'The true meaning of life is to plant trees under whose shade you do not expect to sit.' Nelson Henderson, Under Whose Shade
Bristol Tree Forum
Annual General Meeting
Bristol City Hall
6 December 2021
18:30 – 20:00
Draft Agenda (may be modified nearer the date)
Bristol Tree Forum – bristoltreeforum.org – 6 December 2021
A recent landmark Council motion to Protect the Green Belt and Bristol’s Green Spaces, was approved with cross-party support and no dissensions. As a result, vital green spaces within Bristol now have additional protection, in line with the City’s declarations of Climate and Ecological Emergencies, the recently published Ecological Emergency Action Plan and the new Environment Act 2021.
However, a consequence of the adoption of this motion is that there is greater pressure to develop on other sites. Those advocating development on open spaces within Bristol have begun, arbitrarily and without proper justification, to declare such open spaces to be brownfield. To inaccurately describe a development site as brownfield places Development Committee members under undue pressure to approve a planning application when, as greenfield, a site should fall under the additional protection engendered by the landmark motion.
Recent examples (see below) where the term brownfield has been misused are the Bristol Zoo Gardens car park on College Rd, Clifton and the Baltic Wharf Caravan Park on the Floating Harbour in Hotwells, each of which have been mislabelled as brownfield sites despite not falling within with the recognised legal definition.
The term brownfield site is used to describe certain types of previously developed land. Most dictionary definitions refer to this land as being currently or previously occupied by a permanent structure which generally includes the potential for contamination. In planning law there is a definition which must apply when considering planning proposals. This is detailed in the National planning policy framework (NPPF – called ‘Previously developed land’, p.70) as:
“Land which is or was occupied by a permanent structure…. and any associated fixed surface infrastructure”.
The definition excludes land which is maintained as a garden:
“….. land in built-up areas such as residential gardens, parks, recreation grounds and allotments…“
In addition to the definition, there is a statutory requirement for local authorities to maintain an up to date register of brownfield sites which are appropriate for development:
“Regulation 3 of the Town and Country Planning (Brownfield Land Register) Regulations 2017 requires local planning authorities in England to prepare, maintain and publish registers of previously developed (brownfield) land”.
“Brownfield land registers will provide up-to-date and consistent information on sites that local authorities consider to be appropriate for residential development having regard to the criteria set out in regulation 4 of the Town and Country Planning (Brownfield Land Register) Regulations 2017.”
“Regulation 17 requires local planning authorities to review their registers at least once a year“.
The Town and Country Planning act also addresses the situation where a fragment of the site might be considered brownfield, but other parts of the curtilage is green space:
“Greenfield land is not appropriate for inclusion in a brownfield land register. Where a potential site includes greenfield land within the curtilage, local planning authorities should consider whether the site falls within the definition of previously developed (brownfield) land in the National Planning Policy Framework. Where it is unclear whether the whole site is previously developed land, only the brownfield part of the site should be included in Part 1 of the register and considered for permission in principle”.
Bristol Zoo Gardens car park, College Rd, Clifton (21/01999/F)
The planning proposal makes the statement “The application site is brownfield, previously developed land, as it is a car park“. Mayor Marvin Rees similarly defined the site in a subsequent tweet criticising some members of the Development Committee for voting against the proposal.
This site fails to comply with the proper planning definition of a brownfield site. In relation to the NPPF definition, 7.4% of the site is occupied by buildings whereas tree canopy covers about 17% of the site. Much of the site is covered by unfixed surface, which does not qualify under the definition of a brownfield site. Therefore, according to the Town and Country Planning Act only 7.4% of the site could be considered brownfield, with the remaining 92.6% being classified as greenfield. The site does not appear on the Council’s register of brownfield sites, and therefore cannot legally be classified as such.
Baltic Wharf Caravan Park (21/01331/F)
This planning proposal has also been inappropriately described as a brownfield site in the planning application. Only 2.6% of the site is occupied by a permanent structure, whereas the 100 trees that occupy this site cover over 30% of its area. Thus, only 2.6% of the site could possibly be defined as brownfield, with the remaining 97.4% falling under the classification of greenfield. Furthermore, as much of the site is maintained as a “residential garden”, the site is exempt from the NPPF definition. This site, also, is absent from the necessarily up-to-date register of brownfield sites.
Whilst there may be arguments to develop some parts of some of these sites, the existing trees should be retained in order to comply with Local Planning Policy BCS9. The current approach of flattening all trees, including those on the edge of the site results in third rate developments. Instead, new developments should be built around existing trees.
If you agree that this mislabelling should stop, please sign this petition to protect Bristol’s green spaces from the Council’s mislabelling of them as “brownfield sites”:
We have never been able to understand why Bristol City Council decided to terminate the lease of the longstanding and very successful central Bristol caravan site. It is not a brownfield site crying out for redevelopment, as some would have us believe. Its success and the 91 mature, well-established trees that grace it (74 of which are to be removed) testify to that.
Bristol Chamber of Commerce has described this caravan park as ‘… an important, high performing asset for Bristol’s visitor economy, enabling visitors to stay in walking distance of the city centre and thus providing significant levels of custom for local businesses‘.
And John Hirst, as Chief Executive of Destination Bristol, observed that ‘There are significant financial benefits for Bristol due to the year round supply of visitors to their current caravan site. We know that the current Bristol site at Baltic Wharf has been one of the most popular and successful central sites in the UK’.
So why on earth close the caravan park for a plan that almost nobody really wants – at least 273 at the last count? It seems that it’s worth closing this successful tourist attraction to replace it with new housing, even though the caravan park is estimated to bring some £1 to £1.5 million annually to Bristol’s tourist economy. The scramble for new housing at any cost – while ignoring the wishes of local communities and the economic benefits that the caravan park brings us – seems to take priority over all else.
