Tallest Rainforest Trees Most Likely To Die From Thirst During Drought

A control plot in a tree survival study in the Amazon rainforest. (Credit: Patrick Meir)

Researchers from the University of Edinburgh have found that thirst, not hunger, causes the tallest rainforest trees to die during drought conditions, according to a release. Prior to the study, it was clear that drought conditions killed Amazonian trees, but it was not exactly clear how.

Scientists from the university measured growth, sugar levels and water transport performance in rainforest trees over a 13-year period. Over the study period, a large-scale drought experiment was performed.

The results indicated that sugar levels in the trees subject to drought were similar to those without drought stress, indicating that they had enough food to use for growth and starvation was not a concern. However, scientists discovered that under conditions of drought, air bubbles could enter the trees when they were attempting to transport low amounts of water throughout their systems via their xylem.

The trees’ transport systems became damaged, ultimately preventing them from transporting water effectively, causing them to essentially die from thirst. The effects of a damaged transport system were more extreme the taller the tree, meaning shorter trees were more likely to recover from drought conditions than taller ones.

Top image: A control plot in a tree survival study in the Amazon rainforest. (Credit: Patrick Meir)