Species traits and environmental conditions determine the existence and strength of trophic interactions, but how they do so is poorly understood. To enable the informed inclusion of such driving factors in dynamic trophic-interaction models, we revisit and expand the functional and numerical response functions using a modular approach which is readily integrated into existing models. We divide the trophic interaction between predator and prey into eight steps: (1) search, (2) prey detection, (3) attack decision, (4) pursuit, (5) subjugation, (6) ingestion, (7) digestion, and (8) nutrient allocation. Formulating this as a modular functional-response function, we build a general dynamical model where trophic interactions can be explicitly parameterized for multiple traits and environmental factors. We then concretize this approach by outlining how a specific community can be modeled by selecting key modules (steps) and parameterizing them for relevant factors. This we exemplify for a community of terrestrial arthropods using empirical data on body size and temperature responses. With species interactions at the core of community dynamics, our modular approach allows for quantification and comparisons of the importance of different steps, traits, and abiotic factors across ecosystems and trophic interaction types, and provides a powerful tool for trait-based prediction of food-web structure and dynamics.

The exchange of material and individuals between neighbouring food webs is ubiquitous, but theory remains scarce for how such spatial flows affect ecosystem functioning. Here, we combine dynamic food web models with models for nutrient recycling to explore how animal foraging movement, between habitats of contrasting fertility and plant diversity, affects species persistence as well as the stocks and fluxes of biomass, detritus, and nutrients. We found that the net flow of consumers went from the habitat of higher fertility or diversity to the habitat with lower fertility or diversity, boosting ecosystem functioning in the receiving habitat. By explicitly modelling stocks and interconnecting fluxes we could replicate empirically observed effects of spatial subsidies, such as biomass distribution shifts and effect attenuation, and elucidate the underlying mechanisms. Our results demonstrate how foraging movement can drastically alter local functioning. Overall, our approach offers a start toward understanding ecosystem function in human-dominated landscapes.