Tag: Green Space

Small sites, big losses: The BNG exemption is the strongest argument yet for a national tree replacement standard.

Since 6 August this year, the smallest developments in England (those 0.2 hectares or smaller) no longer have to deliver biodiversity net gain (BNG). To understand what this means for trees, we’ve analysed 505 biodiversity gain plans and 320 readable metric calculations gathered from 59 planning authorities.

The answer is uncomfortable: the exemption removes roughly half of all development sites from the BNG regime, and these are precisely the sites on which trees make up the largest share of the habitat being lost.

In December 2023 we argued for a new Bristol Tree Replacement Standard (BTRS) calibrated to the statutory biodiversity metric. That argument was about making the local standard consistent with national policy. It’s now about something much more critical: on half of all sites, a local standard is the only thing left to protect trees being lost to development.

What changed on 6 August 2026

The Biodiversity Gain (Town and Country Planning) (Amendments and Transitional Provisions) (England) Regulations 2026 (SI 2026/790) took effect for planning applications made on or after 6 August 2026. The three changes made matter here:

  1. A site of 0.2 hectares or less, measured by the red-line boundary of the application, is exempt from mandatory BNG unless on-site priority habitat is negatively affected.
  2. Development that’s wholly temporary, with permission granted for five years or less, is also exempt on the same proviso.
  3. For minor development above the area threshold, the mitigation hierarchy has been relaxed: off-site gains are now seen as just as desirable as created or enhanced habitat on the site itself, so a developer may go straight off site without first showing that on-site provision is unachievable.

The self-build and custom-build exemption has also been removed, on the reasoning that most such schemes now fall inside the new small-sites exemption anyway. While applications already submitted before 6 August continue under the old rules, Defra in its 15 April 2026 response to the consultation, estimated that ‘the new area based exemption for sites of less than 0.2 hectares is expected to remove more than 50% of the smallest planning applications which are currently delivering mandatory BNG, from the BNG requirement’.

Trees aren’t priority habitat

The priority habitat proviso sounds protective, and for some sites it is, but it does nothing for trees. Depending on where it is, an individual tree is recorded in the statutory metric as urban tree or rural tree, both of medium distinctiveness; neither is a habitat of principal importance under section 41 of the Natural Environment and Rural Communities Act 2006. Only ancient and veteran trees sit outside these two categories, as irreplaceable habitat, and they are a vanishingly small proportion of the trees felled for development.

So a mature street-side lime, a garden oak, or a row of maturing London planes on the edge of a school playing field — none of these will be protected if they’re in the way of a 0.2 hectare development. Below the threshold, they can be removed without any obligation to count them, replace them, or compensate for their loss anywhere. Unless the tree is protected by a Tree Preservation Order, or unless the local plan says otherwise, nothing now requires their loss to be made good.

This is the gap; and it’s much larger than the word ‘small’ implies.

Half of all development sites now fall outside the system

We measured site area for every gain plan in our dataset that came with a usable metric calculation — 305 sites across 59 authorities. Site area here is the baseline area-habitat total, net of any individual trees, taken from the statutory metric or, for small-sites metrics.

Table 1. Development sites by size, 305 sites with a usable metric calculation
Site size Sites Share Baseline area HUs Post-development area HUs On-site change
0.2 ha or smaller 151 49.5% 48.79 48.67 −0.25%
Over 0.2 ha 154 50.5% 506.88 512.82 +1.17%
All sites 305 100% 555.67 561.49 +1.05%

Habitat units are on-site figures from sections 6.3 and 6.4 of the biodiversity gain plan. Hedgerows and watercourses are excluded as linear features.

Just under half of the sites that have been going through the BNG process fall at or below the new exemption threshold — consistent with Defra’s own estimate. Two further things stand out in that table. First, small sites were barely holding their own on site even under the old regime that’s just been withdrawn: a baseline of 48.79 area habitat units became a mere 48.67 after development, a small net loss, with any gain bought off site from elsewhere. Second, the small-site total is dwarfed by the large-site total, which is exactly why the exemption looked politically cheap. In habitat unit terms these sites are a rounding error. In tree terms, though, they aren’t.

Small sites are where the trees are

Of the 320 metric calculations we could read, 163 relate to sites of 0.2 hectares or less. Sixty of these — 36.8% — record individual trees in the on-site baseline. Between them they carry 3.12 hectares of tree canopy ‘oversailing’ 15.22 hectares of land.

Table 2. Individual trees in the on-site baseline, by site size
Site size Metrics With trees Site area (ha) Canopy (ha) Canopy as % of site area Tree baseline HUs
0.2 ha or less 163 60 (36.8%) 15.22 3.12 20.5% 26.71
Over 0.2 ha 157 81 (51.6%) 219.64 13.79 6.3% 133.22
All sites 320 141 (44.1%) 234.85 16.91 7.2% 159.94

Site area is net of individual trees, because tree canopy oversails the habitat beneath it and is not additional land. Canopy can therefore exceed 100% of the site area it overlies.

