An Introduction to Arboricultural Consultancy — All Silva

All Silva · Internal Briefing

The Trees, the Law
& the Paperwork

A plain-English introduction to arboricultural consultancy in the UK — what we produce, why clients commission it, and the rules that shape every project.

Prepared for the All Silva team Audience non-specialist / new starter Scope England & Wales planning context

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An arboricultural consultant is, in essence, a tree expert who writes the reports that let other people make confident decisions — planners deciding whether to approve a development, landowners deciding whether a tree is safe, architects deciding where a building can go.

You don't need to identify a single species or climb anything to be brilliant in this role. But knowing what the documents are for, who reads them, and what legal clock might be ticking will make you genuinely useful from week one. That's what this guide is for.

What's inside

What an arb consultant actually does
The cast of documents (in plain English)
The single most important concept: the RPA
How trees are graded — the cascade chart
The planning journey, from a tree's point of view
Tree Preservation Orders & Conservation Areas
Wildlife law: nesting birds & bats
If you're commissioning a consultant
Glossary of acronyms
References & further reading

01 · The role

What an arb consultant actually does

Arboriculture is the care and management of individual trees (as opposed to forestry, which is about woodland as a crop). A consultant is the advisory, report-writing end of that profession — distinct from a tree surgeon or arborist, who does the physical climbing, pruning and felling.

A reputable consultancy is deliberately independent of the people who cut trees down. Because we don't earn money from doing the tree work, our recommendations carry weight with planning authorities, insurers and lenders — they know the advice isn't quietly steering toward a felling invoice. That independence is a selling point worth understanding early.

The work falls into two broad worlds, and All Silva operates in both:

Development & planning — helping land get built on without needlessly losing valuable trees, and proving to the council that retained trees will survive construction. This is the BS5837 world (sections 2–5 below).
Tree safety & condition — inspecting existing trees to tell an owner whether they're healthy, dangerous, or somewhere in between, so the owner meets their legal duty of care.

Tree condition & safety surveys

also called: tree risk assessment · VTA · duty-of-care survey

Anyone who owns or occupies land has a legal duty to keep their trees reasonably safe, under the Occupiers' Liability Act 1957 (and 1984), with extra obligations for businesses under the Health & Safety at Work Act 1974. The consultant inspects the trees — usually a ground-level Visual Tree Assessment (VTA) — flags defects like decay or weak branch unions, rates the risk, and recommends works plus a re-inspection date. Crucially, the written record is the audit trail that shows a court the owner acted reasonably. Schools, estates, golf courses and large commercial sites are typical clients. Where ground-level inspection isn't enough, specialist kit (sonic tomography, resistograph drilling) can map decay inside the trunk without felling.

For everything else in this guide, we're mostly in the planning world — because that's where the document trail gets long, the deadlines get real, and a good VA saves the day.

02 · The deliverables

The cast of documents

When trees sit on or near a development site, the council will usually require a specific sequence of reports. They sound interchangeable but each does a different job, and they're produced in a deliberate order. Here's the whole cast — keep this section bookmarked.

BS5837 Tree Survey

the foundation document — everything else builds on it

Named after the British Standard BS5837:2012 — Trees in relation to design, demolition and construction. The consultant inspects every relevant tree on and near the site and records its species, height, trunk diameter, crown spread, condition, estimated remaining life, and a quality category (see section 4). The output is a schedule of trees — effectively a spreadsheet, one row per tree. It deliberately ignores whether a tree is "protected"; quality is judged on the tree's own merits.

Tree Constraints Plan (TCP)

the survey, drawn on a map

A scaled drawing (produced in CAD) that plots each surveyed tree and draws its Root Protection Area and canopy as a footprint. It shows the design team, before a single line of the building is drawn, where the trees' "no-go" zones are. It turns the spreadsheet into something an architect can design around.

Arboricultural Impact Assessment (AIA)

also written as AIA or "arboricultural implications assessment"

Once a layout is proposed, the AIA judges its effect on the trees: which trees must go, which are retained, how much of each Root Protection Area is encroached upon, and whether the harm is acceptable. It's the document that argues the case — "yes, T17 is removed, but it's a low-quality category C tree, and the net effect is acceptable with mitigation planting."

Arboricultural Method Statement (AMS)

the "how we'll protect them" rulebook

A practical, step-by-step protocol for keeping retained trees alive through demolition and construction: where fencing goes, how foundations near roots are dug, how services are routed, what's banned inside the protection zones (no storage, no concrete washout, no level changes). When the council attaches a planning condition requiring tree protection, the AMS is usually what discharges it.

