Biodiversity Net Gain is increasingly talked about, and is being introduced into legislation and guidance. Hear Scottish Forum on Natural Capital members SLR Consulting share their views about what this actually means, and how it is being used:

What is meant by Biodiversity Net Gain (BNG)?

Biodiversity Net Gain or BNG is generally defined as “development that leaves biodiversity in a better state than before” or “a goal for a development project, policy, plan or activity in which the impacts on biodiversity it causes are outweighed by measures taken to avoid and minimise the impacts, to restore affected areas and finally to offset the residual impacts, to the extent that the gain exceeds the loss”.

In simple terms it is generally considered to be a means by which improvement in biodiversity is secured as part of a development project, both to mitigate the loss from the development but also to provide additional improvement over and above that loss.

BNG uses habitat type and condition as a proxy measure of biodiversity, in the UK this is typically done using UKhab habitat surveys1 and the DEFRA Biodiversity Net Gain 2.0 metric2.

The basic requirements of BNG are:

  • BNG is a target and a process
  • BNG must be a measurable gain from baseline conditions
  • BNG projects must follow the “Mitigation Hierarchy”
  • BNG must avoid loss of irreplaceable habitat e.g. ancient woodlands and blanket bog
  • BNG must be sustainable and long-term

Initial trials of BNG approaches started in the UK in around 2012 with BNG becoming mandatory in some council areas e.g. Warwickshire and Worcester shortly thereafter. 

In addition to BNG arising from development, some companies have also made commitments to BNG under their Environmental Corporate Social Responsibility Commitments, reflecting an increasing trend among people to choose to buy from and work for companies with better environmental credentials3.

The primary focus of BNG is to try and replace lost biodiversity on site, but if this is not practical some or all of the net gain can be off-set to another site e.g. a biodiversity bank4, ideally nearby. The required gain is expected to be a minimum 10% increase in biodiversity units. The cost of creating one biodiversity unit at an off-site location currently ranges between around £9k and £20k, depending on the habitat to be created and its location. The costs will vary between different local authority areas. 

What is the difference between Biodiversity Net Gain and environmental net gain?

BNG is related to biodiversity loss and improvement only and reflects part of the response to a wider global issue where loss and degradation of habitat and ecosystems together with associated climate change are posing an increasing level of risk and costs to societies and economies alike. 

The wider environmental picture and Environmental Net Gain relates to broader Natural Capital and Ecosystems Services impacts and benefits which include issues such as carbon capture, clean water, natural products such as food and timber, clean air and out-door recreational and cultural spaces, as well as biodiversity. The two are closely interlinked.

What are some practical examples of Biodiversity Net Gain? 

SLR’s Bob Edmonds has been heavily involved in the design of the UKhab survey methodology as a director of UKHab.org which forms the measurement basis for biodiversity units/ha that are used in DEFRA Metric 2.0 for BNG calculations. We have used our expertise in this field to work with a number of organisations design development projects to meet BNG requirements, particularly in the housing, industrial, power and mining sectors. The use of either the UKHab or DEFRA Metric 2.0 enable values to be attached to a site for the various component habitat types. This can then be used as part of the design of new/mitigation habitat types to create new and increased biodiversity value, again measured using one of the metrics available.

Which businesses / target audiences has Biodiversity Net Gain been most effective with? 

The audiences which have initially been most receptive to BNG have been those undertaking developments where BNG has been mandatory or those with large land holdings and an existing corporate social responsibility commitments such as large manufacturing clients. Increasingly this has been extended to include mineral companies and the larger residential companies who are at the initial stages of planning a development such as putting forward land for inclusion in a Local Plan.

Opportunities For Scotland

1. NPF4 consultation 

One of the six high level outcome that Scotland’s National Planning Framework 4 (NPF4) will seek to achieve is ‘Securing positive effects for biodiversity'5. NPF4, was due to be put before parliament in September 2020 but due to the Covid 19 pandemic has now been delayed until September 2021 and will likely be approved in early 2025, a year or two later than in England. It will incorporate Scottish Planning Policy so that for the first time, spatial and thematic planning policies will be addressed in one place6. The seventh of a series of think pieces published during the consultation process focuses on Scotland’s Environment. This states that: “From now on almost every development must actively reduce carbon emissions and restore biodiversity”… “There will also need to be a clear mitigation hierarchy approach to biodiversity impacts, using a national ecological network to help identify restoration opportunities and ensure there is a genuine net gain for biodiversity from all development.” 

