Abstract
Predator‐induced changes in prey traits can cascade through ecosystems to impact biogeochemical cycling and community structure. Whether these effects persist, amplify or diminish across prey generations remains uncertain. We tested for predator transgenerational effects using a 3‐year common garden experiment in a terrestrial old‐field ecosystem. Predator exposure was manipulated across two generations of four grasshopper herbivore prey populations, with measurements of ecosystem processes made alongside measurements of prey trait responses. We found predators had larger effects on plant community biomass, plant diversity and soil carbon accumulation in the second generation of predator exposure than in the first generation. Paired with trait data on the grasshoppers, we found this amplification of ecosystem effects corresponded with heightened antipredator behaviours in the second generation. Our results show that transgenerational behavioural plasticity can magnify predator‐driven ecosystem impacts across generations, linking eco‐evolutionary processes with ecosystem dynamics.