The Role of Supplementary Data in Strengthening BNG Submissions
Most Biodiversity Net Gain (BNG) submissions focus on what happens inside the red line boundary. They describe habitat types, condition scores, and biodiversity units. But ecological value doesn’t stop at the edge of a site. To understand how a development really supports nature recovery, we need to look at the bigger picture. That’s where supplementary data comes in.
Supplementary datasets help planning authorities and responsible bodies see how a proposal fits within wider conservation goals. They include designated sites such as SSSIs and Local Nature Reserves, priority habitats, ecological networks, and green infrastructure strategies. They also draw on records from Local Environmental Record Centres, Natural England, and other statutory sources.
BNG is just one piece of a much larger environmental policy landscape. It links to Local Nature Recovery Strategies, the Nature Recovery Network, the Environmental Improvement Plan, and the 30 by 30 commitment. When a submission uses supplementary data, it helps demonstrate how a site contributes to these long-term goals, not just the unit score on paper.
The FRIDAS checklist includes a dedicated section on supplementary data. It asks whether relevant datasets have been referenced, whether the site has been surveyed by an ecologist, and whether supporting information has been included. These checks build transparency and traceability, especially when field surveys are limited or when assessments rely mainly on GIS data.
Supplementary data is also key for auditability. Responsible bodies need to trace where data came from, assess its relevance, and integrate it into long-term monitoring. This matters even more with the 30-year monitoring requirement for BNG sites. Without it, it’s hard to judge whether a site supports local conservation priorities or contributes to ecological connectivity.
While designated sites and ecological networks are central, there’s a whole range of other spatial datasets that can strengthen a BNG submission. They’re not always conservation datasets in the traditional sense, but they provide crucial ecological and practical context.
For example, Digital Elevation Models (DEMs) can help assess slope and terrain, which influence habitat suitability, water flow, and connectivity. Steep slopes might limit habitat success or make monitoring access difficult. Including slope data shows that proposed habitats are both viable and realistic.
Other useful datasets include:
Soil type and permeability: Helps identify suitable habitats and predict likely success.
Flood risk zones: Informs decisions about wetland creation, riparian buffers, and climate resilience.
Land use and agricultural classification: Adds context to baseline conditions and supports justification for distinctiveness or strategic significance.
Historic land cover or aerial imagery: Reveals evidence of past habitat loss or degradation, strengthening the case for restoration.
Infrastructure and access networks: Supports risk assessment and planning for off-site delivery or future monitoring.
These datasets bridge the gap between ecological ambition and practical delivery. They create an evidence base that makes BNG plans more defensible, transparent, and aligned with broader conservation objectives.
