Sourced from Inside Ecology
Defra’s 25 Year Environment Plan makes inspiring but challenging reading for ecologists. Exciting headline statements such as “We will: Embed an ‘environmental net gain’ principle for development, including housing and infrastructure” are tempered by subtlety different details like “We will seek to embed a ‘net environmental gain’ principle for development to deliver environmental improvements locally and nationally.” This sentence is followed by an aspiration that is challenging in itself “This will enable housing development without increasing overall burdens on developers.”
One of the things the Plan recognises is that some industry leaders are already making commitments to work towards biodiversity net gain, so in some ways the UK government is, one hopes, actually catching up with industry best practice.
Defra has produced a draft biodiversity metric, which allows calculations of net losses and gains. It is a proxy, and no-one pretends that a simple metric score could capture all the effects of land use change on rare and common species and habitats or the effects of changes in habitat connectivity, but it does provide an indicator of broad effects on biodiversity.
The basic concept and some ideas for ecologists on biodiversity net gain have been explored in previous Inside Ecology articles  . However, what might a commitment to net gain actually mean for an individual developer?
As part of their sustainability strategy, Redrow Homes is looking to create a company-wide biodiversity strategy. This will look to benefit people and wildlife on Redrow’s sites across the country. Redrow obtained help from SCN Lavalin’s Atkins business to help explore the options that can be included in this strategy, including a retrospective application of the Defra biodiversity metric, to a sample of Redrow’s development sites.
Atkins applied the Defra biodiversity offsetting metric retrospectively to three of Redrow’s existing development sites. Atkins also undertook a literature review and explored wider net gain principles to help Redrow’s thinking on the next steps. Of the three sites that were analysed, two of the sites, Caddington and Saxon Brook, had a positive residual value and a biodiversity net gain for the development, whereas the third, Woodford, had an overall net loss after development.