As part of the BNG process, applications are asked to supply a habitat map, and we are treating it as evidence rather than an output. But what do we actually learn from a habitat map? You may be able to see where habitats have been mapped and how they have been classified, but can you determine when the survey was undertaken? Can you establish who created the data, which basemap was used, how habitat boundaries were interpreted, or whether the GIS dataset supporting the map is the same one used to calculate biodiversity units? A good habitat will be able to allow the user to make informed assumptions, but a habitat map on its own cannot always provide that level of transparency. For BNG, we need evidence that is capable of being:
Interrogated
Verified
Challenged
It should allow another person to understand where the information came from, how it was produced and whether it remains suitable for use. A PDF map can show where habitat boundaries have been drawn and how habitats have been classified, but it does not allow somebody to independently assess the geometry, attributes, topology, metadata or provenance of the data itself. Issues such as overlapping polygons, gaps between habitat parcels, inconsistencies between mapped areas and Biodiversity Metric calculations, missing attributes or undocumented edits may exist within the GIS dataset without being visible on the final map.
As a result, reviewing a habitat map is not the same as reviewing the underlying evidence. The map communicates the outcome of a process, but it does not necessarily provide access to the information required to verify that the process has been carried out correctly. If the GIS data is not available, our ability to independently validate habitat extent, habitat areas, classifications and supporting calculations becomes significantly more limited. By treating the habitat map as evidence, rather than one of several outputs produced from a wider evidence base, there is a risk that decisions are being made on information that cannot be independently verified. The evidence base is not the map itself, but the combination of survey information, GIS data, attributes, metadata, supporting documentation and the audit trail that allows the dataset to be independently understood and validated.
Concepts such as provenance and data lineage are often treated as technical or administrative details, but in reality they provide the context that transforms a dataset into evidence. They document who collected the information, when it was collected, how it was processed and what limitations should be considered when using it. Without this information, it becomes difficult to understand whether a dataset remains reliable over time.
Commitments for BNG created today will continue for decades. Habitat banks, management plans and monitoring obligations may extend well beyond the careers of the people who originally created the data. Organisations will change, staff will move on and software will evolve. The habitat map may still exist, but the story behind it may be lost.
We need to move away from solely focusing on outputs is one of the reasons why I developed FRIDAS. The framework applies a structured assessment of the GIS evidence base that sits behind habitat maps, biodiversity calculations and environmental reporting. Using documented Data Quality Tolerances (DQTs), it examines the quality, completeness and traceability of environmental datasets and provides a consistent basis for understanding the significance of any issues that are identified. A habitat map can communicate the result of an assessment, but the supporting GIS data and metadata provide the context that allows that result to be understood and scrutinised. As environmental datasets become increasingly important within planning, habitat banking and long-term monitoring, the quality of that supporting evidence becomes increasingly important too.
In practical terms, FRIDAS provides a mechanism for independently assessing that evidence before it reaches a decision-maker. Where a dataset achieves a passing assessment outcome, the resulting report can form part of the wider evidence base alongside habitat maps, ecological reports and Biodiversity Metric calculations. The intention is to provide confidence that the underlying GIS data has been assessed against a documented methodology. This creates the potential for reviewers to focus on the biodiversity evidence itself rather than spending time requesting, interrogating and validating supporting datasets from scratch.
