Plant functional traits as determinants of population stability

Understanding the processes regulating population temporal stability is important to infer species coexistence and ecosystem stability patterns. It has been hypothesized that population temporal stability could be driven by functional trade-offs in resource acquisition and growth rate strategies. We tested this hypothesis by analyzing a 13-year data set from a mown grassland community in a factorial experiment with fertilization and dominant removal as the main treatment effects. Population temporal stability, measured as a coefficient of variation of species' biomass over time, was related to plant traits covering different functional trade-offs. These included plant height, leaf dry matter content (LDMC), specific leaf area, seed mass, leaf delta C-13, and rooting depth. Three of the traits (LDMC, rooting depth, and leaf delta C-13) had significant relationships with population temporal stability, even after accounting for species' phylogenetic relatedness. Higher values of LDMC, the best predictor, were consistently associated with greater population temporal stability across all experimental conditions. This suggests a functional trade-off along the leaf economics spectrum, with more conservative, slow-growing species being more stable over time. Incorporating functional trade-offs into the assessment of population temporal dynamics will allow for a more comprehensive understanding of the processes that sustain the stability of ecosystems and species coexistence.