That last comparison is the heart of it. On sites above the threshold, tree canopy is equivalent to about 6% of the site area. On sites at or below 0.2 hectares it’s 20.5% — more than three times the share. Small sites are disproportionately tree rich, probably because they’re disproportionately urban: they include infill plots, back gardens, corners of school and hospital grounds, and the fringes of existing built-up land. These are the places where we usually find the mature tree canopy of a town.

The concentration is sharper still for twenty of the 163 small-site metrics, which record canopy covering more than half the site area. Seven record canopy exceeding the whole of it. One example is a 0.18 hectare site at 22 York Road in Sutton, which carries 0.33 hectares of canopy across 18 recorded tree entries — canopy equal to 182% of the site, and worth 3.42 habitat units. At an average of 0.019 hectares of canopy each, these are mature trees, not saplings — on the replacement standard set out below, losing 18 medium trees would require 90 replacements. On an application made today, that site would be exempt and the trees could be removed without any obligation to replace them under the new BNG regime.

Expressed as trees rather than hectares, the 3.12 hectares of canopy on small sites is equivalent to 762 small trees, using the 0.0041 hectares the June 2026 metric assigns to a small tree. Because much of that canopy belongs to medium, large and very large trees, the actual number of trees is likely to be lower — and their replacement cost, in the metric’s own currency, correspondingly higher.

And they’re where the new trees were coming from

The exemption removes an obligation to plant as well as an obligation to compensate. Of the 163 small-site metrics, 72 record individual trees created as part of the post-development scheme.

Table 3. Individual trees created in post-development proposals
Site size Metrics With tree creation On-site trees Off-site trees Total trees
0.2 ha or smaller 163 72 (44.2%) 597 8 605
Over 0.2 ha 157 97 (61.8%) 3,135 205 3,340
All sites 320 169 (52.8%) 3,731 213 3,944

Tree numbers are the recorded habitat creation area divided by 0.0041 ha per small tree, rounded up. Off-site units bought from a registered gain site do not appear here, because they sit in the seller’s metric.

Over 600 trees across a dataset of a few hundred plans covering barely two years and 59 authorities out of 306. If you scale that across every planning authority in England and across the years ahead, the tree planting foregone is substantial.

BNG was never going to save urban trees anyway

It’s worth being clear that the case for a local tree standard doesn’t rest solely on the exemption. Even where BNG still applies, it often doesn’t keep compensation anywhere near the trees that were lost.

The Biodiversity Gain Sites register as of 19 August 2026 — 2,328 developments across 306 authorities — shows that 87% of developments in urban authorities offset outside their own authority area. Those authorities needed 1,835 area habitat units and hosted 889. In London the pattern is near total: 98% of the 113 registered London borough developments offset elsewhere, requiring 46.8 units and hosting 3.3.

The units are real, and the receiving sites may well be excellent. But a habitat unit delivered in a rural county doesn’t provide shade in Bristol, intercept its rainfall, cool it in a heatwave, or stand outside anybody’s window. Urban tree canopy is a local public good, yet BNG systematically moves its replacement to some distant field that few, if any, will ever visit.

Why we need a tree replacement standard

A tree replacement standard is a local plan policy, not a national biodiversity calculation. It attaches to the tree, not to the site area; it applies whether or not a metric has to be completed; and it keeps the replacement in or close to the place where the loss occurred. It’s the mechanism best suited to fill the gap the exemption has opened.

This is not a novel invention. Bristol has operated the BTRS since 2014 under Core Strategy policy BCS9, and a replacement table is carried forward into proposed local plan policy BG4. What we argued in 2023 was that the ratios should be recalibrated so that the standard delivers what the statutory metric would have delivered, plus the 10% uplift. Our proposal was not adopted then, though our argument stands. What’s changed is who needs it: not just Bristol, but every planning authority that wants any control at all over tree loss on the majority of its planning applications.

We would encourage authorities without such a policy to adopt one, and those with one to check that it’s calibrated to the metric rather than to a historic rule of thumb whose rationale was and remains hard to understand. As the standard is a local plan policy, it can be applied to exempt sites without cutting across the national BNG regime: BNG sets a floor for biodiversity, and a replacement standard sets a separate, local requirement for canopy.

Recalculating the standard against the June 2026 metric

Our 2023 proposal derived replacement numbers from the tree area equivalents then in force. Those figures have since changed. Table 15 of the Statutory Biodiversity Metric User Guide (June 2026), at page 62, now assigns the areas set out below. Applying the same method — the area of the lost tree divided by the area of one small tree, since a newly planted tree is recorded as small, plus the 10% net gain, rounded up because a fraction of a tree is not a tree — gives revised numbers.

