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Demystifying the new biodiversity net gain legislation

Published: 18 April 2024

Written by Keava Mascott - Consultant Ecologist, Adler and Allan

Biodiversity net gain is a phrase which has been thrown around a lot over the last few years, but what does it really mean? With announcements of new legislation making biodiversity net gain mandatory for all new development after 12 February 2024, and small sites (under 1 hectare, without priority habitats) after 2 April 2024, the phrase is more relevant than ever before, with ecologists, developers, and landowners alike expected to get to grips with what this means for their projects - and quickly!

What is biodiversity net gain?

Biodiversity net gain is a way of creating, improving, and protecting natural habitats. This means leaving a measurably positive impact (‘net gain’) on biodiversity, compared to what was there before development.

A discretionary 10% (local councils can set this anywhere between 10-20%) increase in biodiversity net gain is becoming a requirement as part of planning applications, and many sectors need to prepare for what this will mean for future works.

Long-term management

What will biodiversity net gain mean for long-term management of habitats? Who will be responsible for delivering this biodiversity net gain? How long will this go on for? How will this be monitored? All of these questions have been pondered by professionals leading up to the adoption of new biodiversity net gain legislation, but the answers are now coming forward apace.

The set period for monitoring of biodiversity net gain is a minimum of 30 years, which is to be reviewed as monitoring of onsite habitats is carried out.

In terms of managing said habitats, a habitat management and monitoring plan (HMMP) will be required for any approved planning consent in order to deliver the agreed upon biodiversity net gain. The purpose of this document is to set out how habitats will be managed to deliver the biodiversity net gain over the minimum 30-year period. This will be created by ecologists, sometimes working alongside landscapers and landscape architects. The management company or developer in question will be required to follow the management plan once the development is complete. There will be some contingency within these plans, and in cases where habitats do not deliver as expected, remedial measures will need to take place. This is why monitoring is a necessary and key part of delivering biodiversity net gain.

Registering biodiversity net gain units

As part of the monitoring process for biodiversity net gain, land delivering biodiversity net gain off-site will need to be formally registered with Natural England.

With biodiversity net gain becoming mandatory, landowners have added opportunity to enhance their existing land assets through appropriate management, land conversion to more ecologically valuable habitats, and reintroduction/rewilding.

There is new financial incentive for conservation through biodiversity net gain, and the potential to stack schemes for added value. This will, however, be a long-term legal commitment and must be done following the registration of units as set out by Natural England.

Though we don’t know the exact details as of yet, we do know that registered units will be tracked throughout the duration of the monitoring period (minimum 30 years).

Applicants wishing to register biodiversity net gain units are likely to need the following:

  • A boundary plan of the land to be registered
  • Consent from the owner of the land
  • Proof of ownership of the land; a completed biodiversity statutory metric analysis in Excel format for the land
  • A habitat management and monitoring plan
  • A legal agreement securing the habitat enhancement for 30 years (likely to be in the form of section 106 agreements or conservation covenants discussed below)

Natural England credits vs biodiversity net gain units (for purchase or private use)

Because land assets can be converted to offsite biodiversity net gain units, there is an opportunity for companies and landowners to maximise unused land assets by creating more ecologically valuable habitats.

This may aid in terms of their own development projects, where it is not possible to get a 10% increase on-site, as offset units can then be used. It also will incentivise corporations to appropriately manage their existing land assets in a way that maximises benefits to wildlife.

This will be important for many large corporations and developments with existing land assets, as the biodiversity net gain credits offered for purchase as a last resort by Natural England are said to be set at an extremely high cost.

So, how do I prepare for biodiversity net gain with my future development projects?

It’s really important to consider this legislation at the earliest possible stages of new development projects, making sure to have a close working relationship with ecologists or the ecological consultancy you plan to use for your project.

The earlier you consider biodiversity net gain in your planning, the better your chances of achieving your required biodiversity net gain target.

Following the below method for new projects can put you on the right track for success.

1. Feasibility

It is extremely important for developers to understand that the earlier they get ecologists in to perform feasibility assessments, the better.

Some habitats are better than others in terms of ecological value for biodiversity net gain, which can really make it difficult to produce net gain on high-value habitats. It is also important to note that some habitats on the metric are considered ‘irreplaceable’ and should therefore be conserved at all costs.

