Ann Bot. 2025 Jul 10:mcaf138. doi: 10.1093/aob/mcaf138. Online ahead of print.
ABSTRACT
BACKGROUND AND AIMS: Xylem and vessel structures help to maintain water transport in woody plants in response to environmental changes. Many studies have demonstrated the relationships between vessel structures and, in particular, temperature. However, the effects of environmental factors on the of vessel size distribution and on vessels of different sizes have not been fully assessed statistically. Lianas are characterized by large vessels and vessel dimorphism. Liana abundance decreases with decreasing temperature; this pattern is attributed to the vulnerability of their large vessels to freeze-thaw embolism. However, in temperate zones, the relationships between liana abundance and temperature differ between twining and root climber.
METHODS: We sampled wood discs of eight liana species distributed across Japan and measured size and shape of 130,940 vessels in 836 sections from 219 individuals. We classified vessels of each species into two diameter clusters (large and small) and calculated vessel traits and potential hydraulic conductivity (Kp). Vessel traits were compared among climbing mechanisms and the relationships between vessel traits and temperature were analyzed for species.
KEY RESULTS: Twining climbers had larger vessel diameters than root climbers and had greater Kp. However, the relationships between temperature and vessel traits of species were inconsistent within climbing mechanisms. The decrease in Kp in certain species with decreasing temperature might result from species-specific changes in xylem structure. Vessels of the two clusters related differently to temperature in some species.
CONCLUSIONS: The vessel traits in each climbing mechanism might partly explain the distribution patterns of these lianas in the study region. Furthermore, changes in Kp in some species supported the prediction that liana competitiveness decreases with decreasing temperature. Understanding the mechanisms behind the changes in vessel traits and vessel size distribution along environmental factors will provide fundamental insights into how environmental changes affect forest ecosystems by altering plant hydraulic function.
PMID:40638780 | DOI:10.1093/aob/mcaf138