Over fourteen days, a scanning vehicle moved slowly through Lisbon through the tiled facades of Alfama, the gridded blocks of Baixa rebuilt after the 1755 earthquake, the wide avenues where jacarandas bloom purple each spring, capturing trees.
Roughly twenty thousand of them.
This is what it looks like when a historic Southern European capital begins to understand its urban forest digitally for the first time.
Lisbon has mapped its streets for centuries. It has mapped its tram lines, its drainage, its monuments, its azulejo patterns, its UNESCO heritage sites. Until now, it had never mapped its trees at this resolution. The first phase of the city’s smart tree inventory, completed by greehill in partnership with Lisbon City Council, marks a quiet but meaningful threshold.
The pressure Lisbon’s trees are under
Lisbon is one of the warmest capitals in Europe, and the climate it grew up in is no longer the climate it lives in. Summers arrive earlier, last longer, and reach further. Drought cycles across Portugal have intensified. Tourism has returned at scale, millions of visitors moving through neighbourhoods built for far fewer feet. The historic centre is dense, paved, and steep. The infrastructure beneath it is old. The pressure above it is rising faster than the buildings can adapt.
Trees absorb a remarkable amount of that pressure. They cool streets that would otherwise radiate heat long after sundown. They shade pavements where surface temperatures soar on August afternoons. They slow the rare but increasingly violent rainfall events that overwhelm older drainage systems. In neighbourhoods like Alfama and Mouraria, where the streets are narrow and the buildings tall, a single mature tree can change the temperature of an entire block.
But Lisbon also faces what every city eventually faces: it has many trees, and it does not yet fully know them. Records have accumulated unevenly across departments and decades. Some streets have been surveyed, others have not. Conditions change faster than spreadsheets can be updated. Risk, maintenance, and clearance decisions often rest on partial information. According to the European Environment Agency, Southern European cities face the steepest climate-adaptation curve on the continent over the next two decades and they need to make those decisions with better information than most of them currently have.
What fourteen days of scanning produces
The work itself is more physical than the word “inventory” suggests. A vehicle equipped with mobile LiDAR sensors moves through the city at street speed, sweeping each tree it passes with millions of points of light. Branches, trunks, canopies, the buildings beside them, the lamp posts they sit near, all of it is captured in three dimensions. Over fourteen days, greehill’s team covered Lisbon’s main streets and selected park areas, gathering data on approximately twenty thousand public trees.
Back in software, each of those trees becomes something a city can actually work with: a digital twin with measurable height, crown volume, trunk geometry, structural characteristics, and clearances to surrounding infrastructure. The full inventory connects to the operational decisions a city makes year after year: inspection planning, maintenance prioritisation, structural assessment, long-term monitoring, and broader urban tree management planning.
What this changes for Lisbon
Lisbon held the title of European Green Capital in 2020, and the ambition behind that designation has continued in the years since. This project, supported by Catarina Freitas, sits inside a longer arc, a city that has spent the past decade taking its environmental responsibilities increasingly seriously, now equipping itself with the operational visibility those responsibilities require.
The point is not the dataset. The point is what becomes possible once it exists. Inspections can be prioritised by structural condition rather than by the last time someone happened to walk past. Maintenance budgets can be allocated against measurable need. New plantings can be planned against actual canopy coverage rather than estimated coverage. The city can begin to ask sharper questions: where is shade thinnest in the neighbourhoods that need it most? Which streets are aging out of their canopy and need succession planning now, not in ten years? Which trees are most exposed to the heat events arriving each summer?
These are questions Lisbon could not answer with precision before. It can begin to now.
A wider shift across cities
Lisbon is not alone in this transition. More than 130 cities now work with greehill across climates and continents — some focused on risk, others on climate adaptation, canopy expansion, or clearance management. See how Rome and Chassieu approached similar projects in very different contexts. The specifics vary. The underlying shift does not. Urban forests, long treated as soft infrastructure managed mostly by feel and field experience, are becoming legible at city scale.
Cities have mapped their roads and their utilities for over a century. They are only now beginning to map the living infrastructure running alongside them with comparable precision. Lisbon is among the first Southern European capitals to take that step and almost certainly not the last.
What begins here is not a software project, it is a different relationship between a historic city and the trees that have grown up through its streets.
Frequently asked questions
What is a smart tree inventory? A smart tree inventory is a structured digital dataset of urban trees, typically built from mobile LiDAR scanning. Unlike traditional spreadsheet-based inventories, each tree becomes a measurable 3D digital twin that records dimensions, crown structure, health indicators, and clearances and stays connected to ongoing maintenance workflows.
How many trees did Lisbon scan in the first phase? Approximately 20,000 public trees were captured over 14 days, focused on street trees with selected park areas included.
How does mobile LiDAR scanning work for urban trees? A scanning vehicle drives through city streets at normal speed, capturing high-resolution 3D point clouds of trees and their surroundings. The data is processed into individual digital twins for each tree, recording attributes such as height, crown volume, trunk geometry, and clearance to nearby infrastructure.
Who led the Lisbon smart tree inventory project? The initiative is supported by Catarina Freitas, Municipal Director for Environment, Green Infrastructure, Climate and Energy at the City Council of Lisbon, in partnership with greehill.
What happens after the first phase? The first digital baseline supports ongoing inspection planning, maintenance prioritisation, and long-term monitoring, and creates a foundation for expanding coverage across additional parts of Lisbon’s urban forest.
Interested in how a smart tree inventory could work for your city? Get in touch with the greehill team.
