Context

3.34 Portishead has a distinctive treescape, with large areas of woodland visible from within the built environment as well as locally valued significant trees located within and around the town. The number and diversity of street trees is an important feature of the town (many of which are protected with Tree Protection Orders) and the Neighbourhood Area is also home to large areas of Ancient Woodland - nearly 45 hectares in total.

3.35 Ancient Woodlands are our richest land-based habitat for wildlife. According to the Woodland Trust they are home to more threatened species than any other habitat. Ancient Woodland covers a significant proportion of the land in the town area at around 4.7%, which is significantly higher than the national average of 2.5%19 - much of this Ancient Woodland is within Weston Big Wood outside the settlement in the green belt, but also includes East Wood and Wood Hill within the town.

3.36 Weston Big Wood is also home to the rare Round-leaved Whitebeam. The Round-leaved Whitebeam is only found within the Neighbourhood Area, within the Avon Gorge and over the Severn Estuary in the Forest of Dean. The Round-leaved Whitebeam is classed as ‘vulnerable’ on the IUCN Red List of Threatened Species.

3.37 The Standing Advice from Natural England and the Forestry Commission relating to buffers for ancient woodlands, is that the proposal should have a buffer zone of at least 15 metres from the boundary of the woodland to avoid root damage (known as the root protection area). In their ‘Planners’ Manual for Ancient Woodland and Veteran Trees’ (2019) the Woodland Trust state in relation to providing adequate buffers, “Although there is no ‘one size fits all’ with buffer design, each one should be designed to fulfil the specific requirements of its location and the type of proposed development. In order to protect Weston Big Wood as an irreplaceable habitats in Portishead, the biggest possible buffers should separate ancient woodland and any development that comes forward. As a precautionary principle, a 50-150 metre buffer should be maintained between a development and the ancient woodland, including through the construction phase, unless the applicant can demonstrate very clearly how a smaller buffer would suffice. Weston Big Wood is designated as a Site of Special Scientific Interest (SSSI). SSSI impact risk zones around the wood are used as a tool to make an assessment of any development proposals - the first risk zone around the wood extends to 50meters (and there is currently no development within this zone) and the second to 150m.

3.38 Overall tree canopy coverage in Portishead in 2020 is estimated to be an average of 20% which has been mapped to date using the i-tree canopy tool. The Woodland Trust recommend an increase in UK woodland cover from its current 13% of land area to 19% by 2050 to tackle this country’s biodiversity and climate crises.23 The Urban Forestry and Woodland Advisory Committee Network advise that ‘a minimum standard for tree canopy cover is set for a local area, with evidence showing that 20% is a good aspiration’. It is therefore considered necessary and achievable, for any development proposals in Portishead to continue to deliver 20% tree canopy coverage.

3.39 Trees in Portishead have a range of functions, be it contributing towards biodiversity and amenity value, providing shade and helping with other adaptations to the effects of climate change. There 43 are a significant number of trees with Tree Protection Orders (TPOs) reflecting the importance of trees and woodland in and around this town, which are highly valued by the local community. Existing Tree Protection Orders can be viewed on North Somerset Council’s online planning map.

3.40 Inspired by work on the NDP, a group of local people started the Significant Trees of Portishead project which aims to record, map and collect key data on the trees in the Neighbourhood Area, with a view to protect valuable trees and sustainably increase the overall tree cover in Portishead. The aim of the project was to with ecologists, arboriculturalists and local people to ensure the appropriate species and size of tree are planted in the right places to maximise their chance of survival and ensure that the overall GBI network is protected and enhanced through tree planting. The project used iNaturalist – an online mapping tool – to map and record data. Detail and analysis of the treescape in Portishead is included in the Portishead GBI Evidence Base Report (2022), with key features shown on Figure 7.

3.41 As stated in North Somerset Council’s adopted policy framework, retaining trees and hedgerows can influence both the design and layout of any development, and arrangements for their protection should be made during the construction phase. Designs should also take account of the long term setting for important trees and how they will relate to the use of the area in the future. It is important to note here that a Neighbourhood Plan in itself cannot protect a tree from being felled, unless it is protected by a Tree Preservation Order or is within a Conservation Area.

3.42 Hedgerows, like trees, can make an important contribution to the character and can also be important historically as indications of land use and previous ownership. They also contribute significantly to biodiversity and amenity value of the natural and, in places, built environment. Trees will also help with adaptation to the effects of climate change.

3.43 Where tree loss is unavoidable, a Tree Replacement Standard can be used to inform the number of replacement trees for the loss in canopy cover.

3.44 Whilst a particular site or design approach to trees will inform the number and approach to tree planting, the standard below is an established methodology to underpin discussions on the replacement of these key assets.

