Thirty years. That's the statutory minimum for any habitat contributing to a development's BNG requirement—whether on-site, off-site, or delivered through a habitat bank. The obligation runs from when the habitat is created or enhanced, not from when planning permission is granted, and it binds whoever owns the land during that period.
This isn't a target or a guideline. It's embedded in Schedule 7A of the Town and Country Planning Act and secured through legal agreements that run with the land. A developer who sells a site, a farmer who sells a field used for off-site BNG, a habitat bank that changes ownership—the 30-year management obligation transfers to the new owner.
The duration reflects ecological reality. Most habitats don't deliver their full biodiversity value immediately after creation. A newly planted woodland takes decades to develop structural complexity, deadwood, and the species assemblages that make mature woodland ecologically valuable. Wildflower meadows need years of appropriate management before they reach target condition. Wetlands require time for vegetation to establish and invertebrate populations to build.
A shorter period—say, five or ten years—would allow developers to tick the BNG box with habitat that hadn't yet proved itself. The 30-year requirement means habitats must be maintained through the establishment phase and well into maturity, long enough to demonstrate they're genuinely delivering the biodiversity value claimed in the metric calculations.
There's also a practical consideration: 30 years is long enough to outlast most development companies, project teams, and institutional memories. The legal agreements securing BNG need to work even when the people who negotiated them have moved on. Binding the land rather than the individual ensures continuity.
Maintenance isn't passive. Habitats don't look after themselves, and leaving them alone often leads to degradation rather than improvement.
The specific management required depends on habitat type. Grassland needs cutting or grazing at appropriate times to prevent scrub encroachment and maintain species diversity. Woodland may need thinning, ride management, or invasive species control. Wetlands require water level management. Hedgerows need laying or coppicing on rotation.
The Biodiversity Gain Plan and associated legal agreements set out management prescriptions—the specific interventions required, their timing, and the standards to be met. These aren't suggestions. They're obligations, and failure to perform them is a breach of the legal agreement.
Monitoring is also required. Habitat condition must be assessed periodically—commonly at years 2, 5, 10, 20, and 30, though schedules vary—to check whether the habitat is developing as expected and achieving target condition. Monitoring reports typically go to the local planning authority (for on-site habitats secured by section 106) or to the responsible body holding a conservation covenant (for off-site delivery).
Remediation provisions cover what happens if things go wrong. If monitoring shows the habitat isn't meeting its targets—perhaps establishment has failed, or management has been inadequate, or external factors have caused degradation—the legal agreements should specify what corrective action is required. This might mean additional planting, changes to management regime, or in extreme cases, replacement habitat elsewhere.
For on-site BNG, responsibility typically sits with whoever owns or manages the development site. This might be the original developer during construction and early phases, then a management company, housing association, or individual plot owners depending on how the site is structured. The section 106 agreement or planning condition binds the land, so responsibility transfers with ownership.
For off-site BNG, responsibility sits with the landowner or habitat bank operator providing the units. If a developer buys units from a habitat bank, the developer's obligation is to purchase properly secured units—the ongoing management obligation belongs to whoever controls the habitat land. This is why the legal security behind off-site units matters so much: developers need confidence that the provider will actually perform for 30 years.
Conservation covenants add a layer of oversight. The responsible body holding the covenant—which might be Natural England, a local authority, or a conservation charity—has powers to enforce if the landowner fails to manage the habitat as agreed. This provides more robust long-term security than relying solely on council enforcement of section 106 agreements.
Thirty years of habitat management costs money. Grassland needs cutting, fences need maintaining, monitoring surveys need commissioning, ecological consultants need paying. If funding runs out in year 12, the habitat won't be maintained for the remaining 18 years regardless of what the legal agreements say.
This is why financial security is a standard element of BNG legal agreements. Options include:
Upfront endowments—a capital sum paid at the outset, invested to generate income that funds management over 30 years. This requires realistic cost projections and prudent assumptions about investment returns.
Commuted sums—payments from the developer to the LPA or management body, calculated to cover anticipated costs.
Bonds or guarantees—security that can be called on if the responsible party fails to perform.
Ongoing payment obligations—less common, but some arrangements involve periodic payments rather than upfront capital.
The adequacy of financial security is something LPAs and responsible bodies scrutinise when approving Biodiversity Gain Plans and registering habitat sites. A habitat bank that can't demonstrate credible 30-year funding won't get units registered.
The statutory obligation ends at 30 years. What happens then is less clearly defined.
In principle, the landowner could stop managing the habitat, convert the land to other uses, or simply let it develop (or degrade) without intervention. The legal agreements will have expired.
In practice, several factors may sustain habitats beyond the minimum period:
Conservation covenants can be longer than 30 years, or even perpetual, if the parties agree. Some responsible bodies prefer longer terms.
Planning conditions on the original development site may have created permanent green infrastructure—parks, sustainable drainage, landscape buffers—that will be maintained as part of the site's ongoing management regardless of BNG obligations.
Landowner interest may continue. A farmer managing a wildflower meadow for 30 years may choose to continue rather than plough it up, particularly if agri-environment payments or other income streams support ongoing conservation management.
Habitat value may by then be sufficient to attract other protections—local wildlife site designation, for instance—that create separate reasons for continued management.
But none of this is guaranteed. The 30-year period is a minimum, not an assumption about what happens afterwards. Whether BNG delivers permanent biodiversity gains or temporary ones that unwind after three decades depends on factors beyond the current legal framework.
EcoCapital structures off-site BNG delivery with 30-year management secured from the outset. Units come from habitat banks backed by conservation covenants, with management plans, monitoring schedules, and financial arrangements designed to ensure obligations are met for the full term.
For developers, this means purchasing units that won't become a liability if the provider fails to perform—the legal and financial structure is already in place. For the Biodiversity Gain Plan approval process, it means the evidence of 30-year security that LPAs require is ready to submit.