Smart developers will consider conducting preliminary ecological appraisals, biodiversity net gain assessments of habitats, and feasibility studies in order to assess whether the land should even be acquired for development purposes. The later in the process developers leave these assessments, the more likely they are to get caught out by biodiversity net gain requirements. This could lead to having to look elsewhere or acquire third-party biodiversity net gain units or credits, which will be extremely costly in the long run.

2. Biodiversity net gain in development plans

Because biodiversity net gain is now mandatory, developers will be expected to incorporate biodiversity net gain at the design stage.

Feasibility studies can provide great information for developers, especially when it comes to the design plan of new projects. Understanding which habitats are most important and should be retained, where enhancements can be made, and any other ways ecological value can be added to existing on-site habitats will be an integral part to gaining planning permission for projects. Well-thought-out projects which have clearly considered ecology at early stages will be far more likely to acquire planning consent and will make achieving the acquired biodiversity net gain that much more manageable.

Though the rest of your ecological surveys will still be extremely important in planning, it is still a good idea to have a preliminary plan in terms of biodiversity net gain. This can aid in acquiring outline planning permission for development and can later be modified and finalised after appropriate protected species surveys have been conducted, alongside the delivery of an Ecological Impact Assessment (EcIA) for full planning permission.

3. Habitat management and monitoring plan (HMMP)

A HMMP will be required for full planning consent, and will include monitoring schedules, monitoring methods, and intervals.

Monitoring will be carried out regularly by the management development company or legally agreed upon third-party, as well as the relevant planning authority. This will allow for adaptive management of biodiversity net gain habitats over the minimum 30-year period.

Scheduled reporting will need be included in the monitoring plan in order to feed back to the management plan throughout the duration of monitoring period. This does mean that developers will have to commit long-term to their delivered projects.

However, management and monitoring are extremely important for achieving the biodiversity net gain targets and avoiding committing any offence under this new legislation.

What does this all mean for ecology in England?

There has been much discussion around the topic over the last few years, and though there will be major benefits to new legislation, some consultants are concerned about using the metric and worried about the nuances that comes with assessing habitats in terms of ecological value. However, habitats considered a priority within local plans do have more weighted importance within the metric, but it will be interesting to see how this plays out in more complex situations.

One will be to ensure the biodiversity net gain targets that are set out are achievable. Though in theory, a biodiversity net gain plan may seem straightforward to achieve, if proper due diligence is not taken, including soil sampling, assessing surrounding habitats and local environment, or even accounting for potential climate change affects, then the proposed habitats might not deliver as anticipated. It will be important for ecologists and landscapers alike to really work for effective and sustainable habitat creation.

The interest in land conversion potential for biodiversity net gain is also growing. It is possible that farmers and landowners will choose to convert land used for food production to more ecologically valuable habitats due to the financial incentive from selling biodiversity net gain units. This could alter the local agricultural industry over time.

From an ecological perspective, there is still value in arable habitats, especially for many species of nesting birds, and geographical location really does matter when it comes to the value of arable habitats. For example, the many open fields and lack of hedgerows in the Highlands create great opportunities for many waders and other ground nesting bird species. These habitats need to be considered valuable, given local context when it comes to land conversion, which is one of the challenges ecologists and landowners will face with the new biodiversity net gain legislation.

Final takeaways

Overall, adoption of mandatory biodiversity net gain in legislation is a step in the right direction in terms of ecology and conservation of important species and habitats in England.

This does not mean that it will be an easy transition, especially for development. There is sure to be a period of adjustment, for both ecologists that are new to the biodiversity net gain world, as well as for developers who will have to adjust their approach to future project planning.

It is highly likely that adjustments will be made by the government within the first decade of launch to improve the metric and ensure mandatory biodiversity net gain is monitored appropriately.

It is vital to note that developers and ecologists should be aware of and following the 'mitigation hierarchy' when conducting biodiversity net gain assessments:

  1. Avoidance
  2. Minimisation
  3. Rehabilitation/restoration
  4. Offset

At the end of the day, biodiversity net gain should not be seen as a hinderance to projects, but rather an opportunity to conserve ecologically important habitats that benefit both wildlife and people alike.

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