9.14 Reciprocal Relations between Riparian Vegetation, Fluvial Landforms, and Channel Processes

Abstract

Patterns of riparian vegetation are strongly influenced by hydrology and fluvial processes. However, valley form and processes (rates of runoff and erosion and deposition), channel planform, and cross-sectional form and slope are influenced by the presence, physiognomy, structure, distribution, and abundance of vegetation, as well. The interrelationships between geology, valley and channel form, fluvial processes, and riparian vegetation along streams and rivers have been the topics of a tremendous body of research over the past several decades. Theory development in the fields of geomorphology and riparian plant ecology and application to river management have proceeded slowly, with riparian plant ecologists appreciating the role of channel processes in structuring plant communities only in the past several decades and geomorphologists continuing to view plants principally in terms of their physical and structural effects on hydraulics, erosion, and sediment transport and deposition. In this chapter, advances in our understanding of the reciprocal relationships between riparian vegetation and fluvial forms and processes over the past several decades are highlighted. First, an overview is presented of how riparian plant ecologists organize the complex and diverse vegetation that occurs along rivers and across their floodplains. An application of these organization schemes to geomorphologic work examining the reciprocal relationships between plants, fluvial processes, and channel form is provided. The effects of vegetation on channel form and process are then addressed. The chapter concludes with an overview of the reciprocal influences of fluvial processes and characteristics of riparian vegetation in determining patterns at scales from genetic (evolutionary selective pressures) to landscapes.