Vegetation and hydraulic-morphological interactions at the individual plant, patch and channel scale

Abstract.

Interactions between vegetation, flow and sediment are a key ingredient for the development of vegetated islands in highly dynamic, fluvial alpine ecosystems such as the Tagliamento River, north-east Italy. There has been substantial research on factors influencing the establishment of vegetation and feedback mechanisms between vegetation, hydraulic, and geomorphological processes in such environments. This has yielded the development of conceptual models identifying different trajectories of vegetation and landform development from bare gravel to established floodplain forest. Nevertheless, some of the finer-scale processes underpinning such interactions are not well understood and parameterisation concepts that augment our knowledge from process understanding to quantified data and prediction models are not available until now. This paper identifies mechanisms and parameters of vegetation-flow interaction at the individual scale that are reflected at a patch or even at the channel scale. These mechanisms are reviewed from a multi-disciplinary perspective and concepts and analogies are proposed that provide ideas to progress research towards the development of predictive vegetation-flow models. Such models must incorporate both hydraulic and ecological components and this is demonstrated for a simplified force-bending model of Salicaceae seedlings. The development of such models demands advances in the individual disciplines of hydraulics, morphology, plant ecology and biomechanics, which offers many possibilities for multidisciplinary research between these disciplines.