Table 4. Replacement trees required, recalculated against the June 2026 metric
Tree size (DBH) Area equivalent (ha) Multiple of a small tree Plus 10% net gain Replacement trees 2023 proposal
Small (>7.5–30 cm) 0.0041 1.00 1.10 2 1
Medium (>30–60 cm) 0.0163 3.98 4.37 5 3
Large (>60–90 cm) 0.0366 8.93 9.82 10 10
Very large (>90 cm) 0.0765 18.66 20.52 21 20

Areas are from Table 15 of the Statutory Biodiversity Metric User Guide (June 2026), p62. Replacement numbers are the tree’s area divided by the area of one small tree, plus the 10% net gain, rounded up.

Two categories of tree size move. A medium tree is now worth almost four small trees rather than three, so its replacement requirement rises from three to five. A very large tree rises from 20 to 21. Large trees are unchanged at ten.

The small-tree row needs a decision rather than an arithmetic answer. One small tree replaced by 1.1 small trees rounds up to two, which is a real doubling for the commonest category in the surveyed population. The alternative is to hold the small category at one-for-one and take the 10% uplift from the scheme as a whole. We think the honest position is to state the arithmetic and let the policy make the choice explicitly, rather than round the uplift away in silence.

What we’re asking for

  • That local planning authorities adopt, or retain and strengthen, a tree replacement standard in their local plan, applying to all development including sites exempt from mandatory BNG.
  • That the replacement ratios be calibrated to the current tree area equivalents in the statutory metric, so that a local standard delivers no less than the national regime would have done.
  • That replacement be required within the same authority area and as close to the loss site as is practicable, so that canopy is replaced where people live.
  • That authorities continue to require a BS 5837:2012 tree survey with applications on exempt sites, so that the loss is properly recorded even where no metric is required.
  • That Defra keep the 0.2 hectare exemption under review, and specifically consider whether the priority habitat proviso should be extended to sites carrying significant tree canopy.

The exemption was introduced to reduce costs and delays for small applications. Whatever one makes of that aim, it shouldn’t be paid for with the mature canopy of our towns and cities. A tree replacement standard is a cheap, well-understood, locally enforceable way of making sure it’s not.

About the data

Figures are drawn from the Bristol Tree Forum biodiversity gain plan dataset (v11): 505 gain plans logged from 59 planning authorities, of which 320 carry a readable statutory or small-sites metric calculation and 305 a usable site area. Plans are dated 2024 (58), 2025 (254) and 2026 (165). Register figures are from the Biodiversity Gain Sites register extract of 19 August 2026, covering 2,328 developments and 2,686 allocations across 306 authorities.

Two caveats:

  1. Site area in this analysis is the metric’s baseline habitat area net of individual trees, which is a close proxy for the red-line boundary the exemption uses but not identical to it; a handful of sites near the threshold may fall on the other side of it in practice.
  2. The sample is of applications that produced a gain plan, so it describes the population the exemption removes rather than all development across the country.

The saga of the SNCI at Yew Tree Farm continues

What does ‘harmful impact’ mean?

When the Development Control Committee last met to discuss the Council’s application to extend the cemetery at South Bristol into the SNCI at Yew Tree Farm on 6 September 2023, we were disturbed to hear the Chief Planner’s interpretation of the meaning of ‘harmful impact’, as set out in the Local Plan policy, DM19 – ‘Development which would have a harmful impact on the nature conservation value of a Site of Nature Conservation Interest will not be permitted.’

We even wrote an open letter to the Chief Planner asking them to explain their reasoning. We published this as a blog: It seems that SNCIs are nothing special – an open letter to Bristol’s Chief planner.

Update

Unbeknown to us, it seems that the Council’s Nature Conservation officer did comment on the Chief Planner’s earlier advice to the Committee:

This document was disclosed on 1 December 2023 as a result of our Freedom of Information request of 01 November 2023. This appears to have formed the basis of the answers given below.

Update Ends

As we received no reply at the time, we took the opportunity to ask again when the Committee reconvened to make its decision on 29 November 2023. We asked two questions – see page 9 of the Public Forum. As the responses still didn’t really satisfy, we asked two supplementary questions:

  1. When you say, ‘the site’, what do you mean? Is it within the redline boundary or something else such as within the SNCI’s boundary?
  2. You say ‘The crucial additional clarification to highlight, is that to be in alignment with this policy it is NOT the overall biodiversity gain that is determinative. There rather needs to be an assessment that establishes whether there is harm with reference to the specific characteristics that make the site special.’

Does this mean that the replacement of one habitat which forms part of the ‘specific characteristics that make the site special’ – such as a replacing the Grassland Habitat that forms part of the current SNCI designation with a Lake Habitat that does not form part of the current SNCI designation, or that the provision of offsite mitigation measures to compensate for onsite habitat losses (in this case -6.44%) – would not be acceptable?

