C-DRONE GUIDE · 27 JULY 2026
Urban tree inventory by drone: census, decline detection, price
In a few years, the urban tree has gone from scenery to infrastructure: it is expected to cool streets, absorb rainfall, withstand heatwaves — and fall on no one. That last requirement directly engages the municipality's liability, which must maintain its tree stock with due care; but first it must know it. Yet many municipalities have neither an up-to-date inventory nor a view of their avenues' health. The drone offers an efficient starting point: recording every crown, measuring heights, flagging declining subjects through imagery — so the tree expert is sent where it matters. Method, honest limits and 2026 prices.
Published on 27 July 2026, reviewed on 5 August 2026 — regulations in force as of August 2026.
The census: every crown, its height, its position
A photogrammetric flight over public spaces produces an orthophoto and a canopy height model: every tree appears with its trunk position, crown extent and height. Over avenues and parks, individual tree detection automates well; the deliverable is a GIS layer of numbered trees, the backbone of an inventory the technical services then enrich (species, estimated age, interventions).
These methods are widely validated: a study by Nevalainen, Honkavaara, Tuominen and co-authors published in 2017 in Remote Sensing showed that combining drone photogrammetric point clouds with hyperspectral imagery detects and classifies individual trees with good success rates (see the study on Google Scholar). In town the difficulty is lower than in dense forest — trees are spaced out — but occlusions (buildings, street furniture) demand careful flight plans.
Spotting decline before it shows from the street
A multispectral sensor adds the health dimension: vegetation indices (NDVI and relatives) reveal crowns whose chlorophyll activity is dropping — water stress, pest attack, decline — sometimes before foliage visibly yellows. Across a municipality, the index map ranks the avenues: this boulevard is fine, that plane-tree mall shows thin crowns needing expert review. After a heatwave, comparison with the previous campaign objectively measures the impact — a concrete argument for greening plans and species choices, in line with urban heat island mapping.
Thermography completes the toolkit in summer — a crown that no longer transpires is a hot crown — following the same logic as crop water stress monitoring. And the flight incidentally detects foreign bodies: Asian hornet nests in the tops, hanging storm-broken branches, invasive mistletoe.
What the drone does not replace: the tree expert
Let us be plain: the drone does not assess mechanical stability. Decay fungi at the root collar, cavities, scaffold-limb cracks, root anchorage — everything that makes a tree break or topple is assessed on the ground by a tree expert, with a tomograph or resistograph where needed. The drone is the prioritisation tool: across a stock of several thousand trees, it designates the few dozen subjects to assess first, and documents the high crowns the expert cannot see from the ground (top necrosis, deadwood hanging over roads).
It is the same complementarity we describe in forest management: imagery sorts, the expert decides. For the municipality, the typical arrangement is a two-part contract — a municipal drone campaign, then targeted assessments — whose total cost stays below systematic ground surveys.
Flight framework and GIS integration
Flying over parks and street avenues means flying in built-up areas: prior notification, professional scenarios, third-party management — the framework detailed in our flying in cities guide. Campaigns are scheduled outside busy hours (early morning for parks) and, for multispectral work, in leaf-on season with stable light: late spring for the reference state, midsummer for stress.
The deliverable is meant to live on: a GIS layer compatible with the green-space management tool, tree identifiers stable across campaigns, and — for municipalities already flying their territory — integration with the municipal orthophoto, of which the tree inventory can be just an extra processing of the same flight. Pooling the two orders is the simplest optimisation.
Prices observed in 2026
Ranges observed in 2026 (excl. VAT):
- Photogrammetric inventory (tree GIS layer: position, crown, height) over a small town's public spaces: €1,500 to €3,500.
- Mid-size municipality (parks + avenues, several thousand trees): €3,000 to €8,000 depending on flown area.
- Multispectral add-on (index map, prioritised list of subjects for expert review): +40 to 60% on the inventory.
- Follow-up campaign (comparative reflight, same identifiers): 60 to 80% of the initial price.
Per tree, the drone inventory typically comes to €1–3 per subject — against tens of euros for a ground census. Request a quote stating the approximate tree count or public-space area, and whether you run a GIS.