Coordination of economics spectra in leaf, stem and root within the genus Artemisia along a large environmental gradient in China

Aim: The plant economics spectrum provides a fundamental framework for understanding functional trait variation along environmental gradients. However, it is unclear whether there is a general whole-plant economics spectrum across organs at the finer taxonomic scale (e.g. within genera), and if there is, which factors affect the trait coordination of the different organs. Here, we examined whether resource economics spectra of different organs (i.e. leaf, stem and root) can be integrated at the whole-plant level within a single genus, and how environment, intraspecific variation and taxonomic scale shape the whole-plant spectrum. Location: China. Time period: 2018. Major taxa studied: Artemisia. Methods: We sampled 1,022 individuals of 62 Artemisia species in central and eastern China to test trait coordination patterns from organ to whole-plant level. From the resource economics spectrum perspective, 15 traits were chosen to represent the trade-off between structural and nutrient investments, including organs’ C, N, P and dry matter content, specific leaf area, specific stem length and specific root length. Results: Pairwise trait correlations and the trade-off patterns along the resource economic axis were consistent at both organ and whole-plant levels. Environmental gradients did not strongly affect the correlations among leaf, stem and root economics spectra, that is, the intraspecific variation weakened but did not mask this coordination. Taxonomic scale did not affect the degree of trait coordination as the genus-wide whole-plant economics spectrum also emerged within each of the three subgenera. Main conclusions: Our results support the hypothesis that the coordination of economics spectra across organs forms a whole-plant economics spectrum representing a ‘fast–slow’ resource management strategy, which is robust to recent evolution (genotypic variation, even for species within a single genus) and present-day environmental variation. Further studies should elucidate in which circumstances or phylogenetic branches the coordinated pattern found for Artemisia is representative of other widely distributed genera.