SREL Reprint #3573

A floodplain continuum for Atlantic Coast rivers of the Southeastern US: Predictable changes in floodplain biota along a river's length

Darold P. Batzer1, Gregory B. Noe2, Linda Lee3, and Mark Galatowitsch4

1Department of Entomology, University of Georgia, Athens, GA, USA
2Hydrological-Ecological Interactions Branch, U.S. Geological Survey, Reston, VA, USA
3University of Georgia Savannah River Ecology Laboratory, Aiken, SC, USA
4Biology Department, Centre College, Danville, KY, USA

Abstract: Floodplains are among the world’s economically-most-valuable, environmentally-most-threatened, and yet conceptually-leastunderstood ecosystems. Drawing on concepts from existing riverine and wetland models, and empirical data from floodplains of Atlantic Coast rivers in the Southeastern US (and elsewhere when possible), we introduce a conceptual model to explain a continuum of longitudinal variation in floodplain ecosystem functions with a particular focus on biotic change. Our hypothesis maintains that major controls on floodplain ecology are either external (ecotonal interactions with uplands or stream/river channels) or internal (wetland-specific functions), and the relative importance of these controls changes progressively from headwater to mid-river to lower-river floodplains. Inputs of water, sediments, nutrients, flora, and fauna from uplands-to-floodplains decrease, while the impacts of wetland biogeochemistry and obligate wetland plants and animals within-floodplains increase, along the length of a river floodplain. Inputs of water, sediment, nutrients, and fauna from river/stream channels to floodplains are greatest mid-river, and lower either up- or down-stream. While the floodplain continuum we develop is regional in scope, we review how aspects may apply more broadly. Management of coupled floodplain-river ecosystems would be improved by accounting for how factors controlling the floodplain ecosystem progressively change along longitudinal riverine gradients.

Keywords: Ecotonal interaction; Flood-pulse continuum; Hydrology; River continuum; Wetland functions

SREL Reprint #3573

Batzer, D. P., G. B. Noe, L. Lee, and M. Galatowitsch. 2018. A floodplain continuum for Atlantic Coast rivers of the Southeastern US: Predictable changes in floodplain biota along a river's length. Wetlands 38(1): 1-13.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).