Tree species diversity leads to stronger drought resistance: study

Strength is not only in numbers but also in diversity. A new study has found that the more tree species a forest has, the more resistant it is to drought.

Researchers from the Institute of Tibetan Plateau Research under the Chinese Academy of Sciences have revealed that tree species diversity could enhance drought resistance.

Compiling a database of tree species across more than 700,000 forest plots, the researchers mapped the species-diversity effect on forest drought resistance on a global scale. They found that species-rich forests such as moist tropical broadleaf forests, which contain an average total of 65 tree species, showed the highest level of drought resistance. In contrast, species-poor forests such as dry woodlands, which contain just two or three tree species, showed the lowest level of drought resistance.

In the study, researchers also made a prediction regarding the species-diversity effect, positing that the conversion of forests from their current monoculture to mixed-species tree plantations could improve their drought resistance, with the largest improvements being in dry forests.

"We estimate that converting current forest plantations from one species to a mixture of four species could increase the drought resistance of plantation forests around the world by 3.2 percent, with such benefits being greater in dry and drought-prone forests," lead researcher Wang Tao said.

These findings, which were published in the journal Nature Geoscience earlier this week, provide evidence that species diversity could help forests resist frequent and intense droughts that can occur as a result of global warming.

"Restoring species diversity and planting multiple species should be included in forest policy, especially for dry forests," said Liu Dan, the first author of the study.