Luxembourg’s famed "green lung" is under severe threat as its forests grapple with repeated droughts, relentless pest attacks, and increasingly frequent heatwaves.
The latest surveys by the Nature and Forest Agency (ANF) paint a stark picture: just a tiny minority of trees remain in good health, which marks a dramatic reversal from four decades ago.
Where nearly 80% of trees were healthy in 1984, today more than four out of five trees show signs of damage or acute water stress.
Stands of bare trunks, thinning crowns, and withering beeches are becoming a common sight across the Grand Duchy.
Worse still, over half of all trees are now severely damaged or already dead. Only one in seven trees is still completely unaffected.
This decline is omnipresent beneath the country's canopy and shows through sparse foliage, dead branches, desiccated trees, and clear-felled spruce plots.
While forests still cover around 35% of Luxembourg’s territory (92,150 hectares), this apparent stability masks deep-rooted deterioration.
This rapid decline has accelerated dramatically since the late 2010s. Successive summers of heatwaves and prolonged droughts have depleted groundwater and deprived trees of essential moisture.
Chronic water shortages lead to substantial leaf and needle loss, undermining photosynthesis and weakening the forest giants.
Weakened trees have become easy targets for pests such as the spruce bark beetle (bostryche typographe), which bores tunnels under the bark and continues to devastate the country’s spruce forests.
Milder winters further favour the bark beetle and allow its life cycle to speed up. Where once there was a single generation per year, now three or four generations can develop in a single season, compounding the damage.
While climate change is now the primary threat, it is not the only one. The very structure of Luxembourg’s forests is also a concern.
Nearly 9,500 hectares of beech stands have surpassed their optimal harvest age: though these old trees provide invaluable ecological benefits for biodiversity, they are also much more vulnerable to disease and storms.
Urban development and road infrastructure have fragmented the landscape, isolating forest parcels and diminishing their natural resilience against external pressures.
The crisis extends beyond the forest floor. Between 2010 and 2023, forest growth declined by 25% compared to the previous decade, with a 21% drop among broadleaf trees and a 32% decrease in conifers.
Even more worrying, during this period Luxembourg’s forests released more carbon than they absorbed.
But as the forests weaken, their ability to sequester carbon diminishes. The more dead trees there are, the more CO2 is released into the atmosphere, and weakened trees produce less oxygen. Claudine Felten, forestry engineer and director of the NGO natur&ëmwelt, calls this a "vicious cycle".
Climate damage, rising tree mortality, and increased logging have transformed Luxembourg’s forests from a net absorber to a net emitter of CO2.
The consequences of mass forest dieback are already being felt. Each summer, wildfire risks reach critical levels, with dozens of vegetation fires recorded and requiring close coordination between the Grand Ducal Fire and Rescue Corps (CGDIS) and forest rangers.
Furthermore, weakened trees pose unseen dangers to walkers and hikers: heavy, dry branches can fall suddenly and thus cause serious accidents. The ANF continues to urge the public to stay on marked paths for safety.
In the long run, the forest’s regulatory role is under threat. If the trees die, the wood sector, which supports thousands of local jobs, faces collapse.
Claudine Felten, forestry engineer and director of the NGO natur&ëmwelt. is worried that her children will inherit an environment "very different from ours".
The forest of tomorrow will be nothing like that of the past. To preserve what remains, authorities and foresters must now invest in greater species diversity and rapidly transition to a more resilient forestry model.
