New Study Highlights Governance Gaps in BNG Policy Implementation

A new study has examined the effectiveness of Biodiversity Net Gain (BNG) policy in England, finding key issues that should be addressed by Natural England as the policy is rolled out this year.  

The study analyses over 150 development projects covering approximately 1,600 hectares and assesses their ability to meet BNG obligations through on-site compensation, off-site compensation, or purchasing offsets. 

The results indicate significant variability in how developers fulfil their BNG obligations. Out of the examined projects, 24 were expected to achieve a 10% biodiversity net gain (BNG) through off-site compensation, 75 were projected to meet 10% gain through on-site measures, and 53 were required to purchase offsets. The projects, which ranged in size from 0.12 to 246 hectares, delivered an average 23.5% increase in biodiversity as measured by The Metric. 

Certain infrastructure types, notably solar farms, stood out for their ability to generate biodiversity unit surpluses on-site. However, the success of these interventions was contingent on factors such as species shade tolerance, vegetation management, and long-term monitoring. 

The exposure of BNG outcomes to governance risks is a major concern in the study. Over 90% of biodiversity units were planned to be delivered on-site, exposing the policy to risks of noncompliance and unenforceability. This is pertinent because it is currently unclear what capacity planning authorities will have to monitor all planning proposals delivering BNG on-site of the course of their project lifetimes (minimum of 30 years). The study recommends enhancing local planning authorities' (LPAs) capacity for monitoring and enforcement to mitigate these risks. 

A high proportion of BNG units analysed (51%) come as a result of habitat creation, as a pose to habitat enhancement (34%) or retention (15%). Because units created ‘from scratch' through the establishment of entirely new habitats have a higher risk of failure, there are concerns about the long-term viability of enforcing commitments, especially for units taking 20 years or more to reach maturity. 

Finally, the study identifies errors in biodiversity metric calculations in one-fifth of all projects, with over 40% of these errors having a 10–20% difference in area between baseline and post-development scenarios. This highlights the need for greater investment in LPAs' capacity and skills to scrutinize metric reports and ensure accurate assessments. 

In conclusion, the study underscores the wide variation in how developers meet BNG obligations and highlights the associated risks, including governance gaps, temporal challenges, and errors in metric calculations. It suggests that enhancing LPAs' capacity and skills, as well as reconsidering the reliance on on-site gains, could strengthen the effectiveness of the BNG policy in achieving its environmental goals amid continued infrastructure expansion. 

Source: Rampling, E. E., zu Ermgassen, S. O. S. E., Hawkins, I., & Bull, J. W. (2023). Achieving biodiversity net gain by addressing governance gaps underpinning ecological compensation policies. Conservation Biology, 00, e14198. https://doi.org/10.1111/cobi.14198