Giant Trees Defy Gravity — No Trouble Pumping Water to Top Branches, Study Finds

The world's tallest tropical trees have no trouble pumping water to their topmost branches, challenging a century-old theory that height limits water transport. New research published in Science finds Dipterocarp trees in Malaysian Borneo compensate with wider vessels and drought-adapted leaves.

The world's tallest tropical trees have no trouble pumping water to their topmost branches, according to new research published in the journal Science.

Conventional theory has long held that as trees grow taller, gravity and the sheer length of water-carrying vessels make it harder to transport water from roots to leaves — limiting growth and making trees more vulnerable to drought.

But a study led by the University of Exeter and Cardiff University, examining Dipterocarp trees ranging from 7 to 71 meters tall in Malaysian Borneo, found the giants "fully compensated" for their height.

Taller trees developed wider water-carrying vessels near the ground and leaves adapted to withstand greater water stress before wilting. During the severe El Niño drought of 2023–2024, the tallest trees showed no height-related loss in growth compared to smaller ones.

"The tallest 1% of trees store more than half of above-ground carbon in forests," said Dr. Paulo Bittencourt of Cardiff University. "Existing predictions suggest a weaker hydraulic system places them at higher risk of dying due to drought. Our study suggests this may not be correct."

The findings could force revisions to climate-change models that currently assume tall trees are the first to succumb to drought stress. Dipterocarp species are the tallest flowering trees in the world and dominate Asian rainforests.

Sources: University of Exeter News | DOI: 10.1126/science.aea9013