WEMCA’s Local Nature Recovery Strategy (LNRS) will fail to provide Bristol with the benefits promised for nature. While the new Biodiversity Net Gain (BNG) rules require most development in the city to increase biodiversity by at least 10%, unfortunately the LNRS will not apply to most potential development sites.
The LNRS is a locally led and evidence-based strategy which aims to target action and nature investment where it’s most needed. We’re told that the strategy will also focus on biodiversity net gain by increasing the strategic significance of specific habitats. However, it is hard to imagine how the LNRS will help to enhance biodiversity net gain in most, if not all, potential development sites in the city.
We might have been better off, at least as far as the application of biodiversity net gain to new development is concerned, by asking the LPA to specify alternative documents (such as those listed at the end of this article) for assigning strategic significance instead.
The issue
When calculating the impact of a proposed development on biodiversity, one factor taken into account is the strategic significance of any habitat found on a focus area for nature recovery site (coloured purple in the map above). If strategically significant habitats are created or enhanced, then their strategic significance is set to High in the Statutory Metric calculator tool and a 15% uplift to the calculation of its value is applied. Subject to which of the six LNRS areas is being considered, these are the strategically significant habitats in the city:
Ditches
Ecologically valuable lines of trees
Ecologically valuable lines of trees – associated with bank or ditch
Grassland – Floodplain wetland mosaic and CFGM
Grassland – Lowland calcareous grassland
Grassland – Lowland meadows
Heathland and shrub – Mixed scrub
Heathland and shrub – Willow scrub
Individual urban or rural trees
Lakes – Ponds (priority habitat)
Priority habitat (on the River Avon and the Riparian buffers)
Species-rich native hedgerow with trees – associated with bank or ditch
Species-rich native hedgerow with trees
Species-rich native hedgerows – associated with bank or ditch
Species-rich native hedgerows
Urban – Open mosaic habitats on previously developed land
Urban – Biodiverse green roofs
Woodland and forest – Lowland beech and yew woodland
Woodland and forest – Lowland mixed deciduous woodland
Woodland and forest – Other woodland; broadleaved
Woodland and forest – Wood-pasture and parkland
However, a detailed examination of the LNRS map reveals that not all parks and green spaces have been designated as focus area for nature recovery sites. It’s only those which are in one or both of the following:
a location where they can make a greater contribution to ecological networks
deprived areas with a lack of access to nature.
These designations were based on Bristol’s previous work on ecological networks within the city and where wildlife-friendly interventions are most likely to be feasible. This means that the existence, creation or enhancement of these special habitats outside these areas will not attract the 15% strategic significance uplift.
The BNG requirements
The now compulsory Statutory Metric Guide, used for calculating Biodiversity Net Gain (BNG), advises (at page 27) that: ‘Strategic significance is the local significance of the habitat based on its location and habitat type. You should assess each individual habitat parcel, both at baseline and at post-intervention, for on-site and off-site.’
If the LPA has adopted an LNRS then only the High or Low strategic significance multipliers can be used (High – formally identified in local strategy = 1.15. Low – area compensation not in local strategy = 1). If it has not adopted an LNRS, then the Medium strategic significance multiplier may also be used (Location ecologically desirable but not in local strategy = 1.10).
Where an LPA has adopted an LNRS, all those sites which have not been identified as a focus area for nature recovery site will be designated as having Low strategic significance and so attract no uplift, even if they’ve been identified as important habitats in the Local Plan or in another strategic document adopted by the Council. These documents (used where an LPA has not adopted an LNRS) can include:
Draft Local Nature Recovery Strategies
Local Plans and Neighbourhood Plans
Local Planning Authority Local Ecological Networks
Parks and Green Spaces Strategies
Tree and Woodland Strategies
Area of Outstanding Natural Beauty Management Plans
Biodiversity Action Plans
Species conservation and protected sites strategies
Green Infrastructure Strategies
River Basin Management Plans
Catchment Plans and Catchment Planning Systems
Shoreline management plans
Estuary Strategies
Baseline habitats cannot be uplifted
Despite the BNG strategic significance guidance, Defra has stated that LNRS designations only apply to the creation or enhancement of post-development biodiversity mitigation habitats. They don’t apply if these habitats – called the baseline habitats – are found on the site before development begins.
This means that the 15% strategic significance uplift can only be applied where offsite biodiversity mitigation is being delivered in a focus area for nature recovery site. If these habitats are being delivered elsewhere, the uplift may not be applied.
However, even if the baseline habitats were included, it is unlikely to make any difference This is because the focus area for nature recovery sites identified in Bristol are, for the most part, located in public parks or green spaces, on river banks, in riparian buffers or on railway margins, none of which are likely ever to be developed or, in many cases, used to offset habitat lost to development elsewhere.
So far, no announcement has been made as to whether any of Bristol’s focus area for nature recovery sites will be made available for offsite habitat mitigation and the proposed new Local Plan does not commit to using these sites for this purpose.
This, combined with the challenge of finding LNRS suitable for offsite habitat mitigation, registering them as biodiversity gain sites and then managing them, effectively, in perpetuity, suggests that few feasible LNRS sites will be found, especially as many sites are also in demand for public access for recreation.
We urge the Bristol City Council Cabinet to reject the current draft. More nuanced rules, that meet identified real needs, need now to be developed following a proper consultation with Bristol’s allotmenteers. The PGSS must be also integrated into the new Local Plan so that all the sites that have been identified are protected either as Local Green Space or as Reserved Open Green Space and given proper planning weight when decisions about their future use and development are made.
We are particularly concerned that the draft rules relating to trees on allotments are too narrowly drawn and will result in the loss of allotment tenants’ ability to make the best use of the particular conditions of their plot. We urge the relaxation of these proposed limits on the number and types of trees which can be planted.
Food growing as part of the draft Parks and Green Spaces Strategy
We are concerned that the Strategy for Food Growing and Allotments has been included as Chapter 6 of the draft Parks and Green Spaces Strategy (PGSS). This is a departure from the 2008 PGSS, which makes it clear that such spaces are not included, since they are not public spaces: ‘The Strategy does not consider green spaces that are not freely accessible to the public, including allotments, city farms, school grounds, or Sites of Nature Conservation Interest in private ownership.’
The proposed PGSS recognises that: ‘There are other green spaces managed by the council that are not included because they do not offer full public access for recreation …’ [our underlining]. Given that allotments and other land used for growing food (including grazing land) are subject to private tenancies, with rental payments and mutual rights and obligations agreed between tenant and Council, it is hard to understand why they have been included in the strategy proposal.
