A coordinated response to environmental drivers amongst individual functional traits is central to the plant strategy concept. However, whether the trait co-ordination observed at the global scale occurs at other ecological scales (especially within species) remains an open question. Here, for sapling communities of two tropical dry forest types in Costa Rica, we show large differences amongst traits in the relative contribution of species turnover and intraspecific variation to their directional changes in response to environmental changes along a successional gradient. We studied the response of functional traits associated with the leaf economics spectrum and drought tolerance using intensive sampling to analyse inter- and intra-specific responses to environmental changes and ontogeny. Although the overall functional composition of the sapling communities changed during succession more through species turnover than through intraspecific trait variation, their relative contributions differed greatly amongst traits. For instance, community mean specific leaf area changed mostly due to intraspecific variation. Traits of the leaf economics spectrum showed decoupled responses to environmental drivers and ontogeny. These findings emphasise how divergent ecological mechanisms combine to cause great differences in changes of individual functional traits over environmental gradients and ecological scales.
Bibliographical noteFunding Information:
We thank Daniel Perez Aviles, Christina Smith and Erick Calderon Morales for great help with data collection, Helen Simpson and Sarah Chesworth for help with lab analyses, Christopher Baraloto for interesting comments on the protocol, Stéphane Dray for advice on RLQ analysis, Bonnie Waring, Davey Jones, Paul Withers and Andrew Smith for discussion on soil data and Roger Blanco and Maria Marta Chavarria Diaz (Area de Conservación de Guanacaste) for help in obtaining research permits. The chronosequence was set up by Justin Becknell and JSP, and supported by an NSF CAREER Grant (DEB-1053237) to JSP. The soil moisture data were collected by Bonnie Waring and Lisa Rosenthal. This study was supported by the European Commission under the FONASO Erasmus Mundus doctorate programme and by the Coalbourn Trust.
© 2017 The Author(s).