Biodiversity Accounting is a tool for making assessing the predicted change in ecological value of a site before and after a project.
The DEFRA 2019 Biodiversity Metric is one such tool, which has been adapted for other applications (such as BREEAM 2018). The metric provides an assessment of percentage change in ecological value based upon ‘biodiversity units’ (an arbitrary value that allows comparison of before and after scenarios for a project).
There are some limitations with a numerical (quantitative) approach to representing ecological value. However, the method provides a standardised tool which is a recognised method for determining whether a project is likely to deliver ‘Biodiversity Net Gain’.
‘Biodiversity Net Gain’ means that the habitats created after the project (post construction) would have a significantly higher ecological value than the original (pre construction) habitats. Typically, a threshold value (such as 110% change) would be set.
Biodiversity Net Gain is set to be mandated for all development projects, so use of biodiversity accounting tools within habitat assessments are likely to feature more strongly in the near future.