We need to recognise the importance of this specific type of land use and ensure that it is not made an ancillary element in the PGSS. It deserves greater attention, which is why we suggest that it should have been integrated into and protected by the current proposals for the new Local Plan (as, indeed, Parks and Green Spaces should also be) rather than treated as an add-on to the proposed PGSS.
In particular, the current status of and strategy for market gardens, smallholdings and grazing land (and other land not used for food growing), which have an area greater than all current allotments combined, get only passing consideration. Little or no thought is given to the opportunities these sites present for nature recovery, biodiversity enhancement and other environmental gains.
Instead, we are told that these sites:
… have limited benefit beyond the individual users … and many smallholdings tend to use less than 10% of their site for food growing … we now need to review our current landholding agreements so that we can start to explore opportunities to repurpose land to diversify our food growing spaces and ensure land is being used effectively to meet Bristol’s food growing targets. … Once suitable land has been identified we will review how these opportunities are promoted to ensure that the system of securing land is fair and equitable. We are particularly interested in opportunities that will not only ensure land is being sustainably and efficiently managed but that also delivers social value and benefits the residents of Bristol.
In the face of the demand for allotments and the need to increase local food production, which has led at least in part to the proposed changes in the tenancy agreement, these areas must surely warrant greater protection than is given them in the proposed PGSS. These areas also contain many trees (often veterans) and other ecologically sensitive habitats, and many are in SNCIs. It is vital that these matters are properly considered when planning any change of use of such land. This ought to be addressed properly in the proposed new Local Plan, not in this draft strategy.
Trees on allotments
Trees on allotments fall into two categories: those within allotment plots and those on allotment sites but outside the plots.
Trees outside allotment plots
From our analysis of data on the Council’s Open Data site, we estimate that allotment sites total some 105 hectares when community orchards are included. However, only about 87 hectares of these sites are productive. This means that around 17% of allotments, some 18 hectares, are unproductive. We welcome the clarification in the new tenancy agreement that trees in these unproductive areas remain in the care of the Council and may not be damaged by tenants.
Trees within allotment plots
Proposed allotment Rule 4.0 Trees deals with trees growing within allotment plots. We distinguish between newly planted trees and existing trees below.
New trees
Regulation 4.4 limits the height of trees to 2.5 metres (a common constraint in other councils). The limit in Regulation 4.3 of one tree per allotment sized between band B and band C is far too restrictive, particularly since the majority of plots fall within these bands.
Rule 3.1 requires that the tenant uses at least 75% of the plot for ‘a cultivated crop of vegetables, fruit bushes [not fruit trees], ornamental flowers, and herbs.’
Rule 3.3 states that fruit trees will occupy the non-cultivated area of the plot (which may be no more than 25% of the plot) unless they are underplanted with a productive crop, in which case they will be counted as being part of the cultivated area. No trees are permitted on band A or Micro Plots, nor is any consideration given to whether it is possible to underplant ‘a productive crop’. This implies that the food value of the tree does not warrant the space they occupy. According to the RHS, having fruit trees on an allotment adds both structure and permanence, while fruit tree crops have a higher value than many other allotment crops and are easier to manage.
The transitional arrangements require that all trees, except the permitted dwarf rootstock fruit trees, be removed from plots within three years, though mature trees may be permitted.
These rules devalue the role of trees on allotments, not only for their contribution to the ecology of the area but also their food production value. These rules also effectively exclude such fruit-tree-growing techniques as cordons, espaliers or step-over planting.
Regulation 4.3 also constrains the type of fruit trees that may be grown. Since only rootstocks M27 and M26 are allowed (though not the intermediate M9 rootstock), it seems that that only apple trees may be grown, even though dwarfing rootstocks are available for a number of other fruit trees such as Pear, Quince (Quince C), Cherry (Gisela 5), Plum (including Gages and Damsons), Peach and Apricot (VVA-1, Pixy).
The exclusion of hazel and other non-fruit trees (most trees bear fruit) removes the ability of tenants to grow valuable nut crops or to provide locally grown stakes through coppicing – a good way to reduce our carbon footprint. This restriction also precludes the use of allotment space for growing trees from seed with a view to planting them out elsewhere, at a time when there is a great need for locally grown trees for local tree planting.
Established trees
Fruit trees
Many fruit and other trees are already growing on many allotment sites. They provide not only good-value food, but they also provide biodiversity, a rich ecological resource for insects, birds and mammals and are important legacy features of the site. The allotment and its users have adapted to the presence of these trees and their removal would not only be counterproductive to the value of the site and cause distress to tenants but would also risk damaging the soil and the allotment more broadly.
Non-fruit trees
Although such trees may not have obvious value for food production, other considerations apply. We agree that allotments should not be taken over by trees, resulting in the reversion of productive land to woodland and the attendant loss of statuary allotment protection for such land. However, it would be a mistake to create rules which put biodiversity, nature and ecology in conflict with food production; trees are crucial for biodiversity, which in turn is essential for the productivity of the places where we grow food.
Site-appropriate regulations
Allotment plot conditions both within allotment sites and across Bristol vary widely. The gradient and aspect of each plot, its soil type, soil depth and historical development all pose different challenges to tenants, requiring a localised approach to the best way to utilise a site. Imposing a one-size-fits-all set of regulations, based on some notional idealised allotment plot, will not provide sufficient scope to allow for these variations. Tenants’ associations also need to be able to vary the regulations to fit their local conditions. Indeed, arguments in favour of the distribution of local decision making, which we endorse, have recently been made by the Bristol Mayor.
Following discussions with the Council about our recent proposal to revise BTRS, we have drafted a new version which we believe will strengthen tree protection across the city even further if it is adopted into the proposed new Local Plan.
Revisions are shown in red.
The latest version of the Biodiversity Metric (BNG 4.0), just published by Natural England,[1] is likely to become mandatory when the balance of the Environment Act 2021 comes into force later this year. We have revisited our June 2022 proposals and reviewed our calculations. We have met with Bristol City Council Officers and discussed possible alternatives with them. Here is the revised version.
The Bristol Tree Replacement Standard[2] (BTRS), adopted a decade ago, 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 of trees lost to development and within one mile of the development.
The presumption when considering any development involving established trees should always be that trees will be retained. The application of BTRS should only ever be a last resort. Providing funds in exchange for trees that are removed on development sites should not be the default choice which it seems to have become. In addition, in many instances, the locations of the promised replacement trees are not specified and the trees are never planted. As a result, section 106 tree replacement funds continue to accumulate to the 2023 figure of approximately £800K. This figure as barely changed over the years we have been monitoring it.