Tree Protection Plan (TPP)

the AMS, drawn on a map

The companion drawing to the AMS — a site plan showing exactly where protective barriers and Construction Exclusion Zones sit, so the site manager can set them out with a tape measure.

Arboricultural Supervision / ACoW

ACoW = Arboricultural Clerk of Works — boots on site

For sensitive sites, the council may require an arboriculturist to actually attend during the risky phases — a pre-commencement meeting, then periodic monitoring visits — and certify that protection measures were followed. This on-site supervision is often handled by a subcontracted arboriculturist working to All Silva's instruction.

Why the order matters You can't write an AIA without a survey; you can't write a method statement until a layout exists to protect against. When a brief lands, the first question is always "where in this sequence are we?" — it tells you which document is being commissioned and what must already exist.

03 · The core concept

The single most important idea: the RPA

If you remember one technical concept, make it this one. The Root Protection Area (RPA) is the notional circle of soil around a tree that must be left undisturbed for the tree to survive. Almost every argument in a tree report comes back to whether something is happening inside or outside an RPA.

The counter-intuitive part — and the thing most clients get wrong — is that most of a tree's roots are shallow and spread far wider than the branches. Around 90% of roots sit in the top metre of soil, and they can extend well beyond the canopy. So a trench just half a metre deep for a cable or drain, dug in the wrong spot, can kill a mature tree that looks perfectly fine for another two years before it slowly declines.

Figure 1 — The RPA extends beyond the canopy. The protected zone of soil is wider than the branches you can see. Roots are shallow and spreading, which is why shallow trenching far from the trunk is so damaging.

How the RPA is calculated

BS5837 gives a formula a VA can sanity-check: measure the trunk diameter at 1.5m height (this is the DBH — diameter at breast height), then the RPA is a circle with a radius of 12 × the stem diameter. The standard caps a single-stem tree's RPA at 707m². The circle can be re-shaped on a plan to dodge an existing building, but it must keep the same area. You'll see these numbers flowing straight from the survey schedule onto the constraints plan.

Plain version Bigger trunk → bigger protected circle. The RPA is the project's main bargaining chip: a planner will accept minor encroachment (often guided around 10–20% of the area, with justification) but will resist a design that drives a foundation through the heart of a good tree's roots.

04 · Grading trees

How trees are graded — the cascade chart

BS5837 sorts every surveyed tree into one of four quality categories using a "cascade chart". It's the bit non-specialists — including planning inspectors — find most useful, because it turns subjective judgement into a shared shorthand. The categories come with standard colours that you will see on every tree plan, so they're worth memorising.

A HIGH QUALITY

Trees of high value — good examples of their species, prominent, long remaining life. Worth real effort to retain. Drawn in green.

B MODERATE QUALITY

Decent trees with a fair life expectancy that merit retention but aren't exceptional. The most common category. Drawn in blue.

C LOW QUALITY

Young, small, or unremarkable trees of limited value — retain if convenient, but they shouldn't block a sensible design. Drawn in grey.

U UNSUITABLE FOR RETENTION

Dead, dying or dangerous — trees you'd expect to lose within ~10 years regardless of any development. Drawn in red.

This grading is the quiet engine of every impact assessment. Removing three category U and a couple of category C trees is an easy story to tell a planner. Removing a category A tree is a fight you'd usually design hard to avoid. When you see a report wrangling over "strategic wording," it's frequently about defending or down-grading a borderline B/C tree.

Figure 2 — The cascade, simplified. The real chart has sub-categories (1 = arboricultural, 2 = landscape, 3 = cultural value), but the headline grade is what drives decisions.

05 · The process

The planning journey, from a tree's point of view

Here's how the documents from section 2 slot into a real development. BS5837 sets out a logical sequence so that trees are considered before the design is fixed, not bolted on afterwards as an apology.

Survey first

Before anyone designs anything, every relevant tree is inspected and scheduled (the BS5837 survey).

Map the constraints

The Tree Constraints Plan draws the RPAs so the architect can see the no-go zones.

Design around the trees

The design team places buildings, access and services to keep the best trees and their roots intact.

Assess the impact

The AIA judges the proposed layout — what's lost, what's kept, whether it's acceptable, and what replacement planting compensates.

Submit with the application

The survey, plans and AIA go in as part of the planning application to the Local Planning Authority (LPA). The council's Tree Officer reviews them.

Permission & conditions

If approved, the LPA usually attaches conditions — e.g. "no development until an Arboricultural Method Statement is approved." These must be formally discharged.

