Europe’s forests are absorbing less CO₂ than they did two decades ago, and the FORTRESS project will find out why—and which trees are most at risk. Over recent years, record-breaking heatwaves and droughts have weakened the continent’s forest carbon sink, which had previously helped slow climate change by locking away vast amounts of carbon as wood. If this decline continues, it could undermine international efforts to keep global warming within 2°C. The project combines experiments, tree-ring records, a pan-European wireless sensor network, satellite imagery, and machine learning to build the first complete picture of how extreme water stress affects forests—from individual seedlings to entire landscapes. It will identify which tree species are most resilient, reveal how climate constrains growth and water use across timescales from days to decades, and develop early warning signals that predict tree mortality from hydraulic failure using satellite data. If successful, FORTRESS will transform how forest managers, modellers, and policymakers monitor and manage Europe’s woodlands, helping ensure they remain a reliable carbon sink rather than a source of emissions.
View original technical description
Over the past several decades European forest have played a major role in slowing the pace of climate change by sequestering vast amounts of CO2 from the atmosphere and storing it as wood. However, growing evidence suggests that this carbon sink is now weakening, with potentially disastrous consequences for international efforts to keep global warming within 2 degrees C. This recent dip in the strength of the forest carbon sink is thought to be linked, at least in part, to a rise in the frequency and intensity of hot dry summers in Europe - including the record-breaking heatwaves of 2003, 2010 and 2018-19. If Europe's forests are to continue being part of the solution for transitioning to a low-carbon future, we urgently need to understand how these ecosystems are impacted by and recover from periods of extreme water stress. The overarching goal of the FORTRESS project is to generate the first complete picture of how extreme heat and drought impact the ability of European forests to sequester and store carbon: from the growth and survival of individual tree seedlings, to population dynamics across entire landscapes. Using a unique combination of manipulative experiments, long-term retrospective analyses of tree ring records, real-time ecophysiological data from a pan-European wireless tree sensor network, cutting-edge remote sensing and machine learning, this project aims to: (i) reveal which European tree species are most resilient to climate extremes and why; (ii) uncover how climate constrains tree growth and water use at daily, seasonal, annual and multi-decadal time scales; and (iii) develop the next generation of early warning signals that predict a tree's risk of mortality from hydraulic failure using a range of data, including satellite imagery. In doing so, the FORTRESS project will radically transform our ability to manage, monitor and model Europe's forest ecosystems into the future.
Plain English summaries and category classifications on this site are generated by AI and may not perfectly reflect the original research.
Is something wrong? Let us know