3.45 The Neighbourhood Area is located within the Forest of Avon, which is part of a national programme of Community Forests across England, delivering more trees and woodlands. In 2021, the Forest of Avon published its Tree and Woodland Strategy for the West of England, which the NDP Community Actions aim to contribute towards. Looking ahead, the aim is to ensure that the city’s tree cover is, at the very least, protected and maintained in keeping with SDG 15 – Life on Land.

Table 1: Tree Replacement Standard (based on the Bristol Tree Replacement Standard (known as BTRS – see page 21 of Bristol City Council’s Planning Obligations Supplementary Planning Document):

Trunk Diameter of Tree lost to development (cm measured at 1.5 metres above ground level)	Number of Replacement Trees
Less than 15	0 ‐ 1
15 ‐ 19.9	1
20 ‐ 29.9	2
30 ‐ 39.9	3
40 ‐ 49.9	4
50 ‐ 59.9	5
60 ‐ 69.9	6
70 ‐ 79.9	7
80 +	8

 

Relevant Objective

O3 To protect, maintain and expand Portishead’s distinctive treescape and woodland areas such as Weston Big Wood.

Local Policy Context

• CS4 Nature conservation
• CS9 Green Infrastructure
• DM8 Nature Conservation
• DM9 Trees and Woodlands Biodiversity and Trees SPD

POLICY PEN5 – TREES, HEDGEROWS AND WOODLAND

Ancient and Veteran Trees

Development proposals will be expected to demonstrate no loss, or deterioration of the irreplaceable habitats of Ancient Woodland (as shown on Figure 7). Development proposals directly or indirectly affecting Ancient Woodland and ancient trees or veteran trees identified in the Neighbourhood Plan Area will be resisted. A 50 - 150metre buffer should be maintained between any development and the Ancient Woodland of the SSSI Weston Big Wood, including during the construction phase, in order to avoid adverse impacts on this irreplaceable habitat, unless the applicant can demonstrate very clearly how a smaller buffer would be acceptable.

Any ancient or veteran trees must be retained within a development site, including a root protection area and appropriate buffer zone, which should be whichever is greater of, either an area which is a radius of 15 times the diameter of the tree with no cap or (b) 5 metres beyond the crown.

Other Existing Trees, Hedgerows and Woodland

Existing trees and hedgerows on development sites should be considered throughout the design process to be retained and incorporated as placemaking features in new development. Development proposals affecting other existing trees or hedgerows should ensure that there is no damage, or loss of value, to those which demonstrate good arboricultural, biodiversity value nor to the Locally Identified Significant Trees identified on Figure 7 (and as part of the ongoing Significant Trees of Portishead project). Protection before and after development should be in accordance with British Standard BS5837. Where there is an unavoidable loss of trees on site, the number and type of replacement trees should be informed by the quality and size of the lost trees.

New Trees

New tree planting, in development proposals and throughout the built and natural environments of the Plan area, will be supported to maintain and increase the overall tree canopy cover of the Neighbourhood Area, and to provide gateway and landmark trees that contribute to local distinctiveness. This should be informed by relevant ecology and arboricultural assessment and should have regard to the advice set out in the Portishead GBI Evidence Base Report - with a preference for native, large-canopied and orchard species.

Tree Canopy Cover

Proposals should clearly set out what the future tree canopy coverage of a site will be with a target of 20% of the site area on sites outside of the town centre and greater than 0.5 ha in size. This will principally be achieved through retention and planting of trees, but where it can be demonstrated that this is impractical, the use of other green infrastructure (e.g. green roofs) can be used to deliver equivalent benefit. On residential development sites, some of this tree canopy cover will be expected to be met through new trees on streets as well as within gardens.

SIGNIFICANT TREES OF PORTISHEAD PROJECT

During the preparation of the Neighbourhood Plan, members of the Environment Working Group took part in a project to log significant trees in Portishead to catalogue key information such as their species, size, health, function and location. Part of the project’s aim was to identify trees with potential for tree preservation orders (TPOs) and / or for listing on the Woodland Trust’s Ancient Tree Inventory, which would grant them further protection.

Figure 7 shows those that have been identified as part of the project, although there will be many more within the Neighbourhood Area.

Nominations and suggestions for significant trees were made directly from the community via online engagement and other methods.

The project builds evidence around what makes a tree valuable and successful in particular places in Portishead, locations for potential tree planting; useful to inform rewilding projects within the Neighbourhood Area to help ensure that the ‘right trees are planted in the right places’ (NPPF paragraph 131)

FIG 7: Ancient Woodland, Locally Identified Significant Trees: