How to read and compare municipal tree plans

Municipal tree plans can have similar titles and very different functions. Some are inventories and planting programmes. Others define decision criteria, cover targets, protection, management, biodiversity and climate adaptation.

Comparing them only by the number of trees announced says little about the capacity to deliver or about the conditions that will be created for each specimen.

The first point is to understand what data underpin the plan. Inventory, canopy cover, spatial distribution, age, condition, diversity and conflicts help to identify the real problem.

Porto’s Plano Municipal de Arborização (municipal tree plan), presented in 2023, cross-references tree planting with street dimensions, aspect, wind, humidity, soil, movement and ecosystem services. The structure seeks to respond to what exists, what is feasible and what should be prioritised.

A plan with no spatial diagnosis can announce plantings without showing where they fit or where they will deliver the greatest benefit.

Barcelona works to a horizon from 2017 to 2037. Paris organised its Plan Arbre for 2021–2026. London published the Urban Forest Plan in 2020 and updated the programme of actions in February 2025.

Long horizons suit the growth of trees, but they need phases, funding and review. Short-term targets allow accountability, although they can encourage a focus on the number planted rather than on the future canopy.

The number of trees is easy to communicate, but it does not measure survival, size or distribution.

Fuller plans track canopy cover, retention of existing trees and the quality of the rooting space. London updated its work in 2025 and now frames a target of 22% of the area covered by trees at least four metres tall by 2050.

When comparing, the definition and the measurement method need to be confirmed.

A mature tree that is removed is not immediately replaced by a young one. The plan should state how it avoids losses, manages risk and protects trees during construction works.

Paris links planting to regulatory protection, a tree charter, health monitoring and action in public and private space. Its original plan set a target of 170,000 trees between 2020 and 2026, but any reading should include the types of planting and the annual reviews.

The plan should set out minimum requirements for streets, tree pits, soil, water and maintenance. When these conditions are missing, the target depends on later decisions that may not be funded.

Porto spells out the need to cross-reference street dimensions and environmental conditions before deciding where to plant. Barcelona structures its plan around healthy trees, biodiversity, services and public involvement.

The comparison covers the distribution by species, genus and family, the response to pests and the strategy for the future climate.

London now provides a map with information on more than 1.1 million public realm trees and climate suitability scores for 2090. The tool does not decide the species on its own, but it shows how data can support review.

Average cover can hide neighbourhoods with little shade. Some plans cross-reference canopy with deprivation, heat, health and access.

The comparison should ask who benefits from the plantings and whether the priority areas also receive soil, water and maintenance, and not just young trees.

A plan needs people in charge, a budget, teams, nurseries, contracts and indicators. Targets without operational capacity remain declarations.

The London update recorded that, at the start of 2025, almost 70% of the original actions were complete or under way, and it set 75 new priorities. This tracking makes it possible to tell a published plan from a delivered one.

A solution from Paris or Barcelona should not be copied directly to a Portuguese city. Climate, density, legislation, water and municipal structure are different.

The value of the comparison lies in the methods: diagnosis, setting priorities, protection, diversity, rooting space, maintenance and monitoring.

A good plan makes clear what it intends to change, how it will measure the result and who will be responsible for maintaining the trees after planting.

1. Plano Municipal de Arborização do Porto, 2023.
2. Trees for Life: Master Plan for Barcelona’s Trees 2017–2037.
3. Plan Arbre and updated information on the trees of Paris.
4. London Urban Forest Plan and Actions Update 2025.
5. London Public Realm Trees Map.