These were the replies:

To question 1

By ‘the site’, it’s the site as set out in the application document, so it’s the SNCI as contained in the application document the area in the redline boundary.

To question 2 (as it is quite complex, we have reproduced it verbatim)

You need to take the application as a whole and where it is demonstrated as that with regard to the features, particularly the grassland, that there is no impact ultimately or, if anything, a slight enhanced impact.

We intervened to ask – So you are saying that the substitution of the grassland habitat for a lake habitat…?

I am not saying that at all, I am saying that the grassland, actually that there is more grassland and that’s what the ecology report also says – more grassland of the type for which the SNCI is designated will be there through this application than before… within the redline boundary.

Here is the recording of this exchange – https://www.youtube.com/watch?v=-8EvqLA8-Lg (08:05 minutes from the start to 11:30 minutes).

What’s a redline boundary?

Anyone who wants to develop land must produce a location plan of the area proposed for development, delineated by a red line – the so-called ‘redline boundary’.[1]

When planning permission is granted, only the area within the redline boundary may be developed (though ancillary works may take place elsewhere).

Here is the location plan for the South Bristol Cemetery Extension application:

The South Bristol Cemetery Extension location plan (North is at the top)

The redline boundary here is quite complex because it’s made up of two burial areas, in the north and south, and an attenuation pond to collect runoff from the northern burial ground through a series of drains (the southern burial ground runoff will drain straight into Colliter’s Brook to the west). The area within the blue line is also owned by the Council and so is under their control.

The redline boundary is also important when it comes to calculating the biodiversity value (BNG) of the development site. All the habitats within the redline boundary are treated as ‘onsite’, while those outside the boundary are treated as ‘offsite’.

So, when we are told that ‘… there is more grassland and that’s what the ecology report also says – more grassland of the type for which the SNCI is designated will be there through this application than before… within the redline boundary,’ it’s just the onsite area that’s being referred to. This is important, as we show below.

The headline results shown in the most recent BNG 3.1 calculation relied on by the Council[2] show that 6.44% of the baseline onsite area biodiversity will be lost as a result of the development (see Figure 1).

Figure 1: The BNG 3.1 Headline BNG results.

Figure 2 shows the net losses of the onsite grassland habitat:

Figure 2: Grassland Area & Habitat Unit analysis (HUs)

Under the BNG Trading Rules, Medium Distinctiveness grassland habitats may only be replaced with the other Medium Distinctiveness grassland habitats or with habitats of a Higher Distinctiveness. So, in order to achieve the net 2.93% BNG which the Council claims will result from the development, it will be necessary to compensate for these losses by crediting 3.25 Habitat Units of High Distinctiveness Lakes habitat by creating the attenuation pond.

This is not what we are told is happening and it certainly cannot be said that: ‘… there is more grassland … of the type for which the SNCI is designated … within the redline boundary,’ This is plainly untrue and, even on the Chief Planner’s definition (which we do not accept), it is clear that this application will ‘have a harmful impact on the nature conservation value of a Site of Nature Conservation Interest.’ This is contrary to DM19.

What’s more, even if the proposed offsite habitat mitigations were taken into account, there’d still be a net loss of -0.47 HU of Medium Distinctiveness grassland habitat (see Figure 4 below).

Figure 4: Net Medium Distinctiveness habitat losses

There’s one other serious flaw in the application, which was not brought to the attention of the Development Control Committee at its meeting. There’s a shortfall of -0.11 Habitat Units of the High Distinctiveness habitat, Species-rich native hedgerow with trees. Lost High Distinctiveness habitats may only be replaced like-for-like. This has not happened. As a result, the application is in breach of the BNG Trading Rules and should not have been approved.

We have brought this to the attention of the Council and the LPA.

These are just some of the important reasons why we say that the Development Control Committee was wrong to grant this flawed application.

A copy of this blog can be downloaded here – The saga of the SNCI at Yew Tree Farm continues

[1] It seems that no one thought of those with red/green colour blindness, who might find it difficult to see this red line.

[2] 22_05714_FB-SOUTH_BRISTOL_CEMETERY_BNG__25TH_AUGUST_23_-3540800

Our proposal for a new Bristol Tree Replacement Standard

The Bristol Tree Replacement Standard (BTRS), which was adopted nearly a decade ago in 2013, provides a mechanism for calculating the number of replacements for any trees that are removed for developments. It was ground-breaking in its time as it typically required more than 1:1 replacement.

The presumption should always be that trees should be retained. The application of BTRS should only ever be a last resort. It should not be the default choice, which it seems to have become.

