Diverse Forests Are Stronger Against Drought

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Diversity is strength, even among forests. In a paper published in Nature, researchers led by University of Utah biologist William Anderegg report that forests with trees that employ a high diversity of traits related to water use suffer less of an impact from drought. The results, which expand on previous work that looked at individual tree species’ resilience based on hydraulic traits, lead to new research directions on forest resilience and inform forest managers working to rebuild forests after logging or wildfire.

Surprisingly, says Anderegg, a forest’s hydraulic diversity is the predominant predictor of how well it can handle a drought.

“We expected that hydraulic traits should matter,” he says, “but we were surprised that other traits that a lot of the scientific community have focused on weren’t very explanatory or predictive at all.”

Missing the forest for the trees

Anderegg is a veteran researcher of the impacts of droughts on trees, with particular attention to the time it takes for forests to recover from drought. Along with others in his field, he’s also looked at the impact of hydraulic traits on individual tree species’ survival chances in a drought. Hydraulic traits are connected to the way a tree moves water throughout the organism – and how much drought stress they can take before that system starts breaking down.

But droughts, when they strike, don’t go after individual trees – they affect entire ecosystems.

“What’s different about this study is it’s now looking at the whole forest,” Anderegg says.

Read the full article.