
Our results revealed that the effects that follow a wildfire or severe drought vary depending on the location, while arid regions become more sensitive to water stress, but humid regions become more resilient and adapt better.
Environmental disturbances like severe droughts and wildfires have immediate, direct, negative impacts on ecosystems’ productivity and carbon dioxide storage capacity. However, very little is known about the long-term indirect effects of such events. What happens after a forest fire or a major drought? Does the ecosystem recover? According to a study recently published in the journal Nature Climate Change, in which CREAF-based CSIC (Spanish National Research Council) researcher Josep Peñuelas participated, an ecosystem’s ability to bounce back from a disturbance depends on three key factors: water availability, solar radiation, and biodiversity. Specifically, the study’s results show that forests need more water after a drought or fire, and a combination of high solar radiation (more heat), water scarcity and low biodiversity makes recovery an uphill struggle.
Led by Meng Lui from the University of Utah (USA), the study analysed over three decades of satellite data from around the world. It concluded that the most vulnerable ecosystems are found in the planet’s driest and most arid regions, such as parts of western North America, southern Europe, central Eurasia, Australia, and southern Africa.
“Our results revealed that the effects that follow a wildfire or severe drought vary depending on the location,” says Peñuelas, one of the study’s co-authors. “Arid regions become more sensitive to water stress, but humid regions — like Africa’s tropical rainforests or Europe’s boreal regions — become more resilient and adapt better,” he explains.
The study’s findings stem from analysis of Global Land Surface Satellite (GLASS) data spanning 1982 and 2018. With the data in question, it is possible to determine how much light plants absorb and how factors like temperature and humidity affect their development, giving a detailed overall picture of global vegetation growth over time. The researchers behind the study also used machine learning models, specifically to analyse how plants’ sensitivity to water scarcity changes — i.e. whether it affects them more after a fire or drought than it did before — and why. “The information we obtained confirms that dry ecosystems are more sensitive to water scarcity after an extreme event,” Peñuelas remarks.
Image of a recently burned forest in Turkey. Public domain image
Biodiversity: a life insurance policy
Another of the study’s key findings concerns the role of biodiversity in mitigating the impact of droughts and wildfires. “The data shows that biodiversity is a ‘life insurance policy’ in humid areas: the more diverse an ecosystem is, the more resilient it will be,” states Liu. That could be because having a wide variety of species with different traits ensures that at least some will be equipped to survive during droughts or after fires, helping the ecosystem to recover. In drier areas with lower biodiversity, on the other hand, plants are already struggling to meet their water requirements, making them more vulnerable to drought and fires alike. Furthermore, such areas are exposed to high solar radiation, which raises temperatures and the evaporation rate, “exacerbating the effects of disturbances”, as University of Utah researcher and study co-author William Anderegg points out.
A recovery cycle in jeopardy
According to the study’s authors, ecosystems usually take around four or five years to recover from a disturbance, meaning they should generally have enough time to do so before the next one comes along. However, the researchers warn that the growing frequency and severity of droughts and wildfires is jeopardizing ecosystems’ ability to get over such events and leaving less and less time for regeneration, especially in the most arid parts of the world. That, in turn, poses a threat to their ability to function properly and absorb carbon.
“Since terrestrial ecosystems absorb roughly 25% of all carbon emissions from human activities each year, understanding the impact of extreme events is crucial to managing global carbon, protecting the most vulnerable areas, and mitigating climate change,” concludes Peñuelas.
Referenced article: Liu, M., Peñuelas, J., Trugman, A.T. et al. Diverging responses of terrestrial ecosystems to water stress after disturbances. Nat. Clim. Chang. 15, 73–79 (2025). https://doi.org/10.1038/s41558-024-02191-z