New Study Assesses the Impacts of Biodiversity Net Gain in England

The UK government’s Environment Bill will mandate that most new developments in England demonstrate that they deliver a minimum 10% biodiversity net gain (BNG). Currently, six English Local Authorities have adopted a mandatory BNG approach prior to the enactment of the Environment Bill. A recent study, published in Conservation Letters, evaluates the impact of planning applications on habitat changes under these requirements over a year.

The study found most developments were on low biodiversity value cropland and pasture, and across the total study area, BNG implementation resulted in a 34% reduction of non-urban habitats, generally compensated by commitments to deliver smaller areas of higher quality habitat. Authors note there is a need for appropriate governance to ensure promises of future habitat improvements are realistic and delivered.

The largest category of habitat delivered was moderate condition ‘other neutral grassland’. In addition, 95% of BNG was delivered within the development footprint, meaning a small proportion of sites deliver offsite compensation, for example through Nature Recovery Networks.

Authors of the research paper also tested robustness of the metric used in BNG through surveys of grassland experts. Results showed experts only agreed with the findings of BNG reports 34% of the time and there was no agreement regarding the grassland type, raising concerns about accuracy of habitat classification. Authors suggest the quality of information provided in BNG assessments is often insufficient to properly scrutinize and greater training is needed for those assessing BNG.

Finally, the paper discusses governance arrangements, cautioning that ambiguity and a lack of enforcement for on-site gains risks high quality habitat not being delivered, so improvements in capacity are needed. Authors also call for mechanisms to encourage investment in Nature Recovery Networks and other offsite projects.

Read the full paper