how the current mowing regime encroaches within the root zone of one of the Turkey oaks inside the fence.
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?
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] 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 asTreeBristol 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 availablehere. 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 theOne 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.
“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 valueand 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.
There are some 166 educational sites and 63 playing fields across the city. Together they cover over 560 hectares and form a significant proportion and an important part of the city’s open, green spaces.
Despite this, Bristol City Council no longer manages trees growing on many of these sites and their related playing fields. We are not certain, but we imagine that this situation has come about as a result of the decline in local authority control over state educational provision with the rise of independent Academies.
We issued a Freedom of Information request (FoI) to try to find out which sites remain under the control of the Council, but our request has been refused on the grounds that answering it would impose a significant burden on the council. Our more generic request at the end has also been refused on the same grounds.
The trees at Stoke Lodge Playing Fields
Recent events at Stoke Lodge and the playing fields there perhaps best illustrate our concerns and the potential threats to the many trees growing on land set aside for educational purposes.
The site was leased for 125 years to Cotham School in August 2011. Interestingly, the Council agreed to retain its responsibility for all the trees growing on the site. It also agreed to indemnify the school for any damage the school might cause to the trees and to insure against this risk.
Stoke Lodge Playing Fields are located to the west of the city in Stoke Bishop ward and cover some 8.7 hectares of open space. Historically they were part of the grade II listed lodge (now an adult learning centre) of the same name which covers about two more hectares and contains an arboretum of important trees (the survivors of a collection that formerly spread right across the historic lodge grounds).
Unlike most of the land around it, this part of Stoke Bishop is not in a Conservation Area. For some 70 years, the whole estate, which until recently had never been seen as a divided space, has been used by the local community and is designated an important open space. Nearly all the trees on the Stoke Lodge estate are subject to Tree Preservation Orders (TPO) which were placed on the trees in early 2012.
In the summer of 2018 Cotham School announced that it intended to erect a fence along the boundary of its leased land. They stated that they did not require prior planning permission to do so because they were exercising their statutory Permitted Development rights. After an initial dispute about whether the school could indeed use Permitted Development rights, in January 2019 work began to erect the fence.
It was at this point that the Bristol Tree Forum became involved after it became clear that the proposed route of the fence would pass through the root zones of a large number of important trees, many of which were the subject of a TPO.
There then followed a protracted period of back and forth representations while we and the local community fought to get the fence relocated to avoid damaging the trees. This was partly successful. Where it was not, we were able to insist that the methodology for erecting the fence where it still passed through tree roots was modified to minimise damage. Even so, it took the constant vigilance of the local community and BTF representatives to ensure that Cotham School did not ignore the conditions placed upon it.
Setting aside the issue of the siting of the fence, our primary argument has always been that TPO law requires a prior planning application to be made (and approved) before any work is undertaken that could cause damage to TPO trees. Initially, the Council rejected this argument, effectively stating the Permitted Development rights trump primary TPO legislation. It also argued that, anyway, it could not proactively prevent damage to TPO trees, but had to wait until the damage has been done, which is, frankly, absurd. We continued to challenge these interpretations and, eventually, the Council conceded our points, though only after the fencing had been completed.
Things then appeared to return to normal,except that the community was now largely confined the unfenced areas around the boundaries of the site. As a result, the trees around the boundary are being exposed to heavier traffic through their root zones. We are concerned that this may have a long-term, adverse impact on their health.
Then, in August of this year, and without any warning, contractors arrived to lay cable ducting across the site so that video surveillance equipment could be installed. Using a mini digger they immediately set about driving over and cutting through the root zone of a TPO Common Ash growing on the boundary of the site. Other non-TPO trees (some privately owned) were similarly damaged.
We lodged a complaint with the Council’s Planning department. As a result, enforcement proceedings were commenced and the school, whilst narrowly avoiding prosecution, was obliged to take remedial action to try to mitigate the damage caused to the tree. The council also felt obliged to remind the school of its obligations to TPO trees:
And this is a site where the trees are still under the ‘guardianship’ of the Council! What about those sites where the care is vested with the school?
Our concerns remain for the future health of those trees whose root areas had been invaded by the fence installation. We have also continued to express fears about other continuing threats to the trees arising as a result of other activities on the site. So far, our concerns have been ignored.