And the result? We have proposals that will flatten every inconvenient tree rather than incorporating them into the proposed development. This only adds to the steady loss of green spaces and reduces Bristol, especially the centre of Bristol, to a grim, unliveable environment. As Bristol grows hotter with each passing year, with the expectation that by 2050 life-threatening heatwaves will occur once every two years (not to mention the increasing flood risk to this area), we will need the cooling benefit of large, mature trees yet, tree by tree, they are inexorably removed in order to maximise profit and achieve what many say is an unrealisable aspiration. With the majority of new housing being sold at full market price, these will be as much for the benefit of the estimated 1,900 annual migrants from London as they are for the more affluent citizens of Bristol.
It is especially sad that Goram Homes, the much-lauded development arm of Bristol City Council, continues to ignore our very own key green planning policy, BCS9, and the revised National Planning Policy Framework (the Framework) upon which it is based. BCS9 states that ‘Individual green assets should be retained wherever possible and integrated into new development’.
The Framework is the foundation upon which BCS9 is based:
We had hoped that Goram Homes would have set a good example – especially since the Council has recently published its Ecological Emergency Action Plan and announced that it will “embed nature into all decisions” – and abide by these important principles. What has happened to the Framework’s third, overarching environmental objective? Taking Baltic Wharf Caravan Park as an example, it would have been quite straightforward to design any new housing around existing trees, particularly if the focus was on just building affordable and social housing. Instead, nearly all are going. This, it seems, is ‘Placeshaping’, Bristol-style.
And this intransigence has resulted in damaging national press coverage – though note the lovely photo of the trees growing on the site.
Our objections to the proposals are set out here, but we are not the only ones…
Councillor Mark Wright’s experience
Councillor Mark Wright was the councillor for Hotwells and Harbourside until May 2021 when he stepped down. Here he presents his experience of the many attempts he made to engage with the planners and Goram Homes at an early stage to try to secure as good an outcome as possible given that the caravan park was doomed to be closed. They came to nothing.
Mark writes:
‘Sept 2018
Mayor Rees announces that flats will be built on the site.
Dec 2018
I wrote to Cllr Paul Smith (Housing) “There are a number of very nice trees on the caravan park site that residents are already calling for saving (see attached Google 3D image). If done skilfully and at an early enough stage, many of the best trees could be embraced into the development in a way that greatly increases the value of the retail flats. If done too late or not at all, it’s likely that getting planning permission will become a battle over trees, which isn’t what anyone really wants. I think it would be a good demonstration of why Goram is a good thing if it sets the bar high on pre-app planning on things like this – it could really set an example to other developers. I understand that planning policy BCS9 requires the developer (i.e., BCC in this case) to do a tree constraints plan as early as possible – there is no need to wait until the actual plans start to form to do this. Can we get BCC to start this ASAP?” Cllr Smith replied, “I will have a word with officers”, but I got no further response.
I also wrote to the Council’s Arboricultural Officer, Matthew Bennett, asking for a tree assessment report to be done ASAP so that the best trees on the site could be saved and incorporated into the plans. I was interested in getting TPOs put on the best trees, but at that early stage Bennet replied to me: “Our aim through the planning process is to secure the best trees on site and mitigate the loss of those removed through the planning obligations SPD (BTRS). We cannot try and save every tree {…} a tree preservation order would not help the situation because full planning consent overrides a TPO”. That seemed reasonable so I concentrated on trying to get a tree report.
Jan 2019
I contacted officers again for an update but got no info.
Early Feb 2019
Planning Officer Paul Chick told me that no arboricultural tree report would be done until a pre-app was submitted, but no one knew when that would be.
Late Feb 2019
I raised the issue of trees on the site with Cllr Paul Smith and Steve Blake at Goram (Development manager); Cllr Smith said he had raised the issue of trees after my earlier contact, but I heard nothing more.
Jun 2019
I again raised the issue of trees on the site with Steve Blake at Goram and Matthew Bennett but got no response.
July 2019
A tree report was secretly written for the Council, but I wouldn’t see it until December 2020.
Dec 2019
The first concept images of the plans were released to the public. I wrote to Steve, Matthew, and Paul Smith again: “I note with interest the Council’s press release today indicating that a development partner has been selected for this housing site. There is even a picture of the proposed build. I presume this *must* mean that there has been enough preliminary work done to allow a tree constraints report for the site to be drawn up. Please can you assure me that the prime trees currently on the site are being designed into this new plan? A development such as this will be greatly enhanced in value by the intelligent and thoughtful retention of mature trees, and the Council’s reputation as a builder will be greatly enhanced as well, setting a higher bar in the city for other developers to follow…”
I got no responses…
Jan 2020
I wrote to Tim Bluff, a new contact at Goran Homes (taking over from Steve Blake, presumably) I had been given after badgering people. Bluff informed me that a tree report had in fact been done 6 months previously. I had never been told about it, despite asking multiple people for it for 13 months. I was told at this point the document wasn’t public and I couldn’t see it.
Feb 2020
There was a public *showing* of the plans. At this point it was clear that the plans were essentially almost “final” despite there having not been a single public engagement session of any kind, about anything. I declared publicly that I was concerned about both height and loss of trees.
Mar 2020
I discussed with the Bristol Tree Forum doing an informal assessment of the trees, but the Covid lock-down squashed that.
Apr 2020
The pre-app was published privately on the planning portal, but I couldn’t have access.
Early May 2020
The pre-app was made available to me, but not the public. It was clear that all trees on the site would be felled; all that would be saved was some of the boundary hedges. Again, by this point there had still been zero public engagement on any issue, only a showing of the images. The 10-month old Arboricultural report (i.e., July 2019) was still not available to anyone, including the Council’s own Arboricultural officer Matt Bennett, who wanted it too.
Late May 2020
I had a video meeting with Stephen Baker, Development manager at Goram (and Geoff Fox and Glynn Mutton) to discuss the plans. I made it clear I was unhappy with the height, the loss of all trees was a major problem, and the lack of any public input before publishing the plans was a big mistake and contrary to planning requirements on major plans. Steve said the trees were all being lost because the site had to be raised 2m to allow “active frontages” that comply with planning regs. I said that saving trees might be preferable to active frontages inside the site; I asked him who made this critical decision and when, as this was exactly the kind of thing the public should have fed into – at least if the decision had been informed by the public there would be some buy-in. He said he didn’t know and it had all happened before he joined the project. I made clear I was disappointed, but I really didn’t want to end up opposing the plans, and I hoped there would be a reduction in the height.