It therefore seems highly likely that biodiversity net gain (BNG) will be mandated in Scotland in 2022 and that mechanisms will be put in place to help focus at least some of BNG in areas which form part of the national ecological network.

2. What lessons can we learn and improve upon from experiences in England 

We anticipate that BNG implementation in Scotland once mandatory will have much in common with the systems currently developing in England in particular that local councils will play a key role in providing guidance for local development projects and probably to a large extent determining the location of off-setting sites. Based on our experience in England it is important that it is clear for a client at the start of a project how much each biodiversity unit is worth in a local planning authority area, this allows early decisions to be made as to which habitats should be kept, enhanced or could be lost. . It enables a balanced approach when planning and designing a development to retain the more important areas of habitat and perhaps losing the less valuable areas. It also allows a client to fully budget for a proposed development, taking into account any off-setting payment they may need to make and therefore understand if the development they propose is financially viable This will likely also be accompanied by growth in the biodiversity banking sector in Scotland. 

3. What is Scotland specific in context? 

Landcover in Scotland differs from much of the rest of the UK, more than half of England, Wales and Northern Ireland are pastures and arable land, whereas Scotland is dominated by peat-bogs, moor and forest7. This presents both challenges and opportunities. 

One of the bigger challenges will be achieving BNG for projects that impact bog habitats, for example upland wind farm projects. Blanket bog is one of the ‘irreplaceable’ habitats listed in the DEFRA 2.02 metric , these are high value habitats that if lost cannot be replaced or compensated for via offsetting. In practice, there are reasons why some areas of blanket bog may not be considered irreplaceable, including the nature of the impact, the condition of the blanket bog and the wider environmental context8. In Scotland more discussion and guidance on how to approach impacts to bog habitats in relation to biodiversity net gain is required before a transparent and effective way forward can be established . 

The relative abundance of semi-natural habitats in Scotland, however, provides greater opportunity than perhaps elsewhere in the UK for largescale habitat enhancement and creation. While we anticipate much of this to be focussed on a national ecological network, there maybe be significant opportunities in the longer term for landowners to benefit from income from biodiversity of setting schemes and habitat banking.

4. Relevance to the Sustainable Development Goals

Since 2015 Scotland has been a signatory to the United Nations 17 Sustainable development goals910. These are embedded in the 2018 National Performance Framework11. Many of these goals including, Goal 6 clean water and sanitation, Goal 13 climate action, Goal 14 life below water, and Goal 15 life on land, relate to goods and service that are relate fully or in part to Scotland’s Natural Capital and are either direct goals for biodiversity net gain or co-benefits. For example, biodiversity net gain project targeting peatland restoration would not only contribute to meeting biodiversity net gain targets for an individual project in terms of the type and condition of the habitats present but also to sequestering carbon, sorting water and mediating its flow, and providing habitat for terrestrial and aquatic life. While similar things can be said of biodiversity net gain projects anywhere in the UK, the potential in Scotland for BNG to tie in with large scale- nature conservation activities designed to enhance Scotland’s Natural capital are probably greater in the less intensely developed/ farmed Scottish landscape. We therefore anticipate that in order to meet both national and corporate12 sustainability goals, as well as BNG commitments, the coming decade will provide a rapidly developing range of opportunities for investment and innovation in around biodiversity net gain and Natural Capital in Scotland.



http://publications.naturalengland.org.uk/publication/5850908674228224 It should be noted that the DEFRA 2.0 Metric is still at the testing stage with an updated version due for issue shortly.


4 The Environment Bank defines a Biodiversity or Habitat Bank as a land registry with a network of landowners, including farmers and nature conservation organisations, to identify the potential for high quality offset schemes and habitat banks that are good for nature, meet the needs of development and provide landowners with a long-term income to manage their land positively for the future.






10 https://globalgoals.scot/scotlands-goals/

11 https://nationalperformance.gov.scot/sustainable-development-goals

12 E.g. Corporate Environmental Responsibility

SLR Consulting are a large international environmental consultancy firm, and offer a wide range of environmental and advisory solutions to help their clients achieve their sustainability goals. You can find out more about SLR Consulting on their website. If you have any questions about the article please contact: Stewart Lenton, slenton@slrconsulting.com or Sue Swain, sswain@slrconsulting.com