The starting point for any decision on whether to remove trees (or any other green asset for that matter) is the Mitigation Hierarchy. Paragraph 180 a) of the National Planning Policy Framework sets it out as follows:
If significant harm to biodiversity resulting from a development cannot be avoided (through locating on an alternative site with less harmful impacts), adequately mitigated, or, as a last resort, compensated for, then planning permission should be refused.[3]
BTRS is and should always be ‘a last resort’. This is reflected in the Bristol Core Strategy, policy BCS9 adopts this approach and states that:
Individual green assets should be retained wherever possible and integrated into new developments.[4]
However, with the development 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 urban trees to Bristol in the years since the final part (SADMP[5]) 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 Environment Act 2021[6] (EA 2021) will come force later this year. This will require nearly all developments to achieve a Biodiversity Net Gain (BNG) of at least 10%. Our proposal provides a mechanism for complying with this new requirement and so aligns BTRS with the BNG provisions of the EA 2021.
Background
Under current policy – BCS9 and DM17[7] – trees lost to development must be replaced using this table:
Table 1 The Current DM17/BTRS replacement tree table.
However, when the balance of EA 2021 takes effect, the current version of BTRS will not, in most cases, be sufficient to achieve the 10% BNG minimum that will be required for nearly all developments. A new section 90A will be added to the Town and Country Planning Act 1990 and set out the level of BNG required (see Schedule 14 of EA 2021[8]).
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.[9] 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.[10]
This aligns perfectly with Bristol’s recent declarations of climate and ecological emergencies and with the aspirations of the Ecological Emergency Action Plan,[11] which recognises that a BNG of at least 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 4.0 and that the BTRS table (Table 1 above) be replaced with Table 2 below:
The Replacement Trees Required number is based on the habitat area of each of the three BNG 4.0 tree category sizes (Table 8-1 below) divided by the area habitat of one BNG 4.0 Small category tree (see section 3 below) plus a 10% net gain. This is rounded up to the nearest whole number – you can’t plant a fraction of a tree.
Replacing lost woodland
The current BTRS model does not deal effectively with the loss of woodland where it is impractical to measure individual tree sizes. Under BNG 4.0 these habitats are treated as Woodland and forest habitat and their habitat area is measured by the area they cover. We propose using the same method and adding 10% to allow for biodiversity net gain. The ratio will be 1 to 1.1 so that a woodland of, say, one hectare must be replaced with one which is 1.1 hectares.
The definition of a woodland is as set out in the UK Habitat Classification[12], w Woodland and forest: ‘Land with more than 25% cover of trees more than 5m in height.’
Replacing lost trees with hedgerows
The aim of BTRS is to replace lost tree habitat and canopy. Planting hedgerows cannot do this.
Whilst the planting of hedgerows is always to be encouraged, especially native species hedgerows, proposals to replace trees lost to development with hedging is very rarely a suitable solution and will not be permitted unless the developer is able to show that there are exceptional reasons for doing so. The planning arboricultural officer will need to agree the exceptional circumstances.
If a replacement hedgerow is permitted, this cannot be credited towards any BNG 4.0 calculation relating to trees. Hedgerows are a different habitat type, being linear as opposed to area based as trees are.
Making the BTRS calculation transparent
Often, years pass before trees lost to development are replaced and often the lost trees are only shown in the subsequent s106 agreement[13] as a single sum which was calculated years before and indexed to allow passage of time since the adoption of the Supplementary Planning Document (SPD) in January 2013.[14]
We would like to see a schedule set out in the S106 agreement and/or as a planning condition which itemises:
The number and identity (using Id used in the BS5837:2012 survey) of each tree to be removed.
The number and species of the trees to be planted on the development site.
The number and species of the trees to be planted on public land.
Which offsite trees are in to be planted open ground and which in hard standing.
The agreed location and species of each offsite replacement tree which and should be within one mile radius of the lost tree.
Trees planted under BTRS should not replace lost public trees, such as street trees removed in the normal course of tree management.
Like for like replacement. Compensation for the loss of large-form trees should result in large-form trees being planted.
Require that replacement trees or trees damaged as a result of the development that die within five years of planting will be replaced at the developer’s expense – This is the standard condition for trees planted on a development site.
The reasoning for our proposals is set out below:
Applying the Biodiversity Metric to Urban trees
The most recent Biodiversity Metric[15] (BNG 4.0) published by Natural England this April, defines trees in urban spaces as Individual trees called Urban tree habitats. The User Guide states that:
Individual trees may be classed as ‘urban’ or ‘rural’. Typically, urban trees will be bound by (or near) hardstanding and rural trees are likely to be found in open countryside. The assessor should consider the degree of ‘urbanisation’ of habitats around the tree and assign the best fit for the location.
Individual trees may also be found in groups or stands (with overlapping canopies) within and around the perimeter of urban land. This includes those along urban streets, highways, railways and canals, and also former field boundary trees incorporated into developments. For example, if groups of trees within the urban environment do not match the descriptions for woodland, they may be assessed as a block of individual urban trees.
Calculating Individual trees habitat
Table 8-1 in the BNG 4.0 user guide is used to calculate the ‘area equivalent’ of individual trees:
Note that the tree’s stem diameter will still need to be ascertained using BS:5837 2012,[16] and that any tree with a stem diameter (DBH) 7 mm or more and of whatever quality (even a dead tree, which offers its own habitat benefits) is included. Under the current DM17/BTRS requirement, trees with a DBH smaller than 150 mm are excluded, as are BS:5837 2012 category “U” trees. This will no longer be the case.
The Rule 3 of the BNG User guide makes it clear that like-for-like replacement is most often required, so that lost Individual trees (which have Medium distinctiveness) are to be replaced by Individual trees rather than by other habitat types of the same distinctiveness.[17]
Forecasting the post-development habitat area of new Individual trees
The BNG 4.0 User Guide provides this guidance:
8.3.13. Size classes for newly planted trees should be classified by a projected size relevant to the project timeframe.
most newly planted street trees should be categorised as ‘small’
evidence is required to justify the input of larger size classes
8.3.14. When estimating the size of planted trees consideration should be given to growth rate, which is determined by a wide range of factors, including tree vigour, geography, soil conditions, sunlight, precipitation levels and temperature.
8.3.15. Do not record natural size increases of pre-existing baseline trees within post-development calculations.
Our calculations are based on ‘small’ category replacement trees being planted.
