Mandatory Biodiversity Net Gain – A step in the right direction, but more ambition needed

The start of mandatory “biodiversity net gain” (BNG) for new developments in England on February 12th is an important step towards protecting and restoring nature. As an environmental charity based in Oxfordshire that has pioneered biodiversity offsetting agreements since 2013, we welcome these new requirements on developers.

The promise and limits of biodiversity net gain

Biodiversity net gain (BNG) refers to new rules requiring developers to leave the natural environment in a measurably better state than before construction. Under the mandatory minimums starting this week, developers must demonstrate 10% more biodiversity after construction. This policy aims to help halt and reverse the alarming declines in UK wildlife populations and habitats that have led to the UK being one of the most nature-depleted countries in the world.

However, there is debate around whether 10% is sufficient to constitute a genuine “net gain.” Factoring in difficulties accurately assessing losses and gains on paper, some experts warn that 10% may only maintain the status quo rather than increasing biodiversity. In Oxfordshire alone, around 47,000 “biodiversity units” will be required to offset the impacts of housing developments expected over the next 10 years. The majority (42,691 units) compensate for habitat destruction from construction.  Only the remaining 4,309 units represent the extra 10% biodiversity enhancement above pre-development levels. If sold to fund additional habitat restoration, these 4,309 units could be worth around £108 million.

However, experts estimate it would cost over £800 million to meet Oxfordshire’s separate 30×30 target of protecting 30% of land for nature by 2030. So the 10% BNG funds can only contribute around 13% of the 30×30 costs at most. In other words, while BNG is intended to mitigate development impacts and deliver a 10% enhancement, it alone will not pay for major habitat expansion targets such as 30×30.

The vital role of local leadership

So while BNG has promise, greater ambition is needed. Findings from Wildlife and Countryside Link  that just 8% of local authorities plan to go beyond the 10% minimum are concerning. So we are heartened that forward-thinking councils like South Oxfordshire and Vale of White Horse are considering more ambitious  policies of 11-25% BNG. Guidance from Oxfordshire’s Local Nature Partnership suggests that 20% should be the minimum target – and we support this approach.

There are also concerns around implementation and enforcement capabilities from under-resourced local authorities. The hierarchy of decision-making means developers must first offset within the development area and only when this is not possible should they go elsewhere. As an organisation connecting people with nature, we believe strongly in integrating nature into the fabric of everyday lives, by building accessible green spaces that provide richness in wildlife and deepen engagement with communities in development areas.

To achieve this requires a firm policy process, to ensure the proposed hierarchy is adhered to and all options for on-site green space provision are explored before developers purchase biodiversity units for off-site habitat creation.

Our Catalysing Nature Recovery for People & Nature project focuses on embedding social engagement into restoration. To genuinely protect wildlife, nature must permeate how and where people live and work – requiring unprecedented cross-sector collaboration.

We pioneered the UK’s first biodiversity offset in 2013, transforming degraded chalk grassland at Bushey Bank into a haven through our award-winning partnership between developers, brokers and landowners. Economic growth and restoration can thrive together when BNG is done properly.

Of course, targets must be backed by careful monitoring and enforcement.  At Earth Trust we’re actively considering how investment through biodiversity net gain and other types of ‘green finance’ such as carbon credits can help deliver our ambition of providing accessible nature-rich green space for all.

Balancing people’s needs for access and food production through farming with thriving biodiversity and healthy ecosystems is complex. It requires a well-planned and evidence-informed strategy to ensure all of these needs are met. Over the coming months we will be working with a range of partners and specialists to determine how our green spaces can support the delivery of BNG targets, and where our expertise can be best applied.

Ensuring robust delivery

So while biodiversity net gain marks a step forward, its success depends greatly on national and local policy choices in the months ahead.  We are proud to be based in a county leading the charge on translating bold Global Biodiversity Framework commitments into on-the-ground action. Clear guidance and support are needed so more councils can set ambitiously high BNG targets above 10% and embrace green spaces within and close to communities.

Gains should be maximised on-site where possible, with careful monitoring to ensure new habitats are established and maintained. And most importantly, local people must participate in designing and managing new community green spaces that foster active engagement with nature.

With the right frameworks, biodiversity net gain provides a mechanism to tangibly improve nature across England’s towns and cities. But the metrics must not distract from the ultimate outcome: thriving, biodiverse ecosystems entwined with people’s health and wellbeing.