Under the July 2018 revision of the National Planning Policy Framework, the government requires local authorities in England to embed relevant strategies into local plans to deliver a net environmental gain over possible reductions caused by developments and infrastructure. The initial objective of this requirement will be to deliver gains in levels of biodiversity – short for biological diversity, the abundance and variety of species and their physical habitats – at the landscape level. In December 2018, Defra launched a consultation on implementing a mandatory biodiversity net gain requirement for development in England.Jump to full report >>
Industry good practice principles for biodiversity net gain requires following the ‘mitigation hierarchy’ to avoid and then minimise impacts on biodiversity and then achieve gains by the creation or restoration of habitats on the development site, or outside of it if this is not possible (referred to as offsetting). Gains should be made with respect to species composition, habitat structure, the functioning of ecosystems and cultural values associated with biodiversity. A metric originally developed as part of the Defra 2012–2014 Biodiversity Offsetting pilot programme is the means by which quantitative estimates of the impacts on biodiversity and the subsequent gains can be derived (a revised version of the metric is currently being refined in consultation with stakeholders). The habitats on a development site are mapped, and their condition and distinctiveness (attributes intended to reflect the value of the biodiversity present) are scored with the metric to derive biodiversity ‘units’. Developers will be required to gain more biodiversity units than are initially present at the development site.
However, relying on development to fund future biodiversity increases differs markedly from previous conservation approaches. Controversies also exist in relation to the use of offsetting, which aims to increase biodiversity in another location and re-allocates the stock of biodiversity resources across time (as gains in biodiversity may take decades to accrue). Whether net gains are achieved will also depend on governance arrangements, including the rules, policies and institutions implementing the approach, and the resources available to local planning authorities to do this. In the longer term, the concept will be expanded to cover a wider set of benefits delivered by natural habitats, such as flood protection and improved water quality, with a wider ‘eco-metric’ currently being developed.
This POSTbrief summarises the net gain and previous no net loss approaches, the mitigation hierarchy and biodiversity offsetting as well as the ethical and social concerns, and the governance and technical challenges involved.
POSTnotes are based on literature reviews and interviews with a range of stakeholders, and are externally peer reviewed. POST would like to thank interviewees and peer reviewers for kindly giving up their time during the preparation of this briefing, including:
* denotes stakeholders who acted as external reviewers of the POSTnote.
Author: Jonathan Wentworth
The Parliamentary Office of Science and Technology produces independent, balanced and accessible briefings on public policy issues related to science and technology.