While many of us are decorating the Christmas Tree, scientists have just discovered additional trees’ troubles in facing the climate change, especially in drought conditions. A new study published in the journal Science by researchers at UC Santa Barbara and UC Davis, supports the idea that trees growing in wetter regions are more sensitive to drought. The question has long been “Are the trees growing in arid conditions less resilient to drought?”. It seems credible that trees living at their biological limits will be most vulnerable to climate change, but the truth is that these populations have adapted to a harsher setting, so they might be more capable of withstanding a drought [1].
The research group analyzed 6.6 million tree ring samples from 122 species worldwide. For each year, they measured whether the tree grew faster or slower than average based on its ring width. They linked these trends with historic climate data, including precipitation and temperature [1].
It’s impressive how as moving to the drier edge of a species’ range, trees become less and less sensitive to drought.
On the other hand, trees growing in wetter regions are more sensitive to drought: a greater water availability could “spoil” trees by reducing their adaptations to drought.
Another novelty of this work is the use of analysis data methods from economics; they were originally developed to study how people and businesses adjust to a changing climate and apply them to the ecological context to study forest sensitivity to drought. Similarly, heatwaves likely damage people of cool places than in hotter cities.
But there’s a hope also for trees from wetter regions: many species have a reservoir of drought-hearty stock in the drier parts of their range that could bolster forests in wetter areas [1]. This example of adaptation to environmental change, could be the future for many stressed species, also for our beloved Christmas tree.
[1] Drought sensitivity in mesic forests heightens their vulnerability to climate change; Robert Heilmayr , Joan Dudney, Frances C. Moore – Science; Dec 2023, Vol 382, Issue 6675; pp. 1171-1177
