Variation in leaf functional trait values within and across individuals and species: an example from a Costa Rican dry forest

Abstract

Summary1. Patterns of species co-existence and species diversity in plant communities remain an important research area despite over a century of intensive scrutiny. To provide mechanistic insight into the rules governing plant species co-existence and diversity, plant community ecologists are increasingly quantifying functional trait values for the species found in a wide range of communities. 2. Despite the promise of a quantitative functional trait approach to plant community ecology, we suggest that, along with examining trait variation across species, an assessment of trait variation within species should also be a key component of a trait-based approach to community ecology. Variability within and between individuals and populations is likely widespread due to plastic responses to highly localized abiotic and biotic interactions. 3. In this study, we quantify leaf trait variation within and across ten co-existing tree species in a dry tropical forest in Costa Rica to ask: (i) whether the majority of trait variation is located between species, within species, within individuals or within the leaves themselves; (ii) whether trait values collected using standardized methods correlate with those collected using unstandardized methods; and (iii) to what extent can we differentiate plant species on the basis of their traits? 4. We find that the majority of variation in traits was often explained by between species differences; however, between leaflet trait variation was very high for compound-leaved species. We also show that many species are difficult to reliably differentiate on the basis of functional traits even when sampling many individuals. 5. We suggest an ideal sample size of at least 10, and ideally 20, individuals be used when calculating mean trait values for individual species for entire communities, though even at large sample sizes, it remains unclear if community level trait values will allow comparisons on a larger geographic scale or if species traits are generally similar across scales. It will thus be critical to account for intraspecific variation by comparing species mean trait values across space in multiple microclimatic environments within local communities and along environmental gradients. Further, quantifying trait variability due to plasticity and inheritance will provide a better understanding of the underlying patterns and drivers of trait variation as well as the application of functional traits in outlining mechanisms of species co-existence.

Corrigendum to: New handbook for standardised measurement of plant functional traits worldwide

“…Poorter et al 2009). Species may therefore vary in which quantitative traits are stable across given gradients, so tests should be made before a trait is taken to be stable for a given species (Albert et al 2010(Albert et al , 2012Hulshof and Swenson 2010;Messier et al 2010;Moreira et al 2012).…”

A comparative study of growth and leaf trait variation in twenty Cornus wilsoniana W. families in southeastern China

“…In fact, traditional community ecology has mainly focused on interspecific variation, and little work has involved intraspecific variation (Weiher et al 2011, Violle et al 2012. However, many studies have shown that there is high variability at the intraspecific level (Ponton et al 2001, Hulshof & Swenson 2010, provenance level (O'Brien et al 2007, Rawat & Bakshi 2011 and at the family or clone level , Zhao et al 2016.…”

Trait-based community assembly of understory palms along a soil nutrient gradient in a lower montane tropical forest

“…Recent trait-based community studies have suggested that sample sizes >10 are necessary to detect species differentiation among similar species on local scales, whereas smaller sample sizes can be used when comparing among divergent species or at larger scales (Baraloto et al 2010;Hulshof and Swenson 2010). When comparing across species mean trait values in this study, we found differences for most physiological traits as well as for morphological and biochemical traits among the species, indicating that our sampling regime, a compromise between the number of species, traits, and sites, was able to detect differences in trait means at all but the smallest scales (within site) for conserved traits.…”

“…Habitat filtering can lead to changes in trait composition along environmental gradients as a result of either turnover in species composition or differences in species abundance (Keddy 1992;Cornwell and Ackerly 2009;Sandel et al 2010) or intraspecific variation due to plasticity or genetic variation (Cornwell and Ackerly 2009;Hulshof and Swenson 2010;Jung et al 2010). Whereas most trait-based studies focus on species mean trait values, recent work has incorporated intraspecific variation to trait-based frameworks, adding a greater power to detect trait-environment linkages (Cornwell and Ackerly 2009;Hulshof and Swenson 2010;Jung et al 2010).…”

“…Whereas most trait-based studies focus on species mean trait values, recent work has incorporated intraspecific variation to trait-based frameworks, adding a greater power to detect trait-environment linkages (Cornwell and Ackerly 2009;Hulshof and Swenson 2010;Jung et al 2010). Furthermore, the incorporation of intraspecific variation allows a mechanistic approach to predicting species losses due to environmental change and its impact on ecosystem function (Hooper et al 2005;Jung et al 2010).…”