Covariation in leaf, stem and root traits across 62 Artemisia species in China

Plants have a wide variety of trade-offs and correlations between traits that cannot be fully understood from a single organ or a small number of traits. In this thesis, we focused on 62 species of a single genus, Artemisia, and detected the trait covariation pattern among three functionally very different but equally important organs, i.e. leaves, stems and roots, at a broad geographical scale in China. The findings of this thesis highlight the necessity of incorporating multiple organs in trait-based research to gain a comprehensive understanding of plant ecological strategies and their responses to environmental changes. The selection of plant organs in ecological research should be informed by a rigorous consideration of the research objectives, rather than the availability and measurability of the organs in question. For example, stems are a more reliable indicator than leaves for monitoring and predicting plant responses to changing environmental conditions in order to understand community assembly. The consistent patterns of trait covariation across taxonomic and ecological scales and environmental gradients suggest that the fundamental ecological strategies are conserved, aiding in the prediction of community dynamics and species coexistence under varying environmental scenarios. Nevertheless, it is essential to exercise caution when applying these theories to finer scales, such as the subgenus level to ensure accurate ecological interpretations. Overall, the findings of this thesis have enhanced our theoretical understanding in trait-based ecology. This knowledge may also be useful for a better understanding of the ecology and resource economy of the many Artemisia species known to have medicinal (e.g. anti-malaria), anti-pathogen or anti-herbivore properties or uses in food or drinks, i.e. to make the best use of their natural ecosystem services.