What is Biodiversity Net Gain?
See Our Key Terms, Examples and Definitions

A glossary of frequently used words and phrases on the web

Like every kind of business, Biodiversity Net Gain has its buzzwords. Those in the know – the lawmakers, central and local government departments, ecologists, as well as all those involved in the commercial side of the business – understand them and use them freely. But for many more who are affected by the Act but, perhaps not entirely familiar with its ways, the language can be hard to follow and obscures the rights, obligations and opportunities BNG offers. So here is a glossary of everyday words, phrases and examples that we hope will help you keep up-to-date in this new and evolving imperative to our environment planning.

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Ancient Woodlands: There are some habitats that are excluded from BNG metrics. Ancient woodland is one statutorily designated Site of Special Scientific Interest, Special Protection Areas, and Special Areas of Conservation, among others.

Biodiversity: A description of an ecosystem of an area that includes the habitats of a wide variety of wildlife. Biodiversity refers to everything in a particular place in nature and its way of life. 

Biodiversity credits: Biodiversity Credits are an expensive alternative to Biodiversity units. This is a deliberate policy by the government to encourage the units to find a market value. Biodiversity Credits should only be used when there are no other alternatives.

Biodiversity metric: Is the standard unit of measurement of the biodiversity value of a variety of habitats (currently Metric 4.0). The metric has been developed by Natural England in association with the Department of the Environment, Food and Rural Affairs to help developers, landowners, local planning authorities, Construction companies, Ecologists, land banks and professional advisors.

BNG jurisdiction: At present, only England.

Biodiversity Net Gain (BNG): Is the sum of the biodiversity value of the site before construction, less the value of the damage caused by the development’s construction, plus the biodiversity value to be restored to meet the 10% gain. The gain can be achieved both off-site and on-site, depending on a case-by-case basis.

Biodiversity Net Gain Plan: In addressing a developer’s application for planning permission, the local planning authority will want to see a BNG plan. This will set out the developer’s biodiversity goals and targets, how the project will be managed, what benchmarks and indicators will be used, how the project will be monitored, evaluated and reported and, finally, what consequential adjustments may be required to meet the biodiversity objectives.

Biodiversity offset markets: Are for buying and selling biodiversity units. These markets are populated by many kinds of intermediaries:  brokers, landowners, local authorities (who may also be landowners), large land agencies and landbanks such as Civity. Stakeholders and some mediators may also offer strategic guidance and/or internal resources to assist developers in their goal of providing off-site mitigation. 

Biodiversity offsetting: Is the measurable conservation outcome of a developer’s actions to compensate for their project’s biodiversity impact. The residual biodiversity requirement after the appropriate avoidance, minimisation and restoration measures have been explored. More info can be found at Ecology by Design

Biodiversity Site Register: This is being set up as a transparent public record that will show:

  • The location details of the site;
  • The baseline and expected biodiversity of a development site;
  • Date of registration;
  • The owner;
  • The developers and their BNG requirements;
  • And other details.

The register will also reduce the risk of fraudulent or misleading claims.

Biodiversity units: Are a metric used to measure the biodiversity gains and losses of a development. The metric calculates the value of units, taking into account the type, extent and condition of habitats. Units can be bought and sold before any work on the site has been done, provided the work begins within 12 months of the day Biodiversity Net Gain takes effect.

British Standard BS8683: This standard is relevant to landowners and land managers offering biodiversity units and to developers looking for off-site units. Unlike the BNG requirement, the standard applies across the whole of the UK.

Chartered Institute of Ecology and Environmental Management (CIEEM): Is the leading professional membership body representing and supporting ecologists and environmental managers in the UK, Ireland and abroad.

Compliance market: The Environment Act will establish a “compliance market,” ensuring a supply of biodiversity units from landowners and managers to sell to developers who require them. These off-site habitats will meet the required standard, and their creation and enhancement will result in biodiversity units available for sale.

