Mandatory biodiversity net gain introduced under the Environment Act 2021 requires that natural habitats will be extended or improved as part of a development or project. Development must be designed in a way that provides benefits to people and nature and reduces its impacts on the wider environment. Biodiversity net gain will apply to Nationally Significant Infrastructure Projects, including those in marine and intertidal habitats, with a specific marine net gain quantitative metric being developed.

Alongside planning applications developers will have to provide a net gain plan and information, including the outcome of the application of the quantitative metric. Where the required quantitative gains cannot be delivered onsite, they will need to be delivered off site. On site gains will be incentivised over offsite, with local offsite gains incentivised over offsite delivery elsewhere, such as in habitat banks. Offsite gains will be secured for 30 years through legal agreements with landowner, with further incentives to maintain biodiversity after this through tax incentives, investment bonds and sale of additional biodiversity units. Natural England will oversee the Biodiversity Net Gain Register and the sale of biodiversity net gain units as credits. Secondary legislation will set out a definition of irreplaceable habitat with a list of habitat types such as ancient woodland considered irreplaceable and exempted from the quantitative metric.

This POSTnote will summarise the implementation challenges including the latest version of the net gain metric consulted and update the three existing publications on this topic (the latest of which was the net gain POSTbrief in 2019).

Work on this briefing will commence in June 2023

Image: Biomass trees poplar & willow coppicing for renewable energy © David –

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