Biodiversity Net Gain, usually shortened to BNG, is one of the biggest changes to planning, development and land management in England for many years. At its simplest, BNG means that when development happens, nature should be left in a better condition than it was before.
Instead of development simply trying to reduce harm to wildlife, Biodiversity Net Gain asks a more ambitious question: can we build homes, roads, schools, business parks and infrastructure while also improving habitats for plants, insects, birds, mammals and the wider natural world?
In England, most developments now have to deliver at least a 10% biodiversity net gain. This means that the biodiversity value of a site after development must be at least 10% higher than it was before development began.
For landowners and farmers, BNG may also create new opportunities. Developers who cannot deliver all their biodiversity gains on their own site may need to buy biodiversity units from other land managers who are willing to create or restore habitats elsewhere. This has created a new nature market, where land can be managed for wildlife while generating long-term income.
However, BNG is not just a quick payment for planting a few trees or letting a field go wild. It is a measured, legal and long-term commitment, usually lasting at least 30 years. Done well, it could support genuine nature recovery. Done badly, it could become another complicated layer of paperwork that fails to deliver real ecological improvement.
So, what exactly is BNG, how does it work, and what should landowners and farmers know before getting involved?
Biodiversity means the variety of life. It includes everything from soil organisms, fungi and wildflowers to insects, birds, mammals, trees, ponds, hedgerows and grasslands.
Biodiversity Net Gain means improving biodiversity compared with the starting point. In planning terms, this starting point is called the baseline. The baseline measures the biodiversity value of the land before development takes place.
If a development damages or removes habitat, the developer must replace that lost biodiversity and add extra value on top. In England, the required gain is usually at least 10%.
For example, if a development site has a baseline biodiversity value of 100 units, the completed development would need to provide at least 110 units. If the developer cannot provide all those units on the development site, they may need to secure extra units somewhere else.
That is where off-site BNG comes in.
For decades, development has contributed to habitat loss and fragmentation. Fields, hedgerows, ponds, old trees, scrub, brownfield habitats and grasslands have often been lost or degraded as land has been built on.
Traditional planning rules tried to reduce harm, but they did not always result in measurable improvements for nature. Too often, wildlife mitigation was vague, poorly monitored or forgotten once construction was complete.
BNG was introduced to make biodiversity outcomes measurable and legally enforceable. The aim is to ensure that development contributes to nature recovery rather than simply causing less damage.
In theory, BNG should help create more joined-up habitats across the landscape, support local nature recovery strategies, and encourage developers to think about biodiversity from the beginning of a project rather than as an afterthought.
Biodiversity is complex, so BNG uses a standard calculation tool called the statutory biodiversity metric. This metric gives habitats a value in biodiversity units.
The metric looks at several factors, including:
Habitats are not all valued equally. A hectare of species-rich grassland, ancient woodland or wetland has a very different biodiversity value from a hectare of intensively managed improved grassland.
The metric does not measure every single species on a site. Instead, it uses habitats as a proxy for biodiversity. This makes the system more practical, but it also means good ecological judgment is still essential.
Developers can meet their BNG requirement in three main ways: on-site habitat, off-site habitat, or statutory biodiversity credits.
1. On-Site Biodiversity Net Gain
On-site BNG means creating or improving habitat within the development boundary.
This could include:
On-site BNG is often preferred because it keeps nature close to where the impact occurs. It can also improve the quality of life for people living or working in the development by providing green space, shade, wildlife, beauty and better water management.
However, many development sites do not have enough space to deliver the full 10% gain on-site, especially once houses, roads, parking, drainage and infrastructure have been included.
2. Off-Site Biodiversity Net Gain
Off-site BNG is where biodiversity gains are delivered on land outside the development site.
This is where farmers, estates, charities, councils and private landowners may be able to get involved. A landowner can create or enhance habitat, have the biodiversity uplift calculated, and sell those units to developers who need them.
Off-site BNG habitats might include:
Off-site BNG can be very useful where it contributes to larger, better-connected areas of habitat. Rather than squeezing small patches of habitat around a development, it may allow meaningful restoration across whole fields, river corridors or landscape-scale nature recovery projects.
3. Statutory Biodiversity Credits
If developers cannot deliver their required biodiversity gain on-site or through off-site units, they may be able to buy statutory biodiversity credits from the government.
These are designed to be a last resort. The pricing is deliberately set to encourage developers to look first at on-site and off-site options.
For landowners, the private off-site BNG market is usually the more relevant opportunity.
