Earlier this year one of the biggest steps towards environmentally focused planning came into force in England. Even though, as ecologists, many of us have been using metrics to demonstrate positive outcomes for biodiversity within our construction projects, Biodiversity Net Gain (BNG) became mandatory in February. This new framework demonstrated a commitment to nature in which ecologists could lead the way.
For planning officials, however, it meant quickly coming up to speed with new legislation to ensure planning applications would fulfil these new obligations. Not just at the application stage, but throughout a project’s lifecycle. The role of the ecologist is vital within this process and can support planners to follow best practice guidelines, gaining the best possible outcome for planners, developers, their developments and the wildlife living on their sites.
The effects of BNG on planning officials and their authorities
In essence BNG states that any development within a local authority should have a positive impact on biodiversity. At its core, that doesn’t mean replacing or offsetting habitats. Instead, it means considering from the outset how nature can quickly return and then thrive within any new construction development.
Labour has set an ambitious target to build 1.5 million homes over the next five years and Councils will have their own local housing targets to fulfil. New housing, together with the infrastructure, supermarkets, hospitals, offices, factories, warehouses, and car parks that go alongside, inevitably destroy wildlife habitats and food sources. The two objectives – to build and to protect – now need to work in harmony.
During a planning application, a developer must submit a Biodiversity Gain Plan for approval by the planning authority. Government guidelines state that planners should be looking for:
• A common understanding with the developer of the existing habitat biodiversity baselines within the site.
• Accuracy within any plans and drawings on the biodiversity value that’s to be achieved.
• Demonstration of a consideration of biodiversity impact throughout the development timeline.
• ‘Measurable’ net gains, together with a plan as to how to monitor and manage these gains for the next 30 years.
• Open communications with a developer to discuss BNG requirements, expectations and capabilities for success.
The role of a planning authority is to both monitor the implementation of BNG and dish out enforcement action if plans are not adhered to and this leaves a lot of responsibility with LPAs.
Adoption of the Mitigation Hierarchy
One of the ways in which planning authorities can ensure developers are doing the best they can for biodiversity is by examining their understanding of the Mitigation Hierarchy. Described by CIEEM (the Chartered Institute of Ecology and Environmental Management) as “the cornerstone of achieving BNG”, the hierarchy is a linear process; a sequential set of steps from best scenario to worst scenario, namely (1) Avoid, (2) Minimise, (3) Compensate, (4) Enhance.
As ecologists we are, of course, striving for any development to minimise its impacts on wildlife from the start rather than fixing the problem as an afterthought. For this reason, we believe biodiversity should be considered, and shown to be considered, before any plans are drawn up. This represents the experienced way in which we work with developers, whilst at the same time providing comprehensive support to planning authorities through this work.
(1) Avoid
Has a site already been chosen? Could the development be placed elsewhere? Can sensitive habitats of high biodiversity importance be avoided entirely? Are there features of interest within a site such as a bat roost or badger sett which can be retained in situ?
Initial enthusiasm about a site’s location can dissuade developers from investigating alternative potentials. But it’s important to recognise that simply avoiding negative impacts is often the easiest, cheapest and most effective way in which to develop and planning authorities can help here by understanding the potential alternatives. Just as the presence of archaeological features can result in decisions being made to avoid development in historically rich areas, ecological features of interest need to be considered similarly.
Avoidance doesn’t necessarily have to mean such grand decisions. It can come down to project timings. Writing seasonal references into planning applications, such as avoiding the breeding bird season or the movement of vehicles during the amphibian migration season, is another avoidance method which demonstrates a commitment to BNG within planning applications.
At Ecology by Design, we routinely produce ‘constraints and opportunities plans’. These provide a high-level steer on design principles, such as the retention of trees or hedgerows, as well as the avoidance of impacts to watercourses and the maintenance of dark corridors for wildlife. All of this means that it is best practice to factor biodiversity impact into a site selection and design from the very start. The earlier that wildlife degradation and habitat loss is taken into account, the better.
(2) Minimise
If a developer can’t avoid certain negative impacts to the biodiversity of a site, then it must look to minimise those impacts. This can take the form of modifications to the project design, but also an adjustment to the timing of activities within the project’s length. The longer a construction company is on a site, the more noise, pollution and disturbance they cause. Planning authorities can offer value here by gathering insight from ecologists as to the expected scope of surveys and mitigation requirements, and therefore any sensitive timings.