Retain the community benefits of green assets
The current requirement that any off-site tree replacements are within a one-mile radius of the site should be retained. Were tree replacements to be allowed at any distance from the site, the local community that has lost trees due to a development would likely not benefit from their replacements. If trees lost in tree-deprived areas were to be replaced in areas with more available space and often more trees, the result would be greater inequality in tree cover. Currently, the most socially and economically deprived areas in the city centre have the lowest tree cover, and as these areas are also under the most pressure from developments, to lose this localism in tree replacement would lead to a further deprivation in tree cover for these communities.
The likely impact of this policy change
We have analysed tree data for 1,038 surveyed trees taken from a sample of BS:5837 2012 tree surveys submitted in support of previous planning applications. Most of the trees in this sample, 61%, fall within the BNG 4.0 Small range, 38% are within the Medium range, with the balance, 1%, being 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):
Our proposed changes to DM17 and BTRS are set out in Appendices 1 and 2.
Appendix 1 – Our proposed changes to DM17: Development Involving Existing Green Infrastructure…
Trees
All new development will integrate important existing trees[18].
Development resulting in the loss or deterioration of irreplaceable habitats (such as ancient woodland and ancient or veteran trees) will be refused, unless there are wholly exceptional reasons and a suitable compensation strategy exists.[19]
Where tree loss or damage is unavoidable to allow for sustainable development, replacement trees of an appropriate species will be provided in accordance with the tree replacement requirements set out in the Council’s Planning Obligations – Supplementary Planning Document. …
Trees
2.17.6 Due to their characteristics and value, Aged and Veteran trees are considered to be of relatively greater importance than other trees and even trees of a similar species. Aged trees, by definition, have developed characteristics associated with great age and often have particular landscape and townscape value. Veteran trees are considered to have particularly important nature conservation value. Both will often have significant visual amenity, and potentially historic and cultural importance. As such, their loss or harm will not be permitted, and the design and layout of development will be expected to integrate them into development.
2.17.7 Trees are considered valuable multifunctional green infrastructure assets. This policy seeks to protect the most valuable trees and in line with the Core Strategy approach to green infrastructure assets, mitigate for the loss of other important trees by securing replacement trees on-site or in the public realm. The tree compensation standard set out in this policy provides a suitable mechanism to determine the appropriate level of mitigation where loss of trees is proposed as part of development.
2.17.8 The council’s Planning Obligations Supplementary Planning Document sets out the circumstances when off-site tree provision will be necessary. Where trees are to be provided off-site, planning obligations will be sought to provide the appropriate number of replacement trees, utilising the approach set out in the Supplementary Planning Document.
Appendix 2 – Our proposed changes to BTRS
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.[20]
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 and are located as close as possible to the site of the lost tree.
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.
The trees planted will not replace lost public trees, such as street trees or trees in parks, removed in the normal course of tree management.
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:
Tree in open ground (no tree pit required) £765.21
Tree in hard standing (tree pit required) £3,318.88[21]
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 must be 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 8-1 of the Biodiversity Metric (BNG), published by Natural England. This may be updated as newer versions of BNG become mandatory under the Environment Act 2021.
The following table will be used when calculating the level of contribution required by this obligation:
Were it is not reasonably practicable to ascertain the number or size of trees growing in a woodland, the level of compensation required will be 110% of the area covered by the trees, so that, for example, a woodland of one hectare will be replaced with one which is 1.1 hectares. The definition of a woodland is as set out in the UK Habitat Classification, w Woodland and forest: ‘Land with more than 25% cover of trees more than 5m in height.’[22]
The level of contribution required for planting trees in a woodland setting will be £[TBD] per 100 square metres.
Proposals to replace trees lost to development with hedging is very rarely a suitable solution and will not be permitted unless the developer is able to show that there are exceptional reasons for doing so and the planning arboricultural officer has agreed.
Planning obligations will contain the following:
The number and identity (using Id used in the BS5837:2012 survey) of each tree to be removed.
The number and species of the trees to be planted on the development site.
The number and species of the trees to be planted on public land.
Which offsite trees are in to be planted open ground and which in hard standing.
The agreed location and species of each offsite replacement tree which and should be within one mile radius of the lost tree.
Trees planted under BTRS should not replace lost public trees, such as street trees removed in the normal course of tree management.
Like for like replacement. Compensation for the loss of large-form trees should result in large-form trees being planted.
Require that replacement trees or trees damaged as a result of the development that die within five years of planting will be replaced at the developer’s expense.
[17] Table 3-2 Trading rules (Rule 3) to compensate for losses. Any habitat from a higher distinctiveness band (from any broad habitat type) may also be used. [18] Need to define what ‘important means.
[19] This is based on NPPF para. 180 c). We have inserted ‘will’ instead of ‘should’.
[20] These references may need to be changed to reflect any replacement policies adopted with the new Local Plan.
[21] These values should be updated to the current rates applicable at the time of adoption. The current indexed rates as of June 2023 are £1,171.79 & £5,082.29 respectively.
There’s a climate emergency and we need to act. With higher temperatures and more severe weather events than just a decade ago, we must take action at the local as well as the global level.
Bristol City Council declared a Climate Emergency in 2018, reflecting the need to reduce the city’s contribution to the causes of climate change, and to adapt and be resilient to further expected climate impacts. For the declaration to be meaningful, it has to result in practical changes, for example the protection of existing trees on development sites. With important urban trees being routinely felled, there is no evidence that this is the case. If Bristol continues in this way, the city will become unliveable in the climate crisis.
The Council is now drafting a tree strategy for the city, which we hope will become a key element of the forthcoming revised Local Plan. We hope that the strategy will protect existing trees and prioritise the planting of replacement and new trees across the city. We have asked for 18 principles to be included in the strategy.
If our urban environment is going to be liveable in the long term, we need to create new developments that can cope with the changes in the local climate expected in the future. The benefits of trees in the fight against climate change are now well understood: trees lock up carbon, reducing pollution and flooding. They are also the best way of reducing the urban heat island effect, decreasing the temperatures of heatwaves by up to 10°C . It’s therefore vital that green infrastructure forms part of any proposed development. This is particularly crucial in the city centre.
On every occasion that trees are felled, we’re told it will be all right, as they will be replaced. Often these replacement trees are never planted because there is nowhere to plant them, or if planted, they die and are not replaced. At any rate, we need tree canopy and shade now, not in 50 years’ time when any new trees that might survive will replace the canopy lost. This is why we must protect existing trees, and if trees must be lost, local tree replacements must be planted and not just promised.
A warmer climate increases the risk of overheating and heat-related illness, even death. In the heat wave of 2003, around 70,000 people died across Europe due to the extreme heat, with older people and children particularly vulnerable. However, we can reduce much of the risk without the need for active cooling, by incorporating effective measures into development proposals from the earliest design stage. New buildings and external spaces must be designed to provide year-round comfort and support well-being. On-site tree planting for shade will contribute to this by minimising the amount of heat entering buildings. All new developments will be expected to demonstrate through ‘sustainability statements’ how they would incorporate such measures into their design from the outset.
