10 FEB 2021


Planning and development professionals need to consider biodiversity issues as early as possible so that the project team can work together to deliver an optimal outcome, argues Tetra Tech’s David West

Providing biodiversity enhancements as part of development has been a requirement under local planning policies for many years and was set out in the 2012 National Planning Policy Framework (NPPF). In recent years, this has been superseded with a focus on achieving biodiversity net gain (BNG), which is defined as leaving sites in a better state for biodiversity than before. 

The 2018 NPPF refers to providing gains for biodiversity, and this has been followed by the inclusion of mandatory targets for BNG for developments within the forthcoming environment bill. Even in advance of the bill, many local plans now call for measurable biodiversity gains. Given the potential difficulties in achieving BNG - in particular on greenfield sites - it is important for project team members both to have an understanding of this approach, and for it to be considered early on in planning and design. 

Why introduce BNG?

One of the key changes to how we consider biodiversity with a BNG-led approach is in the area of significance. Previously, assessments such as EIA (ecological impact assessment) were focussed only on significant impacts and features considered to be valuable. This inevitably led to a focus on protected and notable species and habitats. Whilst this approach still has its place (for instance to inform EIA), BNG takes into account features which might not be considered significant at site level. The hope is that this change will contribute to addressing the large-scale loss of biodiversity in the UK, as evidenced by a 2019 report from the State of Nature which found that 41% of species had declined since 1970. 

Many of the ten key principles underpinning BNG are familiar, such as the mitigation hierarchy and promoting sustainability. However, BNG provides a consistent framework for these principles to be applied. The headline is the introduction of a quantitative approach to measuring changes in biodiversity using metrics. These calculate biodiversity units pre- and post-development, taking into account impacts and proposed habitat creation to determine the change. 

One of the key benefits of the environment bill for the industry is the establishment of a consistent regulatory framework for BNG. At present, approaches are not consistent across local authorities or other decision makers, which is challenging for project teams. Not only are targets inconsistent, but so are the methodologies required and interpretation. 

The setting out of a standard requirement to be achieved will make project planning easier, and create a more level playing field. The former is vital, as one of the keys to successfully achieving BNG is to consider it as early as possible within the project lifecycle and will allow planners and developers to take centre stage in nurturing and protecting the UK’s wildlife.

Another benefit will be the wider development of strategic compensation schemes, such as that in use in Warwickshire, Coventry and Solihull. These schemes identify suitable areas for habitat creation that can then be delivered by developer funding, where projects are unable to achieve BNG. An established pricing structure for credits will help with viability studies, where at present bespoke off-site compensation schemes may be required. 

Benefits of biodiversity to developments

The provision of biodiverse open space has wider benefits for climate change resilience, mental health and wellbeing and promoting physical activity. Open space which includes walking routes can provide connectivity through a site, and larger areas can contribute to local objectives through habitat creation or supporting ecological networks. From a practical perspective, aiming to create habitats of high distinctiveness when designing open space, such as species-rich grassland and woodland, will maximise the resultant biodiversity gains and minimise the need for off-site contributions. This approach also extends to the smaller areas of a site, for example, replacing mown road verges with species-rich grassland, or formal hedging with native hedgerows. 

The provision of play areas such as Local Areas of Play (LAP) is another open space requirement where biodiversity gains can be targeted, with children shown to benefit from access to natural environments. Individually these gains may be small but taken cumulatively across a site they could provide a significant contribution to achieving a net gain overall and also achieve benefits for placemaking. This results in higher value developments, happy customers and improved reputations for developers and project teams. This is even more important following the pandemic, with many people now placing a much greater emphasis on the outdoors.

Overcoming BNG challenges

Although BNG promises to present a wealth of opportunities for wildlife and nature, as well as high-quality development, it does come with its challenges for developers. Achieving BNG can be difficult, particularly on smaller sites and where other concessions on developable areas are already required to meet wider planning requirements. It is therefore vital that biodiversity is considered as early as possible, and that the project team works together to deliver the optimal outcome for the site and for biodiversity.

David West is an associate ecologist at Tetra Tech.


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