Back to Chassieu: Three Years of Smart Urban Forestry

Every two years, Paysalia brings France’s landscape and urban-nature community to the Lyon region. It’s the country’s flagship trade show for everyone who plans, builds, or manages living green systems from municipal teams and arborists to designers, engineers, and policymakers. This year, that gathering lands in Chassieu, and for us it feels less like a stop on the calendar and more like a return to a place that helped shape our work in France from the very beginning.

Chassieu sits on Lyon’s eastern edge, in a region where the relationship between city and landscape has always been practical rather than ornamental. It was the first municipality in France to adopt greehill in 2023. For the past three years, its teams have used the platform not as a static inventory, but as an operational backbone for understanding their tree population as a living system, something that evolves across seasons, budgets, and climate pressure. Coming back this week alongside our partner ONF Vegetis is therefore a reminder of how change typically happens: the future of urban forestry arrives first where people decide to begin early, without waiting for perfect conditions.

A territory that chose to see its trees as a system  

Every city knows it has trees. The harder question is whether a city can really see what those trees need next and act before small stresses become structural problems. The gap is rarely about intention, but about scale and speed. Urban trees are asked to work harder each year:

• cooling streets through longer heat waves,

• buffering storms that arrive out of season,

• holding biodiversity in compressed habitats, and

• doing all of this under constant pressure from soil compaction, drought, pests, and construction.

  
  

Meanwhile, many of the tools cities still rely on were designed for slower change: partial inventories, manual routines, and knowledge that lives in a few experienced heads, updated too infrequently to keep pace with reality.

Chassieu decided to strengthen that human expertise with a shared, updatable baseline of their trees’ condition and structure. Not once, as a snapshot, but continuously so that the city can monitor change, compare patterns year to year, and plan care with confidence instead of guesswork.

What a digital baseline makes possible

A greehill inventory turns a tree population into a readable landscape: structural profiles, canopy volume, early stress signals, spatial competition, and patterns of risk. That clarity is not an end in itself; it’s a working tool that lets municipal teams answer practical questions with far more certainty than before.

• Where are early warning signs emerging before decline becomes obvious from the street?

• Which trees need action now, and which can safely wait without increasing risk?

• How can work be grouped so crews and budgets are used efficiently, without losing precision?

  
  

The change sounds simple, but it shifts everything. Instead of reacting to scattered events, cities can steer their tree population deliberately. Instead of relying on memory, they can rely on a baseline that evolves as the trees evolve.

And what it never overrides  

Digitalisation can sharpen vision, but its job is not to take the wheel. greehill does not tell cities what to value, it does not dictate priorities, and it does not decide what to cut, plant, or protect. Cities keep full sovereignty over their data and over how they use the platform because every territory carries different goals, constraints, politics, and ecological realities.

Some municipalities use the baseline primarily to guide maintenance planning and budgeting. Others focus on risk prevention and safety strategies. Many connect it to climate adaptation, using evidence to decide where shade is missing, where stress is building, and where care needs to change. Some use it to align departments around one shared reality, so that operational teams, planners, and decision-makers are not working from different versions of the truth. The platform provides clarity. What that clarity becomes remains a municipal choice, shaped by local context.

Why partnership matters: data meets the living tree

If digitalisation stops at data, it stays abstract. Trees don’t inhabit datasets, they inhabit soil, drought, compaction, pruning history, pests, wind loads, and human pressure. They respond to context as much as they respond to climate. That is why our partnership with ONF Vegetis matters, as they bring the field intelligence that completes the digital picture: the trained arborist eye, diagnostic experience and species-level nuance.

In practice, the relationship is straightforward. greehill expands visibility; ONF Vegetis turns visibility into grounded action. Together, this allows cities to manage trees the way they manage any critical system: with continuity, prioritisation, and accountability, without losing the biological reality of what a tree is.

Paysalia as a signal of a wider transition

What was happening this week in the Lyon region reflects a broader change across France. The conversations at Paysalia were not only about planting more trees, but about keeping existing trees alive in a climate they were never planted for. Urban trees are moving from being treated as green amenities to being managed as strategic living infrastructure essential for safety, health, resilience, and long-term city performance.

FAQ 

What is Paysalia, and why does it matter for urban forestry?Paysalia is France’s flagship trade show for landscape and green-infrastructure professionals. It brings together cities, arborists, planners, and solution providers, making it a natural place to exchange field methods and emerging standards for urban tree management.

What does a “digital baseline” mean for a city’s trees?A digital baseline is a precise, structured snapshot of a tree population, including geometry, canopy structure, and early stress indicators, that can be updated over time. It allows cities to track change, prioritise care, and plan maintenance with more confidence.

How do cities use greehill’s data in practice?greehill provides a digital baseline and clear evidence about the tree population. What cities do with that evidence is entirely their choice. Some use it to plan maintenance and budgets, others to strengthen risk prevention or climate adaptation, and many to align departments around one shared view. The platform supports local decision-making, it doesn’t replace it.

What kinds of municipal use cases does this enable?Cities use digital baselines in different ways: maintenance planning, budget prioritisation, risk prevention, climate adaptation, cross-department coordination, and transparent communication with stakeholders.