Determining plant vessel structure is fundamental for further understanding vascular functioning in diverse plant groups. Vessel dimorphism could be an important plant hydraulic strategy and ecological adaptation. Previous studies have found that lianas, a common tropical and subtropical plant growth form, generally have larger vessel diameters than co-occurring trees. However, these results may differ among vegetation types.
In a study published in American Journal of Botany, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) developed a theoretical model to predict how vessel diameters vary between lianas and trees and across sites (Xishuangbanna tropical seasonal rainforest, Yuanjiang savanna , and Ailaoshan subtropical evergreen broadleaved forest in Yunnan).
The researchers evaluated the variations in liana and tree vessel diameter distribution and six xylem hydraulic traits (mean vessel diameter, hydraulically weighted vessel diameter, vessel density, theoretical hydraulic conductivity, vessel area fraction, and sapwood density).
They found that lianas had greater vessel diameter, vessel area fraction, dimorphism, theoretical hydraulic conductivity, and lower sapwood density than trees. Furthermore, those differences were consistent among contrasting forest types.
By contrast, they found that trees had consistently conservative hydraulic traits, with relatively small diameter vessels and low vessel dimorphism due to the lack of large vessels. The difference in liana and tree hydraulic traits may explain why lianas and trees tend to have different distributions and relative abundances across tropical environments.
“Our results suggest that lianas possess large vessels, even in dry and cold habitats,” said Prof. ZHNAG Jiaolin of XTBG.
According to the researchers , a dimorphic vessel pattern may enable lianas to grow well when water is available and also to reduce their risks of embolism when water becomes limiting, ensuring both high hydraulic efficiency and safety, which may contribute substantially to liana occurrence and survival in seasonal, dry, cold habitats.
ZHANG Jiaolin Ph.D Principal Investigator
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China
First published: 13 March 2023