Plant stem xylem provides several important functions. Revealing the coordination or trade-offs between xylem functions is vital to understand plant ecological strategy and adaptation to different environments. However, it remains unclear how xylem cell tissues influence their functions among different growth forms.
In a study published in American Journal of Botany, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) studied the variation and associations in stem xylem water transport, mechanical support, and storage functions between lianas and trees across three different ecosystems in Southwest China.
The researchers measured 18 xylem functional traits related to water transport, mechanical support, and storage in 15 liana species and 16 tree species from three different sites, including a tropical rainforest, a hot and dry valley savanna, and a subtropical evergreen broadleaved forest in Yunnan Province, Southwest China.
They aimed to analyze variations in stem xylem functional traits between lianas and trees, identify key traits associated with these functions, and examine the relationships among water transport, mechanical support, and storage functions in both growth forms.
The results revealed distinct ecological strategies between lianas and trees, with liana species having higher hydraulic efficiency and tree species having greater mechanical strength. Variations in stem hydraulic and mechanical traits were certainly associated with xylem structure, besides growth form and habitat, while variation in stem storage traits were mainly related to sites (environments). Starch and soluble sugars appear to help lianas adapt to changing environmental conditions.
In lianas, there is a consistent trade-off between the water transport capacity and mechanical support by xylem, which contrasts with trees where such trade-offs are less common or infrequent. Additionally, the relationships between water transport and storage functions in both lianas and trees are complex and multifaceted.
"Our study addresses the existing gap in research concerning storage functions in various plant species across different environments. It provides valuable insights into how plants adapt to environmental changes and the distinct ecological strategies employed by lianas and by trees to balance the demands of hydraulic transport, mechanical support, and storage,"said ZHANG Jiaolin of XTBG.

Contact
ZHANG Jiaolin Ph.D Principal Investigator
Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China
E-mail: zjl@xtbg.org.cn