{"id":1479,"date":"2026-08-21T14:41:13","date_gmt":"2026-08-21T14:41:13","guid":{"rendered":"https:\/\/redzine.co.uk\/index.php\/2026\/08\/21\/the-worlds-biggest-trees-could-hold-the-secret-to-coping-with-drought\/"},"modified":"2026-08-21T14:41:13","modified_gmt":"2026-08-21T14:41:13","slug":"the-worlds-biggest-trees-could-hold-the-secret-to-coping-with-drought","status":"publish","type":"post","link":"https:\/\/redzine.co.uk\/index.php\/2026\/08\/21\/the-worlds-biggest-trees-could-hold-the-secret-to-coping-with-drought\/","title":{"rendered":"The world\u2019s biggest trees could hold the secret to coping with drought"},"content":{"rendered":"
<\/span> Chui Wui Jing\/Shutterstock<\/a><\/span><\/figcaption><\/figure>\n

Rising more than 70 metres above the rainforest canopy, a giant skyscraper of a tropical tree can seem almost invincible. Some have survived centuries of storms, droughts and competition.<\/p>\n

Large trees<\/a> face a formidable engineering challenge, lifting water tens of metres from the soil to leaves high above the forest floor. A challenge which intensifies during drought<\/a>.<\/p>\n

But are giant trees uniquely vulnerable to drought or could they help forests remain resilient as temperatures rise?<\/p>\n

Research in this area over the last decade shows there is no single way tropical forests respond to drought<\/a>. In some forests large trees die disproportionately; in others they appear surprisingly resilient.<\/p>\n

In 2015, my colleagues and I analysed how drought affected forests around the world<\/a>. We found that, during drought, larger trees were more likely to die or have stunted growth than smaller trees.<\/p>\n

\n \"view<\/a>
\n Measuring a tree high above buttress roots using a ladder during fieldwork in Sepilok, Malaysia.<\/span>
\n Amy Bennett<\/span><\/span>
\n <\/figcaption><\/figure>\n

It seemed logical to us. Larger trees must transport water over greater vertical distances. They are more exposed to sunlight and atmospheric demands. Their crowns sit above the canopy where temperatures are higher and conditions are harsher.<\/p>\n

Hydraulic theory pointed in the same direction. Trees move water from roots to leaves through a continuous column under tension, like drinking through a straw. During severe drought that column can break, causing hydraulic failure and potentially tree death. In 2012, researchers showed that<\/a> many tree species operate very close to the limits of their water transport systems during drought.<\/p>\n

So, large trees look to be particularly vulnerable. <\/p>\n

Drought in the Amazon during the warm phase of the very strong El Ni\u00f1o event in 2015-16 appeared to confirm the pattern. Working with colleagues across tropical South America, we measured more than half a million trees<\/a> to try to understand forest responses to drought. The region\u2019s forest has acted as a net carbon sink<\/a>, by absorbing more carbon than it emits. But the sink effectively disappeared<\/a> and more trees of all sizes died, with the increase greatest for the largest trees.<\/p>\n

Interestingly, the forests most affected were not necessarily those in the wettest environments. Instead, the strongest consequences occurred in forests already growing in relatively dry conditions, particularly around the edges of the Amazon.<\/p>\n

These forests contain tree species that routinely cope with seasonal drought. Yet they still proved highly vulnerable to extreme heat and water stress. Adaptation to regular drought doesn\u2019t necessarily protect forests from unusually intense heat and water stress.<\/p>\n

Trees with less dense wood were also more vulnerable, a result that matched expectations from hydraulic theory. A 2023 study<\/a> demonstrated that hydraulic traits can directly predict drought mortality risk in Amazon forests. <\/p>\n

Together these findings appeared to strengthen the case that drought vulnerability is tightly linked to the hydraulic challenges faced by large trees. <\/p>\n

But the impacts of drought in African tropical forests told a different story during the same El Ni\u00f1o<\/a>. <\/p>\n

