Biodiversity Net Gain: What does it mean for the landscape industry?
In February 2023 the Department for Environment, Food and Rural Affairs (Defra) announced the introduction of mandatory Biodiversity Net Gain (BNG) in England later this year. This scheme will mandate the assessment of habitats on land that is due to be developed and require this habitat to be enhanced so that it is in a better state than before any development.
Under mandatory BNG, major and minor development projects in England must replace biodiversity lost as part of the development and add a minimum of 10% biodiversity to provide a net gain. The resulting habitat will be secured for at least 30 years via planning obligations or conservation covenants.
The scheme, introduced as part of the Environment Act 2021, will amend the Town & Country Planning Act and apply to new housing, infrastructure and commercial developments. Large developments will be subject to the rules from November 2023, whilst minor development will be included from April 2024.
Minor development is defined as
- For residential: where the number of dwellings to be provided is between one and nine inclusive on a site having an area of less than one hectare, or where the number of dwellings to be provided is not known, a site area of less than 0.5 hectares.
- For non-residential: where the floor space to be created is less than 1,000 square metres OR where the site area is less than one hectare.
Development that exceeds the specification of minor development, above, is defined as major development.
The following types of development are exempt from the remit of mandatory BNG:
- development impacting habitat of an area below a threshold of 25 metres squared, or 5m for linear habitats such as hedgerows
- householder planning applications
- small scale self-build and custom house building
Habitat assessment by biodiversity metric
Underpinning mandatory BNG is a method of assessing habitats called the biodiversity metric. This biodiversity accounting tool is based on a Microsoft Excel document and will calculate how a proposed development will change the biodiversity value of an area of land, as well as the amount of ‘gain’ required. The tool is designed to provide stakeholders with a means of assessing changes in biodiversity value (losses or gains) brought about by development or changes in land management.
Habitat surveys and use of the biodiversity metric will be undertaken by competent persons (likely ecological consultants) working on behalf of developers, before being submitted as part of a planning application and scrutinised by specialists, including ecologists and planners, working within local planning authorities.
The currency of BNG: units and credits
The biodiversity metric tool will calculate the ecological cost of development on an area of land and generate a number which the developer must compensate for. This compensation currency is called a ‘unit’.
The number of units generated by the biodiversity metric for any given development depends on various factors including:
- Distinctiveness: the type of habitat and its features, including species richness, rarity, whether the habitat is protected and the degree to which a habitat supports species rarely found in other habitats
- Condition: variation amongst the same habitat type
There are three types of biodiversity units: area units, hedgerow units and watercourse units. For example, on one site there may be a total of 15.5 biodiversity units, which are comprised of 5.5 units of scrub, 8 of grassland and 2 of woodland.
The long-term goal: biodiversity gain plan
Once assessed using the biodiversity metric tool, a biodiversity gain plan will outline how a development will deliver biodiversity net gain and allow the planning authority to check whether the proposals meet the biodiversity gain objective.
Topics covered by the biodiversity gain plan include:
- How adverse impacts on habitats have been minimised
- The pre-development biodiversity value of the onsite habitat
- The post-development biodiversity value of the onsite habitat
- The biodiversity value of any offsite habitat provided in relation to the development
- Any statutory biodiversity credits purchased
- Any further requirements as set out in secondary legislation
The full biodiversity gain plan will be submitted either with the planning application or after the permission is granted, but before development has commenced.
What habitats will be created?
Local planning authorities have the option of setting priorities (for example, woodland creation or enhancing ecological networks) for biodiversity within their administrative area, which may be identified in collaboration with local wildlife organisations and stakeholders. These priorities will be formalised in local plans and planning decisions.
Therefore, in most cases developers will be given guidance on what form their biodiversity contribution should take. Pre-development assessments will also identify higher value or even irreplaceable habitats already on-site, which will be protected under best practice.
Where will habitat creation take place?
Best practice guidance dictates net gains should be delivered locally to the development site. In addition, a ‘spatial risk multiplier’ attached to the biodiversity metric tool will incentivise developers to undertake biodiversity improvements within the boundary of a development (on-site), by reducing the biodiversity value of habitats delivered further away from the development.
Where on-site improvements are not possible (for example where there is not space on site for the development and habitat areas) improvements can be made off-site. The term ‘off-site’ in the context of BNG may mean on land owned by the developer, which is away from the development site, or alternatively by purchasing units sold by third-party land managers who are already in the process of creating new habitats throughout the UK.
Estimates using 2019 housing delivery data suggest on-site and off-site habitat creation will demand a total of 5,400 ha of land each year in England.
Trading BNG units
The development of a third-party BNG unit marketplace was an intended consequence of the BNG scheme, and numerous businesses already offer units for sale throughout the country.
Off-site units being sold by third parties generally form part of large, privately managed habitat restoration projects, ranging from grasslands to re-wilding and re-wetting projects. Thousands of units are already available for purchase, which is just as well, since Defra estimate 1,300 ha of off-site units will be sought each year by developers.
The cost of each unit being sold by third-party providers will include management of the land for at least 30 years, monitoring and reporting, ecologist or other experts’ costs, insurance, costs to cover work if the habitat fails, machinery, tools and other staff to carry out the tasks, inflation and market competition costs and the cost of legal administration. Defra estimate the cost for each unit is likely to be in the region of £9,000 - £15,000, however, due to the immature nature of the market, this figure may vary. Crucially for developers, once they purchase BNG units from third parties, they absolve themselves of all liability for BNG mitigation.
Developers who cannot use on-site or off-site units to deliver BNG must purchase ‘statutory credits’ (note the difference in terminology between units and credits) from the government. This option is regarded as a last resort and priced accordingly high; statutory credit prices are set to ensure they do not compete with the development of units for sale by third parties. The proceeds from the sale of ‘statutory credits’ will go towards government-led conservation projects.
The biodiversity metric tool is currently being developed so that when BNG becomes mandatory in November 2023, developers who need statutory credits can work out how many they need, depending on their intended development.
In July 2023 the government announced indicative prices for statutory credits, starting at £42,000 per credit for more common habitats, up to £650,000 for rare habitats. Exact prices are due to be released ahead of November 2023.
Will BNG benefit the landscape community?
BNG is one of many government initiatives purported to increase the number of ‘green jobs’ and has the potential to benefit every member of the landscape and wider environmental community, from ecologists to designers, suppliers to contractors.
The potential benefits to the landscape and environmental industries are likely to arise from various aspects of work throughout the BNG process:
- Assessment of development site (pre-development): provision of ecological services for an assessment of the site and delivery of biodiversity gain plan
- Design of habitats for developers, either as part of on-site projects or off-site projects, as part of biodiversity gain plan
- Design of habitats for third-party land owners looking to sell units to developers
- Creation of habitat as described in biodiversity gain plan: the creation of habitats using materials, products and skilled labour
- Creation of habitats for third-party land owners, using materials, products and skilled labour
- Monitoring of sites: provision of regular monitoring services of the site by competent persons. Subject to agreement, may be undertaken during maintenance of site by operatives
- Maintenance of site: regular, skilled maintenance of all living aspects including replacement of failed specimens and damaged products
Aside from the obvious need to enhance and create a wide range of high-quality new habitats on sites of all sizes and locations, habitats created under the BNG scheme must be secured for a minimum of 30 years.
Given the intended life expectancy of projects and the level of scrutiny they will face by the local planning authority and interest groups, it is likely regular, skilled assessment and maintenance will be in demand throughout England. Landscape professionals of all disciplines should benefit from the demand for skilled maintenance work on sites, either on developer-led sites or off-site for private enterprises.
Further reading
