Tall Dipterocarps Defy Drought Vulnerability with Adaptive Water Transport

A study published in Science on July 2 challenges the assumption that tall trees are more vulnerable to drought. Researchers led by Paulo Bittencourt of Cardiff University analyzed 38 dipterocarp trees across five species in Malaysia's Kabili-Sepilok Forest Reserve on Borneo, ranging from 25 to 233 feet tall. They found that taller dipterocarps have wider xylem vessels at the base and leaves that withstand drier conditions, enabling efficient water transport to upper branches. During an El Niño-related drought in 2023-2024, no height-related decline in growth rates was observed, suggesting similar drought impacts on short and tall trees. The findings, consistent with Sierra Nevada mortality patterns noted by ecologist Adrian Das, may inform conservation models that previously predicted higher drought risk for tall trees. Julieta Rosell of the National Autonomous University of Mexico emphasized that trees continuously adapt their anatomy.