Fig. 1: Functional trait diversity-mediated drought responses.

Simulated drought experiments for TNF (A) and CAX (B). Shown is the change in above-ground biomass during drought using the default model setup with no constraints placed on diversity. Each line represents one of 96 replicate simulations. The bold line represents the mean over the replicate simulations. Crosses indicate the observed biomass reduction and the year these reductions were observed. Horizontal bars indicate the start and end of simulated and real-world drought treatments. For (C and D), simulated drought experiments were repeated, and the diversity level was manipulated by initialising the model with varying numbers of unique trait combinations (species). The model was initialised with the following 18 different numbers of species (1, 2, …, 12, 16, 32, 48, 64, 80, and 96). No two species had identical trait values. 96 replicates were run for each species number treatment (see Fig. S1 and “Methods”). C Mean predicted post-drought biomass reductions vs. simulated functional trait diversity. D Residual standard deviation about mean biomass reductions. C, D The results of a Bayesian linear regression analysis (see “Examining relationships between functional trait diversity and changes in above-ground biomass” and Tables S2, S3). Shading indicates the 95% credible interval around mean posterior predictions. Rao’s quadratic entropy, i.e., the mean functional dissimilarity between two randomly selected individuals⁸², was used as a measure of functional trait diversity in (C) and (D). 8T indicates that RaoQ was calculated using the 8 traits displayed in Figs. 2, 3. The data underlying this figure are provided in figshare (https://doi.org/10.6084/m9.figshare.26232395).