How green (and blue) infrastructure reduces climate impacts
Developers must take into account that changes in the local climate are likely to: increase flood risk and water stress; change the shrink-swell characteristics of clay soils affecting foundations and pipework; affect slope stability; and affect the durability of building materials. Incorporating green and blue infrastructure, such as trees and water features, in developments will help to reduce all these effects. Green and blue infrastructure should be multifunctional, that is, provide ecology and biodiversity benefits as well as climate adaptation in developments. Where appropriate, this should include the use of living roofs with a sufficient substrate depth to maximise cooling benefits. However, the cooling effect of green roofs is a fraction of that afforded by trees.
Long-term thinking
As we build more homes, businesses and communities, it’s essential that we retain and integrate important existing trees within any new development. We must also consider carefully the size, species and placement of new trees provided as part of any planned landscape treatment, for example in terms of:
ensuring that any new streets are tree-lined
focusing once again on large-form trees that will be long-lived and provide substantial shade, rather than small, short-lived trees such as Rowan or Amelanchier
reducing or mitigating run-off and flood risk on the site
increasing on-site canopy cover and providing shade and shelter
ensuring that newly planted trees will be maintained in the long term and replaced if necessary.
Where tree loss or damage is unavoidable, and not merely expedient, within a development site, new replacement trees of an appropriate species must be provided either on or off site and their long-term management and maintenance secured.
Bristol City Council is currently writing a tree strategy for Bristol. This is welcome news, as we have been calling for such a strategy to be developed for more than a decade.
A tree strategy should be an evolving process rather than a document which may quickly become out of date. This is particularly true in our rapidly changing world – environmentally, climatically and politically. To provide an effective response to the challenges these present, a group of representatives from both civic and professional groups (along the lines of the Bristol Advisory Committee on Climate Change (BACCC), should be established to help coordinate further research and make recommendations to Bristol City Council and other stakeholders as the situation changes.
We also recommend that the development of a tree strategy should take full advantage of exemplars from other local authorities[1]. We should have the ambition to make Bristol’s tree strategy the best.
Here follow 18 key points that we would expect to see included in a strategy.
Buy in from all the stakeholders involved. Many council departments (as well as Parks, there is Highways, Education and Planning) have a role to play in the management of Bristol’s trees. We need to see evidence that all such departments are fully involved in the development of the strategy. In particular, with the current review of the Local Plan, it is essential that Planning is fully engaged with the strategy, and that the two documents are consistent and properly cross-referenced. The tree strategy needs to be incorporated into the new Local Plan. In addition, other important landowners (such as the universities, utilities providers, housing associations, schools and hospitals) have a role to play in contributing their expertise to the strategy and implementing its goals. As well as the Bristol Tree Forum, many community groups have an interest in tree planting in Bristol and should be involved and consulted.
When council trees are removed, they must be replaced. At present there are more than 800 street tree stumps and empty tree pits around the city – sites where trees once grew. A plan to plant all these missing trees within five years needs to be included. In the future, when any council trees are damaged or felled, they should be replaced within the next planting season.
There needs to be community engagement in tree management decisions both at the level of individual trees and in strategic decisions. In recent years we have seen a rise in community led campaigns to protect trees, such as the Ashley Down Oak, the M32 maples and Baltic Wharf, and this is indicative of a disconnect between the Council and the communities it serves. When the balance of the Environment Act 2021 takes effect later this year, Councils will be obliged to consult when street trees are being considered for removal[2]. This is too narrow and should be extended to include where any public tree is being considered for removal. Therefore, part of the strategy should be promoting community engagement, providing mechanisms for engagement and then taking account of the concerns of the community and tree campaigners alike.
There should be one person responsible for trees within Bristol City Council. At present we have tree planning officers, tree maintenance officers and tree planting officers with no single individual or office accountable overall, often resulting in a lack of appropriate action or people working at cross-purpose. It is also concerning that Highways are able to remove street trees without any consultation.
There needs to be a plan to address the massive inequality in tree cover in Bristol, which often mirrors social and financial deprivation in the City. For instance, additional protections could be given to trees, and tree planting prioritised, especially in deprived areas such as the City Centre, Harbourside and St Pauls.
When developers remove trees, the replacements required should be planted by BCC. Too often developers have shown themselves incompetent or unconcerned when planting trees, so the trees fail or are never planted. In the case of Metrobus, there has been a more than 100% failure rate of trees in some places (trees have been replaced multiple times). We have an excellent tree planting team in Bristol and we should benefit from requiring them to organise and implement the planting required. The cost should be funded by the developer.
Retaining existing trees must be a major part of the strategy. A tree strategy cannot be just about planting new trees, the benefits of which will not be realised for decades, but crucially about retaining and protecting existing trees and the benefits they are already providing. As such, the strategy must address the threats to existing trees. Planning is crucial in this so we would expect major engagement with Development officers to address the current and future problems.
Planning Enforcement must address the illegal removal of or damage to trees. At the moment there are no consequences following the unauthorised damage or destruction of trees. This must change. Other neighbouring local authorities manage to do this but not Bristol. A strategy must include a review of the reasons for the existing lack of effective enforcement and make recommendations as to how this can be rectified.
Developments should be built around existing trees as is already required[3]. Other local authorities do this but not Bristol. This will require a change of culture in the planning department so that pre-application discussions with developers make it clear that this will be required.
The sites for the replacement trees must be agreed before Planning Applications are approved. This is required by planning policy (BCS9 and DM17), but currently developers are being allowed to, instead, pay a “fee” into Section 106, and frequently the replacement trees are never planted. Trees form an important part of our urban habitat. The calculation of tree replacements required to compensate for their loss must be aligned with the Biodiversity Metric as adopted under the Environment Act 2021.
Spend the £ 900K+ reserved for tree planting. Connected with the above point, a strategy needs to include a mechanism for spending the existing £900K+ of unspent tree planting Section 106 money within the next three years.
A strategy to increase Bristol’s tree canopy cover (or at the minimum, maintain existing canopy cover) needs to have a route to implementation This must include addressing the loss of street tree canopy cover by being bolder in selecting new tree planting sites and planting large-form trees wherever possible. Trees such as rowans and flowering cherries are short-lived and will never provide much canopy or become robust enough to survive our challenging urban environment in the long-term.
