FORLUX: Health, adaptation and resilience of Luxembourg City forests

On Thursday 3 April 2025, the City of Luxembourg, in partnership with the Ministry of the Environment, Climate and Biodiversity, the Nature and Forest Agency and the Luxembourg Institute of Science and Technology (LIST), presented the research project "FORLUX - Health, adaptation and resilience of Luxembourg City forests" at a research site in the Bambësch forest. This multi-year project, financed by the Ministry through the Climate and Energy Fund, aims to set up experimental plots to observe and measure, over the long term, the way in which municipal forests react to new weather conditions, and pave the way for new forest management strategies.

The forests in Luxembourg City

Luxembourg's forests, which are largely made up of beech and oak groves, are particularly vulnerable to weather events linked to climate change, with almost 60% of beech trees already showing the effects of drought, while forecasts predict an increase in the intensity, duration and frequency of these dry spells in the coming years. Faced with this climate emergency, the City of Luxembourg has stepped up its environmental action by creating a roadmap with five priorities. These priorities are 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 1,100 ha, or around 20% of the municipal territory, help to preserve the quality of the Luxembourg Grès aquifer, which is used in the city's drinking water supply system. Furthermore, 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 residents of Luxembourg City.

A forest health observatory

Developing strategies to adapt 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. A fundamental step in developing this knowledge is the setting up of observatories at various representative locations in the municipal forests. These observatories are equipped with sensors to collect data on tree health (water stress, disease monitoring, sap flow, etc.), weather conditions, air quality, and the quantity of water infiltrated and of carbon stored in the trees and in the soil. The parameters measured will then be used to create and populate 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 Nature and Forest Agency - and citizens in order to:

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 implementation of the first fully operational observation system on the Bambësch plateau in July 2022 was the starting point for a whole series of research projects aimed at both expanding our knowledge and finding solutions in different research areas:

• Resilience to climate change: Using observation protocols targeting the soil, roots, trunk and crowns, the aim is to observe the response of trees to climate change over the long-term, taking into account the characteristics and properties of different native and non-native varieties. This study will enable us to understand the stresses that forests will be subjected to in the future and identify the actions that need to be considered in order to adapt forest management practices accordingly.
   
• Protecting groundwater resources: Protecting water resources is of vital importance to 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 in municipal forests to accurately anticipate the potential effects of future droughts on groundwater resources by observing weather conditions, soil moisture and spring flows in situ.
   
• Interactions between forest and urban areas: Forests cool temperatures in urban areas during heat waves and help improve air quality in neighbouring urban areas. However, 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.).
   
• Citizen involvement and awareness: By focusing on 'citizen science' - a scientific approach in which citizens participate actively in the production of scientific data - the City of Luxembourg, LIST and the Nature and Forest Agency are also aiming to raise public awareness of the many ecosystem services provided by forests.

The initial results obtained at this first experimental station have enabled the calibration of remote sensing techniques to assess the spatial distribution of water stress in the Bambësch forest. One way of helping adapt forest management practices to future climate disturbance conditions is to couple local measurements taken at the experimental stations with regional visualization using remote sensing techniques.

Adjusting 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 affect all areas of our society, it is essential to take action in every area of political action. The draft strategy for adapting to the effects of climate change, comprising 131 concrete measures, is currently under public consultation. Five information workshops open to all will take place 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.

Photos: (C) Ville de Luxembourg - Fränk Schneider

Joint press release