For example, continuing root compaction and branch damage is being caused to the Persian walnut growing by the gate close to the rear car park and to the trees growing beside the Parrys Lane entrance. This is the result of grass mowers and other service vehicles using these entrances to gain access to the site. We are told the access point has been moved to the Parrys Lane entrance, though that too involves vehicles passing over tree roots.
Historically, it looks like vehicles accessed the site from behind the Children’s Play Ground on the southwest of the site, so did not need to drive over any tree roots. The presence of the fence and lack of any gate there has now closed off that option.
The school’s contractors also continue to mow within the root zones of the two large Turkey oaks (BCC-77025 on the eastern end & BCC-77059 on the western end) that grow inside the playing fields fence.
However, the Council and the school decline to address these issues saying that they have made adequate arrangements to safeguard the trees.
STOP PRESS – 4th January 2020 – since writing this blog, Cotham School has felled a TPO protected Elder (plus five others) on the Eastern side of the playing fields and poisoned it with Glyphosate. We have informed Bristol Council Parks and Planning Departments and asked them to investigate. They advise:
“The felled Elder trees were not included within or protected by the TPO covering the adjacent Sycamore tree.
It is very unlikely that roots from the Elder trees will have grafted with the roots from the Sycamore tree. Also translocation of herbicide between grafted roots is very unlikely.*
We are not aware of any plans to fell the twin stemmed Oak beside the white shed at the eastern end of Stoke Lodge Playing fields.”
But, when we asked Parks if these works were done with their prior knowledge and agreement, or if the department had approved the application of Glyphosate to the tree roots, or if they had seen the School’s Aboricultural Management Scheme, they answered ‘No’.
It seems that the school had complied with their obligation to get consent from the Council, their Landlord, but that the Council’s Education Asset Management team had failed to consult Park’s specialist tree officers about the plans.
Cotham School has issued these FAQs – 33 to 38 in response to this issue.
The fate of other educational sites
In the meantime, we have no idea if or how other schools are managing the trees on their sites, or if the Council is consulted when they do.
Even though, in most cases, educational sites are still on Council-owned land, the Council only needs to be told if the trees have a TPO or are growing in one of the city’s 33 conservation zones (or, we assume, if the Council’s lease with the school keeps the management of the trees in the control of the Council – as was the case at Stoke Lodge).
Given that Bristol City Council does not normally issue TPOs for trees on its own land, arguing that it is a good landlord and will look after important trees appropriately, it is unlikely that trees that have been handed over on other educational sites will have been protected by a TPO. Perhaps the council should now review its policy where it no longer manages trees growing on educational sites in light of this history.
Certainly it seems that new tree planting need no longer involve the Council. For example we recently observed that several newly planted trees at Cotham School’s main site had died. It was only when we noted that the dead trees were missing from the Council’s tree stock data for the school that we learned that they were no longer responsible for the trees on the site. We have now been told by the school that the trees were planted as part of a recent development and that the failure of these dead trees will be ‘rectified’ soon. Meanwhile, it seems that these new trees are no longer selected, managed or mapped as part of the Council’s wider tree stock strategies and that the existing trees on the site are no longer the Council’s concern.
Presumably, similar arrangements are happening across the city with other educational sites being left to make their own, ad hoc arrangements to plant trees or not. 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 of possible new planting sites might have been excluded from helping to achieve Bristol’s plans.
We are also 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 tree stock places upon them. As a result, they are likely to have to buy in (at our expense) ad hoc expertise, thereby possibly overlooking the wider strategic considerations that are needed when it comes to managing trees across the city.
This, coupled with the distinct possibility that well-meaning but unqualified Council officers may be making critical decisions about the welfare of trees on educational sites, makes for a very worrying situation.
The Bristol Tree Forum (BTF) was not consulted about the proposed development of this site, which will result in the removal of hundreds of these trees. Many local residents have submitted comments expressing concern about this aspect of the development.
BTF’s starting position is that trees should not be felled if at all possible, and that everything that can reasonably be done to avoid this should always be considered before a felling decision is made. If trees must be felled, then compensatory planting should be undertaken in such a way that there is no net environmental loss.
order to implement the Council’s recent declaration of a climate emergency, increase
net biodiversity and help double tree canopy cover, this development needs to
be redesigned to fit around the existing trees, not remove them.
current documents make various assertions as to the numbers of trees to be lost
and the calculations for replacements required under the Bristol Tree
Replacement Standard. This can be addressed by the imposition of our proposed
planning conditions (see below).