The starting point for any decision on whether to remove trees (or any other green asset) is the Mitigation Hierarchy[2] which states, firstly, avoid; then, if that is not possible, minimise; then, if that is not possible, restore; and, as a last resort, compensate (the purpose or BTRS). BCS9 adopts this approach and states that:

Individual green assets should be retained wherever possible and integrated into new developments.

However, with the emergence of a new Local Plan for Bristol, we believe that the time has come for BTRS to be revised to reflect our changing understanding of the vital importance of trees to the city in the years since the last version of the Local Plan was adopted in 2014.

In addition, Bristol has adopted Climate and Ecological Emergency Declarations so a new BTRS will be an important part of implementing these declarations. Nationally, the new Environment Act 2021 (EA 2021) is coming into force late next year.

Our proposal provides a mechanism for complying with the new legal requirement for 10% Biodiversity Net Gain (BNG) which will be mandatory when EA 2021 takes effect.

Background

Under current policy – BCS9 and DM17 – trees lost to development must be replaced using this table:

Table 1 The Current BTRS replacement tree table

However, when the balance of the Environment Act 2021 (EA 2021) takes effect late in 2023, the current version of BTRS will not, in most cases, be sufficient to achieve the 10% biodiversity net gain (BNG) that will be required for nearly all developments. Section 90A will be added to the Town and Country Planning Act 1990 and will set out the level of biodiversity net gain required ( Schedule 14 of the EA 2021).

The Local Government Association says of BNG that it:

…delivers measurable improvements for biodiversity by creating or enhancing habitats in association with development. Biodiversity net gain can be achieved on-site, off-site or through a combination of on-site and off-site measures.[3]

GOV.UK says of the Biodiversity Metric that:

where a development has an impact on biodiversity, it will ensure that the development is delivered in a way which helps to restore any biodiversity loss and seeks to deliver thriving natural spaces for local communities.[4]

This aligns perfectly with Bristol’s recent declarations of climate and ecological emergencies and with the aspirations of the Ecological Emergency Action Plan,[5] which recognises that a BNG of 10% net gain will become mandatory for housing and development and acknowledges that:

These strategies [the Local Nature Recovery Strategies] will guide smooth and effective delivery of Biodiversity Net…

Our proposed new BTRS model

We propose that the Bristol Tree Replacement Standard be amended to reflect the requirements of the EA 2021 and BNG 3.1 and that the BTRS table (Table 1) be replaced with Table 2 below:

Table 2 The proposed new BTRS tree replacement table

The Replacement Trees Required number is based on the habitat area of each of the three BNG 3.1 tree categories (Table 7-2 below) divided by the area habitat of one 30-year old BNG 3.1 Small tree (Table 3 below) plus 10% net gain. This is rounded up to the nearest whole number since you can’t plant a fraction of a tree.

The reasoning for our proposal is set out below:

Applying the Biodiversity Metric to Urban trees

The most recent Biodiversity Metric (BNG 3.1) published by Natural England, defines trees in urban spaces as Urban tree habitats. The guidance states that:

the term ‘Urban tree’ applies to all trees in urban situations. Urban trees may be situated within public land, private land, institutional land and land used for transport functions.

Table 7-1 divides Urban tree habitats into three categories:

Paragraph 8.5 of the 3.1 BNG Guidance makes it clear that lines of trees in an urban environment should not be treated as a linear habitat:

Urban trees are considered separately to lines of trees in the wider environment, since they generally occur in an urban environment surrounded by developed land. 

Calculating Urban tree habitat

Urban tree baseline habitat area is measured in hectares and is based on the Root Protection Area[7] (RPA) of each tree impacted by a proposed development. RPA is used instead of tree canopy because it is considered to be the best proxy for tree biomass.

In most cases, RPA is obtained from an Arboricultural Impact Assessment (AIA), which complies with British Standard 5837 2012 – Trees in relation to design, demolition and construction (BS:5837).

Where no AIA is available, Table 7-2 is used:

Note that the tree’s size will still need to be ascertained, and that any tree with a stem diameter (DBH) 75mm or more and of whatever quality (even a dead tree, which offers its own habitat benefits) is included . Under BTRS, trees with a DBH smaller than 150 mm are excluded, as are BS:5837 category “U” trees.

The guidance also makes it clear that, given the important ecosystem services value provided by trees, where possible like-for-like compensation is the preferred approach, so that lost Urban trees are replaced by Urban trees rather than by other types of urban habitat.[8]

Replacing lost trees

To calculate the number of trees required to replace Urban tree habitat being lost, table 7-2 above is used on this basis:

Size classes for newly planted trees should be classified by projected size at 30 years from planting.

We have used the median DBH sizes for new stock trees as set out in BS 3936-1: Nursery Stock Specification for trees and shrubs as the basis for calculating the eventual size of a newly planted trees after 30 years and assumed that a tree adds 2.54 cm (1”) to its girth annually.

