Interacting effects of climate change and invasions by alien plant species on the morphodynamics of temperate rivers

This review explores the implications of climate change for the functioning of plant species as biogeomorphic engineers of temperate river systems, including the potential for an increasing role of invasive alien plant species (IAPS). First, we introduce engineer plants as important controls, along with flowing water and transported sediments, on the morphodynamics of river systems and the likelihood that climate change may affect the contributions of species within their native habitats. We then examine through the prism of the fluvial biogeomorphic succession model how climate change may accelerate the establishment of IAPS, the possible consequences for the performance and/or persistence of native engineer plant species, and thus the potential pathways of influence for IAPS on river morphodynamics. Finally, we present examples of the impacts of invasions by specific plant species along particular river systems and consider their potential biogeomorphic impact against a backdrop of climate change. Loss, replacement, or displacement of native plant species in the river corridor by IAPS can potentially alter biogeomorphic phenomena by directly increasing or decreasing erosion and/or sedimentation and the associated development of fluvial landforms. In the shorter term, increased climate disturbance may provide more establishment opportunities for opportunistic IAPS. In the longer term, under heavy establishment, IAPS may alter the coupled assembly of plant communities, fluvial landforms and ecosystem development, potentially resulting in river landscape metamorphosis and significantly changed habitat conditions.