Implementing Bristol’s declaration of a climate emergency
Bristol City Council was the first UK local authority to declare a climate emergency. As Professor Corinne Le Quéré FRS has said, “Actions to tackle climate change have to penetrate all the decisions that we take in society.”
The Government’s 25-year environment plan states that it will strengthen existing requirements for net gain for biodiversity in national planning policy. As it is, we have calculated (appendix 1) that this scheme, if permitted, will result in a net environmental loss of just over £3.65 million – Our CAVAT valuation of the trees potentially lost to this development is nearly £3.8 million (point 8 of Appendix 1). If the figures for tree felling relied on by the Council are accepted, then the figure will be much higher.
Bristol also has ambitious plans to double its tree canopy by 2046. If it is to implement this, and is serious about its declaration of a climate emergency, and wishes to achieve a net gain in biodiversity, then developments like this need to be radically rethought so that we build houses around existing trees rather than felling them, thereby avoiding or at least minimising the loss of our precious existing tree stock.
addition, we note that the plan is also to remove a row of black poplar trees,
a key landscape feature of the site. This is contrary to Policy BCS9 of the
Bristol Core Strategy.
Conflicting figures for the calculation of replacement trees under the Bristol Tree Replacement Standard
figures for the number of trees to be felled differ within the various planning
documents and the BTRS calculations are confusing. We address this in detail at
technical note (23rd September 2019) identifies 859 trees to be felled, to be
replaced by 1,280 new trees. Elsewhere
in the note, a table lists the values given for each BTRS category, which come
to a total of 181 trees to be felled with 294 replacements. The table produced
at paragraph 5.5.17 of the Environmental Statement Addendum gives different
values again – 674 trees to be felled with 986 replacements.
serious discrepancies need to be resolved before the Committee can form any
clear idea of the impact of this development on the park’s trees. We propose a
number of planning conditions, set out below, to ensure that the BTRS
calculations are correctly made.
are also concerned to read the Tree Officer’s report which states “As a number
of the proposed trees are extra heavy standards it is considered
that these can count as three new trees and overall the BTRS is met”. This is simply wrong. The BTRS contains no
The care of replacement trees after planting
Many trees that have been planted as a result of large schemes like this fail because they are not properly looked after. A recent example is the Metrobus scheme, in which large numbers of trees were planted but have failed, probably due to lack of watering or, in some cases, vandalism. As far as we are aware, Metrobus (the developer) has not given any indication that it will replace these lost trees.
In our view, any replacement planting must be done under British Standard BS8545:2104 (Trees: from nursery to independence in the landscape) with a detailed specification in these terms being made a condition of the development. This should include a clear obligation placed on the developer to replace trees which fail within, say, five years of planting.
Planning conditions requested by BTF
The information that has been used
to undertake the BTRS calculation is both incorrect and two years out of date.
If the Committee allows this
proposal to proceed despite this, we request that the following planning
conditions be imposed:
No felling and replacement of any of the trees on the site should take place unless and until an updated survey is undertaken and the actual numbers and DBH values of all the trees (both individually and in groups) identified for felling are ascertained.
The BTRS replacements required are agreed with the Bristol Tree Forum and a Planning Arboricultural Officer.
All tree planting conforms with British Standard BS8545:2104 (Trees: from nursery to independence in the landscape).
A condition of the development includes a clear obligation on the developer to replace trees which fail within, say, five years of planting.
You can link to the Council’s application here, via our BTF Planning Portal – 19/02632/PB.
The application of BTRS requires that the trunk diameter (called Diameter at Breast Height, or DBH) of each tree identified for felling be measured. This measurement is then used to calculate the number of trees to be planted as replacements for the felled tree using this table:
This planning application is based on a tree survey that was undertaken some time in November 2017 and set out in an Arboricultural Impact Assessment dated May 2019. Part of this survey was updated in Appendix C of an Environmental Statement Addendum dated 4th September 2019. However, the DBH values have not been changed, so these values are now two years out of date. The trees will have grown in the meantime.
There is also a technical note dated 23rd September 2019 which identifies 859 trees to be felled, to be replaced by 1280 new trees. The following table is produced on page 5 of this note:
However, the values
given for each BTRS category come to a total of 181 trees to be felled with 294
replacements, not the totals shown above.
