Scientists flip the script, revealing trees in wetter regions are more sensitive to drought.
This holiday season brings surprising news about your Christmas tree. Scientists just discovered that globally, trees growing in wetter regions are more sensitive to drought. That means if your tree hails from a more humid clime, it’s likely been spoiled for generations.
Debate Over Drought Resilience in Trees
Scientists have long debated whether arid conditions make trees more or less resilient to drought. It seems intuitive that trees living at their biological limits will be most vulnerable to climate change, since even just a little extra stress could tip them past the brink. On the other hand, these populations have adapted to a harsher setting, so they might be more capable of withstanding a drought.
Insights From a New Study
According to a new study in the journal Science by researchers at UC Santa Barbara and UC Davis, greater water availability could “spoil” trees by reducing their adaptations to drought. “And that’s really critical to understand when we’re thinking about the global vulnerability of forest carbon stocks and forest health,” said ecologist Joan Dudney, an assistant professor at UCSB’s Bren School of Environmental Science & Management and in the Environmental Studies Program. “You don’t want to be a ‘spoiled’ tree when facing a major drought.”
Dudney and her co-authors expected trees growing in the most arid regions to be more sensitive to drought, since they’re already living at the edge of their limits. What’s more, climate change models predict that these regions will experience more rapid drying than wetter regions. This shift in climate could expose trees to conditions beyond their adaptive capacity.
Methodology: Analyzing Tree Rings
To measure drought sensitivity, the authors analyzed 6.6 million tree ring samples from 122 Previous research out of UCSB revealed that many species do have the capacity to adapt to environmental change. However, those researchers also found that trees migrate slowly from one generation to the next. That means human intervention — such as assisted migration — may be necessary in order to take advantage of this genetic diversity.
Fate of Christmas Trees and Forests
Whether your Christmas trees grow in a dry or wet region, they’ll likely experience growth declines in the future. But understanding how trees will respond to climate change can help ensure the future of the Tannenbaum and its wild counterparts.
Reference: “Drought sensitivity in mesic forests heightens their vulnerability to climate change” by Robert Heilmayr, Joan Dudney and Frances C. Moore, 7 December 2023, Science.
DOI: 10.1126/science.adi1071