Examples of minimisation include physical works such as the installation of culverts on roads, but also operational works such as a reduction in night working which necessitates floodlights. The CSBI (Cross Sector Biodiversity Initiative) and the charity BugLife, make particular reference here to habitat fragmentation. The role of spatial design can ensure wildlife highways aren’t criss-crossed, and larger areas of wildlife habitat aren’t broken into multiple smaller blocks. Fragmentation of this nature can quickly become vulnerable to edge effects, invasive species, or result in low populations which struggle to breed. For example, dormouse are very sensitive to fragmentation. They require connectivity via hedgerows, scrub, or woodland and planning applications need to consider how connectivity for species like this will be maintained. This is something which shouldn’t just be planned into the start of a project, it must be considered throughout especially where unseen problems occur or timings have to change.
(3) Compensate
Also known as ‘Restore’ or ‘Mitigate’ the third stage is one of repairing any damage or degradation that’s been necessary during the construction phase. With BNG, this stage can be costly as, not only does the area need to return to its original ecosystem state, but an additional 10% net gain in biodiversity needs to be proven. Although mitigation is typically physically introduced at the end of a project, planners should be looking for evidence of it from the start to prove a developer’s awareness of their responsibility. There are also benefits to the developer, particular in phased schemes, in delivering habitat creation early on in the construction process as habitats of biodiversity value have more time to establish and meet their target condition.
It's important to note that temporal lags can occur here. Replacing ancient oak trees with new saplings isn’t like for like. This is where the expertise of ecologists particularly comes into play. Any restoration work needs to happen as quickly as possible to have the best chance of success, and the addition of enhancement measures can make a real impact here.
For example, creating hedgehog highways between newbuild houses produces networks of connected green spaces which allow Britain’s favourite mammal to feed and breed. Integrating bird nest boxes and bat boxes into a house build demonstrates a focus on encouraging nature to return to a site post-build. And it passes on that ethos to the new homeowner who may also plant trees, hedges, and bushes in their gardens or put out seed. Introducing water into a site through a wildlife pond or sustainable urban drainage scheme is one of the most effective ways of encouraging wildlife to return to a site. Not only does it provide habitat, but also a life-giving source of water.
Employing an ecological consultancy here with the right expertise enables a developer to work with an LPA to provide the right habitat at the right time to the right site. The registration of a site under the District Licensing scheme is a good example of compensation in practice where, rather than intensive mitigation for presence or potential presence of great crested newts within a site, compensation for the species is delivered at the landscape level by NatureSpace or Natural England.
(4) Offset
Seen as the ‘final resort’, this is the most expensive way in which to approach BNG. Offsetting refers to a developer replacing what has been lost on the site. It can be done either on site or off site – by purchasing another piece of land to enhance, or by purchasing biodiversity credits provided by a third-party landowner. It is in effect a trade-off between damaging one parcel of land and enhancing another. As a planner, a proposal of this nature where failure to consider avoidance, minimisation or even compensation first can be viewed very negatively by an LPA.
Offsetting is regularly adopted for solar and battery storage sites, for example, where skylark territories are present within arable habitat prior to construction. Skylark plots can be created in offsite areas with appropriate crop rotations to maintain the population locally. For the long-eared bat, offsetting is rarely appropriate as roost protection, mitigation or compensation are typically required at site level.
The Government recommends developers work through offsetting in the following order, much like the Mitigation Hierarchy in its entirety, from best to worst: “the adverse effect should be compensated by prioritising in order, where possible, the enhancement of existing onsite habitats, creation of new onsite habitats, allocation of registered offsite gains and finally the purchase of biodiversity credits.”
Natural England recommends that LPAs and their planners embed BNG into their local planning policies as part of their wider corporate priorities. LPAs who have already identified the habitats and wildlife features struggling or in trouble in their area can benefit from delivering BNG where it’s needed most. So should a developer need to offset or compensate, a planning authority can enter discussions with a planner and their ecology consultancy as to how best to approach this.
Conclusion
Adopting the mitigation hierarchy is best practice because it delivers the best outcomes for biodiversity. It is also beneficial for developers as invariably the higher up the hierarchy you have to go, the more costly it becomes.
Brown long-eared bat handled under licence
Example Case:
Where a bat roost of conservation importance is present, such as a maternity colony of brown long-eared bats:
(1) Avoidance - it is best practice to prevent impacts to the building (i.e. avoidance);
(2) Minimise - where impacts to a building are unavoidable, the proposals can be modified (under a project licence) to ensure the roost is retained in situ e.g. by creating a bat loft and using sensitive lighting.
(3) Compensate - where avoidance of impacts are not feasible and the roost cannot be retained in situ, then a replacement roost can be created under licence in advance of loss of the roost to enable maintenance of the population within the site.
(4) Enhancement - in all instances, enhancements for the species can be achieved through increasing connectivity, creation of additional roosting features, and/or increasing biodiversity e.g. by providing opportunities for their prey sources.
October 2024