Why species tell more about traits than traits about species: predictive analysis

Abstract

Trait analysis aims to understand relationships between traits, species diversity, and the environment. Current methods could benefit from a model-based probabilistic framework that accommodates covariance between traits and quantifies contributions from inherent trait syndromes, species interactions, and responses to the environment. I develop a model-based approach that separates these effects on trait diversity. Application to USDA Forest Inventory and Analysis (FIA) data in the eastern United States demonstrates an apparent paradox, that the analysis of species better explains and predicts traits than does direct analysis of the traits themselves; trait data contain less, not more, information than species on environmental responses. Whereas variation in some traits is dominated by inherent syndromes (tendency for certain traits to be associated with others within an individual and species), others are strongly controlled by variation in species diversity. There is substantial variation in environmental control on trait patterns, between traits and regionally. In terms of environmental response traits do not aggregate into defined plant functional types, as would be desirable for models.

Scaling functional traits to ecosystem processes: Towards a mechanistic understanding in peat mosses

“…In other words, while there was a large interspecific variation in the response of architectural traits to microenvironmental gradients, the response of physiological traits and processes was more univocally determined by a fixed mechanistic pathway with a limited variation among species. This is in agreement with Clark’s () finding that although trait syndromes dominate variation in some traits, others are strongly controlled by variation in species diversity (Evans et al, ). In the genus Sphagnum , the strong weight of interspecific variability is explained by a complementarity effect in the capacity of each species to increase or reduce the explained variance in the model.…”

“…The interplay between architectural and physiological traits mediates the effects of environmental gradients on ecosystem processes (Falster, Brännström, Dieckmann, & Westoby, ; Moor et al, ) (Figure a). Finally, trait variability (c) is the result of an increasing number of species in the community, as new species potentially broaden the trait distribution for a community (Clark, ; Michel, Lee, During, & Cornelissen, ). Integrating these three mechanisms makes it possible to build realistic ecological models that are constrained in multivariate space by allometric relationships, covariation (trade‐offs, selection) and species co‐occurrences (environmental filtering and biotic interactions) (for an example of model constrained in this way, Clark, ).…”

Changes in Community-Level Riparian Plant Traits over Inundation Gradients, Colorado River, Grand Canyon

“…A community-level value was calculated for each trait in each plot using two matrices of primary data (Hollingsworth et al 2013;Clark 2016). A matrix of relative species cover within each 1-m 2 plot was calculated by dividing each species cover by the total vegetation cover of the plot.…”

“…These changes strongly suggest that flooding and water stress influence riparian community-level traits (Kyle and Leishman 2009;Hough-Snee et al 2015). A community-level trait is a metric calculated for an entire field plot from trait values of species that occur in the plot weighted by the relative abundance of species in the plot (Hollingsworth et al 2013;Clark 2016). Comparisons of community-level traits over gradients provide understanding about environmental and plant functional controls over community assembly and ecosystem processes that may be transferable among systems.…”

Generalized joint attribute modeling for biodiversity analysis: median‐zero, multivariate, multifarious data

“…, Pollock et al. ) and predictive trait models (PTMs; Clark ). SDMs and JSDMs omit much of the information contained in field data, where abundances and attributes are often documented in multifarious ways.…”