Can multi-elemental stoichiometry in the leaf-root-rhizosphere continuum explain woody and herbaceous species’ coexistence in subtropical plantations?

Abstract

Abstract Background and aims The multi-elemental stoichiometry of plants provides important information for understanding species coexistence in ecosystems. However, whether or not the multi-elemental stoichiometry of the leaf-root-rhizosphere continuum can better explain the coexistence of woody and herbaceous species within a forest, and what are the linkages among leaf, root and rhizosphere stoichiometries are unclear. Methods In this study, we investigated the concentrations of 12 elements (C, N, P, K, Ca, Mg, Fe, Mn, Cu, Zn, Na, and Sr) and their ratios (C:N, N:P, K:P, K:Ca, P:Ca, K:Mg, Ca:Mg, C:Mg, Fe:Mn, Ca:Sr, Fe:Zn, Cu:Zn, K:Na, and Ca:Na) in leaves, roots and rhizospheres of six woody species and three herbaceous species coexisting in three subtropical plantations. Results The multi-elemental stoichiometry ratios of leaves and roots but not those of rhizospheres varied between coexisting woody and herbaceous species. Woody species had stronger absorption capacity for elements that were most deficient (Ca and P) in the subtropical soil. Most elemental ratios of leaves were closely associated with those of the roots, but only the foliar C:N, N:P, and K:P ratios were associated with those of the rhizospheres, and the Fe:Mn ratio of roots was intimately connected with that of the rhizospheres, highlighting divergent environmental constraints of different elements. Conclusions There is biogeochemical niche separation between woody and herbaceous species at a plant organ scale. Plant multi-elemental stoichiometries were constrained by plant nutrient absorption capacity and soil nutrient supply, which offer new insights into a better understanding of species coexistence in ecosystems.