Oct 2020
Website for the plans went up.
Dec 2020
I finally received a copy of the July 2019 tree report – from the Bristol Tree Forum, not from the Council! It was clear that the decision to fell all trees on site had already been made earlier than July 2019.
Apr 2021
Full Planning app submitted, with no real changes since the pre-application stage. I lodged an objection “with heavy heart”.’
At last, some good news: city trees have been given the same habitat and biodiversity value as their country cousins.
Or have they?
STOP PRESS
Since writing this blog, we have now responded to Defra’s Small Sites Metric (SSM) Consultation. It develops further our critique of the way that urban tree habitats are being undervalued. Perhaps urban trees are now the poor country cousin?
It is available here – Bristol Tree Forum response to the Small Sites Metric consultation
Our second blog dealing with Urban Tree habitat condition assessment is available here – Valuing our urban trees – part II.
Our third blog dealing with habitat selection is available here – Valuing our urban trees – part III.
The important contribution that urban trees (native and non-native) make to our cities has finally been recognised by Natural England, with their publication of Biodiversity Metric 3.0 (BNG 3.0) on 7 July. It states that:
Trees in urban areas can, under the right conditions, provide a large range of habitat opportunities, supporting lichens, bryophytes, invertebrates and birds. Tree planting in urban areas has for over two hundred years also introduced non-native species into towns and cities. In the context of biodiversity, native species are the preferred option. However, non-native tree species can contribute positively to biodiversity richness particularly in relation to providing a seasonal food source for nectar feeders and other invertebrates as well as supporting vertebrates that feed on species that are hosted by non-native trees. Examples are early and late flowering species of Prunus and aphids on varieties of Acer providing food for species higher up the food chain.
Trees in urban areas provide opportunistic sites for biodiversity to colonise and re-colonise, increasing connectivity and contributing to biodiversity critical mass between already established patches or sites. This is especially true where transport corridors are populated with mixed native species.
What’s an urban tree?
The new BNG 3.0 habitat category, urban tree, includes individual trees, lines of street trees and blocks of trees growing within the urban setting.
The previous urban tree habitat categories, woodland, orchard and street tree, which appeared in the beta test version of Biodiversity Metric 2.0 (BNG 2.0) have been discarded.
The urban tree habitat calculation has been set to ‘medium’ distinctiveness and ‘low’ difficulty for both habitat creation and enhancement. Urban trees are categorised into small, medium or large. Their condition may also be assessed as poor, moderate or good.
The problem with BNG 3.0
The three size bands set out in the table below are useful when creating new habitats or enhancing existing ones (for example, nursery-raised standards ready for planting have a stem diameter of around 30 cm and so are Medium). However, these bands are not useful for assessing the baseline habitat of existing urban trees.
This is the size table used in BNG 3.0:
NB: the second column of this table is wrongly labelled. It should read Girth (circumference) at Breast Height, not Diameter.
The RPA formula used is simple: RPA radius = 12 x DBH (Stem Diameter is also known as DBH – Diameter at Breast Height). This value is then used to calculate the RPA using the formula DBH = PI * RPAr^2.
Every application to develop land where trees will be affected should produce a BS:5837-compliant survey, called an Arboricultural Impact Assessment (AIA). This will report the stem diameters of all the trees growing on and around the site. The AIA also reports several other tree features including species, height, cardinal point canopy radii, condition, life stage and the BS:5837 category – a measure of the quality of the tree.
However, the BNG 3.0 table above provides no logical way of establishing whether a given surveyed tree with a stem diameter of, say, 15 cm or 40 cm – halfway between categories – is Small, Medium, or Large.
It would be better if the table gave ranges – say Small up to 10 cm, Medium 10-50 cm and Large 50 cm or more – but this has not been done. Also, doing this would distort the habitat calculation with all Small trees set to their upper range and all Large trees set to their lower range.
Our solution
Why use the table at all? It would be far simpler to calculate a tree’s baseline habitat area just by using the calculated RPA provided in the AIA. It would be better still to use its actual measured canopy area, which will have been reported in the AIA and thus be readily available.
In our view, RPA does not reflect the habitat value of a tree. All it does is use a formulaic approach to solving the problem of finding an acceptable way to protect trees. It bears little relationship to the habitat or biodiversity value of a tree. It would be far better to calculate a tree’s canopy cover (TCC), the standard method of working out the value of a tree. Every AIA reports the canopy radii of the four cardinal compass points of each tree surveyed. These can be averaged and used to calculate TCC.
The Bristol One City Plan adopted TCC as the measure of tree planting success when it set the target to double TCC by 2046. TCC is a standard measure used by the various i-Tree tools and Forest Research uses it in its UK Ward Canopy Cover Map which used i-Tree Canopy. We used it to calculate the TCC of the city’s wards in our 2018 Bristol Tree Canopy Cover Survey and we are using it to update the new city-wide survey for 2021.
We made these observations when Natural England was consulting on its beta test version, but these seem to have been overlooked. We hope they now take note.
Some further thoughts
The introduction of the three new urban tree poor/moderate/good condition criteria, set out in detail in the BNG 3.0 Technical Supplement, will require all AIA surveys to include this data. Perhaps BS:5837 should be updated to require this to be recorded in the AIA.
Where tree surveys identify mixed urban tree conditions, the person undertaking the BNG 3.0 calculation will need to record more than one urban tree baseline habitat to capture this information.
BNG 2.0, which was only published as a beta test to allow for wider public consultation, is still being used by Bristol’s Local Planning Authority (LPA) for pending applications but needs to be abandoned. Pending applications which require a biodiversity net gain report should be required to recast their calculations using BNG 3.0 rather than still relying on BM2.0. This is particularly true for the Council’s own, direct applications such as the one pending for the Baltic Wharf Caravan Park.
