Functional trait analysis reveals the hidden stability of multitrophic communities

Although important for understanding how ecosystems will fare with increasing global change, the relationship between diversity and stability in multitrophic communities is still debated. Our best understanding comes from work within competitive guilds, where the relationship between stability and functional diversity is generally positive and also more direct and mechanistic than the relationship with species diversity. To expand our understanding, there is a need to examine empirically how functional trait identity relates to spatial and temporal stability within multitrophic communities relative to species identity. Here, we measured 13 functional traits of six coastal pond fish communities to examine temporal and spatial community stability through the lenses of functional trait diversity and species diversity. We found that solely considering species composition may underestimate stability. Additionally, we found spatial convergence and temporal divergence in species and trait variability, and we link this variation to processes of deterministic community assembly. Lastly, we found that correlations of species with key functional traits allow us to make inferences about how the trophic position of species relates to trait stability. Inferring community processes and making conservation decisions from species or trophic groups based on functional trait knowledge may be a viable strategy when resources are limited.