Interactions between units of the fluvial hydrosystem

The distribution of the different units within a hydrosystem is related to the geomorphological mechanisms involved in their creation (Chapter 5). In addition to the effects of the environmental constraints specific to each unit (Chapters 6, 7 and 8), the composition of the populations in each unit also depends on their spatial relations because of exchanges and interactions between them. Some species need to be close to different complementary units for their development, or for re-establishment after disturbance. The hydrosystem as a whole has a resilience, with some units within it acting as refugia or foci for recolonization.