Canopy Cover needs to be measured with an agreed methodology with confidence limits (levels of doubt in the estimate) made clear. In the first instance, we need to establish the baseline year and percentage tree cover from which progress will be measured. Only then will it be possible to show whether a trend has been determined. Two measurements using different methodologies should not be used to claim an increase in canopy cover. The metric should take account of trees lost so that the figure reflects the true increase, or loss.
Include trees within road changes. There needs to be proper engagement with Highways at early stages of the design process for road changes to look at retaining the maximum number of existing trees and including innovative planting opportunities for new large-form trees, such as pavement build-outs.
For new developments, trees should be properly considered at the pre-application stage, with appropriate consultation with stakeholder groups. Too often, the mitigation hierarchy requiring the removal of trees to be a last resort is disregarded, so that it is only after the design has been finalised that the existing trees are considered and removed where they conflict with the design scheme.
Biodiversity Net Gain (BNG) calculations need to be checked by the Local Planning Authority and biodiversity loss must not be monetised as BTRS has been. BNG, if properly implemented, makes sure that biodiversity on development sites is properly measured and will provide a net gain (soon to be least 10%) is factored in. However, at present, developers’ calculations are not being checked. When we have provided properly evidenced calculations, these have been dismissed by the LPA as mere differences of opinion. You cannot have differences of opinion on facts. The LPA must require that BNG calculations are presented in a way that can be checked by anyone interested and actually do the checking. In addition, ensuring BNG must require that the development site does not lose its biodiversity. If this is not possible, then its immediate local environment must be used to offset any onsite losses. Onsite losses must not be compensated for in some faraway place completely removed from Bristol.
Planning Applications involving trees must mention this fact in the title. Too often, applications that involve the loss of important trees (or plans to avoid the planting of new trees[4]) do not even mention this fact in the title. This means that it is extremely difficult for community organisations to engage.
Once a planning application has been issued, no removal of trees. A moratorium should be placed on any tree felling pending the outcome of the planning application. This includes applications to demolish buildings which should exclude tree or other habitat removal.
[3] Bristol Core Strategy, policy BCS9 states that, “Individual green assets should be retained wherever possible and integrated into new Developments.”
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.
The need to build housing to meet sustainable economic or social development objectives should not be allowed to take precedence over ensuring that the development is also both environmentally sustainable and meets Net Gain objectives.
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.
The existing trees have a significant asset value which should not lightly be ignored. Using CAVAT, we have valued them at £4,674,918.
Under the Mitigation Hierarchy, trees should not be removed unless there is no realistic alternative. One alternative would be to build around the trees rather than remove them.
BCS9 of the Core Strategy also states that “Individual green assets should be retained wherever possible and integrated into new development”. Clear felling nearly all the trees to the east of the cycle/footpath should not, as it so often is, be the default option.
Trees should not be removed merely because they are diseased or self-sown, or because they are small or not perfect specimens of their species.
The removal of existing trees inevitably means that the eco-services they provided will not be replaced for decades, if at all.
The adverse knock-on environmental impact on biodiversity of removing existing trees far outweighs any short-term benefits achieved by replacing them.
Our submission
The planning background
The National Planning Policy Framework
The National Planning Policy Framework (NPPF) seeks to ensure that new development is sustainable. It stresses the importance of Green Infrastructure as one of three overarching, interdependent objectives – economic, social, and environmental. This means that the presumption in favour of sustainable environmental development is just as important as any in respect of economic or social development objectives.
Trees are an integral part of this because of the importance of trees in relation to the management of air, soil and water quality along with other associated ecosystem services, climate change adaptions and beneficial health effects. The NPPF also seeks to achieve the protection and enhancement of landscapes and achieve Net Gain in biodiversity.
“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”.
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:
[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.
As you are aware, we have been expressing our continuing concerns about the welfare of the trees growing at Stoke Lodge Park and Playing Fields for the best part of a year now.
At the moment, our particular concerns are threefold:
The potential for damage to trees caused by pedestrians being obliged to pass over their root zones and under their canopies since Cotham School erected its boundary fence last year.
The potential for damage being caused to the trees growing within the new fence being caused by the school’s grass mowing regime.
The potential for damage to trees caused by vehicles passing over their root zones and under their canopies.
To a large extend, our concerns about issue three may have been allayed by the school’s adoption of a new access point at the eastern end of the fields, but we will have to see how this develops.
The new vehicle access point at the eastern end.
As for the other two issues, we attach images showing how the very muddy and disturbed path running around the outside of the school’s fence is causing disruption to the root zones of a number of trees – these are not all the trees being affected by this.
The eastern end of the fields.
The path leading to the Pavilion on the northern boundary.
created by dji camera
The path leading to the Pavilion.
These images show how the current mowing regime encroaches within the root zone of one of the Turkey oaks inside the fence.
The Turkey growing at the eastern end of the playing fields seen from above.
The Turkey growing at the eastern end of the playing fields – the mowing line is clearly visible.
Here is a video which shows the mowing issue more clearly.
In our view, something needs to be done about this before any damage being caused becomes irreversible.
Can you advise me what action the Council plans to take to protect these trees, please?
There are some 166 educational sites and 63 playing fields across the city. Together they cover over 560 hectares and form a significant proportion and an important part of the city’s open, green spaces.
This is the Part I of a two-part blog – here is Part II.
Despite this, Bristol City Council no longer manages trees growing on many of these sites and their related playing fields. We are not certain, but we imagine that this situation has come about as a result of the decline in local authority control over state educational provision with the rise of independent Academies.
We issued a Freedom of Information request (FoI) to try to find out which sites remain under the control of the Council, but our request has been refused on the grounds that answering it would impose a significant burden on the council. Our more generic request at the end has also been refused on the same grounds.
The trees at Stoke Lodge Playing Fields
Recent events at Stoke Lodge and the playing fields there perhaps best illustrate our concerns and the potential threats to the many trees growing on land set aside for educational purposes.
The site was leased for 125 years to Cotham School in August 2011. Interestingly, the Council agreed to retain its responsibility for all the trees growing on the site. It also agreed to indemnify the school for any damage the school might cause to the trees and to insure against this risk.
Stoke Lodge Playing Fields are located to the west of the city in Stoke Bishop ward and cover some 8.7 hectares of open space. Historically they were part of the grade II listed lodge (now an adult learning centre) of the same name which covers about two more hectares and contains an arboretum of important trees (the survivors of a collection that formerly spread right across the historic lodge grounds).
Unlike most of the land around it, this part of Stoke Bishop is not in a Conservation Area. For some 70 years, the whole estate, which until recently had never been seen as a divided space, has been used by the local community and is designated an important open space. Nearly all the trees on the Stoke Lodge estate are subject to Tree Preservation Orders (TPO) which were placed on the trees in early 2012.