Protect & build

The AMS and Tree Protection Plan govern the build. Fencing goes up; on sensitive sites an arboriculturist supervises and signs off.

The term you'll hear constantly "Discharging a condition." A planning permission is rarely a clean yes — it's a yes with strings. Each string (condition) needs its own little submission and approval. A large share of an arb consultancy's repeat revenue is exactly this: producing the AMS or detail that discharges a tree-related condition after permission is granted.

The felling-licence wrinkle

Separately from planning, felling a significant volume of timber outside a garden can need a felling licence from the Forestry Commission. It rarely bites on the small urban sites we mostly handle, but it's worth knowing the phrase exists so it doesn't blindside you in a brief.

06 · Statutory protection

Tree Preservation Orders & Conservation Areas

Some trees carry legal armour. Recognising it early can be the difference between a smooth project and a criminal offence, so this is one of the highest-value things to flag in an enquiry.

Tree Preservation Orders (TPOs)

A TPO is a legal order made by a council to protect a specific tree, group, or woodland it judges valuable to the public. The power sits in the Town and Country Planning Act 1990, with the detail in the Town and Country Planning (Tree Preservation) (England) Regulations 2012. The Government's plain-English guidance lives on GOV.UK.

Once a TPO is in place it is an offence to cut down, top, lop, uproot, or wilfully damage the tree — including cutting its roots — without the council's written consent. Penalties are serious: fines up to £20,000 in a magistrates' court, and unlimited in the Crown Court. TPOs come in four flavours you'll see referenced on orders: individual, group, area, and woodland.

Checking status is a routine early task — most councils have an online map or register, and it shows on a property's land-charges search.
Dead trees can be removed without consent, but you must give the council 5 working days' notice first so they can verify it really is dead. (This exact scenario — a reportedly dead tree mid-application — is a live issue we've navigated.)
A full planning permission can override a TPO — if consent is granted for a development that necessitates removing a protected tree, the TPO doesn't separately block it.

Conservation Areas

A Conservation Area is a designated district of special architectural or historic interest. Trees within one get an automatic, lighter-touch protection even without a TPO. The mechanism (a "section 211 notice") is simple to remember:

Figure 3 — The Conservation Area clock. You give the council six weeks' written notice of intended works; they either consent, do nothing (work then proceeds), or make a TPO to protect the tree properly.

Rule of thumb A TPO overrides Conservation Area rules — where both apply, follow the (stricter) TPO consent route. And remember the precedence the other way too: a granted planning permission can clear the way through a TPO.

07 · Wildlife law

Nesting birds & bats

Even a completely unprotected tree on private land can't simply be cut whenever convenient. Wildlife legislation runs in parallel to planning law, and timing is everything — which makes it a classic VA flag when a client wants work done "next week."

Nesting birds — a seasonal window

Under the Wildlife and Countryside Act 1981, it's an offence to intentionally damage or destroy the nest of any wild bird while it's in use or being built, or to harm the eggs or chicks. The practical effect: tree and hedge work is usually pushed outside the nesting season, commonly taken as March to August (some bodies stretch it February–September to be safe). Work inside that window isn't banned outright, but it requires a careful pre-works check by a competent person, and the legal risk sits with whoever does the cutting. The RSPB's summary is a good lay reference.

Bats — protected all year, every year

Bats are far stricter. All British bat species and their roosts are protected under the same Act and the Conservation of Habitats and Species Regulations 2017. A roost is protected whether or not bats are present at the time — so a hollow or crevice-rich tree can't be felled on the assumption it's empty. If bat potential is suspected, a qualified ecologist must assess it before works, and a Natural England licence may be needed. The Bat Conservation Trust is the go-to authority.

Figure 4 — The wildlife calendar. Birds create a seasonal block (roughly March–August); bats require assessment regardless of the month. The quiet windows for routine tree work are autumn and winter.

The VA instinct to build When a client says "we need this tree gone soon," three questions decide the timeline: Is it protected (TPO / Conservation Area)? Is it nesting season? Could it hold bats? Any "yes" changes the route — and All Silva looking smart for spotting it is exactly the value clients pay for.

08 · The client's view

If you're commissioning a consultant

Most enquiries we field come from people who half-know they need something but not what. Here's the shape of when an arb consultant is needed and what a good one looks like — useful both for understanding our clients and for triaging enquiries.

When you need one

Building near trees

Any planning application with trees on or beside the site will likely need a BS5837 survey and supporting documents.

A planning condition

Permission granted "subject to" a tree method statement or protection plan — that condition needs discharging.

Managing tree safety

Owning land the public uses (school, estate, car park) means a duty of care best met with a documented inspection.

