FORLUX - Health, adaptation and resilience of the City of Luxembourg's forests

On Thursday 3 April 2025, the City of Luxembourg, in partnership with the Ministry of the Environment, Climate and Biodiversity, the Administration de la Nature et des Forêts and the Luxembourg Institute of Science and Technology (LIST), presented the research project «FORLUX - Health, adaptation and resilience of the City of Luxembourg's forests» at a research site located in the heart of the city. Bambësch. The aim of this multi-year project, financed by the Ministry via the Climate and Energy Fund, is to set up experimental plots to observe and measure, over the long term, the way in which communal forests react to new weather conditions, and to pave the way for new forest management strategies.

The City's forests

It has to be said that Luxembourg's forests, which are largely made up of beech and oak stands, are particularly vulnerable to weather events linked to climate change, and that almost 60 % of beech trees are already showing the after-effects of droughts, while forecasts predict an increase in the intensity, duration and frequency of these dry spells in the years to come. Faced with this climate emergency, the City of Luxembourg has decided to step up its environmental action by drawing up a ‘Roadmap’ containing 5 priorities broken down into concrete projects aimed at protecting and preserving the forests and the functions they perform in the fight against climate change. The municipal forests, covering 1,055 ha, or around 20 % of the municipal territory, help to preserve the quality of the water from the Luxembourg Gré springs, which is used in the town's drinking water supply system. In addition, forest ecosystems buffer global warming by humidifying and cooling the air, filtering atmospheric pollutants, helping to sequester carbon, providing a haven for biodiversity and offering a large recreational area for the inhabitants of Luxembourg City.

A forest health observatory

Developing strategies for adapting forest management to climate change requires an in-depth understanding of the physiological responses of trees to different variables such as water, carbon and nutrients in the forest environment. Setting up observatories at various locations representative of local forests is therefore a fundamental step in developing this knowledge. These observation systems are equipped with sensors to collect data on tree health (water stress, disease monitoring, sap flow, etc.), weather conditions, air quality, the quantity of water infiltrated and the carbon stored in the trees and in the soil. The parameters measured will then be used to create and feed a future modelling tool capable of simulating the evolution of forests according to different climate scenarios and forest management methods.

The project has a threefold objective, bringing together LIST researchers, forest managers - namely the City of Luxembourg and the Administration de la Nature et Forêts - and the general public:

1. quantify and anticipate the response of forests to climate change,
2. develop strategies for adapting forest management,
3. raise awareness and involve citizens in forest conservation.

The installation of the first fully operational observation system since July 2022 on the Bambësch is the starting point for a whole series of research projects aimed at both expanding knowledge and finding solutions in different areas of research:

• Resilience in the face of climate change The aim is to observe the response of trees to climate change over the long term, using observation protocols targeting the soil, roots, trunk and crowns, while taking into account the characteristics and properties of different native and non-native species. This study will enable us to understand the stresses to which forests will be subjected in the future and to identify the actions that need to be considered in order to adapt forest management practices accordingly. 
• Protecting groundwater resources The protection of water resources is of vital importance for the supply of drinking water, and is closely linked to the management of forest ecosystems. It is therefore important to measure and model the water balance of communal forests so as to be able to correctly anticipate the potential effects of future droughts on groundwater resources by observing in situ weather conditions, soil moisture and spring flows.
• Interactions between forest and urban areas Forests have a cooling effect on temperatures in urban areas during heat waves and help to improve air quality in neighbouring urban areas. On the other hand, the proximity of built-up areas is likely to affect the ecological functioning of forests, particularly because of the urban heat effect linked to the characteristics of the built environment (heat-absorbing materials, buildings blocking air circulation, pollution and heat emissions from cars and industry, etc.).
• Engaging citizens and raising their awareness The City of Luxembourg, LIST and the Administration de la Nature et Forêts (Nature and Forests Administration) are also seeking to raise public awareness of the many ecosystem services provided by forests by focusing on «citizen science» - a scientific approach in which citizens actively participate in the production of scientific data.

The initial results obtained at this first experimental station have made it possible to calibrate remote sensing techniques to assess the spatial distribution of water stress in the Bambësch forest. Coupling local measurements taken at the experimental stations with regional visualisation using remote sensing techniques is one way of helping to adapt forest management practices to future climate disturbance conditions.

Adapting to climate change now

The impact of climate change on society, health and ecosystems has intensified in recent years, and its effects are being felt more frequently and intensely in Luxembourg. To meet these growing challenges and increase Luxembourg's resilience, the strategy for adapting to the effects of climate change proposes measures and actions to counter these negative consequences. The «FORLUX» project is a concrete example of how the State, municipalities and research institutions can work together to prepare our society by preserving our forests.

Given that the effects of climate change will impact every area of our society, it is vital to take action in every policy area. The draft climate change adaptation strategy, comprising 131 concrete measures, is currently out for public consultation. Five information workshops open to all will be held in April and May, giving everyone the opportunity to contribute to the development and implementation of these concrete actions. Act now for a better future: https://www.zesumme-vereinfachen.lu/fr-FR/projects/klimaadaptatiounsstrategie.