Plant Trait Networks: Improved Resolution of the Dimensionality of Adaptation

Abstract

Functional traits are frequently used to evaluate plant adaptation across environments. Yet, traits tend to have multiple functions and interactions, which cannot be accounted for in traditional correlation analyses. Plant trait networks (PTNs) clarify complex relationships among traits, enable the calculation of metrics for the topology of trait coordination and the importance of given traits in PTNs, and how they shift across communities. Recent studies of PTNs provide new insights into some important topics, including trait dimensionality, trait spectra (including the leaf economic spectrum), stoichiometric principles, and the variation of phenotypic integration along gradients of resource availability. PTNs provide improved resolution of the multiple dimensions of plant adaptation across scales and responses to shifting resources, disturbance regimes, and global change. Rapid Advances in Data, Analyses, and Applications of Trait-Based Plant Ecology Plant functional traits, defined as those that influence growth, reproduction, and survival [1,2], are important indices for predicting how plants respond and adapt to changing environments across levels of organization, that is, from organs, to species, and to ecosystems [3,4]. Indeed, functional traits can contribute to the prediction of species' distributions, vital rates, and responses to climate change [5]. Highlights Most functional traits are multifunctional and adaptations to multiple selective pressures, complicating the use of traditional correlation and clustering approaches to establish their integration and relative mechanistic importance. New developments in the analysis and application of plant trait networks (PTNs) increase the resolution and inference of adaptations and responses of plants across scales. Communities vary in their constraints on given traits, resulting in variation in PTN topology, and the relative importance of component traits. PTNs provide a multidimensional approach for evaluating the adaptations and response of plants across lineages, life forms, ontogenetic stages, and environments.

Leaf trait variation in species-rich tropical Andean forests

“…Yet, environmental filtering apparently has increased the integration of leaf traits in higher-elevation trees, as is suggested by the trait network analysis. This indicates that the tree community responds with a more efficient acquisition and mobilization of resources 30 , 32 , 34 , 35 . Even if the colder and less fertile site conditions did not reduce interspecific trait variation in all leaf traits, they seem to have restricted the degrees of freedom of possible trait combinations.…”

“…For each study site, we calculated a matrix of trait-trait relationships using Pearson correlations. To avoid considering spurious correlations among traits, only statistically significant correlations ( p < 0.05) were included 32 , 33 . Then, an adjacency matrix was created by assigning below threshold as 0 and above threshold as the integer of |r|× 10; thus, the adjacency matrix only shows the weighted presence or the absence of connections between pairs of plant traits.…”

“…Most plant traits are multifunctional and connected to other traits through complex direct and indirect interactions, and the study of plant trait networks is a promising new tool to understand plant adaptation to their environment 30 – 32 . Trait constellations and network topologies differ among plant communities, and they thus may shift along gradients of resource availability and with changes in species composition 32 . The analysis of plant trait networks along environmental gradients at the local scale may also be a straightforward approach to understand the importance of different traits for plant adaptation within a given community 33 .…”

Involvement of soluble proteins in growth and metabolic adjustments of drought‐stressed Calligonum mongolicum seedlings under nitrogen addition

“…Recent studies have provided a novel perspective toward visualizing the relationships among different plant traits and their significance using network theory, i.e. a PTN (Flores‐Moreno et al 2019; He et al 2020; Kleyer et al 2019). We observed many trait–trait correlations using the PTN method, supporting the concept of the plant as a harmonized system of biological functions (Fig.…”

“…The P ‐values of the correlation matrix were adjusted using the Benjamini and Hochberg false discovery rate (FDR) control procedure (Benjamini et al 2006). We used the plant trait network (PTN) to explore the relationships among a series of plant traits and their significance (He et al 2020). First, we calculated the matrix of trait–trait relationships and quantified the correlation coefficient ( r ) using Spearman’s method with the ‘psych’ R package (Revelle 2018).…”