“Large Vessel Dimorphism Detected in Lianas”

Determining the structure of plant vessels is key to further understanding the function of blood vessels in different plant groups. Vessel dimorphism may be an important hydraulic strategy and ecological adaptation of plants. Previous studies have found that lianas, a common form of tropical and subtropical plant growth, generally have larger pot diameters than synchronous trees. However, these results may vary between plant species.

In a study published in American Journal of Botanyresearchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences developed a theoretical model to predict how vessel diameters vary between lianas and trees and across sites (Xishuangbanna tropical monsoon rainforest, Yuanjiang savanna, and Ailaoshan subtropical broadleaf evergreen forest in Yunnan.) .

The authors evaluated the variability in the distributions of tree and vine pot diameter and six xylem hydraulic traits (mean pot diameter, hydraulically weighted pot diameter, pot density, theoretical hydraulic conductivity, pot area fraction, and sapwood density).

They found that lianas have larger vessel diameter, fraction of vessel area, dimorphism, theoretical hydraulic conductivity, and lower density than trees. Moreover, these differences were consistent across contrasting forest types.

By contrast, they found that trees had consistently conservative hydraulic traits, with a relatively small bowl diameter and low bowl shape doubling due to the lack of large vessels. The difference in the hydraulic traits of lianas and trees may explain why trees and lianas tend to have different distributions and relative abundances in tropical environments.

“Our results indicate that lianas are large vessels, even in dry and cold habitats,” said Professor Zhang Jiaolin of XTBG.

According to the researchers, the dimorphic pot pattern may allow lianas to grow well when water is available and also to reduce the risk of blockages when water becomes limited, ensuring both high hydraulic efficiency and safety, which may contribute significantly to the occurrence and survival of lianas in seasonal, dry and cool habitats.