Biodiversity is essential for life on Earth, providing us with essential services like clean air, freshwater and fertile soil. Whilst there is a growing recognition of the importance of preserving and enhancing biodiversity, not just for the sake of nature itself but also for our own well-being, it is also recognised that the UK is one of the most nature-depleted nations on Earth. Our track record is poor, and our biodiversity continues to decline. In an effort to halt this decline, particularly with regard to developments, a new system called Biodiversity Net Gain has been developed in England. It was launched on the 12th of February this year (2024). Wales and Scotland are also developing their own versions of this. Here, we will look at what Biodiversity Net Gain is and what it means for us as ecologists.

What is Biodiversity Net Gain?
What is Biodiversity Net Gain?

What is Biodiversity Net Gain?

Biodiversity Net Gain is a concept that seeks to ensure that all developments result in an overall increase in biodiversity, compared to the pre-development baseline. In simple terms, it means that if a piece of land is developed for housing, infrastructure, or any other purpose, the biodiversity that is lost should be compensated for by enhancing biodiversity either on site or elsewhere.  The difference now is that this gain is measurable and a minimum of 10% gain is now mandatory. 

How does Biodiversity Net Gain work?

The process of achieving Biodiversity Net Gain typically involves several steps.

Baseline assessment 

Before any development takes place, an assessment of the existing biodiversity on site is conducted by mapping the habitats and assessing their condition. 

This includes surveys to identify habitats and ecological features as well as the plants and animals that live on site.

Development planning 

Next the developers work with the Ecologist and other experts to design the development in a way that minimises harm to biodiversity. This may involve measures such as preserving important habitats, creating green spaces, incorporating wildlife friendly features and enhancing habitats. Where the gain cannot be achieved on site the developer will need to secure land and management offsite. These are all incorporated into the design both on and off site. 

Calculating net gain

To calculate the net gain, or loss, the Ecologist will use the Statutory Biodiversity Metric. This is a spreadsheet that calculates losses and gains based on habitats present,  their quality, condition and size. The calculation then produces Units. These are then calculated for the baseline conditions on the site and for the post-development conditions on the site. 

With most developments, a loss is almost inevitable, and so the gains will need to be carried out offsite. In order to calculate gains offsite, a baseline assessment of the offsite habitats also needs to be done. We also need a plan for how new habitats will be created or how existing habitats will be enhanced. This will give us enough Units for a 10% gain in biodiversity.

Offsetting measures

To achieve net gain, developers will try to include on-site gain but are most likely to have to provide it offsite. The gain can be through enhancing habitats, restoring degraded habitats , or creating new habitats. The motto with the offsetting is that the habitat must be like for like or better so you cannot replace a grassland with a woodland for example. 

Developers are penalised if the offsetting is further away from the site and this will incur more cost. Developers will have the opportunity to buy offsetting Units from landowners, conservation organisations and the government. However, caution should be made if they are situated a long way from the development site. 

Implications for developments

The implementation of Biodiversity Net Gain has several implications for developments in England. 

There will be increased scrutiny and developers must now consider biodiversity impacts as a key aspect of the planning process. This means more thorough assessments and greater scrutiny of development proposals by planning authorities.

Incorporating biodiversity enhancements into developments will also add to the overall cost. However, the long-term benefits, including improved ecosystem services and public health outcomes, outweigh the initial investment. It should also be remembered that England is already very poor for wildlife and a lot of the loss was due to developments in the past.

In the long term, by prioritising biodiversity conservation and enhancement, developments are more likely to be sustainable. The Biodiversity Net Gain activities have to be secured for a minimum of 30 years. Careful design considerations that include wildlife corridors and quality habitats will ensure that biodiversity can thrive in to the future. In addition to this, there are benefits for people. Green spaces and wildlife habitats improve the quality of life for residents and contribute to resilient and vibrant communities. 

The role of Ecologists

Biodiversity Net Gain will also have a huge influence on the role of Ecologist and new skills will need to be developed. 

Ecologist carry out the baseline surveys to assess existing biodiversity on the development sites. This requires expertise in species identification, in particular botany, habitat mapping, habitat assessment, and ecological monitoring techniques.

Working closely with the developers the Ecologist also needs to help design and implement the mitigation measures to minimise the impact of development on biodiversity. This may involve relocating sensitive species, creating wildlife corridors, or introducing green infrastructure. It will also involve working with other landowners on the offsetting habitat creation and enhancement. 

Ongoing monitoring and evaluation will also be the responsibility of the Ecologist. Monitoring is essential to gauge the success of the biodiversity enhancement measures. And evaluate whether Biodiversity Net Gain targets are being met. This will involve ongoing monitoring of the habitats that are being created or enhanced. 

It will therefore mean that there will be a lot more work for Ecologists. 

Ecologist skills needed for Biodiversity Net Gain

On top of more work Ecologists will also need more skills.

Habitat mapping skills will be needed and the Statutroy Biodiversity Metric uses UKHab. If you are used to mapping habitats using the Phase 1 methodology then a conversion course will be required. Only UKHab provides these courses currently. 

Botanical skills are essential for habitat mapping and in particular for identifying key species that are indicators of important habitats e.g. ancient woodland indicators or calcareous grassland indicators). Being able to identify plants and plant communities will be essential for delivering Biodiversity Net Gain.

Digital mapping skills will also be needed and larger consultancies may have GIS mapping expertise in house but for smaller consultancies Ecologists will need to be upskilled.

For Biodiversity Net Gain The area of the habitat needs to be accurately mapped and measured on GIS for the Metric calculation tool. 

Ecologists will also need to have varied and extensive experience of habitat restoration, creation and enhancement. They will also need to be able to create designs, management plans and monitoring schedules. 

And finally Ecologist will be responsible for monitoring the progress of any habitat enhancements or creation and be able to react and tweak the prescriptions to ensure that the projected habitat is on track. 

In conclusion, Biodiversity Net Gain represents a significant shift in how we approach development in England, placing greater emphasis on the conservation and enhancement of biodiversity. By ensuring that new developments result in a net increase in biodiversity, we can protect our natural heritage for future generations whilst also creating more sustainable and resilient communities.


The implementation of Biodiversity Net Gain presents both challenges and opportunities, requiring collaboration between developers, planners, Ecologist, and other stakeholders to achieve positive outcomes for biodiversity and people. 

BNG will provide more work for ecologists but at the same time more challenges. It s time to ensure that we are all upskilled to meet this demand. It is possible that some ecologists may specialise in BNG and set up businesses to provide this support to developers and other ecologists. 

Ecology training UK is keen to support ecologists to gain new relevant skills and has courses on Biodiversity Net Gain, QGIS – for beginners and for BNG, botanical identification (Beginners Botany) and habitat management, habitat restoration and river restoration.