Timescale hierarchy determines the indirect effects of fluctuating subsidy inputs on in situ resources.

Empirical studies have shown that temporally fluctuating inputs of resource subsidies can indirectly increase or decrease the abundance of in situ resources by affecting generalist consumers that feed on both subsidies and in situ resources. By mathematical modeling, we develop a theoretical framework that can explain these variable consumer-mediated indirect effects. We show that the hierarchy of timescales among fluctuations in the subsidy input rate and consumers' reproductive and aggregative numerical responses predict the signs of the indirect effects. These predictions are consistent with field observations from a variety of natural systems. Our results suggest that the timescale hierarchy of ecological processes is fundamentally important for understanding and predicting indirect effects in nonequilibrium food web dynamics.