Biodiversity Net Gain: Four essentials for success
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The concept of Biodiversity Net Gain (BNG) is simple: biodiversity is better off because of development. In other words, development projects such as housing, transport and energy all have the potential to restore and improve our environment.

While the concept is simple, BNG is a step-change in the way that we think, plan, budget, design, build and maintain infrastructure. We’re moving from ‘development versus nature’ to development as a driver of a healthy and thriving natural environment. This is as much a cultural change as a physical one whereby environmental restoration becomes embedded in the lifecycle of construction activities.

This matters. It matters to our way of life because the natural environment cleans water, purifies our air, maintains healthy soils, regulates the climate and provides us with food, medicine and other basic necessities. This matters to our wellbeing, as time in nature boosts our happiness. This really matters to our infrastructure and industry because we rely on increasingly scarce natural resources and must deal with climate change impacts that can significantly increase construction costs.

BNG began as a grassroots movement in the UK with companies and projects making voluntary commitments. In 2016, the landmark publication of the Good Practice Principles clearly set the benchmark for BNG. Policy and legalisation are now catching up and from 2023, in England, certain developments will be mandated to achieve BNG. Elsewhere, measures are coming into force to protect nature and reverse the degradation of ecosystems, such as the EU's Biodiversity Strategy, developed as part of the European Green Deal.

Looking back since the early inception of of BNG, we’re starting to see what it takes for BNG to truly succeed. There are the big-ticket items of a mandated BNG requirement together with resources for local authorities and enforcement. Then there’s the day-to-day working life and, at that level, here are my top four essentials:

1. Innovate through engineering

The Mitigation Hierarchy is a process of first avoiding and then minimising impacts on biodiversity, before restoring and finally offsetting residual impacts. It has long been the foundation for Ecological Impact Assessment and underpins UK law to protect species and designated sites.

BNG brings a fresh perspective, especially to the first step of avoidance. Put simply, the more site clearance and habitat removed, the greater the biodiversity deficit and the more costly it is for developers to first compensate for losses and then achieve BNG. Avoiding highly valuable habitats can make business sense and engineering design and construction teams have a vital role to play.

Measures to avoid such biodiversity impacts can involve re-locating or reshaping a development footprint, which requires engineering input and innovation. While ecologists can (and indeed must) drive the conversation, the wider design and construction teams are the ones to lead and find solutions. Here, the benefits of multidisciplinary project management really come out: BNG doesn’t work in the appendices of an Ecological Impact Assessment report – it must be up front and central to project design.

2. Make space

Natural England’s Biodiversity Metric is based on habitats and how they change from before to after a development. Having input data including the type of habitat, its condition, size and location, it calculates ‘biodiversity units’ before and after a development, quantifying the change. In England, a minimum 10% increase in biodiversity units is required under the forthcoming mandatory requirement for developments to achieve BNG.

This habitat-based metric gives us three main options to achieve BNG: we can enhance existing habitats, create new habitats, or do a mixture of both.

They all require space. BNG is not installing bat boxes or planting a few trees in the corner. Rather, much about BNG is about enhancing and creating habitats, and habitats need space. Planning space for BNG measures at the start of a project can save a great deal of time and cost, and generate the best outcomes for both biodiversity and the development.

3. Track it

“Get a tracker for BNG, everyone in industry loves them!”

That was advice from a colleague when I asked how to best gain interest in BNG. And she was right, trackers are a regular part of working life and have certainly helped me to engage people on BNG.

With the Biodiversity Metric, we can develop trackers to monitor progress towards BNG throughout design and construction. I’ve seen this work really well, demonstrating how ‘minor’ design or construction decisions hugely affect BNG outcomes. Trackers are also a great engagement tool when working with multiple disciplines including landscape, earthworks and drainage. Each discipline has design priorities, and BNG trackers illustrate how their priorities connect with and influence the BNG outcome, bringing everyone onto the same page.

Our BNG trackers range from a simple bar chart to master trackers showing change in multiple habitats across time and space. We’re also developing GIS-based trackers for design teams themselves to see how design decisions are make-or-break for BNG. Essentially, trackers simplify and bring BNG into the day-to-day of project design and construction.

4. Empower teams

I’m part of the ecology profession within infrastructure development, undertaking ecological surveys and impact assessments, designing and implementing ecological mitigation measures. Historically, we ecologists often work on siloed protection for individual species and sites over short timescales, such as dormice mitigation measures for a three-year licence.

BNG is even more of step-change for ecologists than it is for developers. We now need to design and produce management plans for habitat restoration, enhancement and creation over 30-year timescales. While BNG does not change existing legal protection for species, species-specific mitigation is part of a holistic and at times landscape-level BNG design. This requires skills and expertise in habitat restoration and long-term management. We cannot expect ecologists to simply pick this up: but rather must invest in their technical training and skill development.

As well as technical skills, it’s equally important to recognise the wider skills that ecologists need. My points above are all about engaging, motivating, communicating and collaborating with design teams, clients, stakeholders and construction teams. Let’s recognise the full range of these skills, and provide the dedicated training, resources and support needed to empower ecologists seeking to lead BNG.

At this critical time for our natural world, and with ESG performance ever more prominent in our boardrooms, BNG is not just a requirement but an opportunity for infrastructure development to become a force for good in our increasingly challenged world. Making it a success will require innovative engineering approaches, an effective use of space, clear impact measurement, and a transformation in our skills to build a better future.

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