The table produced at
paragraph 5.5.17 of the Environmental Statement Addendum gives different values
again: 674 trees to be felled with 986 replacements. However, this excludes the
number of individual trees within groups G1, G354, G355, G380 and G417, so it
is impossible to make any like-for-like comparison.
Having collated the two surveys published in the Arboricultural Impact Assessment and in Appendix C of the Environmental Statement Addendum into a spreadsheet (click here to download), we note the following:
533 individual trees have been identified and their DBH values recorded. Of these, 167 are identified for felling.
43 tree groups have also been identified, 13 of which are listed for removal or part removal.
Save for groups G347, G347b and G347c (which have 5, 24 and 7 trees respectively in them) the number of trees in each group (or the number of trees to be removed) is not given.
Save for groups G347, G347b and G347c (which have 5, 22 and 7 DBH values respectively listed), only one DBH value is given for each group.
If we assume one tree per species listed for each unnumbered group, then 228 trees in total are identified for felling.
This produces a BTRS value of 294 replacement trees (again, if we assume one tree per species for each unnumbered group and that all these trees have the same DBH as that given).
Of the trees surveyed, 176 are given an ‘Estimated Remaining Contribution’ (life expectancy) of 10+ years; 46 have a life expectancy of 20+ years; and the remaining six have <10 years of life left. These 10+ and 20+ values are meaningless as they give no upper range. The CAVAT approach is to set life expectancy within these bands:
>=5 & <10 years.
>=10 & <20 years.
>=20 & <40 years.
>=40 & <80 years.
Applying a life expectancy of between 40 and 80 years and a CTI factor for Bristol of 150, we calculate that the 228 trees we have identified for felling have a CAVAT value of £3,784,282. Using the same factors, the 294 BTRS trees (assuming standards with a DBH of 5 cm) would have a CAVAT value of £134,184, a net environmental loss of £3,653,652.
 We accept that each group probably contains more trees than our working assumption.
 We accept that the DBH values will vary from tree to tree.
 A CTI factor is applied to the base CAVAT value to account for population density. Bristol has a population of 459,300 and a land area of 10,970 hectares. This gives a population density per hectare of 41.9 and so a CTI Index of 150.
We have now received an explanation, via a local Councillor, for why the trees on Redland Hill were felled – see our recent blog – Redland Hill street trees felled by the Council. Why?As we are anxious to update the record as soon as possible, we have decided to make it public. Here it is, received just yesterday:
“Contractors removed some of those trees along this strip in error. The contractor is planting replacements free of charge (hence the blue markers) [small posts painted blue, which we noticed had recently been inserted in a line along the wall – just visible in the image below].
The history I’m told goes as follows:
The tree officer selected and marked the specific trees to be removed with a green paint spot. The thinning out was necessary due to the lack of space on the narrow strip of verge. It is good arboricultural practice. It has been suggested this row used to be part of an old beech hedge, this isn’t the case because the trees removed were a mix of species, ash, sycamore and elder.
Unfortunately other trees, without the green spots and which were scheduled to remain, had previously been marked up with orange paint spots. It was made clear to the contractor’s manager when they met the Council’s tree officer on site which trees were to be removed and which should stay.
The contractor’s team leader who subsequently carried out the felling work had not been given the full information from the manager and felled all the trees except the large Beech on the corner. The felling was also done much quicker than expected which is why the Councillors weren’t notified in advance thus compounding the error.
[The Trees and Allotments Manager] has discussed this communication error with the contractors and they have agreed to replace the trees that were incorrectly felled (i.e. the orange spot ones). The new replacement trees will be much better suited to the location than the original species. The new trees are birch with a very narrow and upright form. This will be much more suited to the narrow planting location and should have potentially less conflict in the future with pedestrians with pushchairs and will be easier to maintain next to the highway. They will all be planted by the end of tomorrow.”
Here they are…just planted…and we are very pleased to see them.
We have asked the Council to comment. We await their response, though we see that they have already commented to BristolLive.