This results in a predicted stock tree size after 30 years’ growth. This is then assigned to one of the three Urban tree categories set out in table 7-2: Small, Medium or Large. In all cases save for Semi-mature tree stock, the eventual size of stock trees after 30 years falls within the BNG 3.1 size category Small, which has a habitat area of 0.0041 hectares. This value is then used to calculate how many new trees will be required to replace trees lost to the development, plus a 10% biodiversity net gain. This gives a compensation size per replacement tree of 0.0045 ha (0.0041 hectares + 10%).

Table 3 below shows the basis our our calculation:

Table 3 Annual stock tree growth predictions

The Trading Rules

It may be that a notional positive biodiversity net gain can be achieved by replacing fewer trees than this analysis indicates. However, this is not enough. The calculation should also comply with the Trading Rules that apply to Urban tree habitats.

Paragraph 7.6 of the 3.1 BNG Guidance states:

The mitigation hierarchy and trading rules apply to Urban trees. Given Urban trees are a ‘Medium’ distinctiveness habitat, trading rules stipulate that the same broad habitat type (or a higher distinctiveness habitat) is required. However, given the important ecosystem services value provided by trees, where possible ‘like for like’ compensation is the preferred approach (i.e. where possible any loss of Urban trees should be replaced by Urban trees – rather than other urban habitats).

Rule 3 of the User Guide states: ‘”Trading down’ must be avoided. Losses of habitat are to be compensated for on a ‘like for like’ or ‘like for better’ basis. New or restored habitats should aim to achieve a higher distinctiveness and/or condition than those lost…’

The likely impact of this policy change

We have analysed tree data for 1,038 surveyed trees taken from a sample of AIAs submitted in support of previous planning applications. Most of the trees in this sample, 61%, fall within the BNG 3.1 Small range, 38% within the Medium range, with the balance, 1%, categorised as Large.

Table 4 below sets out the likely impact of the proposed changes to BTRS. It assumes that all these trees were removed (though that was not the case for all the planning applications we sampled):

Table 4 Proposed BTRS impact analysis

The spreadsheet setting out the basis of our calculations can be downloaded here – RPA Table 7-2 Comparison.

Our proposed changes to BTRS (published in the Planning Obligations Supplementary Planning Document, page 20) are set out in Appendix 1.

This article was amended on 7 November 2022 to include references to Lines of Trees in the urban environment, the application of the Trading Rules to Urban tree habitats and fix a broken link.

Appendix 1

Our proposed changes to BTRS, set out in the Planning Obligations Supplementary Planning Document, page 20.

Trees – Policy Background

The justification for requiring obligations in respect of new or compensatory tree planting is set out in the Environment Act 2021, Policies BCS9 and BCS11 of the Council’s Core Strategy and in DM 17 of the Council’s Site Allocations and Development Management Policies.

Trigger for Obligation

Obligations in respect of trees will be required where there is an obligation under the Environment Act 2021 to compensate for the loss of biodiversity when Urban tree habitat is lost as a result of development.

Any offsite Urban tree habitat creation will take place in sites which are either on open ground or in areas of hard standing such as pavements.

Where planting will take place directly into open ground, the contribution will be lower than where the planting is in an area of hard standing. This is because of the need to plant trees located in areas of hard standing in an engineered tree pit.

All tree planting on public land will be undertaken by the council to ensure a consistent approach and level of quality, and to reduce the likelihood of new tree stock failing to survive.

Level of Contribution

The contribution covers the cost of providing the tree pit (where appropriate), purchasing, planting, protecting, establishing and initially maintaining the new tree. The level of contribution per tree is as follows[9]:

  • Tree in open ground (no tree pit required) £765.21
  • Tree in hard standing (tree pit required) £3,318.88

The ‘open ground’ figure will apply where a development results in the loss of Council-owned trees planted in open ground. In these cases, the Council will undertake replacement tree planting in the nearest appropriate area of public open space.

In all other cases, the level of offsite compensation required will be based on the nature (in open ground or in hard standing) of the specific site which will has been identified by the developer and is approved by the Council during the planning approval process. In the absence of any such agreement, the level of contribution will be for a tree in hard standing.

The calculation of the habitat required to compensate for loss of Urban trees is set out in Table 7-2 of the Biodiversity Metric (BNG), published from time to time by Natural England. This may be updated as newer versions of BNG are published.

The following table will be used when calculating the level of contribution required by this obligation:

A copy of this blog can be downloaded here:

BTF proposal for a new Bristol Tree Replacement Standard

[1] Biodiversity Metric 3.1 – Auditing and accounting for biodiversity – USER GUIDE.

[2] https://nationalzoo.si.edu/ccs/mitigation-hierarchy.

