No evidence that England’s new ‘biodiversity boost’ planning policy will help birds or butterflies - University of Cambridge

A new legal requirement for developers to demonstrate a biodiversity boost in planning applications could make a more meaningful impact on nature recovery if improvements are made to the way nature’s value is calculated, say researchers at the University of Cambridge.

From 2024, the UK’s Environment Act requires planning applications to demonstrate an overall biodiversity net gain of at least 10% as calculated using a new statutory biodiversity metric.

The researchers trialled the metric by using it to calculate the biodiversity value of 24 sites across England. These sites have all been monitored over the long-term, allowing the team to compare biodiversity species data with results from the metric.

Plant biodiversity at the sites matched values produced using the metric, but bird and butterfly biodiversity did not.

This means there’s no evidence that a 10% net biodiversity gain calculated using the statutory biodiversity metric will translate into real-life gains for birds and butterflies, without additional conservation management.

This is the first comprehensive study of the performance of Defra’s statutory biodiversity metric across England. The results are published today in the Journal of Applied Ecology.

Plants, birds and butterflies have been comprehensively surveyed in England over many years, and are used as indicators for the national state of nature.

The researchers say the metric must be improved to better capture the intricacies of the different species within an ecosystem.