DOI: 10.5061/dryad.np5hqc045
title: Data from: Testing the biogeochemical niche hypothesis using leaves, stems and roots of 62 Artemisia species across China

description: The biogeochemical niche (BN) hypothesis is based on the concentrations of
 the predominant elements of a given organism to be stoichiometrically
 matched in order for it to function adequately. However, it is unknown how
 BN is represented by different plant organs and to what extent environment
 or evolution affects BN. We measured C, N, P, K, Ca and Mg concentrations
 in leaves, stems and roots of 1,022 individuals of 62 Artemisia species
 collected across China to quantify BNs of the three organs. The BN of
 leaves was offset from and smaller in volume than that of stems and roots.
 BNs of the three organs differed in their sensitivities to environmental
 gradients, and leaves were less responsive to environmental variation than
 stems and roots in both BN volumes and positions. Environmental gradients
 had larger effects on BN positions than on BN volumes of all three organs.
 The BN volumes and positions of leaves and roots had no phylogenetic
 signal, while stem BN had a weak signal, i.e. repeated species divergences
 from various Artemisia branches explained most of the BN variation of the
 three organs. Synthesis. The BN hypothesis cannot be fully tested using
 the elemental composition of a single organ owing to different
 physiological mechanisms and diverse responses of BN among organs. At
 least in Artemisia, leaves are strongly constrained in a limited elemental
 niche space to support a relatively stable supply of elements for leaf
 functioning, especially photosynthesis. In contrast, stems and roots
 develop larger elemental hypervolumes also representing nutrient storage
 and other functions. The BNs of Artemisia showed different environmental
 responses between volumes and positions, allowing these species to adjust
 elemental concentrations while maintaining the variation in overall
 elemental composition under different environmental conditions. In
 conclusion, BNs of extant Artemisia populations are determined mostly by
 short-term phenotypic responses to current environmental conditions and/or
 genotypic variation, while the recently evolved species diversity results
 mostly from species-specific and organ-specific use of nutrients and
 little by early divergence in the phylogeny.
description: We sampled <em>Artemisia</em> from of natural
 communities in 81 sites across China in 2018. At each site, we identified
 all <em>Artemisia </em>species and collected mature
 individuals of each species but excluding those with damage or herbivore
 attack. The depth of the holes dug around the base of the plants was based
 on the plant size and was sufficiently deep to excavate the whole root
 system. In total, 1,022 individuals of 62 <em>Artemisia</em>
 species were sampled.  Each plant sample was separated
 into leaf, stem and root, and oven-dried at 65 °C for a minimum of 48 h.
 The root systems were cleaned with running water on a fine mesh sieve to
 remove sand, clay, litter and other matter before drying the samples. For
 element analysis (C, N, P, K, Ca and Mg, units are all mg/g), all leaves,
 whole stems, and whole roots were ground into fine powders. Total C and N
 concentrations were determined with an elemental analyzer (Vario Max CN
 Elemental Analyzer, Elementar, Hanau, Germany). For determination of the
 concentrations of P, K, Ca and Mg, samples were pretreated with an acid
 mixture of 1:4 of HClO<sub>4</sub> (60%) and
 HNO<sub>3</sub> (60%), digested in a MARS 5 microwave
 digestion system (CEM GmbH, Kamp-Lintfort, Germany) and determined using
 an inductively coupled plasma optical emission spectrometer (iCAP 6300
 ICP-OES, Thermo Scientific, USA).
description: # Testing the biogeochemical niche hypothesis using leaves, stems and
 roots of 62 <i>Artemisia</i> species across China
 [https://doi.org/10.5061/dryad.np5hqc045](https://doi.org/10.5061/dryad.np5hqc045) ## Description of the data and file structure Elemental concentrations in leaves, stems, and roots of 62 *Artemisia* species across China ### Files and variables #### File: elemental\_concentrations.csv **Description:**  ##### Variables * Organ: plant organs * Site:  site number * Species: species name * NO: replicate of each species * C: carbon concentration * N: nitrogen concentration * Ca: calcium concentration * K: potassium concentration * Mg: magnesium concentration * P: phosphorus concentration