The importance of demonstrating Biodiversity Net Gains in development projects

The revised NPPF published in July 2018 and amended in February 2019 reinforces the emphasis on achieving biodiversity net gain for development projects with reference to being able to demonstrate “measurable net gains”. Natural England are understood to be pushing the Government to seek to stipulate that measurable biodiversity net gain should become a mandatory requirement.

As with any amendment to policy it often takes a period for the precise implications of the changes to be fully understood and often how the rather ambiguous wording within the NPPF is to play out in practice.

At DHA we are finding that more and more we are being asked to provide evidence to demonstrate measurable net gains using the Defra Biodiversity Metric. The latest version of the Metric is available on Natural England’s website.

The metric calculates the value of a habitat type currently present within a site in terms of ‘biodiversity units’ by attributing it a numerical value (0-8) multiplied by the area it occupies.  It then calculates the relative loss of a habitat in comparison to the proposed replacement habitat types being created or restored and managed, which is presented as a numerical value e.g. a net gain of numerical biodiversity units or a net loss.

However, as with any system that tries to simplify a complex natural system the Metric is not without its flaws but is nonetheless a tool promoted by Natural England. Irrespective of its shortfalls, the Metric approach often requires larger areas of habitat creation than would typically be expected in order to demonstrate net gain.

It is therefore prudent to engage an ecologist who is familiar with the Metric to define areas needed to achieve net gain early in the project design.  In order to prevent delays later in the project and the implications of having to retrofit a scheme later in the process or even after submission.

Whilst off-site biodiversity offsetting remains an option in theory the mechanism through which to secure this either doesn’t exist or is more convoluted.

We are therefore recommending to our clients that the Metric is used in the early design stages of a proposal. 



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