Format: ORAL

Yan Wang1, Alan Crivellaro2, Jiri Dolezal3,4, Patrick Heuret5, Sandrine Isnard5, Johannes Liesche6, Olivier Maurin7, Yann Salmon1

1 University of Helsinki, Helsinki, Finland 2 Stefan cel Mare University of Suceava, Suceava, Romania 3 Institute of Botany, Czech Academy of Sciences, Trebon, Czech Republic 4 University of South Bohemia, Ceské Budejovice, Czech Republic 5 AMAP, Université de Montpellier, CIRAD, CNRS, INRAE, IRD, Montpellier, France 6 University of Graz, Graz, Austria.   7 Royal Botanic Gardens, Kew, Richmond, UK

Studying the anatomical structure of phloem contributes to our comprehension of how phloem transport plays a role in the ecological success of species. Additionally, integrating both xylem and phloem traits enhances our understanding of how plants strategically adapt their morphological and anatomical features to diverse climates. In recent years, the importance of the scaling relationship between stem length and the size of xylem and phloem conduits has been highlighted for conducting more precise ecological studies. For some species, it has been observed that the intra-specific variance in vessel and sieve element size is more influenced by stem length than by climate. Further, stem length dominates inter-specific variance of vessel traits compared to species habit climate. However, the extent to which climate contributes to the inter-specific variability of phloem anatomical traits is not well investigated. The aim of our study is to examine stem anatomical traits of woody angiosperm species in relation to sample distance from apex and their native climate factors across different biomes. We collected stem cross-section images of species from a wide range of climates. We measured the size and frequency of sieve elements and vessels of outer layer rings. The optimum climate for species was extracted from CHELSA V2.0 based on their occurrence records on GBIF. Our preliminary result shows that when data from all species are aggregated, the radius of sieve elements follows a power law with distance from the apex. After correcting for the scaling factor and phylogenetic correlation, both temperature from the wettest quarter and precipitation in the warmest quarter are related to the radius of the sieve tube element. Our study demonstrates the importance of considering scaling geometry when conducting ecological research on anatomical traits. It also suggests that different phloem traits enable various species to cope with distinct environmental conditions.