Conservation Covenant: Is a private, voluntary agreement between individuals or Responsible Bodies to conserve the natural or heritage features of the land. It must conserve the land for the public good or have some other conservation purpose. See Gov UK Conservation Covenant Agreement.

DEFRA: The Department of the Environment, Food and Rural Affairs.

Distinctiveness: The distinctiveness of the different kinds of habitats is one of the determinants of habitat value. It measures the difference between such ecological factors as the rarity of the habitat and the richness of the species within it. DEFRA categorises distinctiveness into two types: Broad, such as grassland and wetland, and Specific, such as orchards, hedges and reedbeds. These types are further divided into six tiers accounting for some 35 kinds of habitat.

Ecology By Design: An established ecology consultancy licensed to survey and value land for the purposes of Biodiversity Net Gain. The director and staff are all members of the Chartered Institute of Ecology and Environmental Management (CIEEM).

Environment Act 2021: The principle of Biodiversity Net Gain is to aim to leave a development site in a better state than it was before development. Until The Act becomes the law, the requirement by most LPAs is to treat an application as if the law already existed. The Environment Act 2021, otherwise known as Biodiversity Net Gain, comes into effect on the 12th February 2024. For planning permission to be granted, all new developments must show an increase in the biodiversity value of the site by 10% minimum. Note that for small and Nationally Significant infrastructure projects, enactment will follow in due course.

Equivalence: When offsetting the development sites’ biodiversity deficit, there has to be a fair exchange of habitat sites in the first instance. That is to say, the same biodiversity values for habitats, species, ecosystems or ecological functions that were lost should be replaced in kind and value plus 10%. In special cases, the offsite area may be different so long as the biodiversity is of a higher value or distinctiveness than those impacted by the development.

Financial compensation: If off-site habitat is not possible to obtain, financial compensation may be considered. Some local authorities have a system in place for this and will charge a fee which will contribute towards habitat creation and/or enhancement of the local area.

Habitat: A habitat is where insects, plants, fishes, animals, reptiles, invertebrates and other living organisms live. They are dependent not only on their habitats but also on each other. They also contribute to the natural countryside’s health and wealth. 

Habitat banking: Once an area of land has been surveyed and awarded a habitat value in biodiversity metrics (version 4.0 – see Biodiversity Metrics), that value can be ‘banked’ awaiting a sale to a developer. The actual value of the habitat is dependent on many factors, principally its potential for habitat creation or improvement. For now, the trading is subject to market forces. Habitat banks can be landowners, land agents or specialist companies such as Civity.

Habitat types: For the benefit of common understanding, habitats are defined and valued by their ‘distinctiveness’: low, medium and high. Within that definition, they are further defined as ‘broad’ or ‘specific’. They are then listed into ‘tiers’: A1, A2, A3, A4, A5, H (for hedgerow) and W (for watercourses), depending on the rarity of their distinctiveness. The value of these habitat types in biodiversity units increases with each tier. Trading prices are governed by market forces, which may include a Spatial Risk Multiplier that will affect the agreed price. 

Land Bank: See Habitat Banking.

Landowner Obligations: Fall into three parts:

Restrictive obligations: things that the landowner must not do. For instance, apply fertiliser to hay meadows or planting trees at archaeological sites;

Positive obligations: things that the landowner or Responsible Body must do, such as planning a flower-rich meadow;

Enabling obligations: things that the landowner must allow a Responsible Body to do on the land.

Local Authority: See Local Planning Authority Below.

Local Planning Authorities (LPA): A local planning authority is usually a department within the local authority. Whilst the local authority has wide responsibilities over its designated area, the local planning authority is limited to regulating, controlling and determining the planning and development direction of its area. It is the local planning authority to whom developers apply for planning permission together with the supporting biodiversity plans for permission to be granted.

Maintenance agreement. See the Thirty-Year Maintenance Agreement.

Management agreements: May be entered into when there is a Conservation Covenant, and changes are required to alter the way the land is managed. It is legally binding and carries obligations but does not interfere with the covenant itself. Legal advice may be required.

