Contrasting responses of terrestrial and aquatic consumers in riparian - stream networks to local and landscape level drivers of environmental change

The biodiversity of streams and riparian zones is highly interlinked by multiple cross-habitat flows of organisms, nutrients and materials, and are thus increasingly recognized as forming an extended meta-ecosystem network spanning both within and across entire catchments. However, current understanding of how these extended networks respond to environmental change is limited by the lack of studies quantifying the local and larger-scale drivers of biodiversity in both terrestrial and aquatic systems simultaneously. Using high-resolution species and environmental data from eight boreal riparian stream meta-ecosystems, half of which were situated in forest and half in agricultural catchments, we quantified land-use impacts and the importance of catchment and local (riparian, instream) scale variables on the diversity and community composition of three epigeal arthropod groups (spiders and staphylinid and carabid beetles) and aquatic macroinvertebrates. All four organism groups responded to quantifiable environmental variables. Staphylinid beetle and spider assemblages differed significantly between forested and agricultural sites and were strongly correlated with riparian variables such as vegetation type and soil properties, but also instream variables such as conductivity and floating macrophytes. By contrast, carabid beetle and aquatic macroinvertebrate assemblages did not differ between forested and agricultural sites and showed similar responses to catchment and local scale variables. Our results indicate that measures that only address local scale drivers of terrestrial biodiversity might be ineffective if the catchment-scale variables regulating aquatic biodiversity and aquatic terrestrial linkages are not adequately addressed in ecosystem management. (C) 2021 The Author(s). Published by Elsevier GmbH on behalf of Gesellschaft fur Okologie.

Automated summary

The study focused on the biodiversity of boreal riparian stream meta-ecosystems and found significant differences in response to land use, catchment, and local scale variables between forested and agricultural sites. Results indicate the importance of considering catchment-scale variables and addressing aquatic biodiversity and aquatic terrestrial linkages in ecosystem management to effectively preserve biodiversity.