From early 2024, developers of all projects in England will need to deliver a 10% net gain in biodiversity on their sites. Guidance on the metric that will be used, and other key details, is expected to be released by the end of this month, November 2023. Engineering Matters spoke to Tom Butterworth, head of ecology at WSP, about the requirements of the new regulations.

The new Biodiversity Net Gain requirements were laid out in the Environment Act (2021), and will come into force over the coming months, Butterworth, explains. As well as his role at WSP, Butterworth plays a role in the development of national and international standards for biodiversity.

The right tool for the job

Butterworth, and experts like him, have developed BS 42020, “a code of practice for biodiversity in planning and development”. That’s currently under review, but is, Butterworth says, well worth a look.  Another major British Standard that should be considered is BS 8683, ‘Process for designing and implementing Biodiversity Net Gain’. Outside of the UK—and the British Standards system—other countries are developing their own approaches, drawing on local and international standards. Butterworth is contributing to these standards, through the ISO system.

This plethora of standards isn’t coming about just because every government’s bureaucrat wants to do things their way. The complexity of biodiversity means that every measure has to be appropriate to the outcome sought. “There’s lots of different ways that we can assess and measure biodiversity,” says Butterworth. “Biodiversity is the diversity of all life and the interactions of all of that life. And those then interact with all of the non-living systems to create ecosystems. We can measure change in biodiversity at a whole range of different scales and levels: we can measure it at a global scale, at a country scale, or on an individual project.

“We can also measure change, looking at the change at an ecosystem level, how the functionality of that ecosystem is shifting. We can measure change at the level of a habitat, and see how the quality of a specific habitat is changing. And we can measure change for specific species, whether it’d be populations of species or communities of species. And there are metrics for each of these aspects.”

When the challenge is the potential loss of a species, one appropriate measure is STAR, or the Species Threat Abatement and Restoration tool, developed by the IUCN, the International Union for the Conservation of Nature.

“Equally there are metrics that use habitats, like the metric that has been developed by Defra for England, that looks at ‘quality hectares’, the area of the habitat and the quality of those hectares,” explains Butterworth.  “There are lots of different ways of measuring change in biodiversity, which creates quite a lot of noise and debate about how best to do it. But there isn’t one way that’s better than any other.”

According to Butterworth, “We, in the UK, have some really good data on the habitats that are present. We can measure the quality of those habitats. We understand what the species requirements are within those habitats. In heathland, for example, you might need a certain amount of bare ground, you might need a certain amount of scrub encroachment and so on to create the right habitat for the species. In a case like that, then a quality hectares measure is absolutely the right way to go.” 

In other ecosystems, by contrast, other metrics might be more appropriate. “If you’re looking at a large area where you’ve got some protected species,” Butterworth explains, “You need to make sure that what you’re putting back is the right habitat for those protected species or those threatened species, to avoid increasing that threat to those species. Then, something like the Species Threat Abatement and Restoration tool (STAR) might well be the right one to use.”

Ecologists believe that delivering biodiversity net gains has to start by considering your local ecosystem. That’s the approach that has been taken in the new regulations in England.

Butterworth mentions the requirement from January is that the major developments under the Town and Country Planning Act will be required to deliver a minimum of a 10% net gain using the metric. This statutory metric will be released by Defra, as part of the planned guidance document. “It’s a quality hectares measure,” Buttwerworth says, “So it takes the area and the quality of those habitats that are impacted as a way of assessing the impact you’re having and any compensation you’re putting in.”

Local priorities

Developers can work out the steps they should take to maintain those ‘quality hectares’, using a mitigation hierarchy. “These are the steps we need to take when assessing and understanding our impacts on biodiversity,” explains Butterworth. “The first step is to avoid impact wherever possible. The next step is to minimise any impacts we can’t avoid. The third step is then to restore those habitats where we can on site. And then the last step of this is to enhance or create habitats off-site, outside of that development site, in order to compensate for any losses that we have after we’ve taken those other steps.”