Mitigation hierarchy: There are five mitigation steps a developer should consider in the biodiversity impact of his development of the construction site: damage avoidance, damage minimisation, damage restoration, damage offset to break even and the on-site or off-site biodiversity gain required to meet the 10%.

National Planning Policy Framework: The revised National Planning Policy Framework sets out the government’s planning policies for England and how these are expected to be applied. See Policy Here. 

Natural England: Is the government’s independent advisor on wildlife and is charged with conserving and enhancing England’s natural environment for its intrinsic value, well-being, and enjoyment of its people as well as for the economic prosperity that it brings.

Nutrient Neutrality: Construction can create an excess of mainly nitrates and phosphates, which can pollute lakes, rivers and streams through seepage. This encourages algae growth and can disrupt healthy ecosystems and the wildlife dependent on the water.

Planning Permission: The licence to build awarded by the government or, more usually, the local planning authority (or local authority). From 12th February 2024, planning permission can only be granted if the developer/ builder/engineer can show a sustainable biodiversity net gain of 10% over the original biodiversity value of the site.

Protected species: Many animals and plants are protected, but BNG does not include them in its metric and is unlikely to do so in the foreseeable future. However, in assessing planning permissions, the Local Planning Authority will consider their status as well as their habitats.

Responsible Body: In the context of BNG, an organisation created to carry out its conservation functions properly. It can include a local authority, public body, charity or other body whose main activities relate to conservation. An application for planning consent may involve a responsible body, and if the membership includes the local authority, there could be areas of conflict of interest.

Riperian zones: A typical riparian zone is a riverbank where the land meets a stream, river, pond, lake or wetland. Owners of land containing a Riperian zone have multiple responsibilities, including environmental stewardship and habitat protection.

Section 106 Agreements: Section 106 of the Town & Country Planning Act 1990 enables a local planning authority to enter into a legally binding agreement or planning obligation with a landowner, contractor or other party as part of the grant of planning permission. From 12th February 2024, permission will be dependent upon a BNG of 10% in all but a very few exceptions.

Spatial Risk Multiplier: When an application is made for planning permission, the Local Planning Authority likes to see, where possible, the biodiversity net gain on-site. If this is not possible, then off-site. However, the biodiversity value of the habitat diminishes the further away it is from the development site. This loss of value is known as the ‘spatial risk multiplier’.

Stacking: The part payment for biodiversity units using other environmental credits and subsidies.

Stakeholder: A stakeholder is a person or group of people who have an interest in the business without necessarily being directly financially involved. The stakeholder’s role is to help a company meet its strategic objectives by contributing their experience and perspective to a project. Stakeholders bring a deeper understanding of how the enterprise’s operations affect people, groups and communities more widely.

Statutory credits: These are a form of biodiversity credits but are sold as Statutory Credits by the government when the Environment Act becomes law. It is the last resort for developers unable to use on-site or off-site units to deliver a biodiversity net gain. Buying Statutory Credits comes with a ‘Spatial Risk Multiplier‘, which can double the number of Statutory Credits required. Their value depends on the rarity of the habitat and the richness of the species that live within it. More info can be found at Ecology by Design

Thirty-year maintenance agreement: When a plot of land is converted to biodiversity units, there is an obligation by the owner to maintain or improve its biodiversity for a minimum of 30 years. If ownership is transferred to a developer, the developer must guarantee the biodiversity quality for the period. If the landowner is still the owner after the lease of the land, he carries the obligation unless a maintenance agreement is made with the lessee. If there is a lease of more than 7 years, the leaseholder is responsible. The leaseholder could also be a landbank such as Civity.

Trading rules: Specify the types of habitat that can be used to replace existing habitats on the basis of like-for-like. For ‘very high’ and ‘irreplaceable’ habitats, a bespoke compensation may be required.

UKHAB: Is the categorisation that defines a habitat, its condition and strategic significance. DEFRA, supported by the professional judgements of experienced ecologists, assesses the loss, retention or enhancement of specific habitats.

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