Introduction
In recent years there has been growing recognition of the need to rapidly restore habitats and species populations, instead of purely conserving and protecting them. Notably, adopting the Kunming-Montreal Global Biodiversity Framework at the 15th COP for the UN Convention on Biological Diversity (COP15) marks a major milestone in the world’s efforts to halt and reverse nature loss.
This page and its subpages are intended to act as an area where members can easily find information about different Biodiversity Enhancement (BE) Approaches in England, Scotland, Wales and on the island of Ireland.
Information on relevant training courses can be found on the CIEEM Training and Events webpages.
CIEEM, with support from Defra, Natural England, the Environment Agency, and the Forestry Commission, has launched The Biodiversity Net Gain Forum on LinkedIn. The forum provides a dynamic space for practitioners to connect, share expertise and experiences, and discuss challenges and successes in delivering BNG. Stay updated on best practices, guidance, and innovative approaches shaping BNG across sectors. Join The Biodiversity Net Gain Forum on LinkedIn.
Biodiversity Net Gain (England)
Biodiversity Net Gain is an approach to development that intends to leave biodiversity in a better state than before. Where development has an impact on biodiversity it encourages developers to provide an increase in appropriate natural habitat and ecological features over and above that being affected in such a way it is hoped that the current loss of biodiversity through development will be halted and ecological networks can be restored. Biodiversity net gain relies on the application of the mitigation hierarchy to avoid, mitigate or compensate for biodiversity losses. It is additional to these approaches, not instead of them.
Mandatory biodiversity net gain as set out in the Environment Act 2021 will require all new developments (unless exempt) under the Town and Country Planning Act 1990 to deliver at least 10% biodiversity net gain from 12 February 2024, with small sites requiring BNG from 2 April 2024.
From 12 February 2024, BNG will be mandatory for new planning applications for major development made under the Town and Country Planning Act (TCPA) 1990, subject to the confirmed exemptions. Major development includes residential developments with 10 or more dwellings, or where the site area is greater than 0.5 hectares.
BNG for small sites will have an extended transition period and will apply from 2 April 2024. Small site development includes:
- Residential development where the number of dwellings is between 1 and 9, or if unknown the site area is less than 0.5 hectares
- Commercial development where floor space created is less than 1,000 square metres or the total site area is less than 1 hectare
Find out more about small sites BNG on the Natural England website and in this news item.
The value of habitats for biodiversity net gain will be measured using the Biodiversity Metric (see below). The metric will use changes in the extent and quality of natural habitats as a proxy for nature and then compare the habitat on-site before and after development. This comparison is underpinned by four key factors:
- Habitat size
- Habitat condition
- Habitat distinctiveness
- Strategic significance
The Biodiversity gain plan for development can then be achieved through:
- On-Site (Units) – Delivered on-site through habitat creation/enhancement via landscaping/green infrastructure
- Off-Site (Units) – Delivered off-site through habitat creation/enhancement
- Statutory credits – Only available as a last resort, delivered through large-scale habitat projects delivering high-value habitats which also provide long-term nature-based solutions
The statutory Biodiversity Metric is a biodiversity accounting tool that can be used for the purposes of calculating biodiversity net gain.
The Metric can be used to:
- Assess the biodiversity unit value of an area of land
- Demonstrate biodiversity net gains or losses in a consistent way
- Measure and account for direct impacts on biodiversity
- Compare proposals for a site – such as creating or enhancing habitat on-site or off-site
The Metric is intended to be used by:
- Ecologists or developers carrying out a biodiversity assessment
- Developers who have commissioned a biodiversity assessment
- Planning authorities who are interpreting metric outputs in a planning application
- Communities who want to understand the impacts of a local development
- Landowners or land managers who want to provide biodiversity units from their sites to others
Put simply, it involves the use of a metric as a proxy for recognising the negative impacts on habitats arising from a development and calculating how much new or restored habitat, and of what types is required to deliver sufficient net gain.
Online resources:
- Useful resources on the Planning Advisory Service (PAS) website
- Find CIEEM training courses on BNG
- WCL briefing arguing that 10% gain is not enough
See further useful links on our Biodiversity Net Gain Resources page.