[3] https://www.local.gov.uk/pas/topics/environment/biodiversity-net-gain.

[4] https://www.gov.uk/government/news/biodiversity-30-metric-launched-in-new-sustainable-development-toolkit.

[5] https://www.bristol.gov.uk/documents/20182/5572361/Ecological_Emergency_Action_Plan.pdf/2e98b357-5e7c-d926-3a52-bf602e01d44c?t=1630497102530.

[6] DBH = Diameter at Breast Height. RPAr = Root Protection Area radius. Area = the calculated BNG habitat area.

[7] RPA area = π × r2 where r is 12 x the tree’s DBH for a single stemmed tree. For multi-stemmed trees, the DBH of the largest stem in the cluster should be used to determine r.

GOV.UK advice is that r should be at least 15 times larger than DBH – https://www.gov.uk/guidance/ancient-woodland-ancient-trees-and-veteran-trees-advice-for-making-planning-decisions.

The Woodland Trust also recommends that r be set to 15 x DBH for ancient and veteran trees – https://www.woodlandtrust.org.uk/blog/2021/04/root-protection-areas.

[8] Paragraph 7.8 – Trading Rules.

[9] These values should be updated to the current rates applicable at the time of adoption. The current indexed rates as of April 2022 are £1,041.6 & £4,517.89 respectively.

[10] DBH = Diameter at Breast Height. RPAr = Root Protection Area radius. Area = the calculated BNG habitat area.

Trees under threat at the Eastgate Centre!

Bristol’s trees are constantly under threat from development, especially when the commercial value of the land they grow on is so great and the public amenity value they offer is not thought worthy of consideration.

Here is (yet) another example.

An outline planning application – Number 17/01580/P – has been made to at the Eastgate Centre on Eastgate Road  for the demolition of the existing drive-thru restaurant. It will be replaced by new retail units with a health and fitness club above and a replacement drive-thru restaurant.

Part of this application will require the destruction and removal of a delightful stand of trees that grow on a triangle of land between the roundabout on Eastgate Road and the existing retail park. This is so that larger retail units can be built and goods vehicles can more easily gain access to the rear of the site. This is a plan of the trees affected.

Eastgate Trees

This is the proposal for what will be planted in their place – a souless echo of what is already there:

Eastgate Trees2

The Council’s own arboricultural officer has objected to the proposal. He advises:

“I have conducted a site visit and reviewed the supporting arboricultural documentation. The trees on site are located on the edge of the proposed development area and provide a significant screen to the already extensive retail development. The group of trees fall within 2 distinct age ranges, a mature group of ash, oak and poplar and a young understorey of secondary infill planting.

The mature trees are protected by TPO 282. The ash and oak are a historic remnant of a landscaped garden (Circa 1900) from the former gas works that occupied the site, the ash appear to of been managed as old pollards which have now grown out. They are historic trees with potential veteran tree characteristics that warrant the TPO status and must be retained. Due to poor management or lack of management the trees have a number of less than satisfactory defects associated with them that have in part been identified within the supporting tree survey from February 2015. The understorey planting appears to date back to the original development of the retail park, this understorey now has a more complex relationship with the larger TPO trees. They reduce the target area of people and property by the restriction of movement within this area and they also provide shade to the lower portions of the main stems which when considering the potential veteran tree characteristics offer significant ecological benefits. The management of this area for the benefit of the mature TPO’d trees would need careful consideration.

The supporting arboricultural survey is out of date and only provides basic survey detail that does not consider age and historic relevance of the TPO’d trees. The survey in not a full BS5387 report as required with DM17: Development Involving Existing Green Infrastructure.

The proposal seeks to redevelop the current Burger King site to increase the number of commercial units with associated HGV delivery bays to the rear.

This proposal would remove the vast majority of the historic TPO’s trees and associated understorey, This would be detrimental to the TPO status of the trees. The final design would be in constant conflict with the trees identified for retention leading to further applications to remove the tree following occupation of the individual units.

The Mature Oak T10 is a key amenity feature located in an elevated position over the roundabout at the gateway of the Eastgate centre; this is a TPO’d tree and no evidence has been provide to justify its removal.

I object to the proposed and would recommend refusal of the application on the grounds of a detrimental impact to the only green infrastructure on site and historic environment. Insufficient detail has been presented in accordance with BCS9, DM15 & DM17. There has been no consideration of the TPO status of the trees or their current or future management.

The arboricultural documentation is poor, out of date and insufficient to support an application, the tree planting plan produced to mitigate the loss of such significant trees has not considered the “Planning obligation SPD, Tree.” (Bristol tree replacement standard (BTRS). I hope you find these comments of use.

Matt Bennett Arboricultural Officer (Planning) City Design Group – Place Directorate City Hall.”

We agree with Matthew! We shall be lodging our objections.

