GoKawiilThe world’s tallest tropical trees have no trouble pumping water to their topmost branches, new research reveals.
Conventional scientific theory suggests that as trees grow, it becomes harder to transport water from roots to leaves – limiting growth and making trees more vulnerable to drought.
But the new study – led by the University of Exeter and Cardiff University and published in the journal Science – finds that adjustments to water transport inside giant Dipterocarp trees “fully compensated” for the challenges of drawing water to the top.
As a result, the height of these trees does not make their water systems more vulnerable to drought compared to shorter trees, and separate testing found they suffered no height-related loss in growth (compared to smaller trees) during a severe drought.
“Trees contain lots of thin, hollow vessels and they suck water upwards by creating low pressure at the top,” said Professor Lucy Rowland, from the University of Exeter.
“These vessels have evolved intricate adaptations that can maintain the water in liquid form, even under the extreme low pressures required to move to the top of trees which can reach over 80 metres.
“However, a widely accepted theory suggests that in tall trees, the sheer length of vessels and the effects of gravity limit water transport, photosynthesis and growth.
“Our results challenge this by showing that the hydraulic systems of very tall Dipterocarp trees are perfectly evolved for their height, and should not suffer more than small Dipterocarp trees exposed to the same drought conditions.”
Dipterocarp species are the tallest flowering trees in the world and dominate Asian rain forests.
The researchers examined Dipterocarp trees ranging from 7 to 71 metres tall in Malaysian Borneo, and measured a variety of traits at multiple positions along each tree.
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