How Planted Trees Are Verified: Satellite, GPS, Drones and Field Data

A planted tree is only as credible as the evidence behind it — and credible reforestation uses four layers of verification: satellite imagery to plan and watch the site, handheld GPS to record boundaries and individual trees, drone mapping to measure growth from above, and field inventory plots to count what actually survived. This is what separates a traceable planting programme from a headline number, and it is the part most buyers never think to ask about.

The four layers, and what each one answers

• Satellite imagery — what was here before, and what is here now? Establishes the pre-planting baseline and tracks canopy change over years.
• Handheld GPS — where exactly is this site, and where exactly is this tree? Produces the coordinates behind every certificate.
• Drone mapping — how is it developing between satellite passes? Centimetre-scale detail on growth, gaps and failures.
• Field inventory — how many are actually alive? The only layer that answers the survival question honestly, because it involves someone walking the site.

No single layer is sufficient. Satellite alone cannot tell you a sapling died; a field count alone cannot prove the site was not already forested. Used together they make a planting claim checkable by someone who was not there.

Satellite: the baseline nobody can retrofit

Before planting begins, satellite imagery establishes what the land was: bare, degraded, previously forested, or — critically — already an intact ecosystem that should not be planted at all. That baseline matters because it is the one piece of evidence that cannot be reconstructed after the fact. A project that cannot show you its pre-intervention imagery is asking you to take the most important claim on trust.

Afterwards, the same imagery tracks canopy development, detects disturbance such as fire or clearing, and gives an independent check on what field reports say. It is the layer that makes a claim auditable years later, by anyone, without a site visit.

Handheld GPS: from "somewhere in Kenya" to a coordinate

On the ground, field teams use handheld GPS units to demarcate the site boundary and record planting positions. This is unglamorous work and it is where traceability is actually created. It produces two things a buyer can use:

1. A verifiable site polygon — the boundary within which the planting happened, checkable against the satellite baseline.
2. Per-tree coordinates — the GPS pin that appears on a certificate, turning an abstraction into a place on a map.

The difference between "we planted 10,000 trees in East Africa" and a set of coordinates inside a mapped polygon is the difference between a marketing claim and a record. Every Evertreen tree carries the latter.

Drone mapping: the detail satellites miss

Drones fill the resolution gap. Flown over a site, they capture overlapping high-resolution photographs that are stitched into an orthomosaic — a single, geometrically corrected aerial map where distances and areas can be measured accurately rather than estimated.

That gives project teams several things satellites cannot provide at useful resolution: individual crown identification on young plantings, precise measurement of gaps where establishment failed, evidence of encroachment or grazing damage, and repeatable flight paths so the same area can be compared season to season. Where satellite imagery tells you a site is greening, an orthomosaic tells you which parts are not, and by how much — which is what actually drives replanting decisions.

Field inventory: the layer that decides the number

Everything above is remote sensing, and remote sensing cannot count a dead sapling under a canopy. That is what forest inventory is for.

Field teams record what was planted, then return to measure what survived using semi-random circle plots: sampling points distributed across the site, within which every tree is counted, identified and assessed. Because the plots are sampled rather than exhaustive, a whole site can be characterised without walking every metre of it, and because their placement is semi-random rather than chosen, the result cannot be flattered by surveying only the healthy patches.

From those plots come the numbers that matter: survival rate, species composition, growth rates and health indicators. Survival is the metric that separates serious programmes from promotional ones — planting figures are trivially easy to publish, while survival requires somebody to go back and look.

Why this matters for your reporting

Verification is not a technical footnote; it is what makes a corporate claim defensible. A stakeholder, an auditor or a journalist asking "how do you know?" should receive coordinates, imagery, a survival figure and a methodology — not a press release.

It also disciplines the carbon maths. Absorption estimates depend on how many trees are alive, of what species, at what age — which is why Evertreen publishes its assumptions in how we estimate tree CO₂ and applies conservative, species-specific values that already allow for mortality. An impressive per-tree figure attached to an unverified survival rate is arithmetic built on sand.

The wider point applies well beyond planting: plot-level geolocation is becoming the default expectation for environmental claims, from supply chains under the EU deforestation regulation to carbon credits. "Prove it, with coordinates" is the direction of travel.

What to ask any planting partner

1. Can you show me the pre-planting satellite baseline for this site?
2. Can you give me the coordinates of an individual tree?
3. What is the measured survival rate, and how was it sampled?
4. Who does the field monitoring, how often, and are they paid to maintain the site?
5. What happens when a section fails — is it replanted, and is that recorded?
6. Is the CO₂ methodology published, or just the headline number?

A partner who can answer all six without hesitating is rarer than it should be. You can see how Evertreen answers them across its planting projects, or start with the trees available to plant from £1.5 each — each one geolocated, photographed and filmed in the field.

Frequently asked questions

How are planted trees verified? Through four combined layers: satellite imagery for baseline and change, handheld GPS for boundaries and per-tree coordinates, drone mapping for high-resolution growth measurement, and field inventory plots for measured survival.

What is an orthomosaic map? A single geometrically corrected aerial image stitched from many overlapping drone photographs, accurate enough that distances and areas can be measured directly from it.

What are forest inventory circle plots? Sampling points distributed semi-randomly across a site, within which every tree is counted and assessed, so survival and growth can be estimated for the whole site without surveying all of it.

Why is survival rate more important than trees planted? Because planting figures are easy to publish and survival is what determines whether a forest actually results. Carbon estimates depend on surviving trees, not planted ones.

Can satellites confirm individual trees? Not reliably for young plantings. Satellites establish baselines and track canopy change; individual-tree confirmation comes from GPS records, drone imagery and field visits.

How often should a site be monitored? Most intensively in the first three years, when establishment is decided, then periodically to confirm the forest is developing and has not been disturbed.

What evidence should a company receive? Coordinates, project and species detail, imagery or video from the site, a measured survival figure, and a published carbon methodology.