Our initial analysis shows a significant net gain deficit when BNG 2.0 is used instead of BNG 3.0. This is especially true for urban street trees, which are significantly undervalued under BM2.0. Furthermore, the LPA is currently allowing applications which propose a zero net gain outcome, even though the Environment Bill (currently being considered in Parliament) will require a net gain of 10% above the baseline valuation.
Given that the Council has declared climate and ecological emergencies and aims to achieve carbon neutrality by 2030, it is surprising that developers continue to be allowed to present biodiversity net gain proposals that either undervalue biodiversity or offer no net gain whatsoever.
Conclusion
We welcome the publication of BNG 3.0, but its flaws need to be corrected.
As Natural England recognises in its recent blog – Biodiversity Metric 3.0 – a milestone moment for biodiversity net gain:
Publishing Biodiversity Metric 3.0 was a landmark moment for biodiversity net gain, it will become the metric used to calculate and evidence whether a project has achieved the biodiversity net gain requirements set out in the Environment Bill. Biodiversity Net Gain (BNG) is:
‘an approach to development, and/or land management, that leaves nature in a measurably better state than beforehand‘ …
Biodiversity Metric 3.0 ensures that:
all habitats, from street trees to woodlands, green roofs to grasslands are recorded, scored and valued for their importance for wildlife. At the same time, it provides an evidence-based, transparent, consistent and easy to use way of ensuring that nature is considered within the design of developments and in land management practice, leaving nature in a better place than it was before, benefitting wildlife, people and places.
Bristol City Council’s declaration of climate and ecological emergencies and its commitment to achieve carbon neutrality by 2030 means that it needs now to ensure that the latest, most accurate biodiversity net gain calculations are part of all pending and future planning applications.
“Bristol ranks as the 5th greyest city in England”
This statement was made in a recent article in Wales Online, the Express, and elsewhere. The article, with a by-line of Neil Shaw, seems to be based on a press release by OVO Energy who are promoting a petition to create a legally binding target to plant 30,000 ha of new woodland each year to 2050. The article reported tree cover in a number of countries and cities around the UK based on data supplied by the aerial survey and GIS company BlueSky. Amongst the results is :
Bristol, known for its green credentials, ranks as the 5th greyest city in England at 8% – and only 1 tree per person.
This is very different from the estimate produced by our own tools which estimate tree canopy cover (TCC) in 2020 at around 17.5%. Thankfully, as the following analysis discovers, Bristol can hold its head as a green city.
i-Tree Canopy
Our estimate is based on a desktop survey using a methodology called i-Tree Canopy. The methodology is pretty simple: take any boundary, randomly place a number of points within the boundary, examine each point in Google Maps and decide if the point lies within a tree canopy or not; the ratio of canopy points to the total number of points is the TCC, Uncertainty arises from the nature of the random sampling and interpretation of the image, particularly to distinguish a tree from hedges and low ground cover.
Our version of this approach is integrated with the Trees of Bristol website so that it can used to estimate TCC for any area in our database with a known boundary. In particular, we have used this tool to estimate TCC for all wards in Bristol which are mapped here. These values have joined the many hundreds of estimates across the UK to form the GB Ward Canopy Map organised by Forest Research. With this pedigree, we have been advocating this approach for use in Bristol as the means to assess progress towards Bristol’s ambitious goal of doubling tree canopy by 2046. Aggregating the samples across all 32 wards, we estimated that Bristol had 17.9% TCC in 2018 and by 2020 it was 17.5%. (This change from 2018 to 2020 is not statistically significant)
National Tree Map
The estimates in the press article were based on the National Tree Map, a commercial product from Bluesky. This uses a combination of their own imagery and LIDAR data. Complex analysis of the LIDAR data, using the difference in return time from ground and canopy reflections enables an estimate of the canopy above 3m high.
Discussion with Bluesky revealed a probable cause of the discrepancy for Bristol. Any comparison between estimates needs to be based on the same boundary definition using imagery from the same time period. For the i-Tree Canopy approach we have used the City of Bristol boundary which has an area of about 11,000 hectares (110 sq km) . In contrast, it turns out that the data provided to OVO energy by Bluesky was based on the Unitary Authority Boundary. For Bristol this is a rather odd area, taking in a swath of the Bristol Channel down as far as the islands of Flat Holm and Steep Holm. This is because historically, the boundary of the Port of Bristol is included.
The area within this boundary is 23,500 hectares. Since Bristol can hardly be criticised for failing to plant trees in the Bristol Channel, this dramatically distorts the estimate. Adjusting for this difference in definition, I arrived at a figure of 17%, within the statistical bounds of the i-Tree canopy estimate.
The National Tree map was also used back in 2014 as reported in the Daily Mail. The accompanying map similarly shows a very low value for tree canopy in Bristol so I suspect that the same boundary was used there too.
Comparison
After discussion with BlueSky, I supplied four boundaries for assessment using the NTM methodology for comparison with the i-Tree approach: the Bristol City Boundary and three wards chosen to have low, medium and high levels of canopy. These are the results:
NTM uses a strict height of 3 metres when assessing canopy whereas using i-Tree canopy, the distinction between tree canopy and lower greenery including hedges is assessed visually, so a slight upward bias might be expected and has also been observed in Forest Research data. On the whole though, this comparison shows very strong agreement between the two methodologies.
The bad news
The gross error in Bristol’s tree canopy percentage actually made it easy to see that something was amiss. One must assume that similar issues will have occurred in the case of other cities whose boundaries are subject to debate. Indeed, the Unitary authority boundary for Portsmouth, which with only 4% cover is reported to the be worst in the UK, includes the expanse of Portsmouth and Langstone Harbours. According to the Portsmouth Council website, land is about two-thirds of the area of the authority so a better figure would be 6%, still low.
Problems with boundary definitions plague this data. Bristol City is only the core of the conurbation with large parts of what we think of as Bristol in South Gloucestershire and Bath and North East Somerset. Comparison with the figure given for Leeds, also 17%, is not possible since the City of Leeds boundary includes all the surrounding towns and countryside.