The TPO trees and canopies
In the summer of 2018 Cotham School announced that it intended to erect a fence along the boundary of its leased land. They stated that they did not require prior planning permission to do so because they were exercising their statutory Permitted Development rights. After an initial dispute about whether the school could indeed use Permitted Development rights, in January 2019 work began to erect the fence.
It was at this point that the Bristol Tree Forum became involved after it became clear that the proposed route of the fence would pass through the root zones of a large number of important trees, many of which were the subject of a TPO.
The original plan – the fence passing through the root zones of many protected trees.
There then followed a protracted period of back and forth representations while we and the local community fought to get the fence relocated to avoid damaging the trees. This was partly successful. Where it was not, we were able to insist that the methodology for erecting the fence where it still passed through tree roots was modified to minimise damage. Even so, it took the constant vigilance of the local community and BTF representatives to ensure that Cotham School did not ignore the conditions placed upon it.
Setting aside the issue of the siting of the fence, our primary argument has always been that TPO law requires a prior planning application to be made (and approved) before any work is undertaken that could cause damage to TPO trees. Initially, the Council rejected this argument, effectively stating the Permitted Development rights trump primary TPO legislation. It also argued that, anyway, it could not proactively prevent damage to TPO trees, but had to wait until the damage has been done, which is, frankly, absurd. We continued to challenge these interpretations and, eventually, the Council conceded our points, though only after the fencing had been completed.
Things then appeared to return to normal,except that the community was now largely confined the unfenced areas around the boundaries of the site. As a result, the trees around the boundary are being exposed to heavier traffic through their root zones. We are concerned that this may have a long-term, adverse impact on their health.
Then, in August of this year, and without any warning, contractors arrived to lay cable ducting across the site so that video surveillance equipment could be installed. Using a mini digger they immediately set about driving over and cutting through the root zone of a TPO Common Ash growing on the boundary of the site. Other non-TPO trees (some privately owned) were similarly damaged.
We lodged a complaint with the Council’s Planning department. As a result, enforcement proceedings were commenced and the school, whilst narrowly avoiding prosecution, was obliged to take remedial action to try to mitigate the damage caused to the tree. The council also felt obliged to remind the school of its obligations to TPO trees:
And this is a site where the trees are still under the ‘guardianship’ of the Council! What about those sites where the care is vested with the school?
Our concerns remain for the future health of those trees whose root areas had been invaded by the fence installation. We have also continued to express fears about other continuing threats to the trees arising as a result of other activities on the site. So far, our concerns have been ignored.
For example, continuing root compaction and branch damage is being caused to the Persian walnut growing by the gate close to the rear car park and to the trees growing beside the Parrys Lane entrance. This is the result of grass mowers and other service vehicles using these entrances to gain access to the site. We are told the access point has been moved to the Parrys Lane entrance, though that too involves vehicles passing over tree roots.
Driving over the walnut’s roots on the way to mow the playing fields
Historically, it looks like vehicles accessed the site from behind the Children’s Play Ground on the southwest of the site, so did not need to drive over any tree roots. The presence of the fence and lack of any gate there has now closed off that option.
The school’s contractors also continue to mow within the root zones of the two large Turkey oaks (BCC-77025 on the eastern end & BCC-77059 on the western end) that grow inside the playing fields fence.
The eastern Turkey oak
However, the Council and the school decline to address these issues saying that they have made adequate arrangements to safeguard the trees.
STOP PRESS – 4th January 2020 – since writing this blog, Cotham School has felled a TPO protected Elder (plus five others) on the Eastern side of the playing fields and poisoned it with Glyphosate. We have informed Bristol Council Parks and Planning Departments and asked them to investigate. They advise:
“The felled Elder trees were not included within or protected by the TPO covering the adjacent Sycamore tree.
It is very unlikely that roots from the Elder trees will have grafted with the roots from the Sycamore tree. Also translocation of herbicide between grafted roots is very unlikely.*
We are not aware of any plans to fell the twin stemmed Oak beside the white shed at the eastern end of Stoke Lodge Playing fields.”
But, when we asked Parks if these works were done with their prior knowledge and agreement, or if the department had approved the application of Glyphosate to the tree roots, or if they had seen the School’s Aboricultural Management Scheme, they answered ‘No’.
It seems that the school had complied with their obligation to get consent from the Council, their Landlord, but that the Council’s Education Asset Management team had failed to consult Park’s specialist tree officers about the plans.
Cotham School has issued these FAQs – 33 to 38 in response to this issue.
The fate of other educational sites
In the meantime, we have no idea if or how other schools are managing the trees on their sites, or if the Council is consulted when they do.
Even though, in most cases, educational sites are still on Council-owned land, the Council only needs to be told if the trees have a TPO or are growing in one of the city’s 33 conservation zones (or, we assume, if the Council’s lease with the school keeps the management of the trees in the control of the Council – as was the case at Stoke Lodge).
Given that Bristol City Council does not normally issue TPOs for trees on its own land, arguing that it is a good landlord and will look after important trees appropriately, it is unlikely that trees that have been handed over on other educational sites will have been protected by a TPO. Perhaps the council should now review its policy where it no longer manages trees growing on educational sites in light of this history.
Certainly it seems that new tree planting need no longer involve the Council. For example we recently observed that several newly planted trees at Cotham School’s main site had died. It was only when we noted that the dead trees were missing from the Council’s tree stock data for the school that we learned that they were no longer responsible for the trees on the site. We have now been told by the school that the trees were planted as part of a recent development and that the failure of these dead trees will be ‘rectified’ soon. Meanwhile, it seems that these new trees are no longer selected, managed or mapped as part of the Council’s wider tree stock strategies and that the existing trees on the site are no longer the Council’s concern.
Presumably, similar arrangements are happening across the city with other educational sites being left to make their own, ad hoc arrangements to plant trees or not. Given that the One City Plan aims to double tree canopy cover over the next 25 years, it seems a great shame that this important land bank of possible new planting sites might have been excluded from helping to achieve Bristol’s plans.
We are also concerned that school governors (quite apart from lacking the necessary skills to manage the trees growing on their sites) may not yet have realised the full implications of the practical and strategic obligations that taking on such an important part of Bristol’s tree stock places upon them. As a result, they are likely to have to buy in (at our expense) ad hoc expertise, thereby possibly overlooking the wider strategic considerations that are needed when it comes to managing trees across the city.
This, coupled with the distinct possibility that well-meaning but unqualified Council officers may be making critical decisions about the welfare of trees on educational sites, makes for a very worrying situation.
