‘It seems inevitable Bristol will see a steady, inexorable biodiversity decline’

On the face of it, this Monday (February 12) is a red-letter day for Bristol. After Monday, most developers will be required to set out in their planning applications how they will achieve at least ten per cent more biodiversity than already exists on their proposed development site.

Developers must show this ‘biodiversity gain’ by measuring how they’ll enhance the existing habitat on their site.

If the biodiversity gain on the site doesn’t reach ten per cent, the developer must show how it will provide the gain offsite – outside the development area. This should be done as closely as possible to the development site, or at least within the Local Planning Authority area. However, if this can’t be done, other sites may be used. These can be anywhere in England.

This approach is called the biodiversity gain hierarchy (found in Schedule 7A of the Town and Country Planning Act 1909 at section 37A). The hierarchy says it’s a priority to avoid the ‘adverse effects’ to ‘onsite habitat with a habitat distinctiveness score … equal to or higher than four.’

If this can’t be avoided, only then is mitigation permitted. In our experience, nearly all developers ignore the requirement to avoid adverse effects and move straight on to mitigation.

Habitats that score four are designated as having medium distinctiveness. While many habitats have medium distinctiveness, many don’t. For example, managed grassed areas (called ‘modified grassland’) are often found on urban sites but have a low distinctiveness score. So too do many other urban habitats such as allotments and gardens. Developers are not required to avoid harming these, so that losses to them may be mitigated in any event.

There’s no definition of what an ‘adverse effect’ is or how it will be assessed. However, recent advice from the Bristol’s chief planner about the meaning of ‘harm’ suggests that this could be interpreted very broadly.

In the last extreme, developers may purchase ‘biodiversity credits’, although Defra has set a high price for buying these.

The squeeze on green spaces

Land use in Bristol is subject to intense competition from many interests. This is especially true for our green and open spaces, which offer many ‘services’ beyond just habitat provision. The latest proposed Local Plan has no proposals for creating more open spaces beyond what developers might offer. There is very little, if any, space available for new biodiversity to be created. At best, some green spaces might be enhanced, but opportunities to do this are very limited.

Bristol Tree Forum says nearly 400 new trees will need to be planted to compensate for the lost tree habitat if the three proposals for Bedminster Green go ahead as they are

For example, Bristol Tree Forum’s examination of the three proposals to develop Bedminster Green shows that, if these proposals are allowed, then nearly 400 new trees will need to be planted to compensate for the lost tree habitat – a medium distinctiveness habitat.

There’s no room to plant these trees onsite, so offsite provision will be needed. The opportunities for doing any new tree planting (as opposed to replacing lost trees) in the surrounding wards or even across Bristol, let alone – as is usually required – within a mile of a development site, are very limited.

Instead, these replacement trees will have to be planted somewhere else: ‘in some foreign field that is forever Bristol’. This will inevitably lead to a net loss of biodiversity across the city as nature is ‘hollowed out’. This is unacceptable. The whole purpose of the new biodiversity gain regime is to improve overall local biodiversity, but it seems inevitable that Bristol will instead see a steady, inexorable decline.

We are disappointed that the current draft of the new Local Plan addresses none of these issues and have said so in our responses to the latest consultation: www.bristoltreeforum.org/wp-content/uploads/2024/01/BTF-Representations-on-the-Bristol-Local-Plan-2023-publication-version.pdf.
www.bristoltreeforum.org/wp-content/uploads/2024/01/BTF-Representations-on-the-Bristol-Local-Plan-2023-publication-version-Addendum.pdf.

Mark Ashdown warns there will be a net loss of biodiversity across the city as nature is ‘hollowed out’

Mark Ashdown is the chair of the Bristol Tree Forum

All photos: Mark Ashdown

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