Trait plasticity in response to soil silica content goes beyond leaf silicon concentration in annuals

Abstract Background and aims Silica content in the soil has been shown to affect plant’s traits and performance. Trait plasticity and performance responses to soil silica content, however, have so far been addressed in a few traits and single species. Multi-species studies considering various traits and performance parameters are thus necessary to increase our understanding on ecological consequences of varying soil silica content. Methods We investigated plasticity in leaf silicon concentration, structural leaf traits, and nutrient stoichiometry as well as performance responses to differing amorphous silica (ASi) level in the soil under controlled conditions in nine annual plant species from Israel, representing the three functional groups: grasses, non-legume forbs, and legumes. Results Leaf silicon concentration increased in all species under higher ASi level, with the strongest plasticity in grasses. Plasticity in structural leaf traits was hardly pronounced, but some species showed a trade-off between leaf silicon and carbon concentration as expected. Leaf nitrogen concentration decreased in all functional groups with higher ASi level, whereas leaf phosphorous concentration increased only in legumes. Performance responses to ASi level were ambiguous: Plant’s fecundity increased across all study species, while growth rate analysed at the level of functional groups decreased under higher ASi level. Conclusion Our multi-species study shows that soil ASi level influences not only leaf silicon concentration but various traits and species’ performance in annuals. The effects vary among species and/or functional groups. Consequently, soil ASi level can influence composition and ecosystem functioning of annual plant communities in the Eastern Mediterranean Basin.