A biodiversity unit is the standard measurement used in BNG. It is not a simple acre or hectare measurement. Instead, it reflects the ecological value of a habitat.
A site with large areas of poor-quality habitat may have fewer biodiversity units than a smaller site with high-quality habitat. Likewise, improving the condition of an existing habitat may generate biodiversity uplift, even if the land area stays the same.
There are different types of biodiversity units, including:
These cannot always be swapped freely. For example, if a development destroys hedgerows, it will normally need to provide hedgerow units, not just create grassland units somewhere else.
This is important because it means a landowner’s opportunity depends not only on the amount of land available, but on the type of habitat that can realistically be created or enhanced.
BNG is meant to follow the mitigation hierarchy. This means developers should not simply destroy habitat and buy units elsewhere as the first option.
The hierarchy is:
In other words, BNG should not become a licence to trash nature. The best outcome is still to protect important habitats in the first place.
For landowners and farmers, BNG may provide a new income stream for managing land in a way that benefits wildlife.
A farmer might take a block of low-diversity improved grassland and restore it into species-rich meadow. An estate might create wetland, woodland pasture or hedgerow networks. A landowner with land near development pressure might be able to sell biodiversity units to local developers.
However, entering the BNG market is not the same as joining a short-term environmental scheme. It is a long-term commitment. The habitat must usually be legally secured and managed for at least 30 years.
That means the landowner is agreeing to deliver and maintain specific ecological outcomes over time.
This could affect:
BNG can be an excellent opportunity, but it needs careful thought.
Land that is suitable for BNG often has good potential for biodiversity uplift. This usually means land that is not already at very high ecological value but could be restored or enhanced.
Examples might include:
Ironically, land that is already very biodiverse may not always generate as many new units, because BNG is based on improvement from the baseline. Existing species-rich land is extremely valuable ecologically, but there may be less additional uplift to sell.
That said, protecting and enhancing existing habitats can still be part of a wider BNG strategy.
BNG projects can take many forms. Some may look like traditional conservation work, while others may fit well into regenerative farming systems.
Examples include:
Species-Rich Grassland: Improved grassland can sometimes be restored into a more diverse meadow using reduced fertility, appropriate cutting, conservation grazing and seed introduction. This can benefit pollinators, birds, soil biology and wildflowers.
Hedgerow Restoration: Planting, laying and managing native hedgerows can create valuable wildlife corridors. Hedgerows provide food, shelter and nesting habitat for birds, insects, bats and small mammals. They also help with shelter, water movement and landscape connectivity.
Ponds and Wetlands: Creating ponds, scrapes, wet grassland or reedbeds can support amphibians, invertebrates, birds and wetland plants. Wetlands can also help slow water flow, store carbon and improve water quality.
Traditional Orchards: Traditional orchards can be valuable mosaic habitats, especially when combined with low-intensity grazing, wildflower grassland, deadwood, old trees and hedgerows.
Woodland and Scrub Mosaic: Native woodland, wood pasture and scrub can provide excellent habitat when designed well. Scrub is often undervalued, but it can be incredibly important for birds, insects and mammals.
River and Stream Restoration: Watercourse units can be valuable, but river restoration is specialist work. It may involve restoring natural river edges, reconnecting floodplains, planting riparian buffers or improving in-stream habitat.
The standard minimum period for BNG habitat management is 30 years. This is one of the most important points for landowners to understand.
A 30-year agreement is a serious commitment. It means the land must be managed according to an agreed habitat management and monitoring plan. The habitat must be created, maintained, monitored and reported on.
This is not a “plant it and forget it” arrangement.
Habitats can fail if they are badly designed, poorly managed, overwhelmed by weeds, affected by drought, overgrazed, undergrazed or neglected. Responsibility for failure will depend on the legal agreement, but landowners should make sure risks are clearly understood before signing anything.
Off-site BNG land usually needs to be legally secured through a planning obligation or conservation covenant.
A planning obligation, often known as a Section 106 agreement, is made with a local planning authority. A conservation covenant is a private legal agreement between a landowner and a responsible body.
These agreements make the habitat management commitment legally binding. They ensure that the biodiversity gain is not just promised, but secured for the long term.
Land used for off-site BNG also needs to be registered on the biodiversity gain sites register before units can be allocated to a development.
BNG can work well with regenerative farming, but only if the design is thoughtful.
Many regenerative practices support biodiversity, such as:
However, BNG requires defined habitat outcomes. Regenerative farming is often more whole-system and adaptive, while BNG can be more prescriptive because the habitat targets must be measured and legally secured.
