Environmental policy

• The idea is that, instead of driving a loss of habitats for wildlife, developments will now contribute to a recovery.
• The new policy will be rolled out to small sites in April 2024 and nationally significant infrastructure projects in 2025.
• It’s an exciting moment – we are academics who assess policies like these, and we recognise that this is one of the world’s most ambitious ecological compensation policies.

What does a ‘biodiversity net gain’ actually mean?

• This is a calculation tool which assigns numerical values (“units”) to habitats based on their size, type and ecological condition.
• A small lawn might be one unit, while a small patch of woodland could be 16 units.

• But some harms are inevitable, and these will need to be compensated for – both by improving the quality of the remaining habitats, and by creating new habitats.
• In practice, this means the net gain rules generally promote more grassland, ponds, hedgerows and other natural habitats within developments.
• Researchers have learned a lot about the outcomes of biodiversity net gain from studying councils such as West Oxfordshire and Cornwall, where equivalent commitments were adopted early.

Is it delivering for wildlife?

• A key concern is that the metric used to score biodiversity may not work in the best interests of wildlife – particularly insects.
• The metric is intended to be a practical proxy for biodiversity, by assessing and scoring different habitat features.

• This is because the metric allows large “poor” quality habitats to be traded for small “good” ones.
• This reduces the demand for offsets, and hence the private investment that could be going into large nature recovery projects.

How will it be enforced?

• Our team has previously estimated a quarter of habitat units promised under net gain regulations could be unmonitored and effectively unenforced.
• As developers and planners get used to biodiversity net gain, we hope to see these gaps addressed in further policy tweaks.
• Biodiversity net gain is an exciting, ambitious policy, and we want it to achieve its full potential.

Natalie Duffus receives funding from the Natural Environment Research Council NE/S007474/1 Oxford-NERC Doctoral Training Partnership in Environmental Research and an Oxford-Reuben Scholarship. Sophus zu Ermgassen receives funding from the European Commission via EU Horizon 2020 project SUPERB (Systemic Solutions for Upscaling of Urgent Ecosystem Restoration for Forest Related Biodiversity)