The proposed updated Defra Biodiversity Metric is designed to provide ecologists, developers, planners and other interested parties with a means of assessing changes in biodiversity value (losses or gains) brought about by development or changes in land management. The metric is a habitat based approach to determining a proxy biodiversity value.
The updated metric is described and short summaries are provided to describe the component parts and multipliers. It is an improved version of the metric piloted by Defra in 2012 in the context of the biodiversity offsetting pilots and incorporates many of the changes since made or requested by industry experts. The revised metric includes some new features:
- Improved consideration of ecological connectivity
- Covers an extended range of habitat types including green infrastructure and rivers
- A forthcoming spreadsheet-based tool will support the application of the metric in practice
The metric is designed to complement and work with ecological advice, where appropriate, and is not designed to replace such advice.
The update has been developed by Natural England with input and support form a number of external organisations. Subject to any additional substantive comments received during the consultation on Net Gain a more detailed update with accompanying guidance and supporting user tool will be published by Natural England in 2019. Both the tool and the guidance will be freely available to download and will increase the transparency and ease of use of the metric.
NOTE: A minor calculation error was found in the annex of the version of this document that was originally published. This has now been corrected (7th December 2018)