If you also agree, please lodge your objections here in the Planning application comments section. These are the Important dates:

Eastgate Trees3

Bristol’s trees in crisis!

With Bristol City Council’s budget cuts, two decisions have been made regarding the management of Bristol’s treescape that make no economic sense, and threaten the reputation of the City as a Green and pleasant place to live and locate a business.

With Bristol City Council’s budget cuts, two decisions have been made regarding the management of Bristol’s treescape that make no economic sense, and threaten the reputation of the City as a Green and pleasant place to live and locate a business.

Decision 1: Slashing of street tree management budget

  • The budget for managing street trees has been cut by nearly 78% from £240,000 to £53,000.
  • As a result there will be no pollarding of street trees or removal of epicormic growth around the tree.
  • Emergency cover outside normal working hours is no longer being provided through the tree management contract, despite having no cost benefit.
  • Tree management will be limited to felling to address safety risks, despite greater initial costs and the long term consequent loss of tree sites – felling costs the same as 16 years of maintenance.  As a result, Bristol’s street tree population will rapidly fall into decline as they are steadily removed, never to be replaced.

Decision 2: No planting of street trees, either replacement or new, even when cost neutral

  • Bristol City Council has operated a number of innovative schemes allowing residents or community groups to sponsor replacement or new street trees. Despite fully funding the planting, and maintenance for two years, such planting will no longer be permitted.
  • At the moment, when a tree is replaced in an existing tree pit it costs £295. This covers regular watering until the tree is established and two years maintenance. If the trees dies whilst establishing itself, it is replaced at no extra cost.
  • If the Council can be persuaded to change its mind about not planting new trees, then this cost could to increase to the £765 that developers are required to pay – the overall costs of planting a tree and maintaining it during its lifetime. Planting a tree at a brand new site could add around £2,000-£2,500 if a special tree pit needs to be installed.
  • Currently there is huge support from the community for replacing lost trees. Around £200,000 of developers’ money is set aside for this purpose, Metrobus is committed to planting 200-300 trees as part of their planning condition, and Bristol University has donated funds to plant 60-100 public street trees.
  • It makes little sense, in times of budget constraints, to renounce external funding sources that fully cover planting and maintenance costs.

These decisions are a false economy for Bristol City Council

  • With no pollarding of street trees, increased tree growth will lead to more subsidence claims against the Council, and create more highway damage, pavement trip hazards, and infrastructure damage.
  • New tree growth from previous pollarding points will become unstable, increasing the probability of personal injury and property damage claims against the Council.
  • Just a couple of additional subsidence or injury claims could negate the Council’s entire “cost saving”.
  • This short-term decision makes no sense – if a tree can be maintained for some 16 years – the one-off cost of felling it, then surely it makes better economic sense to spread this inevitable cost and maintain the tree rather than fell it as a short-term ‘solution’ – a ‘solution’ which loads all the costs up front and will lead to greatly increased and unavoidable expenditure in not very many years time?

These decisions will threaten Bristol’s reputation as a Green City

These decisions were taken with no consultation with stakeholders

There has been no consultation regarding these decisions with other Departments within Bristol City Council, who will have to deal with the foreseeable consequences, with insurers, who will face additional damage claims, Avon and Somerset Police, who will have to address public order consequences of mass felling, or Bristol Tree Forum, with its wide-reaching understanding of tree issues.

What you can do

  • Contact your Councillor and email the Mayor and demand that these decisions be overturned.
  • Contact us here at Bristol Tree Forum to register your support and offer to help defend Bristol’s public tree spaces.
  • Spread the word and forward this blog to others interested in saving trees.

Green space and our health

The evidence for physical and mental health benefits from contact with nature, such as reducing rates of non-communicable diseases is clear.

A range of bodies, including Government agencies, have promoted the potential physical and mental health benefits of having access to green spaces.

The evidence for physical and mental health benefits from contact with nature, such as reducing rates of non-communicable diseases is clear. So are the challenges for preserving and extending urban green spaces.

Green space is natural or semi-natural areas partially or completely covered by vegetation that occur in or near urban areas and provide habitat for wildlife and can be used for recreation. They are many and varied – from tree-covered streets & avenues to squares, play areas, schools, cemeteries, parks, woodlands, nature reserves and allotments.
Sadly, only half of us live close to green space. Green space is expected to decrease as urban infrastructure expands.

Key benefits include:

  • Physical and mental illnesses associated with sedentary urban lifestyles are an increasing economic and social cost.
  • Areas with more accessible green space are associated with better mental and physical health.
  • The risk of mortality caused by cardiovascular disease is lower in residential areas that have higher levels of ‘greenness’.
  • There is evidence that exposure to nature could be used as part of the treatment for some conditions.
  • There are challenges to providing green spaces, such as how to make parks easily accessible and how to fund both their creation and maintenance.