A global meta‐analysis of the relative extent of intraspecific trait variation in plant communities

Abstract

Recent studies have shown that accounting for intraspecific trait variation (ITV) may better address major questions in community ecology. However, a general picture of the relative extent of ITV compared to interspecific trait variation in plant communities is still missing. Here, we conducted a meta-analysis of the relative extent of ITV within and among plant communities worldwide, using a data set encompassing 629 communities (plots) and 36 functional traits. Overall, ITV accounted for 25% of the total trait variation within communities and 32% of the total trait variation among communities on average. The relative extent of ITV tended to be greater for whole-plant (e.g. plant height) vs. organ-level traits and for leaf chemical (e.g. leaf N and P concentration) vs. leaf morphological (e.g. leaf area and thickness) traits. The relative amount of ITV decreased with increasing species richness and spatial extent, but did not vary with plant growth form or climate. These results highlight global patterns in the relative importance of ITV in plant communities, providing practical guidelines for when researchers should include ITV in trait-based community and ecosystem studies.

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

“…These results are an important reminder that comparative studies must control for environmental and ontogenetic effects when comparing plant phenotypes, and that traits measured under standardized conditions remain the gold standard for understanding genetically based functional differences among species (Grime et al., 1997). Traits measured on wild plants are clearly valuable for addressing many other research questions, such as identifying broad biogeographic relationships between traits and the environment (Simpson, Richardson, & Laughlin, 2016; Violle, Reich, Pacala, Enquist, & Kattge, 2014), the sources of intraspecific trait variability (Siefert et al., 2015), and the effects of traits on ecosystem processes (Freschet et al., 2012). We recommend that future global tests of the interspecific whole‐plant economic spectrum account for the potentially confounding effects of intraspecific trait variation in response to environmental gradients.…”

Gap-filling a spatially explicit plant trait database: comparing imputation methods and different levels of environmental information

“…We show that species mean imputation may result in substantial information loss that may hinder research development on important topics in functional biogeography, such as the ecological drivers and implications of intraspecific trait variability (e.g. Siefert et al, 2015). Gap-filled multivariate trait datasets may increase the robustness of syntheses of plant form and function and trait-driven modelling approaches (Yang et al, 2015).…”

“…The strong phylogenetic signal may then be sufficient to impute speciesaveraged trait values using taxonomic information (Swenson, 2014). However, intraspecific variability in plant traits may be substantial (Siefert et al, 2015;Vilà-Cabrera et al, 2015) and imputation methods that use environmental information may be more appropriate when assessing trait relationships and trait-environment covariance in a spatially explicit context. Biotic or abiotic variables other than the trait matrix of interest can be included in imputation algorithms as auxiliary variables to reduce imputation bias (Azur et al, 2011;Rezvan et al, 2015).…”

Trait-based plant ecology: moving towards a unifying species coexistence theory

“…However, intraspecific trait variation (ITV) has been shown to be critical for responding to key questions in community ecology (Bolnick et al 2011;Violle et al 2012). In a recent metanalysis (Siefert et al 2015), ITV was evaluated and recommended for use in trait-based community ecology due to its importance, i.e., representing 25 % of the total trait variation, and extent, i.e., higher in whole plant traits and in regional studies. Volf et al (2016) evaluated these two components as a response to disturbances of different intensity in meadows.…”