Biodiversity Gain Hierarchy

Accomplishing the Requirements of BNG

Far before a plan for biodiversity net gain (BNG) can be submitted and approved by the local authority – seeing existing local policies related to mandatory BNG met and planning permission granted – a lot of steps play an important role in delivering the legal requirement. The biodiversity net gain requirements expect applicable developers to improve the state of the environment to a measurably better state, reaching at least 10% BNG and seeing it maintained for at least 30 years using various methods of enhancement, creation and restoration.

Developments have been subject to biodiversity net gain since the Environment Act 2021 was announced, but it became mandatory on 12 February 2024, followed by a small-sites metric for smaller developments on 2 April 2024. In other cases, development is exempt from BNG, such as with de minimis exemptions, planning applications made before February 2024, planning applications for a householder development, the temporary exemption for minerals development projects until 2030, and the many cases of self-build and custom-build development for no more than 9 dwellings on sites no larger than 0.5 hectares.

As for nationally significant infrastructure projects and a large percentage of commercial and residential development schemes, mandatory biodiversity net gain will be part of the planning process and an important material consideration in the eyes of the local planning authority for determining applications that outline planning permissions. A biodiversity net gain mitigation hierarchy is used to ensure that each development is completed, irreplaceable habitats within the site are protected at all costs, and an ecological consultant manages to achieve 10% that lasts for years after the development.

Difference Between Mitigation Hierarchy and Biodiversity Gain Hierarchy

All of the ecological surveys we provide are carried out using the mitigation hierarchy – a framework for deciding effective outcomes that will benefit the natural environment while allowing development projects to continue. Before the commencement of development, one of our team will visit your site and use the circumstances to suggest steps involving habitat creation, habitat enhancement and/or habitat restoration, and the defence of statutory protected sites and protected species.

Although the biodiversity net gain hierarchy is extremely similar to the mitigation hierarchy, it has different aims and goals, resulting in hitting the biodiversity gain objective of at least a 10% increase as opposed to simply avoiding adverse effects on existing habitat areas and compensating for any habitat lost as a result of development proposals. With the BNG hierarchy, the statutory framework represents a structured approach to meet the legal agreement of the BNG regime.

That said, there are loads of similarities between the two concepts. For instance, both abide by local policy, and both address the concerns of local communities. Although the mitigation hierarchy is created following actions for various types of ecological surveys, both consider biodiversity and the impact caused by the development process. The proposed approach for each type even uses the exact same steps in the hierarchy and follows an identical order of priority to confirm planning decisions.

The Role of the Biodiversity Gain Hierarchy

To meet the general biodiversity gain condition and see your development granted planning permission, you will need to organise an impact assessment that will outline the unavoidable impacts of new developments on priority habitat areas and present protected species. Even if no important habitats are found, a habitat distinctiveness score ranging from low to high distinctiveness will work out the chances of the site housing rare species in the future.

With all of the further information about the site recorded and post-development and pre-development biodiversity value figures created using the statutory biodiversity metric, the ecological consultant will be able to understand the identified scale of changes needed to achieve BNG. All linear habitats will be considered, with the completed metric calculation tool setting out what needs to be done to remove any deficit between the two figures before increasing by 10% or a higher percentage depending on the local planning conditions.

Ecological consultants act as decision-makers and play a vital role in ensuring that the project design doesn’t have a negative impact on rare or valuable species, ruining any chance of meeting the BNG requirements. By using the mitigation hierarchy for biodiversity net gain, the following types of parameters will be used to decide how best to move forward, guaranteeing that the biodiversity objective has been met and that planning permission is granted.

Steps in the Biodiversity Net Gain Mitigation Hierarchy

In the BNG mitigation hierarchy, avoiding ecological assets will always rank as the most favourable outcome. If, however, they cannot be avoided, other routes are available that will deal with the ecological elements appropriately to meet any and all potential planning obligations.

Below, each stage of the biodiversity gain hierarchy from most to least desirable is explained:

Avoidance

Always considered the top priority outcome, avoidance sees the ecological consultant using site selection and anywhere that existing local policies apply to work out any areas where disturbance to ecological features should be avoided at all costs. A survey of the site will also uncover supporting evidence that will confirm or suggest the presence of protected species, and from there, moves will be made to entirely avoid harsh impacts.

Minimisation

As soon as it becomes apparent that avoidance isn’t feasible, minimisation is classed as the second best option. At the planning application stage, if a negative environmental impact cannot be completely avoided, minimisation makes it possible to alter the development plans by tweaking the design, location, execution or level of intervention. The pre-commencement condition can then confirm how the information submitted managed to minimise harm.

Restoration/Rehabilitation

It is common for ecosystems to suffer as a result of ecological assets getting damaged or not being correctly looked after. Restoration/rehabilitation enables an ecological consultant to work with land managers and comply with nature recovery measures to reverse the degradation of existing natural assets. It can be a money-saving option that utilises existing features, and ongoing management is then available with the help of a habitat management and monitoring plan (HMMP).

Offsetting/Compensation

Known as the last resort option in securing overall biodiversity gain, offsetting/compensation enables developers to make up for any habitat lost through the development works, especially if it had a negative effect on biodiversity value. With the help of an ecological consultant, developers can buy statutory biodiversity credits or off-site biodiversity units. A biodiversity gain site register lists available sites for buying off-site biodiversity gains, and if units aren’t enough, developers can purchase statutory biodiversity credits to benefit wider development.

At all stages of using the biodiversity net gain hierarchy, lots of different factors need to be considered, such as:

• Input of minimum information requirements
• Conservation covenants between developers and land-owners
• Relevant legislation such as Schedule 7A of the Town and Country Planning Act 1990
• Permitted development rights
• Local development orders
• Simplified planning zones
• Neighbourhood development orders
• Statutory instruments

Get Help with Delivering BNG on Your Development Site

Whether you like it or not, the biodiversity gain hierarchy will be a fundamental principle in securing BNG on new planning applications that would be subject to the development project. Developers must provide an overall biodiversity gain plan, the biodiversity gain plan must be submitted with solutions based on the BNG hierarchy, and – as long as the planning practice guidance from our team has been followed – the local authorities must approve the biodiversity gain plan and confirm that planning permission has been granted.

From measuring biodiversity value on your site at the earliest stage in the relevant planning application process to seeing planning permissions granted and approved by the local planning authority, the team at Arbtech can help every step of the way with effective further guidance and an expansive knowledge of the latest good practice guidelines. Our solutions for a development subject to the mandate could range anywhere from on-site gains within the red-line boundary to buying off-site BNG units or statutory credits from trusted providers who own land.

If the likelihood of a successful planning application relates to how you make BNG apply to your development, you should speak to Arbtech. You can request a free quote from our team by emailing us, calling us, completing a quote form or visiting our contact page. We can then work with you to decide on a suitable date to visit your site, undertake a BNG assessment, and use the biodiversity gain hierarchy to find effective solutions for implementing the appropriate national approach and local planning policy to your development plans.