It is clear that unitary authority boundaries are not directly suitable for urban canopy evaluation.
The need for full data publication
In addition to the 2014 report and the recent publicity by Ovo Energy, another survey by Bluesky was publicised late last year on the BBC but no figure for Bristol is mentioned. These press articles give only selective figures rather than the full data across England. I searched for published reports containing the full data, which I expected to include the base area, canopy area as well as the computed percentage and rankings. I found nothing. This makes it impossible to correct other derived data, such as the ranking of Bristol as the “5th greyest in England”.
I would hope that in future, companies like Bluesky and Ovo Energy will see that making full data openly available in support of extracts and assertions would reduce mis-interpretations, provide a public good and better promote their company.
Journalists too have a responsibility here, not only to critically assess press releases but to request and link to the supporting data. Neither happened in this case.
The good news
This exercise has turned out to be good news for both the National Tree Map methodology and our own work with i-Tree Canopy. The results are very similar and differences are rather consistent and explainable. Our implementation of i-Tree Canopy is free to use by citizen-scientists with known error bounds and can be quickly applied to any chosen boundary. With the inclusion of historical imagery from Google Earth, it can also be used to compare canopy over time.
This exercise has also confirms the doubts we held about the figure from an i-Tree Eco survey carried out in 2018. This survey used volunteers to ground-survey 200 random plots in Bristol. The survey arrived at a figure of 12% with wide error bounds but much less than the i-Tree Canopy value. All methods have some uncertainty but we can be pretty confident that Bristol’s Tree Canopy in 2020 is in the region of 17 – 18%.
The National Tree Map is primarily intended as a means to locate and measure the canopy of individual trees in an area. The canopy estimate is only a by-product and agrees well with the i-Tree canopy approach. For its primary purpose, NTM appears to provide a very much more economic solution than on the ground surveying. Indeed it would be very interesting to compare this map for Bristol with the mapping of individual trees in Trees of Bristol.
Forest Research is at the forefront of research into the UK Urban Tree canopy and their 2017 paper on the Canopy Cover of Englands Towns and Cities remains the most authoritative UK -wide survey. We look forward to an update to this excellent work.
Chris Wallace
First published in The Wallace Line on 11 May 2021
Individual planning decisions, development designs and local and national plans for development all impact local communities. We urge the Ministry of Housing Communities and Local Government to consider our views on the design codes and to continue to engage communities and groups such as ours in local planning decisions.
Here are our detailed responses to the consultation.
Paragraph 7 – We agree with the introduction of the 17 Global Goals for Sustainable Development. These have been adopted by Bristol as part of its One City Plan so their adoption in the NPPF will be essential for ensuring that the city’s core planning policies are aligned with its wider goals.
Paragraph 8 states:
‘Achieving sustainable development means that the planning system has three overarching objectives, which are interdependent and need to be pursued in mutually supportive ways (so that opportunities can be taken to secure net gains across each of the different objectives).’
We would also like it to be made as clear as possible that these three overarching objectives are indeed ‘interdependent and need to be pursued in mutually supportive’ ways so that no one objective takes precedence over the others, as has been our experience with a number of recent planning decisions made in Bristol.
We propose that the paragraph amended to read: ‘Achieving sustainable development means that the planning system has three overarching objectives, which are interdependent and need to be pursued in mutually supportive ways so that no one objective is treated as having precedence over the others (so that opportunities can be taken to secure net gains across each of the different objectives)’
Paragraph 11 a) – We also endorse the proposed change that ‘all plans should promote a sustainable pattern of development that seeks to: meet the development needs of their area; align growth and infrastructure; improve the environment; mitigate climate change (including by making effective use of land in urban areas) and adapt to its effects’. Trees are an important component of this, particularly where green space is limited.
Paragraph 22 – We agree that ‘where larger-scale development such as new settlements form part of the strategy for the area, policies should be set within a vision that looks further ahead (at least 30 years), to take into account the likely timescale for delivery’. Too often, trees that were planted where a site was last developed (often only a few years before) are sacrificed to the short-term goals of the new proposal. Setting longer-term goals can help prevent this.
Paragraph 53 – Of the two options offered[1], we prefer the second – ‘where they relate to change of use to residential, be limited to situations where this is necessary in order to protect an interest of national significance’. In our view, the phrase ‘wholly unacceptable adverse impacts’ is open to too wide an interpretation which may not be rooted in wider national goals.
We agree that that Article 4 directions should be restricted to the smallest geographical area possible.
We welcome many of the additions and changes proposed, including the recognition that a well-connected network of high-quality, open, green and wooded spaces is important for both our mental and physical health.
Paragraph 97 – We believe that access to a network of high-quality open spaces and opportunities for sport and physical activity ‘should always deliver wider benefits for nature and efforts to address climate change’.
Paragraph 128 – We agree that all guides and codes should be based on effective community engagement and reflect local aspirations for the development of their area.
Meaningful community engagement at all stages of the planning process is essential if the changes proposed are to succeed. Too often, communities are not asked to engage with planning proposals until they are published and the formal approval process has started. By this time most of the key decisions have been agreed between the developer and the planner and it is too late for any meaningful consultation with the wider community.
Paragraph 130 – We welcome the introduction of this new paragraph:
‘Trees make an important contribution to the character and quality of urban environments, and can also help mitigate and adapt to climate change. Planning policies and decisions should ensure that new streets are tree-lined, that opportunities are taken to incorporate trees elsewhere in developments (such as community orchards), that appropriate measures are in place to secure the long-term maintenance of newly-planted trees, and that existing trees are retained wherever possible. Applicants and local planning authorities should work with local highways officers and tree officers to ensure that the right trees are planted in the right places, and solutions are found that are compatible with highways standards and the needs of different users.’
We must learn to value our urban trees and woods growing in Bristol (and in other cities), so we were pleased to see this addition with the ambition to ensure that all new streets are treelined, but city-wide planning involving existing streets and road networks must also make space for new tree planting in the design process as well as ensuring that existing trees are retained.