The best approach may be to use BNG on parts of the farm where long-term habitat restoration makes sense, while keeping other areas flexible for food production, agroforestry, grazing or future enterprise.
For example, BNG might support:
The key is not to let BNG dictate the whole farm design unless it genuinely aligns with the long-term vision for the land.
Yes, landowners can potentially earn money from BNG by selling biodiversity units to developers. However, the income varies hugely depending on location, habitat type, local demand, unit availability, legal costs, ecological potential and market conditions.
BNG is not priced simply by the acre. The value comes from the number and type of biodiversity units generated.
A small area of high-value habitat in the right location may be worth more than a larger area of lower-value habitat somewhere with little demand. Watercourse and specialist habitats may command higher prices, but they also require more expertise and careful management.
Landowners need to account for costs, including:
A headline unit price is not the same as profit. The important figure is the net return after 30 years of obligations and costs.
If done well, BNG could bring several benefits.
For nature, it can help create and restore habitats that might otherwise lack funding. It can support pollinators, birds, mammals, insects, plants, soil organisms and aquatic life.
For communities, it can improve access to green space, reduce flood risk, improve air quality, support wellbeing and make places more attractive.
For developers, it provides a clear framework for meeting biodiversity obligations and securing planning permission.
For landowners, it may provide long-term income from nature restoration and offer a way to diversify beyond conventional farming or land rental income.
For regenerative farmers, it may help fund landscape features that also support soil health, water management, shelter, resilience and ecological function.
BNG is not without criticism.
Some people worry that it could allow developers to damage habitats in one place while creating replacement habitats somewhere else. Others argue that biodiversity is too complex to be reduced to a metric.
There are also concerns about enforcement. A habitat may look good on paper, but will it really be delivered and maintained for 30 years? Local planning authorities need enough ecological expertise and resources to monitor commitments properly.
Another issue is time lag. If mature habitat is lost and replaced with newly created habitat, it may take many years for the new habitat to reach its target condition. Some habitats are extremely difficult, or impossible, to recreate.
BNG also needs to avoid becoming a box-ticking exercise. Real nature recovery depends on good design, local ecological knowledge, long-term management and honest monitoring.
Before entering a BNG agreement, landowners should get professional advice and ask some important questions.
These include:
A proper feasibility study is usually the best first step. This should include a baseline habitat survey, an indicative biodiversity metric calculation and a realistic assessment of the business case.
BNG is part of a much bigger shift in how society values land. Land is no longer seen only in terms of food, housing or development. It is also being valued for carbon storage, water management, biodiversity, flood resilience, landscape beauty, public health and climate adaptation.
For farmers and landowners, this creates both opportunities and challenges.
The opportunity is that nature recovery may become a real income stream, helping to fund habitat creation and long-term stewardship.
The challenge is that these markets can be complex, uncertain and legally binding. Farmers and landowners need to make sure they are not giving away too much flexibility or taking on poorly understood liabilities.
BNG could be a powerful tool for restoring nature, especially if it supports joined-up habitats across whole landscapes. But it must be used carefully, with ecological integrity at its heart.
Biodiversity Net Gain is a system that requires most developments in England to leave nature in a better state than before. Developers must usually deliver at least a 10% improvement in biodiversity value, measured using the statutory biodiversity metric.
They can do this on-site, off-site, or, as a last resort, by buying statutory biodiversity credits. For landowners and farmers, the off-site BNG market may create opportunities to earn income by creating or enhancing habitats for wildlife.
However, BNG is not a quick or simple scheme. It usually involves a 30-year commitment, legal agreements, habitat management plans, ecological monitoring and long-term responsibility.
For regenerative farmers and nature-minded landowners, BNG could help fund meaningful restoration: species-rich grassland, hedgerows, wetlands, orchards, wood pasture, ponds and wildlife corridors. But it should be approached with care.
The best BNG projects will not simply chase biodiversity units. They will restore living landscapes, connect habitats, support local nature recovery and work alongside food production, water management, soil health and rural livelihoods.
In plain English, BNG is about making development pay something back to nature. The big question is whether we use it as a genuine tool for ecological recovery — or just another planning spreadsheet.
Done well, it could help shift land use towards a future where nature is not treated as an obstacle to development, but as essential infrastructure for life.
Resources
GOV – Understanding biodiversity net gain:
Step by step guide for developers
Step by step guide for land managers
Guide for local planning authorities (LPAs)
Calculate biodiversity value with the statutory biodiversity metric:
