Components of leaf-trait variation along environmental gradients

• Published in: The New phytologist 2020-10, Vol.228 (1), p.82-94
• Main Authors: Dong, Ning, Prentice, Iain Colin, Wright, Ian J., Evans, Bradley J., Togashi, Henrique F., Caddy-Retalic, Stefan, A.McInerney, Francesca, Sparrow, Ben, Leitch, Emrys, Lowe, Andrew J.
• Format: Article
• Language: English
• Subjects: Acclimation; Acclimatization; Adaptation; Australia; Carbon dioxide; Carbon isotope ratio; Carbon isotopes; Climate; Covariance; Economic analysis; Economics; Environmental factors; Environmental gradient; Geographical variations; Gradients; intraspecific variation; Isotope ratios; Leaf area; leaf economics spectrum; Leaves; Phenotype; plant functional traits; Plant Leaves; Regression analysis; Soil; Soil chemistry; Soil pH; Soil temperature; Species; species selection; trait‐gradient analysis; Tropical climate; Vapor pressure; Vapour pressure
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.16558

• Leaf area (LA), mass per area (LMA), nitrogen per unit area (Narea) and the leaf-internal to ambient CO₂ ratio (χ) are fundamental traits for plant functional ecology and vegetation modelling. Here we aimed to assess how their variation, within and between species, tracks environmental gradients. • Measurements were made on 705 species from 116 sites within a broad north–south transect from tropical to temperate Australia. Trait responses to environment were quantified using multiple regression; within- and between-species responses were compared using analysis of covariance and trait-gradient analysis. • Leaf area, the leaf economics spectrum (indexed by LMA and Narea) and χ (from stable carbon isotope ratios) varied almost independently among species. Across sites, however, χ and LA increased with mean growing-season temperature (mGDD₀) and decreased with vapour pressure deficit (mVPD₀) and soil pH. LMA and Narea showed the reverse pattern. Climate responses agreed with expectations based on optimality principles. Within-species variability contributed < 10% to geographical variation in LA but > 90% for χ, with LMA and Narea intermediate. • These findings support the hypothesis that acclimation within individuals, adaptation within species and selection among species combine to create predictable relationships between traits and environment. However, the contribution of acclimation/adaptation vs species selection differs among traits.