Generally, planning requirements must be tightened to ensure that existing trees are retained. Only in exceptional cases where there are clear, justifiable and compelling reasons to do so should trees be removed. In all cases the cascading principles of the Mitigation Hierarchy must be applied and, where there is no option but to remove a tree, the loss of habitat and biodiversity that the tree provided must be compensated for by an adequate tree replacement calculation such as that used in the Biodiversity Metric calculation.
We agree that ‘development that is not well designed should be refused’ (paragraph 133). Designs that fail to make provision for preserving existing trees and providing new trees are not, in our view, well-designed and so should be refused.
New Paragraph 149 – We propose the deletion of this text, which is too general and open to interpretation. Certain other forms of development are also ‘not inappropriate in the Green Belt provided it preserves its openness and does not conflict with the purposes of including land within it’.
In Bristol there are just over 596 hectares of Green Belt left within the metropolitan boundary, mostly confined to the few remaining green margins of the city. The last draft of the Local Plan proposed the removal of some 50 hectares for development. Already parts of the Green Belt are disappearing without any hint that this ‘preserves its openness and does not conflict with the purposes of including land within it’. Little by little, development by development, Green Belt land is being lost.
Paragraph 160 c) – Tree preservation and the planting of new trees are key elements of ‘using opportunities provided by new development and improvements in green and other infrastructure to reduce the causes and impacts of flooding, (making as much use as possible of natural flood management techniques as part of an integrated approach to flood risk management)’ We would like to see text added that states this.
Paragraph 179 d) – This states that ‘development whose primary objective is to conserve or enhance biodiversity should be supported; while opportunities to improve biodiversity in and around other developments should be pursued as an integral part of their design, especially where this can secure measurable net gains for biodiversity and enhance public access to nature’.
It is essential that core planning policies mandate a standard metric for measuring baseline and created and enhanced habitat biodiversity proposals. Developers must be obliged to provide a Net Gain calculation when submitting their proposals. The latest version of the Biodiversity Metric Is designed for this purpose and should be mandated for all new planning proposals. All planning permissions should require the delivery of Biodiversity Net Gain plans of at least 10%.
The design codes must deliver three key things to ensure that new developments always provide access to high-quality, local green space and to trees, with all the benefits these provide for communities.
New developments must incorporate and protect existing trees from the outset. There must be a presumption that the design will accommodate the existing trees growing on and around the site – especially those growing around the edges of sites. Designs should consider the long-term health of trees in and adjacent to new developments and aim to promote this. This will include providing adequate buffers for ancient, veteran and self-seeded trees and woods.
New developments must have a target of providing a combined minimum of 30% canopy cover on and off site. This should be made up of a mix of tree-lined streets, community woodlands, Tiny Forests, parks and gardens. Where tree provision will be made off site, the cost of providing, planting and caring for the trees on a long-term basis should be funded by the developer and incorporated into tree-specific S106 agreements (T&CPA 1990). Where possible, trees should be native and sourced and grown in the UK. Trees that will become large and are long-lived should be selected where possible.
As we have already noted, meaningful community engagement is essential if communities are going to consider that they ‘own’ planning decisions rather than having them imposed on them.
We have published a paper on the issue as it relates to consultation on the management of trees which we commend to you: ‘Community engagement in urban tree management decisions: the Bristol case study’.
3 March 2021
You can download a copy of our submission here.
Here are copies of the draft National Planning Policy Framework and National Model Design Code.
The consultation closes on 27 March 2021 and can be accessed here – National Planning Policy Framework and National Model Design Code: Consultation proposals.
[1] ‘a) where they relate to change of use to residential, be limited to situations where this is essential to avoid wholly unacceptable adverse impacts’ or ‘b) where they relate to change of use to residential, be limited to situations where this is necessary in order to protect an interest of national significance’.
The M32 Norway maples are, or were, a group of mature and majestic street trees on Lower Ashley Road, St Pauls. They were due to be felled as part of a development on the adjacent site, an action the Save the M32 Maples campaign group contend is illegal as the protected trees are on public land and not the property of the landowner.
The Development
In 2016 outline planning permission was granted to Mr John Garlick to build a four storey development, comprising ground floor offices and student accommodation above on the site of the former probation office, 31-45 Lower Ashley Road. Reports stated that the development required removal of five mature Norway maple trees. There was no mention in the application or the arboricultural report that the trees were protected by Tree Preservation Orders, a crucial consideration in any consultation, and the supposition was that the trees were sited on land owned by Mr Garlick. Full planning permission for this development was granted in May 2019.
In May 2019, a second application was submitted for construction of a 4-storey block of flats to provide 28 units including some affordable housing. Over 400 objections to this development were submitted, mostly citing the loss of trees, air pollution, noise and flooding issues.
The Bristol Tree Forum was one of the objectors on the basis that legally binding planning policies aimed at protecting green infrastructure (BCS9, DM15), protecting against air pollution (BCS23, DM33), addressing climate change (BCS13), reducing flood risk (BCS16), limiting noise pollution (BCS23, DM35) and protecting public health (DM14), were contravened in the proposal (https://bristoltreeforum.org/2020/07/09/bristol-city-development-where-did-all-the-green-go/).
Illegal tree felling
At 6 am on June 19th 2019, a crew of workmen arrived with chainsaws and proceeded to attack the maple trees on site. There were no safety precautions applied either for the workmen or the public. None of the required permits were in place and no pavement or road closures were implemented. Local residents stepped in and the police intervened to stop the illegal felling. However, two of the trees were severely damaged. This contravention of planning conditions was reported to the Council’s Planning Enforcement Officer, but no action was taken.
At 5.30 am on December 31st 2019, the felling crew returned. Again, no permit was in place and no safety measures were applied. Again, the public intervened, with some chaining themselves to the trees. The area tree officer attended, and members of the Bristol Tree Forum arrived in support. As previously, the police put a stop to the illegal activity, and Mayor Rees attended to witness the damage. Two of the 5 original trees had been felled. The contravention of planning conditions was again reported to the council Enforcement officer, and, as previously, no action was taken, on the basis that other unrelated enforcement issues were being investigated.
