| In northern Yellowstone National Park, restoration of large carnivores had cascading
consequences for stream-riparian habitats, transitioning their plant communities from herbaceous
to their historical state of willow-dominated. However, the extent of these consequences was
mediated by varying wildlife dynamics, geomorphic context, and climate, resulting in a habitat
mosaic. Ecologists have hypothesized that the restored willow state indicates that restored
carnivores, especially wolves, indirectly increased the diversity and productivity of
Yellowstone’s rivers. Though this narrative invokes the reciprocal linkages which define
stream-riparian habitats, how these linkages vary across space (i.e., a mosaic) is unclear. Despite
possible dynamic interdependence among aquatic-terrestrial food webs and calls for integrating
reciprocal linkages with landscape ecology to evaluate spatially linked food webs, such an
investigation has not been undertaken. Conceptually, meta-community theory addresses this, but
empirical investigation has been limited. We investigated how diverse aquatic and terrestrial
communities interact to mediate reciprocal land-water-land links across a mosaic of stream-
riparian ecosystems.
From 2018-2021, we intensively sampled a mosaic of eight headwater streams-riparian
ecosystems to characterize riparian plant communities, terrestrial organic matter and invertebrate
inputs, the diversity and productivity of aquatic primary producers, invertebrates, and fishes,
aquatic foodweb linkages and trophic transfer efficiencies, aquatic insect emergence, and
riparian insectivore composition and abundance.
Riparian vegetation state determined dominant organic matter sources, which influenced
benthic invertebrate community composition and productivity. The resulting phenology and
vulnerability of benthic invertebrates, and the consumption of their production and terrestrial
invertebrate input by fish assemblages, mediated the timing and magnitude of aquatic insect
emergence. In turn, the timing and magnitude of emergence, coupled with riparian vegetation,
mediated responses by riparian insectivores. Throughout the year, reciprocal fluxes of
invertebrates varied by orders of magnitude both within and among sites and were tracked by
consumers, revealing asynchronies in spatially-linked food webs across the mosaic.
Traits and interactions of organisms were critical to understanding localized stream-
riparian ecosystems which, rather than occurring as homogenous states, appeared to contribute to
heterogeneity across the mosaic. My findings highlight an empirical link between habitat
complexity and the maintenance of biodiversity via aquatic-terrestrial reciprocal linkages and
dynamic interdependence across a habitat mosaic.
Keywords: Aquatic-terrestrial links, food webs, meta-communities, northern Yellowstone
National Park, stream-riparian ecosystems, trait-mediated interactions |