What Biodiversity Net Gain Means on the Ground

Biodiversity net gain (BNG) is now part of the planning system in England. The principle is straightforward: new development must leave nature measurably better off, usually by at least a 10% increase in biodiversity value. Developers can achieve this on-site, but many cannot. That is where small landowners come in.

The biodiversity metric measures habitats in units. Woodland, species-rich grassland, ponds and hedgerows all have a value based on their size, condition, distinctiveness and location. If you create or improve habitat on your land, you may be able to sell those units to developers who need them. You can also use them for your own planning application, such as a barn conversion or new dwelling.

This is not a quick scheme. Off-site gains normally require a legal agreement, a management plan and a commitment of at least 30 years. But for the right piece of land, it can provide a modest, steady income alongside genuine wildlife benefits.

Why Small Parcels Still Count

You do not need hundreds of acres. A wet corner, a tired hedge and a strip of rough grass can add up. Ponds and hedgerows often score well in the metric because they are distinctive and support a wide range of species. A single well-designed pond of 100 square metres can be more valuable than a larger area of improved grassland.

• Half an acre or more can be worth assessing if it sits near a river, woodland or other semi-natural habitat.
• Connectivity matters. Units are worth more when habitat joins up with existing wildlife corridors.
• Local demand varies. Check your local planning authority's area and any emerging Local Nature Recovery Strategy.
• Stacking is possible in some cases, but you cannot claim BNG payments and agri-environment payments for the exact same activity on the same land. Take advice before committing.

Ponds: Small Water, Big Gains

A wildlife pond is one of the most effective things you can create. Aim for gently sloping sides, shallow margins and a depth of around 1.5 metres in the middle. Avoid stocking fish, which eat larvae and tadpoles. Native plants such as water forget-me-not, marsh marigold and hornwort will establish naturally if the water is clean.

• Location: part sun, part shade, away from large trees to reduce leaf fall.
• Size: at least 25 square metres, but bigger is better. A cluster of ponds is more resilient than one.
• Management: leave rough grass around the edge, fence from livestock, and never use fertiliser or pesticide nearby.
• Wildlife: expect dragonflies, damselflies, frogs, newts, bats and thirsty birds within a season or two.

Hedgerows: The Original Wildlife Corridor

A good hedge is a highway, a larder and a nest site in one. Plant native species: hawthorn, blackthorn, hazel, field maple, dog rose, guelder rose and holly. Use whips of 30 to 45 centimetres, planted in two staggered rows about 40 centimetres apart. Water well in the first summer.

• Structure: aim for a dense base, a wide bottom and a trimmed top. A rounded profile lets light reach the base.
• Laying: traditional hedge laying every 10 to 15 years rejuvenates the hedge and thickens it.
• Gaps: fill any gap wider than two metres with new whips. Gaps reduce condition scores.
• Margins: leave a two-metre uncultivated strip on both sides. This rough margin is vital for nesting birds and small mammals.

Wildflower Areas That Work with Your Land

Species-rich grassland needs low fertility. If your soil is enriched from years of grazing or fertiliser, you may need to remove topsoil or take repeated hay cuts before wildflowers will thrive. Yellow rattle is a useful ally: it weakens grasses and gives flowers a chance.

• Seed: use native, local-provenance seed or green hay from a nearby donor site.
• Cutting: take a hay cut in late July or August, then remove the cuttings. Graze the aftermath lightly.
• Patience: a flower-rich sward can take three to five years to establish.
• Size: even a 10-metre by 20-metre strip can count, especially if it links to a hedge or pond.

Making It Pay Without Losing the Plot

Before you commit, get a baseline survey from an ecological consultant. They will use the statutory biodiversity metric to calculate your existing units and estimate what you could create. You will also need a management plan, a legal agreement such as a conservation covenant, and registration on the national biodiversity gain site register.

Think about the long term. Thirty years is a long time, and the habitat must be managed, not just created. Budget for monitoring, hedge laying, pond maintenance and hay cuts. Choose habitats that suit your land and your abilities. A damp hollow that wants to be a pond will always outperform a dry field forced into a wildflower meadow.

Most importantly, this is countryside living at its best: practical, patient work that leaves your land richer than you found it. Start small, record everything, and enjoy the dragonflies.