Defining stream riparian zones across multidimensional environmental gradients

Year: 
2025
Publications Type: 
Journal Article
Publication Number: 
5418
Citation: 

Dodds, Walter K.; Barmuta, Leon A.; Bernal, Susana; Corman, Jessica; Harms, Tamara K.; Johnson, Sherri L.; Li, Li; Fernandes Cunha, Davi Gasparini; Olden, Julian D.; Riis, Tenna; Silva, Lucas C. R.; Stella, John C.; Sullivan, Pamela; Wohl, Ellen. 2025. Defining stream riparian zones across multidimensional environmental gradients. Journal of Environmental Quality.1-24. doi:https://doi.org/10.1002/jeq2.70080

Abstract: 

Riparian zones are a critical terrestrial-aquatic ecotone. They play important roles in ecosystems including (1) harboring biodiversity, (2) influencing light and carbon fluxes to aquatic food webs, (3) maintaining water quality and streamflow, (4) enhancing aquatic habitat, (5) influencing greenhouse gas production, and (6) sequestering carbon. Defining what qualifies as a riparian zone is a first step to delineation. Many definitions of riparian boundaries focus on static attributes or a subset of potential functions without recognizing that they are spatially continuous, temporally dynamic, and multi-dimensional. We emphasize that definitions should consider multiple ecological and biogeochemical functions and physical gradients, and explore how this approach influences spatial characterization of riparian zones. One or more of the following properties can guide riparian delineation: (1) distinct species, elevated biodiversity, or species with specific adaptations to flooding and inundation near streams relative to nearby upland areas; (2) unique vegetation structure directly influencing irradiance or organic material inputs to aquatic ecosystems; (3) hydrologic and geomorphic features or processes maintaining floodplains; (4) hydric soil properties that differ from the uplands; and/or (5) elevated retention of dissolved and suspended materials relative to adjacent uplands. Considering these properties for an operational and dynamic definition of riparian zones recognizes that riparian boundaries vary in space (e.g., variation of riparian corridor widths within or among watersheds) and time (e.g., responses to hydrological variance and climate change). Inclusive definitions addressing multiple riparian functions could facilitate attainment of research and management goals by linking properties of interest to specific outcomes.