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The planting is in. The ecology consultant has signed off the biodiversity gain plan. The condition is discharged. You might think that the job’s done, but there’s still work to do.
For many developments, this is precisely where the risk begins. Biodiversity net gain is not a capital works item to be completed and closed out. It is a legal commitment to manage and monitor living habitats for a minimum of 30 years. Getting the installation right matters enormously, but it is what happens in the decades that follow that will determine whether BNG obligations are genuinely met, or quietly unravel.
GOV.UK guidance on biodiversity net gain is unambiguous on this point: the landowner is legally responsible for creating or enhancing habitat and managing it for at least 30 years to achieve the target condition. This applies whether the gain is delivered on-site or off-site.
The mandatory requirement for biodiversity net gain came into force under the Environment Act 2021 for major developments in February 2024, and for small sites from April 2024. Every qualifying development must deliver a measurable 10% uplift in biodiversity value. Crucially, that uplift must be demonstrated and maintained over the long term.
Underpinning this is the Habitat Management and Monitoring Plan, or HMMP. Natural England’s HMMP template frames it explicitly as a plan for managing land over at least 30 years, covering how habitats will be created, enhanced, managed and monitored. It is not a box-ticking exercise. It is a detailed, legally significant framework that sets out management prescriptions, monitoring frequency, reporting obligations and the adaptive actions required if a habitat is failing to reach target condition.
Local planning authorities can take enforcement action where these obligations are not being met. That is not a theoretical risk; it is a provision built into the legislative framework from the outset.
There is a well-established pattern in how construction and development projects handle ecology. Habitat creation gets designed, specified, installed, and then handed over. At that point, responsibility typically passes to whoever manages the site: a facilities team, an estate manager, a grounds maintenance contractor. They often have no BNG-specific brief, and sometimes lack any awareness that the new wildflower meadow or scrub planting they have just inherited is the subject of a 30-year legal obligation.
The consequences can be serious. A newly planted habitat needs time and active stewardship to develop into good ecological condition. Seeding a wildflower meadow does not deliver the target condition on its own: the sward needs managing to the right cutting regime, at the right time of year, with arisings removed. Scrub planting needs to establish correctly. Ponds need to be managed to prevent dominance by a single species. Without that ongoing care, habitats plateau or decline, and biodiversity units that were promised on paper simply do not materialise on the ground.
Context matters here. The State of Nature report found that species studied across the UK have declined by an average of 19% since 1970, and the UK is now considered one of the most nature-depleted countries in the world. BNG was introduced precisely to begin reversing that trajectory. But it can only do so if habitat gains are real, lasting, and properly evidenced.
The HMMP is more than a document to accompany a planning application. Once approved, it becomes the operational guide for how a habitat must be managed across its entire 30-year lifespan.
In practice, this means the plan will specify:
What this demands, in short, is continuity. The same level of ecological understanding that informed the design of the habitat needs to be present throughout its management. That is not something a standard grounds maintenance contract is designed to deliver.
It is worth noting that the Royal Town Planning Institute has highlighted that 41% of local planning authorities are concerned about having sufficient ecological expertise to manage BNG requirements effectively. If that pressure exists at the regulatory level, the importance of rigorous, expert-led aftercare at the site level becomes even more critical.
The gap between habitat installation and long-term habitat management is where BNG is most vulnerable. It rarely involves deliberate neglect. More often, it is the result of the wrong contractor, the wrong brief, or no brief at all.
A wildflower grassland cut on the same schedule as an amenity lawn will lose its botanical diversity within a few seasons. A hedgerow trimmed hard every autumn will not develop the structure that drives biodiversity value. A pond edge strimmed back to the waterline loses the marginal habitat that makes it ecologically functional. These are not dramatic failures: they are gradual, incremental, and easy to miss until monitoring reveals a site that is nowhere near its target condition.
Good habitat management plans exist precisely to prevent this. They translate the ecological intent of a BNG scheme into practical, site-specific management instructions that can be followed by the people on the ground, and audited by the people responsible for compliance.
Effective biodiversity net gain aftercare is structured, evidence-led, and tied directly to the conditions of the approved HMMP. In practice, it involves several interconnected elements.
Every habitat type has its own management requirements, and those requirements may change as the habitat matures. Annual management visits should be guided by what the monitoring is showing, not by a fixed schedule set at the start of the contract and never reviewed.
Monitoring is not a formality. It is the mechanism by which you can demonstrate, to yourselves and to the LPA, that the habitat is progressing as required. Condition assessments should capture species composition, structure, and any emerging pressures such as invasive species or hydrological changes.
Monitoring reports need to be clear, consistent, and filed systematically. When the LPA requests evidence, or when the habitat enters a formal review period, that documentation record is what compliance rests on.
If monitoring shows that a habitat is underperforming, the HMMP will set out what actions should follow. Aftercare that responds to monitoring data by adjusting regimes, addressing problems, and escalating where needed is what separates genuine BNG delivery from paper compliance.
At Great Oaks, we work with clients across Preston and the North West to deliver the full lifecycle of biodiversity net gain, from habitat creation through to long-term maintenance and monitoring.
Our approach starts with the right foundations. Whether that is habitat creation designed to achieve target condition efficiently, or tree planting selected to deliver lasting biodiversity value, the choices made at the outset shape what is achievable over 30 years. Choosing the right trees for BNG, for instance, is not just about species: it is about provenance, structure, and long-term suitability for the habitat type being created.
From there, we provide commercial grounds maintenance that is genuinely aligned with ecological objectives, not generic amenity management applied across a site regardless of what different areas need. For habitats subject to a HMMP, that distinction matters enormously.
We also support our clients through biodiversity projects that span the monitoring and reporting cycle: condition assessments, adaptive management recommendations, and the documentation needed to evidence compliance at every stage of the 30-year obligation.
As an ARB Approved Contractor, with Constructionline Gold accreditation, and with a team that combines arboricultural expertise with a genuine commitment to ecological outcomes, Great Oaks is well placed to be a long-term partner, not just a one-off installer.
Who is responsible for BNG aftercare once a development is complete?
Ultimately, the landowner. GOV.UK guidance makes clear that legal responsibility for habitat management over 30 years sits with the landowner, whether gains are on-site or off-site. In practice, that responsibility is often delegated to estate or facilities teams. This is why having a clear management brief and a competent contractor in place is essential from day one.
What happens if a habitat fails to reach target condition?
The HMMP should specify adaptive management actions to be taken if monitoring shows a habitat is underperforming. Where those actions are not taken, or where obligations are consistently unmet, the LPA has enforcement powers. Early identification of problems through regular monitoring is far preferable to enforcement action further down the line.
Can a standard grounds maintenance contractor manage BNG habitats?
Only if they understand BNG requirements and manage each habitat in line with its HMMP prescriptions. A contractor applying standard amenity management to a BNG habitat, regardless of good intentions, risks steadily undermining the ecological condition the site is meant to achieve.
BNG aftercare is not an optional add-on. It is the mechanism by which habitat gains become real and stay real, for the 30 years the law requires. The ecological and compliance risks of treating it otherwise are significant, and they grow quietly over time.
If you are responsible for a site with BNG obligations in the North West, talk to Great Oaks now. We can help you understand what your HMMP demands, put the right management in place, and keep your site on track, for this year and every year that follows.
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