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Biodiversity Net Gain

In 2021, the Environment Act came into force, and with it the requirements for Biodiversity Net Gain (BNG) for most developments in England. From February 2024, all developments granted planning permission under the Town and Country Planning Act 1990 (with some exemptions) will need to demonstrate a biodiversity net gain. From April 2024, small sites will also be required to demonstrate biodiversity net gain.

What is Biodiversity Net Gain?

The core idea behind biodiversity net gain is that the natural environment should be in a better state after a development than before. This goes above and beyond the idea that a development shouldn't cause harm, stating that it must actively improve nature, and habitats for wildlife, in and around the development. Under the Environment Act, developments must demonstrate a minimum of 10% net gain in biodiversity, and be able to secure this for 30 years.

Why is this important?

In the most recent State of Nature report (2019), there was a 13% decline in average species' abundance, with 15% of UK species being threatened with extinction. The pressures on the UK's wildlife mainly come from issues such as agriculture, climate change, pollution and urban development.

Within the UK legislation there are various measures in place to protect the most vulnerable sites and species, such as the Wildlife and Countryside Act 1981. These are quite limited in their extent, with protection limited to a few species, or a specific site, such as a Site of Special Scientific Interest (SSSI). Outside of these areas, habitats continue to be lost. Biodiversity net gain aims to go someway to reducing this loss by ensuring future developments are improving the biodiversity for current and future generations.

How is it measured?

Biodiversity net gain is measured both as a percentage, but also in biodiversity 'units'. These units are tradeable, and schemes exist to purchase biodiversity units for developments that are unable to meet the net gain targets.

Biodiversity net gain percentage and units are calculated using Natural England's Biodiversity Metric tool. The tool takes information gathered by ecologists, such as the extent of habitats, their composition and condition, as well as the proposed site plan.

Habitats that are more sensitive, and difficult to re-create, are assigned a higher unit value, and habitats of low value have a lower unit value. Habitats are also separated into "distinctivness" groups, and rules around trading between groups mean that a small area of high distinctive habitat (such as good quality woodland) cannot simply be replaced with a large area of amenity grass.

There are also 3 groups of habitat types - Broad area habitats, such as fields, woodland and ponds; linear habitats, such as hedgerows and treelines; and linear aquatic habitats, such as rivers, streams and ditches. Each habitat type must demonstrate 10% net gain, and units are not tradable between these groups (eg, you can't offset loss of an area of meadow with a new hedge).

Net gain can be delivered on site, within the development itself, or offsite.

What does this mean for you, the developer?

From February 2024, any development going through planning permission in England must demonstrate that the development delivers a 10% net gain to biodiversity. (And some local planning authorities are requiring it before this date)
Meeting this target isn't a simple tick box exercise, but requires careful consideration throughout the design and application process, and there are a lot of considerations to take into account.

Key considerations

Aside from involving ecologists early in the design process, there are a few other considerations that will help you meet the BNG requirements.

  • Consider the mitigation hierarchy:
    1. Avoidance - Avoid damage to valuable habitats if possible. Consider how the development can incorporate and enhance existing habitat
    2. Minimisation - If damage to a habitat cannot be avoided, consider how the damage can be minimised.
    3. Restoration - Can the habitat be restored after development?
    4. Offset - If damage and loss of a habitat is unavoidable, how can it be offset?
  • You gain a greater amount of units by enhancing existing habitat on site, rather than removing it, and replacing it.
  • You cannot 'trade down' units. In practice, this means that you cannot replace the loss of a high quality habitat such as woodland with lawn.
  • The time to establish the habitat is taken into consideration with the unit cost/value of the habitat. Habitats that take a long time to develop will cost more units if you are removing them. If these habitats are being planted, they are worth fewer units, as it takes a long period of time for the habitat to establish. It is best to avoid removing these habitats, as offsetting them can be difficult.
  • Area habitats, hedges, and watercourses are are all separate types, and units cannot be traded between them. Each one that is found on site must demonstrate 10% net gain.
  • A Habitat Management and Monitoring Plan (HMMP) will also need to be completed and updated in conjunction with project stakeholders to ensure the habitats are managed for the statutory 30 year period.
Photograph of a sunrise at Chickerell. Taken by Hannah Barlow

How can we help?

LC Ecological Services can be there to help you deliver 10% net gain right from the beginning of the design process. We have extensive experience helping our clients incorporate biodiversity net gain into their projects and can guide you through a comprehensive process. Our approach includes conducting thorough baseline surveys and condition assessments to evaluate the existing ecological status. We calculate the areas of these baseline habitats, potentially integrating your topographical maps if available, and use this data to quantify baseline habitat units.

Next, utilising your CADs or other plans, we determine the post-development habitat units. We work closely with you to ensure that the proposed development achieves a 10% net gain in biodiversity. Our collaborative process involves providing suggestions and solutions, working alongside developers to enhance plans that may fall short of the target, and ensuring a harmonious integration of ecological considerations into the overall project design. At LC Ecological Services, we are dedicated to facilitating the successful delivery of biodiversity net gain in every stage of your project.

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