Table 1.
Summary of diversity metrics used in this study.
Figure 1.
Illustration of abundance weighting procedure for FD and Hulls.
Calculations are shown for a simplified community of three species with unequal abundances (abundance represented by the size of circles). Subscripts are for species i and trait j. Trait values for species are standardized to a mean of zero and standard deviation of one (Z-scores). Trait values for species are then multiplied by the proportional relative abundance (bound between zero and one), which results in a translation towards the origin, more so for rare species and less so for abundant species (see Appendix 1 for calculation). This modified distribution is then used for subsequent metric calculation. Weighing by the CV involves multiplying each standardized trait value by the CV (a positive value). This “stretches” trait axes with CV>1, effectively spreading species further apart along that axis, and “compresses” trait axes with CV<1, effectively crowding species closer together along that axis. We performed CV weighting prior to abundance weighting.
Figure 2.
Associations among functional diversity metrics explored in this study.
Shown below are bivariate plots (upper panels), distributions (diagonal), and Pearson’s ρ (lower panels, significant terms are in bold, P<0.05) for the 19 diversity metrics examined here.
Figure 3.
Illustrative bivariate plots for select functional diversity metrics and ecosystem function.
Relationships between aboveground biomass (top row) or light (bottom row) with functional diversity metrics. Leftmost panels show the strongest predictors based on AIC, and selected representative metrics are shown to the right for comparison. Reproduced from Tables 1 and 2 are Akaike weights (wi), with larger weights indicating greater relative strength of evidence for that predictor.
Table 2.
Results for linking functional diversity with aboveground biomass.
Table 3.
Results for linking functional diversity with belowground biomass.
Table 4.
Results for linking functional diversity with light capture.
Figure 4.
Associations between FD’ and species abundances.
Shown are associations between FD’ and three example species: Lupinus perennis (N-fixer), Bromus inermis (C3 grass) and Schizachyrium scoparium (C4 grass).
Figure 5.
Association between Lupinus perennis and aboveground biomass.
Linear association between the relative abundance of Lupinus perennis and aboveground biomass.