Councillor Clive Stevens (and ex-Chair of Bristol Tree Forum) commented: “Although conspiracy theories are more fun to read about, sometimes it is due to a good old fashioned cock-up. Lessons to be learned on communication with the public which I think was the main theme of the Tree Forum’s original blog is the need for more and better consultation. That applies to many things the Council does. If the Government decided to increase the duty to consult on tree works lets hope they provide some extra money to pay for someone to do it. And secondly, often the Council takes a while to respond and in this case probably because they wanted to finalise the solution first; its the same department dealing with Stoke Lodge and ex Wyevale Garden Centre situations and probably a hundred or so other active planning applications all with tight deadlines which take priority.”
As a precaution, we have asked the Council to take urgent steps to protect the last remaining beech tree on the boundary wall with a Tree Preservation Order. This is partly because of what has happened, but also because we have had to advise the Planning Department that someone on the site has dumped a large amount of builders rubble and other materials on the tree’s roots on the other side of the wall from the tree. Clearly this important tree (the last vestige of a historic hedge which probably predates both the wall and the buildings nearby) is still under threat and needs protection.
We are sad to have lost what was once a significant aspect of one of the approaches to the Downs, but are pleased to see the whole sorry saga resolved. We hope that lessons have been learned and look forward to watching the replacement birches grow and flourish.
The study has revealed that there are some 600,000 trees growing in Bristol – and that they are worth £280 million to the city.
The study, the initiative of a partnership between us, Bristol City Council, the Woodland Trustand the Forest of Avon Trust, saw the latter work with 29 volunteers and local partners to help uncover the remarkable story of our Bristol trees.
Using the latest i-Tree Eco 6 model, the survey ran between May and September 2018 and has revealed that Bristol’s trees store around 360,000 tonnes of carbon dioxide and remove about 14,000 tonnes more each year – equivalent to the annual carbon dioxide emissions of some 9,000 cars.
The study also found that Bristol’s urban forest is worth around £280 million. This includes the cost of replacing the trees, plus the value of all the carbon stored in all the wood.
Each year trees in Bristol provide environmental services worth around £1.6 million, removing about 100 tonnes of air pollution and reducing flood risk by soaking up some 90,000 cubic metres of water thereby preventing this from running into drains and saving us about £140,000 annually.
Bristol’s tree canopy cover is currently around 12%. However, experts believe that this figure needs to increase substantially to help us combat the effects of climate change and air pollution, and protect biodiversity and promote our health and wellbeing.
Bristol’s One City Plan, published in January 2019, is calling for tree canopy cover to be doubled by the end of 2045. That means adding another 1,316 hectares of new trees by adding around 53 hectares of new tree plantings annually for the next 25 years. This is an ambitious goal, but it could be achieved if everyone in Bristol planted just three new trees each.
We have identified a need to increase the city’s tree canopy cover in order to enhance Bristol’s urban environment and provide a wealth of benefits. We are calling upon all citizens and businesses in Bristol to show their support for urban trees.
I am delighted that our partnership was recognised at the recent Street Trees Awards, as it shows we are moving things in the right direction.
Mark Ashdown, Chair of the Bristol Tree Forum said:
The Forum would like to commend Forest of Avon Trust for all their hard work and dedication to this important project. This report helps set the base line for the One City Plan’s goal to double Bristol’s tree canopy cover by 2046. It is an ambitious plan, but with the full support of Bristol City Council – ensuring that planners and developers always think ‘tree’, making sure that enough land is set aside for tree planting, protecting existing trees and ensuring that adequate funding is made available – we can all secure the future of Bristol’s urban forest and help Bristol’s citizens lead healthier, happier lives.
I would like to thank the volunteers who helped us with this study, which makes the case that Bristol’s trees have a really important role in mitigating the growing impact of climate change in the city as well as in managing the health impacts of vehicle and wider CO2 emissions. Looking after the trees we have now and working with communities across Bristol to plant many more of them will make the city a healthier, more sustainable place to live and one in which people will be actively involved.
The Woodland Trust’s South West External Affairs Manager Catherine Brabner-Evans said:
Intuitively we know trees are good for us. They are the green lungs of our city. Urban trees bring life and colour, connecting us with nature, reducing stress, and boosting our mental health. Now we can also demonstrate the economic value of some of the services that trees provide. It is vital we protect our beautiful urban canopy and plant for future generations.
If you would like to help us plant, protect and care for Bristol’s trees, please complete our five-minute survey HERE. The survey closes on May 3rd, 2019.
To request a pdf of the full iTree Bristol report or to ask any questions about the study, please contact us or email Jon Clark at the Forest of Avon Trust.