It’s important for nature, and for people, that offsetting—when used—is kept as local as possible. The impact of biodiversity changes matters more, perhaps, if you are in a dense urban area like London’s Tower Hamlets than out in the countryside, somewhere like the Chilterns.

As Butterworth points out, green space in a dense urban environment like Tower Hamlets, “Is crucial for providing the communities that live there, the human communities that live there, with space, with places to sit, have picnics, kick a ball around, whatever it might be, as well as creating spaces where the air quality is better.”

In recent years, carbon offsetting has been used by many big consumer brands to support Net Zero claims, and has recently faced considerable criticism. Biodiversity offsetting, under the new English regulations, will be harder in many ways, but will not be open to the same criticisms.

The core concerns around carbon offsetting involve the idea of ‘avoided loss’. This can be hard to substantiate in carbon offsetting. 

Avoided loss is a concept that isn’t accepted by the British government when it comes to biodiversity, as Butterworth explains. “If you’re losing a beautiful woodland, you need to put back a beautiful woodland. That’s embedded in the metric. And it means that you can’t say you’ve met your requirements for biodiversity net gain, unless you meet ‘like-for-like, or better’ principles.

“If you’re starting with a low-quality habitat, perhaps a grassland that’s only got one or two species of grass in, if you are replacing it with something nicer, like a chalk grassland, then that’s acceptable. That’s okay. That’s the ‘or better’ part of the principle. And again, that’s embedded in the metric.”

Long term commitment

The regulations will require that biodiversity net gain is measured over a thirty year period. To achieve this, funding will need to be set aside, to ensure that work can be continued, as part of the planning process. These funds will then be managed by residents’ committees, local authorities, or other third parties. “Sometimes the roads are passed to the local authorities to look after, sometimes the green spaces, but very often a management company can do that,” says Buttwerworth. “And then you can set up a community body that is inputting into that, so the people that are living in that space can help shape it, which I think is a brilliant way to go about it.”

Over such a long period, fate, or climate change, or even bad decisions, may impact a site. Mechanisms within the planning process will ensure that this is monitored, and any losses in biodiversity are avoided. But who will help councils and other authorities ensure this happens? Westminster has made available £15m to support local authorities, but, as Butterworth points out, “It comes down to not very much money per local planning authority.”

It’s not just cash that is in short supply; expertise will be needed to perform this monitoring. “It’s really important that local planning authorities have access to ecological expertise,” says Butterworth. “It’s really important that they have that for their existing requirements, whether it’d be under the requirements for our protected species and protected sites, or the requirements out there about accessible green space. There’s a whole range of existing reasons why having access to ecological expertise is important for local authorities. This just adds one more clear reason.

“We probably don’t have enough trained ecologists at the moment. There’s a shortage, especially at a more senior level.” But the requirements are creating a market for these skills. “There are some fantastic ecologists coming out of university every year,” says Butterworth. And while, when Butterworth graduated, job options were largely limited to academia and the charity sector, these graduates can now look for jobs in a growing private sector.

Ecology at the cutting edge

Young ecologists now leaving university can look forward to an enthusiastic response from potential employers, as they rush to meet the long term needs of biodiversity monitoring. For a generation who will bear the brunt of climate change, this is an opportunity to align their personal aims with those of their employers. And they’ll be using some cutting edge tools, alongside the traditional quadrats, sweep nets, and pitfall traps that have been used in the field since the birth of ecology.

Digital techniques are increasingly important. Butterworth and his team regularly use remote sensing from satellite data and aerial photography. They use drones to take photographs. They collect DNA from the soil, from insects, or even from the air, to gather information about the species present. They can use bioacoustics, listening to the environment, and using these sounds to identify the species present and the level of biodiversity. Or they can take visual data from camera traps, and then use AI to identify the species walking past those cameras. All of this information can then be used by engineers and architects, as they present options to clients.

The new regulations set ambitious goals for developers and planners. They create a new market for innovative ways of monitoring and maintaining biodiverse landscapes. And they will bring ecologists out of the academy and the charitable sector, into the heart of the engineering and construction industry.