Protected-tree works

Wanting to prune or fell a TPO or Conservation Area tree needs a properly argued consent application.

A mortgage or insurance ask

Lenders sometimes demand a tree report where a large tree sits close to a property (subsidence concern).

A dispute or claim

Neighbour disagreements, subsidence claims, or alleged unlawful works often need independent expert evidence.

What a credible consultant looks like

Professional standing — membership of the Arboricultural Association, ideally an Registered Consultant, plus relevant qualifications. (All Silva's principal carries the Professional Member designation, M.Arbor.A.)
Independence — a consultancy that doesn't also sell the felling work gives advice the council and insurers trust.
Professional indemnity insurance — essential, because these reports carry real liability.
Local knowledge — familiarity with the specific LPA's expectations and Tree Officers speeds approvals.
Clear scope & fees — a good proposal states exactly which documents are included and what isn't, so there are no surprises when a council asks for "one more thing."

How All Silva frames this — the four tiers

Our packages — Survey, Assess, Protect, Mitigate — are a ladder that climbs with the project's complexity. Survey establishes what's there; Assess adds the impact assessment so the application is submission-ready; Protect adds the method statement and detailed protection plan that keep trees alive through the build (and pre-empt a pre-commencement condition); and Mitigate is the tree-planting package — a replacement planting scheme, a planting schedule, and a 10-year aftercare & management report, for complex sites or where felling is likely. When you're handling enquiries, placing a client on the right rung is half the job done.

Deliverable	Survey	Assess	Protect	Mitigate
Best for	Feasibility & design	Simple, low-risk sites	Standard development	Complex / felling likely
BS5837 Tree Survey	✓	✓	✓	✓
Tree Constraints Plan (TCP)	✓	✓	✓	✓
Impact Assessment (AIA)	—	✓	✓	✓
Planning submission ready	limited	✓	✓	✓
Tree Protection Plan (TPP)	—	outline	detailed	detailed
Method Statement (AMS)	—	—	✓	✓
Engineering solutions	—	—	✓	✓
Tree planting plan & schedule	—	—	—	✓
10-year aftercare report	—	—	—	✓

The default recommendation For most sites where trees are retained, Protect is the recommended package — it produces the AMS and detailed TPP up front rather than waiting for the LPA to impose a pre-commencement condition. Assess suits simple, low-impact sites where the proposals don't touch any Root Protection Areas. The consultant advises which fits; your job is to recognise roughly where an enquiry sits.

09 · Cheat sheet

Glossary of acronyms

The alphabet soup, decoded. Bookmark this — it's the fastest way to look fluent in your first month.

BS5837: The British Standard governing trees in relation to design, demolition & construction (2012 edition). The backbone of all development tree work.
RPA — Root Protection Area: The circle of soil around a tree that must stay undisturbed. Radius = 12 × stem diameter.
DBH — Diameter at Breast Height: Trunk diameter measured at 1.5m. Feeds the RPA calculation.
TCP — Tree Constraints Plan: The survey drawn to scale, showing RPAs and canopies.
AIA — Arboricultural Impact Assessment: The report judging a design's effect on trees.
AMS — Arboricultural Method Statement: The how-to for protecting retained trees during construction.
TPP — Tree Protection Plan: The drawing showing fencing and exclusion zones.
CEZ — Construction Exclusion Zone: The fenced no-access area around a protected tree on site.
VTA — Visual Tree Assessment: Ground-level inspection of a tree's condition and safety.
TPO — Tree Preservation Order: A council's legal order protecting a tree; breach can mean a £20,000 fine.
LPA — Local Planning Authority: The council body that decides planning applications. Its Tree Officer reviews our reports.
ACoW — Arboricultural Clerk of Works: On-site supervision and certification during construction.
QTRA / VALID: Two recognised systems for quantifying tree risk in safety surveys.

10 · Sources

References & further reading

Every link below is an authoritative primary or sector source — safe to cite, safe to send a client.

BS5837:2012 — the British StandardBSI Knowledge TPOs & trees in conservation areasGOV.UK planning guidance Town and Country Planning Act 1990legislation.gov.uk Tree Preservation (England) Regs 2012legislation.gov.uk Wildlife and Countryside Act 1981legislation.gov.uk Habitats & Species Regulations 2017legislation.gov.uk Occupiers' Liability Act 1957legislation.gov.uk Trees & planning permissionPlanning Portal Registered Consultant DirectoryArboricultural Association Birds & the law, explainedRSPB Bats, trees & the lawBat Conservation Trust Plain-English TPO guideWoodland Trust