‘Only when the last tree has died, and the last river has been poisoned and the last fish has been caught, will we realise that we cannot eat money.’ – A Cree Indian speaking in the 19th Century.
Members of the Bristol Tree Forum (BTF) recently met with senior Planning Officers and the two Arboricultural Officers working in the Department. We wanted to raise a number of planning issues that have been concerning us.
The Bristol Tree Replacement Standard (known as BTRS – you can find it at page 21 of the Council’s Planning Obligations Supplementary Planning Document) is a flagship policy copied by other planning authorities. Bristol should be proud of it. We are because it goes a long way towards making sure that trees and tree canopy lost to development is replaced at the expense of the developers.
This is how the BTRS formula is applied (the diameters shown are in centimetres):
However, in the years since its inception about ten years ago it has become apparent to us that the policy could be improved if some changes to the way it is applied were made to it. Two things that have particularly concerned us are:
Firstly, it had become apparent that developers and householders developing land in Conservation Areas were avoiding their obligation to mitigate tree loss by submitting two separate planning applications – the first for the trees to be felled (usually for some spurious reason), then, months later, a substantive application to develop the now tree-free land.
Outside Conservation Area, where there is no protection for trees (unless they have a TPO) at all, the trees were simply being felled, sometimes in large numbers, some time before an application to develop the land was submitted.
In either situation, if the development was permitted, the trees were lost, never to be replaced, because the loss was not considered to be “in association with” the development of the land.
Secondly, if developers or householders were developing land and the BTRS was being applied, we noticed that in some cases, hedging was being approved as a replacement for the lost tree canopy. Whilst grand hedging might indeed be appropriate as part of the planning proposal – say as screening or as a pollution mitigation measure – we do not believe that it can ever be used as an adequate substitute for lost tree canopy.
In particular, we noticed that this option was being proposed by those developers who had filled nearly all of the site so that there was little, or no room left for replacement tree planting on site. In our view this was being done to avoid having to pay the Council (us really) for replacement trees to be planted nearby.
We are pleased to report that, after several meetings with Officers to discuss our concerns, the following has finally been agreed:
Where there is evidence of prior felling, BTRS will be applied retrospectively to include all trees felled within the year before the planning application. In this way any trees felled before the development will be taken into account when considering the application of BTRS.
Other than in exceptional circumstances, hedges will no longer be acceptable as mitigation for tree canopy loss when applying BTRS.
If council officers think it is necessary, these new protocols will be written into the Council’s Planning Practice Note so that there is no possibility of any future misunderstandings by either developers or planning officers how BTRS is the be applied.
BTF has more ideas which we believe will strengthen the application of BTRS (for instance, why should trees under 15 cm not be replaced?; should BTRS be applied in non-development tree felling applications?) . We will continue to advocate for these and other possible changes.
We accept that there is always going to be development, but we must try to ensure that the city’s tree cover is, at the very least, protected and maintained in keeping with SDG 15 – Life on Land of the One City Plan Sustainable Development Goals which commit to doubling tree canopy cover by 2046.
These two terms are in common use, but they have specific meanings when it comes to their conservation. All ancient trees are veterans, but a tree may qualify as a veteran without being ancient. Most British trees increase in girth over their lifetimes by 2.5 cm a year. They grow faster when young, when in the open as opposed to woodland, and when in good soil rather than bad. They grow slower as they get older. Some species grow faster than average, such as Black Poplar, Plane, and Wellingtonia, and some more slowly, especially Limes and Hawthorns.
Trees are very good at vegetative reproduction, so that they are effectively eternal. Some create their own clumps, each tree being a clone. They do this by branches that arch down to the ground, root, and send up new vertical trees. The Tortworth Chestnut, which was regarded as ancient in King Johns reign, is a good example, but some of the limes on the Downs are doing this. Some trees send up new shoots from the base of the trunk which eventually replace the original tree. Many trees if cut to the ground, by storm or men, will promptly create new shoots, and this is the basis of coppicing which was a standard woodland management tool from at least Roman times. There is a Small-leaved Lime at Westonbirt Arboretum that now consists of a ring of clones about forty metres in diameter.
Ancient trees should be at least two hundred years old, and hence have a girth of more than five metres. I have measured 120 trees in Bristol with this girth, and there are many more in Ashton Court that I have not checked. They matter because they provide a range of habitats to a range of species. They are always hollow, often squat, having long since lost their upper branches, their hearts eaten out by fungi and beetles, full of nooks and crannies, and often clothed in lichens and ferns. They are most frequently Oaks, Sweet Chestnuts, Planes and Cedars.
Veteran trees are defined by their individuality. They will be mature, around 140/150 years old, about three metres in girth, mostly still standing tall. Fine, significant specimens of their species both in form and biodiversity. They are candidates to become Ancient, they may be starting to go hollow, and hence be of concern. They may need management to avoid their becoming top heavy, or developing a dangerous lean. They will stand out from other trees in their particular locality and may have planning protection as a consequence. They may also have special features of note, such as being multi-trunked.
Ancient or veteran tree: A tree which, because of its age, size and condition, is of exceptional biodiversity, cultural or heritage value. All ancient trees are veteran trees. Not all veteran trees are old enough to be ancient, but are old relative to other trees of the same species. Very few trees of any species reach the ancient life-stage.
Ancient Woodland. An area of woodland that has been wooded continuously since at least 1600 AD. It includes ancient semi-natural woodland and plantations on ancient woodland sites.
Irreplaceable habitat: Habitats which would be technically very difficult (or take a very significant time) to restore, recreate or replace once destroyed, taking into account their
age, uniqueness, species diversity or rarity. They include…ancient woodland and ancient and veteran trees….
Paragraph 175 (at page 51) of the framework states:
When determining planning applications, local planning authorities should apply the following principles:
c) development resulting in the loss or deterioration of irreplaceable habitats (such as ancient woodland and ancient or veteran trees) should be refused, unless there are wholly exceptional reasons and a suitable compensation strategy exists;
Paragraph 2.17.6 of DM17: Development Involving Existing Green Infrastructure – part of the Bristol Local Plan echoes this:
Due to their characteristics and value, Aged and Veteran trees are considered to be of relatively greater importance than other trees and even trees of a similar species. Aged trees, by definition, have developed characteristics associated with great age and often have particular landscape and townscape value. Veteran trees are considered to have particularly important nature conservation value. Both will often have significant visual amenity, and potentially historic and cultural importance. As such their loss or harm will not be permitted, and the design and layout of development will be expected to integrate them into development.
These guidelines apply whether the tree or woodland grows in a public or a private place.
Bristol Tree Forum 