Biodiversity Net Gain

Wildflower meadow on Cornwall housing site

Over the past few years we have seen a number of milestone reports leading to shifts in Government policy which aim to halt the decline of biodiversity across the UK.  The first inkling of change was the Lawton report “Making Space for Nature: A review of England’s Wildlife Sites and Ecological Network” published  by Defra in 2010 which identified that the existing system of protected sites and reserves was inadequate and insufficient to halt the rapid decline in UK wildlife.  Some of the recommendations of this report passed into policy In 2011 within the Government  White Paper “The Natural Choice  – securing the value of nature”.  Last year saw the publication of the 25-year Environment Plan which makes it clear that all future industrial, residential and infrastructure development is dependent on improving conditions for wildlife.

As a first step in implementing the 25 year plan the Chancellor of the Exchequer recently confirmed that the Government will mandate ‘Biodiversity Net Gain’ within the forthcoming Environment Bill and that the delivery of infrastructure and housing will no longer be at the expense of biodiversity.  This makes sense in the context of the National Planning Policy Framework, which has a presumption in favour of sustainable development, but where current policy is demonstrably unsustainable.

Biodiversity Net Gain (BNG) requires developers to ensure habitats for wildlife are enhanced and left in a measurably better state than they were prior to development.  They must assess the type of habitat and its condition before submitting plans, and then demonstrate how they are improving biodiversity – such as through the creation of green corridors, planting more trees, or forming local nature spaces.  A key principle of BNG is that the ecological hierarchy is maintained. Primarily adverse impacts must be avoided, or else mitigated on site.  It is not always possible to achieve an overall  improvement in biodiversity within a development site, so in circumstances where this is not possible, developers will need to pay a levy for habitat creation or improvement elsewhere.

The London Olympic Park landscaping was designed to enhance biodiversity

Environment Secretary Michael Gove said: “Mandating biodiversity net gain will ensure wildlife thrives at the same time as addressing the need to build new homes.  Whether it’s through planting more trees or creating green corridors, developers will now be required to place the environment at the heart of new developments.  This new approach will not only improve habitats for wildlife and create healthier places to live and work but is central in our ambition to leave the environment in a better state for future generations.”

The Environment Bill aims to fill the gap in environmental protection that will result from leaving the EU.  The timing of its implementation is therefore dependent on Brexit actually happening, but it is most likely that it will come into force early in 2020.  This means that many developments which are currently under consideration may not come before planning authorities until after the act is in place.  Developers should therefore be considering BNG for all of their future schemes.

We still have no guidance on the amount of net gain that should be achieved. It is likely that initially a figure of 10% will be adopted but this will need to be reviewed over time.  It is quite possible that the 10% level may be too low to achieve measurable net gain, and that more ambitious targets will need to be set in the future.  A new assessment metric is currently being produced by Natural England which will also require ecologists to assess habitats by using the UK Habitats Classification (UKHab) which is more precise than the current Phase 1 Habitats Classification.

Bee bricks are now a standard requirement for new houses in Cornwall.

In practice this will require an early base line ecological  assessment of any development site, using the Defra metric to convert the site data into a score of Conservation Units.  Given the likely impact of the proposed development, the Scheme on completion will need to exceed the original score of Conservation Units by at least 10%.  This will require a combination of avoidance and mitigation measures on a significant scale, involving ecologists at the core of the design process.  Many schemes will find it impossible to achieve BNG without radical re-design or contributing financially towards offsite mitigation.

The metric uses a range of multipliers to allow for the time taken to re-create habitats, their connectivity and distance from the development site.  While offsite mitigation can generate excellent outcomes for wildlife, it is expensive to achieve, and many developers may be better off reducing the impact of their original scheme.

Parallel legislation, currently under consultation, will allow for the creation of so-called Conservation Covenants.  These can be applied to land which has been specifically set aside for nature conservation purposes, either within a development or as off-site compensation.  This is a useful legal device to protect habitats in the long term which have been created or improved in order to provide biodiversity gain for development sites.

Sustainable urban drainage is a good way to achieve biodiversity gain. © Copyright Hugh Venables

For many years Biodiversity Net Gain has applied to large developments in Australia and parts of the USA. Results have not always been successful, usually because of poor design, lack of monitoring and weak enforcement. The current emasculated state of Natural England raises concerns as to whether BNG will be adequately regulated but local authorities may be better placed to take on the role of regulator.

Staff at Land and Heritage have experience of working with the 2012 Defra metric within the North Devon pilot area and have also worked on No Net Loss of Biodiversity on the HS2 Scheme. We can advise on the likely effects of BNG on individual development sites and projects.

Simon Humphreys