Barcelona climate change - Capellino Foundation

Target

Cities around the world are facing the increasingly urgent challenge of countering the growing phenomenon of extreme heat, a phenomenon amplified by urban heat islands. And as heat waves increase in duration and intensity, severe drought areas, as well as illnesses and deaths due to high temperatures, are growing alarmingly, putting the well-being of the entire community at risk.

The new and adverse climatic situation that is being generated in recent times therefore implies a better choice of novel tree species and soils that will ensure their adaptability. But the choice of such species should not be the result of the offer of the moment or merely aesthetic decisions. Decisions based su scientific evidence are needed. Therefore, it is necessary to have data to draw objective conclusions that can highlight which tree species can provide the best environmental solutions, and with what impact on the urban environment (better thermal comfort, biodiversity...).

Selection of tree species

For this project, Zelkova serrata and Pistacia chinensis were chosen. These species are not yet common in Barcelona’s urban tree population but show promise for wider use in the future. The project aims to collect data to see how well they perform. The two species have complement each other. Zelkova serrata grows a large canopy and provides strong shade, making it a possible alternative to elms. Pistacia chinensis is very hardy and can withstand tough city conditions, such as drought and variable soils. Both are deciduous, which means they provide shade in summer and let sunlight through in winter, helping to make the city's climate more comfortable.

Area of intervention

In response to this emergency, the Capellino Foundation first launched the project in Florence in 2023, making it a replicable model in other cities around the world. Collaboration among other organizations was then also initiated in Germany(Mannheim) and Norway(Bergen), with the aim of exchanging knowledge and experience in the areas of education, politics and science in the context of EduNate Cities. But as a replication of the Florentine model, in collaboration with the City of Barcelona, the Capellino Foundation has since also developed another project aimed at testing, in the Catalan metropolis already considered among the 5 best smart cities in the world, effective green solutions for the cities of the future.

Project

With Barcelona (specifically PARCS I JARDINS, a municipal institute of the City Council), which is already particularly focused on adopting solutions that promote biodiversity in the city, the Capellino Foundation has designed a project against extreme drought in urban areas. This project aims to use exotic plant species that are more resilient to extreme weather conditions.

The project, which began in 2025 and will last four years, will involve five urban areas with varying degrees of environmental pressure. Resilient tree species, such as Zelkova serrata and Pistacia chinensis, will be tested to identify solutions best suited to adverse climatic conditions.

The planting sites were carefully chosen to represent different environmental conditions across Barcelona, including coastal areas, more inland locations and a nursery used as a reference site. This makes it possible to see how the different species perform in a range of environments and to understand whether any differences are due to the species themselves or to the surrounding urban conditions.

The projects takes place in several public urban spaces — Parc de Xavier Montsalvatge, Plaça Manuel Corachán, Jardins Zamora - Ramon Turró and Plaça Carmen Amaya. These locations allow the trees to be observed in real city conditions. Viver Tres Pins is used as a non urban reference site, making it possible to compare results and better understand the effects of urban stress on the trees.

With the support of the Parcs i Jardins municipal entity and the collaboration of research institutes such as CREAF (Catalan) and CNR (Italian), the use of these species in different areas will therefore be tested, ensuring scientific validity to the conclusions. Various parameters including irrigation, soil quality, plant health and urban microclimate will be monitored. The goal is to develop a scientific database to guide planting choices in the city, promote a more resilient urban environment and improve the quality of life for citizens. The project is inspired by a multivariable approach, similar to that already adopted in Florence.

Barcelona, already at the forefront of adopting urban biodiversity solutions, is therefore an ideal context for testing such a replicable and scientifically-based approach to addressing the current climate crisis. The future of our cities depends on thoughtful decisions that take into account a changing climate.

Duration: 4 years, starting in 2025.

Locations: 5 different locations with different gradienti of urban pressure (4 on critical urban streets covering the city and one in "nursery" hilly neighborhood area, to collect data from opposite and representative environments).

Soil: Use of two different soil types.

Trees: Evaluation of 10 trees for each of the 5 locations, for a total of 50 units.

Species used: Zelkova serrata and Pistacia chinensis.

Measurements: Data collected at least twice a year through a variety of instrumentation.

Monitoring:

Frequency and amount of irrigation.
Geomorphological characterization of sites.
Spectral library.
Microclimate and air quality.
Tree health status.
Measurement of plant parameters.

Objectives:

Learn about the evolution of trees and their interaction with the environment.
To identify the most adaptable and resilient species and soil substrates for Barcelona's urban environment.
To study the impact of trees on urban climatic and environmental regulation, therefore solutions that improve urban well-being.

Partners

Ajuntament de Barcelona / Parcs i Jardins is the municipal public agency responsible for the management, conservation and enhancement of the city's urban green spaces, with the goal of making Barcelona more livable, sustainable and resilient through the care of parks, gardens and street trees.

CREAF is a public research center dedicated to terrestrial ecology and spatial analysis, producing knowledge and methodologies for the conservation, management and adaptation of the environment to global changes.

Barcelona: Climate Change & Biodiversity

Target

Selection of tree species

Area of intervention

Project

Partners

Project data