Tall Trees Were Thought to Be More Vulnerable to Drought. But These Towering Plants in Southeast Asia Have Adapted to Move Water Efficiently

A new study found that enormous dipterocarp trees have special adaptations to transport water up to their highest limbs, challenging the assumption that they would more easily succumb to dry conditions

Sara Hashemi | Daily Correspondent

July 7, 2026 3:29 p.m.

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The rainforests of Southeast Asia are home to towering trees called dipterocarps, which are some of the tallest flowering plants in the world. For years, conventional scientific wisdom held that giant trees were more susceptible to drought—with gravity and their sheer height making it harder to transport water from their roots to their uppermost limbs. But now, a new study is challenging that assumption.

A team of scientists looked at the tallest dipterocarps and determined that they have developed adaptations for transporting water to their highest branches. The findings, published in the journal Science on July 2, don’t necessarily apply to all trees. But understanding these super-growers is important for informing conservation efforts, especially since more than half of the above-ground carbon in forests is stored in the tallest 1 percent of their trees.

“These trees are rare and important, and existing predictions suggest a weaker hydraulic system places them at higher risk of dying due to drought,” says Paulo Bittencourt, the study’s lead author and a forest ecologist at Cardiff University in Wales, in a statement. “That prediction is included in some models of climate change impacts, and our study suggests this may not be correct. More research is now needed to investigate the hydraulic systems and drought resilience of other tall trees.”

Throughout three months in 2022, Bittencourt and his colleagues collected branch, leaf and trunk samples from 38 dipterocarp trees across five species in Malaysia’s Kabili-Sepilok Forest Reserve, located on the island of Borneo. These trees ranged from about 25 feet to 233 feet tall, and the researchers enlisted the help of trained climbers for the field work.

“These are people who, in the middle of the forest, can thread a rope through a tree as tall as a 20- to 30-story building, climb it and collect branches,” Bittencourt says in a different statement. “Some collections had to be done at night, without sunlight. It isn’t just about knowing how to thread the rope and being physically fit. You have to check for wasp nests, know if a branch is suitable, if the wood is strong—it isn’t a trivial matter.”

The researchers then analyzed the samples for traits related to water transport and found that the taller trees have come up with different ways to compensate for their height. For instance, vessels called xylem, which carry water and nutrients to the plants’ leaves, are wider at the base of tall dipterocarps, allowing them to make up for the extra resistance to water flow as it travels up the tree. The leaves at the top of the trees are able to withstand drier conditions without wilting.

To better understand how the dipterocarps react to water stress, the researchers also measured trunk growth rates before, during and after an El Niño-related drought in 2023 and 2024. They found no height-related decline in growth rates associated with the drought, which suggests that both short and tall trees are impacted by changes to the climate in similar ways.

The findings are consistent with patterns of tree mortality seen during droughts in the Sierra Nevada mountains, says Adrian Das, a forest ecologist at the U.S. Geological Survey who was not involved in the work, to Mona Patterson at Science. “The relationship between size and mortality during drought varied by species,” he explains. In that case, it seemed to have more to do with ecological factors, like vulnerability to bark beetles, than physiological factors, like the height of the tree.

Julieta Rosell, a functional ecologist at the National Autonomous University of Mexico who was not involved in the study, tells Fechi Inyama at Science News that the findings prompt us to reconsider the nature of trees.

“They’re doing things all the time, making changes in their anatomy all the time,” she says to the outlet. “And that gives a different perspective to trees, because they seem so quiet.”

Sara Hashemi | Read More

Sara Hashemi is a science writer and fact-checker currently based in New York City. Her work has appeared in Sierra, The Body, Maisonneuve magazine and more.