Interplay between ecology and geomorphology in river systems

It can be shown by a simple single-species model that disturbance may increase plant population if its intrinsic growth rate is sufficiently high. It does so when the population that controls propagule production is differentiated from the one that limits propagule establishment and only the latter is affected by the disturbance. In river systems, dispersal already causes similar differentiation, while disturbance is also present and heterogeneous. Consequently, the dynamics of plants in the production and transportation zones of a river system are expected to differ from the mean-field system and from each other. These issues are studied through a structured metapopulation model. The random nature of growth rate and disturbance due to hydrological fluctuation and the non-monotonic response to disturbance of plant population are likely to have important consequences on ecological and geomorphic evolution and patterns of river networks.