Intraspecific trait variation can weaken interspecific trait correlations when assessing the whole-plant economic spectrum

Daniel C. Laughlin (Corresponding Author), Christopher H. Lusk, Peter J. Bellingham, David F. R. P. Burslem, Angela H. Simpson, Kris R. Kramer-Walter

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The worldwide plant economic spectrum hypothesis predicts that leaf, stem, and root traits are correlated across vascular plant species because carbon gain depends on leaves being adequately supplied with water and nutrients, and because construction of each organ involves a trade-off between performance and persistence. Despite its logical and intuitive appeal, this hypothesis has received mixed empirical support. If traits within species diverge in their responses to an environmental gradient, then interspecific trait correlations could be weakened when measured in natural ecosystems. To test this prediction, we measured relative growth rates (RGR) and seven functional traits that have been shown to be related to fluxes of water, nutrients, and carbon across 56 functionally diverse tree species on (1) juveniles in a controlled environment, (2) juveniles in forest understories, and (3) mature trees in forests. Leaf, stem, and fine root traits of juveniles grown in a controlled environment were closely correlated with each other, and with RGR. Remarkably, the seven leaf, stem, and fine root tissue traits spanned a single dimension of variation when measured in the controlled environment. Forest-grown juveniles expressed lower leaf mass per area, but higher wood and fine root tissue density, than greenhouse-grown juveniles. Traits and growth rates were decoupled in forest-grown juveniles and mature trees. Our results indicate that constraints exist on the covariation, not just the variation, among vegetative plant organs; however, divergent responses of traits within species to environmental gradients can mask interspecific trait correlations in natural environments. Correlations among organs and relationships between traits and RGR were strong when plants were compared in a standardized environment. Our results may reconcile the discrepancies seen among studies, by showing that if traits and growth rates of species are compared across varied environments, then the interorgan trait correlations observed in controlled conditions can weaken or disappear.
Original languageEnglish
Pages (from-to)8936-8949
Number of pages14
JournalEcology and Evolution
Issue number21
Early online date21 Sept 2017
Publication statusPublished - Nov 2017

Bibliographical note

This research was supported by a grant (UOW1201) from the Royal Society of New Zealand Marsden Fund (DCL), Australian Research Council Discovery Grant DP1094606 (CHL), core funding to Landcare Research from New Zealand's Ministry for Business, Innovation and Employment's Science and Innovation Group and a Hayward Fellowship (PJB and DFRPB), and University of Waikato Scholarships (AHS, KRK-W).


All data used in this study, including all plant traits, by species, for cultivated juveniles, wild juveniles, and wild mature trees are available online at Landcare Research Datastore, (Laughlin et al., 2017).


  • fine root tissue density
  • leaf economic spectrum
  • ontogenetic development
  • relative growth rate
  • root economic spectrum
  • wood density
  • wood economic spectrum


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