Positive Effects for Biodiversity (Scotland)
The Scottish Government through its National Planning Framework 4 (NPF4) has previously recommended a qualitative not quantitative approach to biodiversity enhancement, relying on ecologists to use their professional judgement to determine what steps are needed to enhance development sites. However, the Scottish Government now appears to be taking a more hybrid approach.
In September 2023 the Scottish Government published a commissioned report undertaken by the SRUC (Scotland’s Rural College) titled ‘Research into Approaches to Measuring Biodiversity in Scotland‘. The report recommends a biodiversity framework or standard is needed, making use of multiple metrics or tools for different sectors to monitor biodiversity. The report highlights the priority biodiversity indicators identified across policy sectors, including habitat condition, species, ecological connectivity and ecosystem integrity/function, as well as the need for an approach to consider wider ecosystem benefits. The report specifically makes the recommendation that the Biodiversity Metric be adapted to include connectivity measures, as well as the other priority indicators noted above, concluding that “with refinement, Natural England’s Biodiversity Metric 3.1 could be adapted for planning and development use, and as part of a wider set of metrics within a biodiversity framework. These refinements include the coverage of habitats, and adjustments to condition assessment and multipliers to reflect Scottish contexts.” Following the release of the report, the Scottish Government has announced that NatureScot will be developing a metric to support the delivery of policy 3b.
Importantly, the Scottish approach provides different expectations for BE depending on the scale of the development, rather than introducing a single rule for all developments (in contrast to the English approach). Biodiversity Enhancement is required under planning policy for all “development proposals for national, major and of EIA development or development for which an Appropriate Assessment is required”. These developments “should only be supported where it can be demonstrated that the proposal will conserve and enhance biodiversity, including nature networks within and adjacent to the site, so that they are in a demonstrably better state than without intervention, including through future management.”
Net Benefits for Biodiversity (Wales)
Net Benefits for Biodiversity is a qualitative (requires professional judgement) and primarily site-based approach to biodiversity enhancement/BNG which has been driven by the Section 6 Duty of the Environment (Wales) Act (2016) to maintain and enhance biodiversity and the resilience of ecosystems in Wales. The NBB policy is defined in Planning Policy Wales as “the concept that development should leave biodiversity and the resilience of ecosystems in a significantly better state than before, through securing immediate and long-term, measurable and demonstrable benefit, primarily on or preferably immediately adjacent to the site”.
NBB policy has been developed with reference to the principles outlined in the Placemaking Wales Charter, and is supported by the Natural Resources Wales (NRW) DECCA framework which sets out the attributes of ecosystem resilience that the planning system must consider:
- Diversity – not only biological but also structural and physical.
- Extent – the bigger an ecosystem extends, without fragmentation, the more resilient it is likely to be.
- Connectivity within and between ecosystems – facilitates the movement of genes, species and ecosystem components, such as water, across landscapes, allowing ecosystems to function effectively and to adapt spatially, for example in response to climate change.
- Condition – the underpinning supporting services of ecosystems need to be in a healthy condition to function effectively, to deliver a range of important ecosystem services.
- Adaptability – the key question here is whether the ecosystem in question will adapt and change in the desired direction given future environmental and economic changes, and demands such as climate change.
PPW12 emphasises that NBB are easier and cheaper if planned from the start and this must begin with application of the step-wise approach, including the acknowledgement of off-site compensation measures as a last resort, and the need to consider enhancement and long-term management at each step.
The use of the green infrastructure statement (see ‘Building with Nature guidance’ below) as a means of demonstrating the stepwise approach is made explicit in PPW12.
All development must deliver a net benefit for biodiversity proportionate to the scale and nature of the development proposed. Even if the existing biodiversity is maintained, enhancement must still be actively sought
Biodiversity Net Gain/Biodiversity Enhancements (Ireland)
Current policy in the Republic of Ireland (Action 3C1, Ireland’s 4th National Biodiversity Action Plan 2023- 2030) is for public authorities and private sector bodies to move towards no net loss (i.e. negative impacts on biodiversity from development must be mitgated). There is currently no formal legislation or policy regarding BNG in the Republic of Ireland or Northern Ireland. CIEEM has recognised that in recent years there has been growing recognition of the need to go beyond ‘No Net Loss’ and has produced a briefing paper, ‘Biodiversity Net Gain in Ireland’. The paper reviews existing approaches to BNG, has set out the current situation and establishes some thoughts on how it could be implemented in an Irish context.