Search

Rivers have an intricate relationship with the vegetation that colonizes them. Riparian plants, capable of thriving within river corridors, both respond to and influence geomorphology. Yet interactions between river morphodynamics and vegetation tend to be context specific, making it challenging to generalize findings between locations. The current comprehension of vegetation interaction with physical processes, and especially its effects on river morphodynamics, still lacks clarity. This article examines numerous sources of variation in plant responses to, and effects on, river morphodynamics. Vegetation influences on geomorphological parameters vary in terms of intensity and spatial extent along the gradient of river energy and according to the fluvial style. Whilst feedbacks between vegetation and river morphodynamics are readily discernible at a local scale, on larger spatial scales, it can remain difficult to precisely determine cause-and-effect relationships that link hydrogeomorphic and vegetation drivers and the outcomes of their feedbacks. This is especially problematic for those feedbacks that give rise to emergent system landscape behaviour in meandering and island braided rivers. By contrast, in certain river configurations, such as anabranching rivers, the imprint of vegetation on the riverscape can be clearly evident. The imprint of vegetation is also supported by evidence from the ancient alluvial record. Through this review, we highlight key perspectives from a wide range of modern and ancient rivers of varied configuration in order to inform future studies of vegetation responses to, and effects on, river morphodynamics. • Vegetation responses to, and effects on, river morphodynamics are modulated by environmental and biological contexts. • Vegetation-geomorphology interactions are embedded into a complex adaptive system. • Vegetation drives discernible scale-dependent effects on geomorphology at the local scale (10-1 - 102 m). • Large scales: determining cause-and-effect relationships linking hydrogeomorphic and vegetation drivers remains challenging. • Vegetation: Insufficient but Non-redundant parts of Unnecessary but Sufficient (INUS) conditions for various river types. [ABSTRACT FROM AUTHOR]

The structure and function of riparian ecosystems generally result from feedbacks between plant dynamics and fluvial processes and landforms, i.e., river morphodynamics. Taxonomic approaches do not allow direct identification and quantification of the mechanisms involved in the interaction between plant communities and the geomorphological environment. Although riparian ecosystems show enormous taxonomic variations, comparable patterns of plant response traits across different taxa may evolve in response to the exposure to similar hydrogeomorphological processes in relation to flow dynamics, sediment transport, and nutrient and water availability. Biogeomorphological functional classifications for plant responses to, and effects on, river morphodynamics at the levels of individual plants, populations, and communities have been proposed in the literature. They serve herein as a basis for identifying and quantifying, within a presented standardized functional trait framework, key plant response and effect traits that can help to explain feedbacks between plants and morphodynamics. In particular, functional guilds and functional diversity metrics can be applied at the population and community levels for exploring feedbacks between vegetation and river morphodynamics worldwide. In this framework, the variability in plant effects across different environments and spatiotemporal scales, related to the biological characteristics of the plants (i.e., morphological reconfiguration of plants into the flow, seasonal phenology, phenotypic plasticity, and vegetation succession), can be explored. New opportunities including remote sensing and numerical modelling approaches, coupled with the inclusion of plant traits through our original framework, will improve our understanding of feedbacks between vegetation and morphodynamics and contribute to an improved prediction of biogeomorphological river trajectories. • Taxonomical approaches do not permit the analysis of plant-geomorphology feedbacks. • Functional traits links hydrological, geomorphological and biological drivers and processes which shape river systems. • Riparian plant traits converge despite taxonomic variation. • The functional trait approach is an opportunity for quantifying riparian vegetation-river interactions worldwide. • The functional trait approach can be supported by remote sensing and numerical modelling of river trajectories of change. [ABSTRACT FROM AUTHOR]