What is the biodiversity metric?
In the UK the biodiversity metric is an official and statutory term referring to a way of measuring biodiversity value for the purposes of the Biodiversity Net Gain (BNG) regulations. The statutory biodiversity metric measures the biodiversity value of habitats by calculating the number of biodiversity units. There are three types of biodiversity units, which are calculated in three separate 'modules' of the metric (area units, hedgerow units and watercourse units).
The approach uses this to calculate how many units a habitat contains before development takes place and how many units are needed to replace the units of habitat lost in order to achieve 10% BNG according to the regulation, through the creation or enhancement of habitat. A professional ecologist, will use the metric tool for a particular project, including gathering, inputting and assessing data., guidance on finding a suitable consultant is published by the Chartered Institute of Ecology and Environmental Management.
The biodiversity metric used to calculate biodiversity units takes into consideration the size, condition, strategic significance and type of the habitat under consideration. For habitats that are enhanced or newly created the formula also takes account of; the difficulty of the creation or enhancement, the time it takes a habitat to reach its target condition and the distance from the habitat loss.
It measures all types of habitat, including:
- grassland
- hedgerows
- lakes
- woodland
- watercourses such as rivers and streams
The statutory (official) biodiversity metric calculation tool must be used in order to demonstrate that a developer has calculated the number of biodiversity units for existing habitat or habitat enhancements in accordance with the statutory biodiversity metric.
For further information on the Biodiversity Net Gain (BNG) visit here
For further information on the biodiversity metric calculation tools and guides visit here
In general global biodiversity terms there are also other approaches in applying metrics to the assessment of biodiversity, some of these include the GLOBIO model (developed by the Netherlands Environmental Assessment Agency), the Species Threat Abatement and Restoration or STAR metric (by the International Union for Conservation of Nature) and the Biodiversity Intactness Index (BII) along with some others.
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