“Our results suggest that the small trees are actually quite resilient,” says study author David Bartholomew, a PhD candidate at the University of Exeter’s Global Systems Institute. Bartholomew and his colleagues studied 30 small trees in the drought half of the experimental area, and a further 36 from the non-drought half, conducting a number of tests to learn more about the trees. They studied the dimensions of the trees as well as their position in the canopy hierarchy, and they collected branches to study the leaves of each tree. The tree species they selected were based on common species in the area, and chosen to also correspond with prior work on the effects of drought on large trees. They also studied 61 large trees. Relative to the other small trees, they found that small trees in the drought area had an increased ability to perform photosynthesis, that is, to take in sunlight and use its energy to power the exchange of carbon dioxide for oxygen, the use of water and the production of sugars the trees need for energy. This suggests that small trees are capable of responding to drought conditions that kill off larger trees by changing their morphology to take advantage of added access to sunlight. But even more importantly, says Bartholomew, the small trees were able to do all this in drought conditions. “The drought wasn’t really affecting them,” he says. But not all kinds of trees have these abilities. “Some species responded better than other species,” Bartholomew says. “This might show that some species will survive the drought and others might be more likely to become extinct.” “Because it assesses the impacts of multiple environmental changes (light and drought), this paper provides important additional insight,” Sophie Fauset, an environmental science professor at the University of Plymouth in England, told Popular Science in an email. Faucet, who was not involved in the current work, studies how tropical forests respond to climate change and human impacts like deforestation. There’s less data right now on the response of small trees to drought, she says, compared to canopy trees.
