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.