Contrasting patterns of leaf trait variation among and within species during tropical dry forest succession in Costa Rica

Abstract

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 dierences amongst traits in the relative contribution of species turnover and intraspecic 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-specic responses to environmental changes and ontogeny. Although the overall functional composition of the sapling communities changed during succession more through species turnover than through intraspecic trait variation, their relative contributions diered greatly amongst traits. For instance, community mean specic leaf area changed mostly due to intraspecic variation. Traits of the leaf economics spectrum showed decoupled responses to environmental drivers and ontogeny. These ndings emphasise how divergent ecological mechanisms combine to cause great dierences in changes of individual functional traits over environmental gradients and ecological scales.