At 5.50 am on November 2nd 2020, an anonymous chainsaw crew arrived, and whilst still dark, during a storm and fully 2 hours before permitted construction hours, proceeded to fell two of the trees. As on previous occasions, there were no safety measures applied, either for the workers or the public. Local residents again intervened, and the workmen attempted to flee the site, which residents prevented, despite being threatened. Again, the police arrived to bring the illegal activity to an end, and the site was left in a dangerous state, with only one of the original five trees still standing. The contravention of planning conditions was again reported to the Council’s Planning Enforcement Officer, but no action was taken on the basis that this was an “isolated incident”. This was despite the fact that three previous illegal fellings, stopped by the police, had been reported to the enforcement office.
The legal case disputing the ownership of the land on which the five maples are located
Early in 2020, a local residents group, the Save the M32 Maples campaign, was formed to protect the trees. The group has been active on a number of fronts.
The legal dispute is whether the five Norway maple trees were, and are, sited on public land or land sold to private landowners in 2005. The Save the M32 Maples group have presented substantial legal documentation showing that that the strip of land sold by Bristol City Council (BCC) to private landowners in 2005 did not include a strip of land on which 5 mature maple trees were located. These include the deed Register, Sale Contract (1), Heads of Terms, plan of Adopted Highway asset 384 (2), Deed of Covenant Release, BCC Corporate Estate Document, and BCCs Pinpoint map (3), all of which are in agreement. If the group’s contention is correct, it is illegal for the landowner to fell the trees as part of this development.
However, BCC Development Officers refused to accept legality, accuracy and validity of these documents, instead presenting a Registry Transfer document overdrawn with a thick black line (4), claiming the thickness of this line undermined the accuracy of all legal documents. On the basis, therefore, that all drawn boundaries are unreliable, BCC regard that text in some documents referring to “trees” is proof that the 5 maples are part of the land sold in 2005.
Accurate measurements from all the above legal documents showed the land transferred was 180m2, in agreement with the 180m2 cited in the Heads of Terms. That this 180m2 excludes the five trees is not disputed by either party.
In response, BCC undertook a survey in 2020. The area in question increased to 210m2 with no reason given, transferring some of Asset 384 to the landowner and depleting Adopted Highway accordingly.
Thus, the campaign group contend that BCC has illegally given away 30m2 of public land without legal sale/transfer, and that it is on this land that the five maples were located. This has led to a long running dispute and police investigation, and incited illegal felling of publicly owned and protected trees.
The Save the M32 Maples group have instigated a formal complaint about the BCC’s alleged misconduct in dealing with this case. This complaint was not upheld by BCC, and therefore the group began proceedings to mount a Judicial Review, with the help of Paul Powlesland, barrister and environmental rights activist. BCC resisted the move to have the case heard in a court of law, and the group ultimately had to abandon the case because BCC threatened imposing punitive costs. Alleged misconduct by Council Officers has been investigated by the police, who recognised “irregularities”, but were unwilling to pursue the case until the council’s complaints procedure had been exhausted. There is currently an appeal being prepared for the Local Government Ombudsman.
Ground contamination
There is a strong possibility that the 31-45 Lower Ashley Road site is contaminated. The adjacent property is the site of a former petrol station which suffered a major contamination event in the 1990s in which a long-standing leak from fuel storage tanks was detected. A confidential report, commissioned in 2003 by the former owners, revealed that a cocktail of toxic chemicals, including lead, chromium, benzene, toluene, xylene, naphthalene and MTBE, a lead replacement, soaked into the ground over at least five years. Many of the chemicals are associated with neurological disorders and can cause miscarriages and severe learning disabilities in children.
Despite a statutory requirement, the latest planning applications for the 31-45 Lower Ashley Road site did not include a ground contamination report, and referred only to a “desk report” prepared for the 2016 application. This report makes no mention of the documented contamination event, despite this report being copied to BCC and the Environment Agency, and no samples were analysed for pollutants. The Councils Public Protection group has insisted that a full investigative survey is undertaken, but this has still not been carried out.
Because of the likely contamination of the site, and the threat this poses to the public, the Bristol Tree Forum have advocated that this site is allowed to recover naturally through the actions of the trees on site removing toxins from the soil.
The campaign continues
Though there is only one of the original five maple trees remaining, the Save the M32 Maples group continues to campaign, in part to save the final maple tree, but also as a matter of principal that the council and developers should not fell mature trees unless absolutely unavoidable. In this case, as the trees are, at worst, on the margins of the development, efforts could and should have been made to incorporate the trees in the construction. The council and developers regard that planting replacement trees, in accordance with the Bristol Tree Replacement Standard (BTRS), is adequate mitigation. However, recent work by the Bristol Tree Forum (https://bristoltrees.space/trees/tree-benefits/interactive-1.xq) demonstrates that, even with the BTRS applied, the carbon (also representative of the other benefits of trees) will not be recovered for 40 to 60 years.
The one remaining tree has been reinforced by layers of protection around the trunk, and a daily vigil has been mounted to guard the tree, should the illegal felling crew return. The media campaign continues, and local support for the group continues to grow. The group has also begun coordinating with other tree protest groups nationally, to share experiences and effective campaign strategies.
Sadly, the issue that this campaign highlights is all too common in Bristol, that mature trees are not sufficiently valued, either by developers or the council’s own development office. A major rethink is needed if we are going to protect the trees of Bristol and the benefits they provide. (https://bristoltreeforum.org/2020/01/18/shocking-treatment-of-lower-ashley-road-trees-shows-urgent-need-for-bristol-planning-rethink/).
John Tarlton.
Because we could not hold our AGM this year, we have decided to publish a number of articles highlighting issues that have been prominent over the past year. We hope you find them of interest.
Sadly, it has not been possible to hold our annual AGM this year, so we have postponed it until next Spring. Subject to the state of any COVID 19 restrictions against us meeting, we will let you know when we have been able to find a new date as soon as we can.