Rather than large trees suffering the most, growth declines were strongest among smaller trees. The largest trees appeared comparatively buffered from drought stress.<\/p>\n

The contrasting responses demonstrate that not all trees or forests respond to drought in the same way. There may not be a universal link between drought and tree mortality. The major cause of death may differ among forests<\/a>, in some hydraulic failure may dominate, while in others competition, carbon limitation or disturbance may be more important.<\/p>\n

We\u2019re no longer asking whether large trees are vulnerable, but under what conditions do they become vulnerable?<\/p>\n

A recent study published in Nature<\/a> across a rainfall gradient in Puerto Rico adds another layer. Researchers found that drought-resistance traits varied, even within species, with trees in drier forests having greater resistance to hydraulic failure.<\/p>\n

Forest resilience may depend not only on which species are present, but also on the capacity of species to adapt to local drought conditions.<\/p>\n

Dipterocarps are the giants of the forest. Trees in this family grow to massive sizes, have high wood density and therefore store large amounts of carbon. They often emerge high above the canopy like skyscrapers. Dipterocarps dominate many Southeast Asian forests and include some of the tallest tropical trees on Earth. Measuring them is extraordinarily difficult.<\/p>\n

Having worked in these forests in Borneo, I know how hard these trees are to study. The terrain is steep, the trees enormous and often buttressed. Making physiological measurements throughout trees so tall is an extraordinary achievement. <\/p>\n

A recent study<\/a> found that these giant trees appear able to compensate for the hydraulic challenge of height through anatomical and physiological adjustments, maintaining hydraulic function despite their great size. <\/p>\n

Size might not be everything<\/h2>\n

The findings suggest that, in these forests, size alone does not necessarily increase drought vulnerability.<\/p>\n

One implication is that size itself may not drive vulnerability. Instead, size may simply be a proxy for exposure to brighter, hotter and drier canopy conditions. <\/p>\n

In many studies, large trees are more vulnerable because they experience these harsher conditions. But if a species or individual tree can compensate physiologically, as dipterocarps on the island of Borneo appear able to, the relationship between size and vulnerability becomes more complicated.<\/p>\n

Truly giant trees are rare. Surprisingly little is still known about them. <\/p>\n

In most long-term forest inventory plots, the largest trees are only a handful of stems. The so-called large trees in many datasets are often much smaller than the skyscraper trees found in places such as Borneo. <\/p>\n

Are dipterocarps exceptional? Or have we simply under-sampled resilience among giant trees globally? At the moment, scientists don\u2019t know.<\/p>\n

What is becoming clearer is that there is no single rule to predict the drought responses of forests.<\/p>\n

\"The<\/p>\n

Amy Bennett has received funding from the Natural Environment Research Council (NERC), the European Research Council, the European Space Agency, the British Council, the Royal Society and the European Union.<\/span><\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

Chui Wui Jing\/Shutterstock Rising more than 70 metres above the rainforest canopy, a giant skyscraper of a tropical tree can seem almost invincible. Some have survived centuries of storms, droughts and competition. Large trees face a formidable engineering challenge, lifting water tens of metres from the soil to leaves high above the forest floor. A […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-1479","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/redzine.co.uk\/index.php\/wp-json\/wp\/v2\/posts\/1479","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/redzine.co.uk\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/redzine.co.uk\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/redzine.co.uk\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/redzine.co.uk\/index.php\/wp-json\/wp\/v2\/comments?post=1479"}],"version-history":[{"count":0,"href":"https:\/\/redzine.co.uk\/index.php\/wp-json\/wp\/v2\/posts\/1479\/revisions"}],"wp:attachment":[{"href":"https:\/\/redzine.co.uk\/index.php\/wp-json\/wp\/v2\/media?parent=1479"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/redzine.co.uk\/index.php\/wp-json\/wp\/v2\/categories?post=1479"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/redzine.co.uk\/index.php\/wp-json\/wp\/v2\/tags?post=1479"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}