Multiple Trophic Levels of a Forest Stream Linked to Terrestrial Litter Inputs

TLDR

Riparian detritus inputs are essential for conserving diverse stream food webs. The study evaluated terrestrial‑aquatic linkages by conducting a 3‑year large‑scale exclusion of leaf litter inputs to a forest stream. Excluding leaf litter caused a strong bottom‑up cascade that reduced most invertebrate taxa in the main habitat, while moss‑habitat fauna remained largely unchanged, demonstrating ecosystem‑level consequences of detrital input removal.

Abstract

The importance of terrestrial-aquatic linkages was evaluated by a large-scale, 3-year exclusion of terrestrial leaf litter inputs to a forest stream. Exclusion of leaf litter had a strong bottom-up effect that was propagated through detritivores to predators. Most invertebrate taxa in the predominant habitat declined in either abundance, biomass, or both, compared with taxa in a nearby reference stream. However, fauna in moss habitats changed little, indicating that different food webs exist in habitats of different geomorphology. Thus, the ecosystem-level consequences of excluding detrital inputs to an ecosystem were demonstrated. Inputs of riparian detritus are essential for conservation or restoration of diverse stream food webs.