In the meantime, we have decided to publish a number of articles highlighting issues that have been prominent over the past year. We hope you find them of interest.
We wish all our followers a very happy holiday season and all the very best for the New Year.
In defence of Bristol’s trees – Mark Ashdown
Why are we felling so many trees in Bristol when the city’s stated aim is to double tree canopy cover by 2046? To achieve this aim, we will need to stop felling existing trees, failing to replace those that have to be felled trees AND see at least a five-fold increase in our current tree-planting rate!
Miyawaki or Tiny forests – Chris Wallace
Miyawaki or Tiny Forests are a promising approach to rewilding urban areas and we look forward to being involved in future schemes. However their contribution to overall tree canopy is limited by their size.
Don’t Stop The (Christmas) Rot – In praise of Ivy – Guest Editor, Nick Gates, Naturalist
There is a weird craze amongst a certain type of well-meaning nature lover. It involves taking an axe, leatherman or small saw, and severing limbs. Not at random, but of one of our favourite and most important Christmas plants. Ivy.
On the Verge – Planting for the future – Guest Editor, Nick Haigh
The A4320 Bike Path Verge is a tree planting initiative between Bristol’s Lawrence Hill roundabout and Stapleton road; currently a bare stretch of grass, void of plants and animals, it will soon be turned into a wildlife, carbon-capturing haven, with thanks to support from the Bristol Tree Forum.
Bristol City Council’s Tree Management Policy – has it changed, or did we misunderstand it all along? – Stephanie French
Why does Bristol City Council have one standard when it comes to protecting its own trees, but another standard when it comes to trees protected with a TPO or growing in a Conservation Area?
Dealing with Ash Die Back disease – Guest Editor, Victoria Stanfield Cert. Arb & For
It was shocking to see the prevalence of the disease in our area when the trees were in full leaf this Summer, a large number of the trees which had been showing some sign of the disease in 2019, had deteriorated dramatically over the Winter months and come back into leaf with less than 50% of their canopy cover.
Trees and Planning: Artists’ Impressions and Heritage Statements – Stephanie French & Vassili Papastavrou
Plans with delightful illustrations of tree-filled spaces around new developments, either showing existing trees retained or new trees planted, are so often a ‘misdirection’, drawn in to make you think that everything will be alright and is acceptable, and that it doesn’t matter really. Please don’t be fooled. You need to read the detail.
The Morley Square arboretum – Chris Wallace
Morley Square is the only privately owned square in Bishopston. The deeds of the 28 houses around the square, including ours, state that the house owners have the rights of access to the square and the responsibility for its maintenance. One of our main concerns are the trees, some impressively large, mapped here on BristolTrees. Although only covering half an acre, the square contains 29 species of tree, a minor arboretum.
New Developments should be built around existing trees – Vassili Papastavrou
We always see glib promises that more trees will be planted than are removed, with the insinuation that the environment will be better afterwards. In our experience, replanting often fails or, if it does survive, produces meagre results, and take years to replace what is lost, assuming it ever does. It is perfectly possible to build around existing trees.
Our 2020 Blogs
Shocking treatment of Lower Ashley Road trees shows urgent need for Bristol Planning rethink – January 18, 2020
Council no longer manages trees on educational sites – Part II – January 27, 2020
The trees at Stoke Lodge Park and Playing Fields – a letter to the Council -February 5, 2020
A Manifesto for protecting Bristol’s existing Urban Forest – February 13, 2020
In Defence of Dead Wood – February 21, 2020
Congratulations BCC on its successful Defra Urban Tree Challenge Fund bid! -February 26, 2020
Tree replacement and carbon neutrality – March 31, 2020
A letter to our Councillors – May 4, 2020
Bristol City Development – Where did all the Green go? – July 9, 2020
Wales and West Utilities helps to protect Bristol’s precious trees – July 10, 2020
Trees valued at over £4.6m are under threat at Bonnington Walk, Lockleaze – July 18, 2020
Bristol Tree Forum tree planting campaign – free Oak saplings available for planting – October 26, 2020
STOP PRESS
We delighted to report that nearly 1,600 tree orders have been received. We have bought another 600 trees to cover the extra orders and expect delivery soon.
Many thanks to all of you who have placed an order. We shall soon let you know when and where you can collect your trees.
Due to COVID-19 restrictions and delays in government funding, there has been postponements and cancellations of many major tree planting projects. As a result, large numbers of tree saplings are due for destruction in tree nurseries. This includes 750,000 two year old English oak tree saplings at the Maelor Forest Nursery in Wrexham.
Rather than see these trees destroyed, Bristol Tree Forum has purchased 1,000 of the oak saplings for free distribution to anyone able to plant them, whether this is one tree or a hundred.
We will get delivery early in November. The trees can be collected from a site in Redland, Bristol and a few collection dates will be organised hopefully to suit all. They should be planted as soon as possible afterwards.
The saplings are between 10cm and 90cm high. They come bare-rooted (i.e. out of the soil) and need to be planted as soon as possible after collection, although the viability of the trees over winter can be extended a little by storing the trees with the roots covered in damp soil.
This form is to find out who would like to have saplings for planting and how many, and for you to provide basic contact details (email and/or phone number) for us to organise collection of the trees. Contact details will not be used for any other purpose.
Why plant a tree?
A single mature oak tree is the equivalent of 18 tonnes of CO2 or 16 passenger return transatlantic flights.
Despite advances in carbon capture technology, the most efficient and cost-effective way to sequester carbon from the atmosphere is to plant trees.
Recent scientific reports calculate that planting trees wherever we can, without occupying land used for other purposes, would absorb up to two thirds of the carbon emitted in the last century.
Oak trees can support over 2300 different species, including birds, mammals, invertebrates, mosses, lichen and fungi.
Trees improve air quality by absorbing both gaseous (e.g. NO2) and particulate pollution.
Trees reduce traffic noise and flooding, reduce excessive heat in cities and improve physical and mental wellbeing.
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.
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 Forum – July 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.
Bristol Tree Forum 